Title: Minimum Flows and Levels Draft Rules
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 Material Information
Title: Minimum Flows and Levels Draft Rules
Physical Description: Book
Language: English
 Subjects
Spatial Coverage: North America -- United States of America -- Florida
 Notes
Abstract: Jake Varn Collection - Minimum Flows and Levels Draft Rules
General Note: Box 16, Folder 1 ( SWFWMD - 1997 - 1998 ), Item 20
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00003927
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text




MINIMUM
FLOWS
AND LEVELS
DRAFT RULES








RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-2
CONSUMPTIVE USE OF WATER

40D-2.091 Publications Incorporated by Reference
40D-2.301 Conditions for Issuance of Permits

40D-2.091 Publications Incorporated by Reference
The "Basis of Review for Water Use Permit Applications" April- --4, 4,
the "Agricultural Water Use Form," July 24, 1990, and the "Agricultural Water Allotment
Form," July 24, 1990, are hereby incorporated by reference into this Chapter and are
available from the District upon request.

Specific Authority 373.044, 373.113 FS. Law Implemented 373.219, 373.239, 373.243 FS.
History New 10-1-89, Amended 11-15-90, 2-10-93, 3-30-93, 7-29-93, 4-11-94,


40D-2.301 Conditions for Issuance of Permits
(1) In order to obtain a Water Use Permit, an Applicant must demonstrate that
the water use is reasonable and beneficial, is in the public interest, and will not interfere
with any existing legal use of water, by providing reasonable assurances, on both an
individual and a cumulative basis, that the water use:
(a) Is necessary to fulfill a certain reasonable demand;
(b) Will not cause quantity or quality changes which adversely impact the
water resources, including both surface and ground waters;
(c) Will not cause adverse environmental impacts to wetlands, lakes,
streams, estuaries, fish and wildlife, or other natural resources;
(d) Will comply with the provisions of 4.3 [OR 7.1/3]of the Basis of Review
describedin 40D-2.09****nt cauoc water' .lvels r rates of flw to, devite frm tho
ranges set forth in ChaptAr 40D-8;
(e) Will utilize the lowest water quality the Applicant has the ability to use;
(f) Will not significantly induce saline water intrusion;
(g) Will not cause pollution of the aquifer;
(h) Will not adversely impact offsite land uses existing at the time of the
application;
(i) Will not adversely impact an existing legal withdrawal;
(j) Will utilize local water resources to the greatest extent practicable;
(k) Will incorporate water conservation measures;
(I) Will incorporate reuse measures to the greatest extent practicable;
(m) Will not cause water to go to waste; and
(n) Will not otherwise be harmful to the water resources within the District.
(2) Permit Applicants for projects which require both a water use permit and a
surface water management permit pursuant to District Rules shall submit a completed


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APRII IQA Ann q .PT.VF I F WAT. nATE 2
-. ~ ~ C3 E LVE x A**


surface water management permit application to the District prior to issuance of a Water
Use Permit. If the District determines that a permit application involves an area where the
Water Use Permit may not be granted because of water resource problems, the
requirement for a complete surface water management permit application may be waived
by the District. Where such waivers are granted, the Water Use Permit shall specify that
a well construction permit will not be issued and withdrawals cannot commence until the
appropriate District surface water permit is issued.
(3) The standards and criteria set forth in the "Basis of Review For Water Use
Permit Applications," identified in Rule 40D-2.091, shall be used to provide the reasonable
assurances required in Rule 40D-2.301 (1).

Specific Authority 373.044, 373.113, 373.149, 373.171 FS. taw Implemented 373.219,
373.223, 373.229 FS. History Readopted 10-5-74, Amended 12-31-74, 2-6-78, 7-5-78,
Formerly 16J-2.11, 16J-2.111, Amended 1-25-81, 10-1-89, 2-10-93,


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APRIL 1994


T~nhlSIIMPTIVF IISF nF \NdTFR


CUA P *









WATER USE PERMITTING BASIS OF REVIEW

4.0 CONDITIONS FOR ISSUANCE--TECHNICAL CRITERIA

4.3 MINNY UIVI FLOWS AND LEVELS

Applicants shall demonstrate compliance with established minimum flows and levels as set
fodh in 40D-8 FA.C. by showing that the proposed withdrawal is consistent with the District's
applicable Regional Water Supply Plan including an recover state ies co t i d ithi


-,-i-"--- g\-- **~.. y.~.^. y-^^.T g nU... ...a.^^....M n*Ie wUwV ^.r nugioI oj ^ .IHC IIII
the Plan.

Water withdrfwfl3 must nCt cause:

SV Lake levels to be reduced below th applicable minimum water level
establishd in Chaptcr 40D 8, Fr.A.C.

-2. Stroamflew to be reduced belw the minimum regulatory flew level as
established in Chapter 40D 8, F.A.C.

3. P-tentiometrie surfazz or water table levels to be reduced below minimum


d in haptee 49D9-8, r .A-G


M


regulatory level established









RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-4
INDIVIDUAL ENVIRONMENTAL RESOURCE PERMITS


40D-4.091 Publications and Agreements Incorporated by
Reference.
The following documents are hereby incorporated into this chapter and Chapters
40D-40 and 40D-400, F.A.C.:
(1) "Basis of Review for Environmental Resource Permit Applications within the
Southwest Florida Water Management District, Apfril17-497." This
document is available from the District upon request.
(2) (3) No change.

Specific Authority 120.54(8), 373.044, 373.046, 373.113, 373.171, 373.414 FS. Laws
Implemented 120.54(8), 373.046, 373.103(8), 373.114, 373.403, 373.413, 373.414,
373.416, 373.429, 373.441 FS. History New 4-2-87, Amended 3-1-88, 9-11-88, 10-1-88,
4-1-91, 11-16-92, 1-30-94, 10-3-95, 12-26-95, 5-26-96, 7-23-96, 4-17-97,

BASIS OF REVIEW AMENDMENTS

3.2.2.4 Water quantity impacts to wetlands and other surface waters

Pursuant to paragraph 3.1.1(a), an applicant must provide reasonable assurance
that the regulated activity will not change the hydroperiod of a wetland or other
surface water, so as to adversely affect wetland functions or other surface water
functions as follows:
(a) Whenever portions of a system, such as constructed basins, structures,
stormwater ponds, canals, and ditches, could have the effect of reducing the
depth, duration or frequency of inundation or saturation in a wetland or other
surface water, the applicant must perform an analysis of the drawdown in
water levels or diversion of water flows resulting from such activities and
provide reasonable assurance that these drawdowns or diversions will not
adversely impact the functions that wetlands and other surface waters
provide to fish and wildlife and listed species.
(b) Increasing the depth, duration, or frequency of inundation through changing
the rate or method of discharge of water to wetlands or other surface waters
or by impounding water in wetlands or other surface waters must also be
addressed to prevent adverse effects to functions that wetlands and other
surface waters provide to fish and wildlife and listed species. Different types
of wetlands respond differently to increased depth, duration, or frequency of


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inundation. Therefore, the applicant must provide reasonable assurance
that activities that have the potential to increase discharge or water levels will
not adversely affect the functioning of the specific wetland or other surface
water subject to the increased discharge or water level.
(c) Whenever portions of a system could have the effect of altering water levels
in wetlands or other surface waters, applicants shall be required to monitor
the wetland or other surface waters to demonstrate that such alteration has
not resulted in adverse impacts, or to calibrate the system to prevent
adverse impacts. Monitoring parameters, methods, schedules, and reporting
requirements shall be specified in permit conditions.
( The activity shall reduce or suppress the flow of a watercourse or the level
of water in a wetland or other surface water below a minimum flow or level
that has been established pursuant to Section 373.042. F.S.

4.6 Overdrainage and water conservation Where practicable, systems shall be
designed to:
1. maintain water tables at the highest practicable level; the depth to which the
water table can be lowered will be determined based on the potential
adverse impact on recharge, the effect on water resources (quality and
quantity), and the necessity for fill and its impact on existing natural upland
vegetation; and
2. preserve site environmental values; and
3. not waste freshwater through overdrainage; and
4. not lower water tables which would adversely affect existing legal uses; and
5. preserve site groundwater recharge characteristics; and
6. retain water on-site for use and re-use for irrigation and other reasonable
beneficial uses.

4.6.1 In addition to the design considerations in 4.6 above, the system shall not reduce
or suppress the flow of a watercourse or the level of water in a wetland or other
surface water below a minimum flow or level that has been established pursuant to
Section 373.042. F.S.


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RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-8
WATER LEVELS AND RATES OF FLOW


400-8.011 Policy and Purpose
400-8.021 Definitions
400-8.031 Implementation
400-8.041 Minimum Rates of Flow andiLevels
400-8.603 ManagemF~enLevels for Lakes, Wetlands, and Other Impoundments
410D 8.605 Cyclic Variations for Minimum ''ater Level


4GIQ8.613
Af^r 0 M'4&


Ten (10 IYIII F IIoU L 'gVeIi
Ten (10) Year Flood Wa\rning Levels
M-i-4-i.j Ml-&:--


40D-8.621

40D-8.624
40D-8.626


Operating Levels for Lakes and Other Impoundments with
Structures
Schedule-ef Levels for Lakes, Wetlands, and Other Impoundments
Minimum Aquifer Levels in Northern Hillsborough. Pasco, and Pinellas
Counties


40D-8.011 Policy and Purpose.
(1) The purpose of Chapter 40D-8 is to establish minimum flows and levels at
specific locations throughout the District and to describe guidance levels for lakes and
other impoundments.
(2) Where appropriate, minimum flows and levels may reflect seasonal variations
and may include a schedule of variations and other measures appropriate for the
protection of non-consumptive uses andef the water resources.
(3) A further purpose of Chapter 40D-8 is to establish minimum flood levels and
warning levels for surface waters which are anticipated to occur on a somewhat regular
basis, and which shall serve as a precautionary warning to all persons who would propose
to construct facilities which may be damaged by periodic high water levels.
(4) Minimum flows and levels prescribed in Chapter 40D-8 are used as a basis
for imposing limitations on withdrawals of water and certain other activities. These
limitations are prescribed in this and other chapters parts of the rules of the District.
(5) In establishing minimum rates of flow and levels the Board shall use the best
information available.
(6) In establishing minimum rates of flow and levels the Board shall also
consider, and at its discretion may provide for, the protection of non-consumptive uses,
including navigation, recreation, and aesthetic and scenic attributes.
(f Where existing flows or levels are below the established minimum flow or
level, the District shall address achieving the established flow or level via a recovery
strategy over a reasonable time period considering both regulatory and non-reaulatorv
mechanisms.


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E! ==== = M ==-- Z W;= = !:=;; !=-









Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.026,
373.042, 373.044, 373.086 FS. History New 6-7-78, Amended 1-22-79, Formerly 16J-
8.01, Amended

40D-8.021 Definitions.
The terms set forth herein shall have the meanings ascribed to them unless the
context clearly indicates otherwise, and such meanings shall apply throughout all District
these rules. To facilitate easier reference, certain terms define d by applicable statute have
been included .erbati;m with appror;ate c;itati;n. The terms defined in Rule 40D-1.102
40D 0.024 shall also apply throughout Chapter 40D-8.
(1) "Best surface water management practice" in the design, construction,
operation, and maintenance of structures or devices requires a consideration and
evaluation of both long-term and short-term effects of the activity upon the water resources
of the District. Factors to be considered include the following:
a_ Conservation and proper utilization of surface water.
b. Prevention of damage from floods, soil erosion, and excessive
drainage.
c. Preservation of natural resources, fish, and wildlife.
d. Storage for aquifer recharge.
e_ Navigation, recreation, and aesthetic and scenic attributes.
(2) "Guidance Levels" Levels, determined by the District using the best
available information and expressed in feet relative to National Geodetic Vertical Datum,
utilized either for advisory purposes or to aid in the control of operable structures;
Guidance Levels include: Ten Year Flood Warning Level; Pre-modification Flood Level:
Post-modification Flood Level: Pre-modification Low Level: and Post-modification Low
Level.
(3) "Minimum Flow" means the level of flow for a surface watercourse at which
further withdrawals would be significantly harmful to the water resources or ecology of the
area.

minimum water levels and minimum flood levels, and represents the capability of an
impoundment to receive, carry, or store water, to preserve non-consumptive uses of a
surface water bod", and within this range the District applies and requires best surface
water management practices.
(42) "Minimum water Llevel" means the level of surface water, water table, or
potentiometric surface at which further withdrawals would be significantly harmful to the
water resources of the area. Such level shall be expressed as an elevation, in feet relative
to National Geodetic Vertical Datum. ab"ve mean sea and may incorporate a low
management level and an extreme low management level, which together establish the
lower limits of the management range, to which a water body shall be allowed to fluctuate
naturally.
(5) "Management range" means the difference between the applicable Low Level
and Flood Level pursuant to 40D-8.603, and within this range the District applies and
requires best surface water management practices.


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(6) "Pre-modification" a period prior to when the lake level fluctuations were
altered by anthropogenic activities.
(7) "Post-modification" a period after lake level fluctuations were altered by a
surface water conveyance system.
(8) "P10" a percentile ranking defined as the elevation of a water surface that
is equaled or exceeded more than 10 percent of the time as determined from a stage
duration analysis.
(9) "P50" a percentile ranking defined as the elevation of a water surface that
is equaled or exceeded more than 50 percent of the time as determined from a stage
duration analysis.
(10) "P90" a percentile ranking defined as the elevation of a water surface that
is equaled or exceeded more than 90 percent of the time as determined from a stage
duration analysis.



(12) "Reference Low Value" A value determined from the median of the
differences between the annual P10 value and annual P90 value for lakes in the same
geographic region with similar hydrogeologic features and stage records for at least 6
years.
(13) "Stage-duration" A plot of water surface elevations of a water body (e.g..
lake, wetland, impoundment) versus the cumulative frequency of occurrence of those
elevations expressed as the percent of time the water surface fluctuates at or above a
particular elevation.
(3) "Minimum flood level" means the highest level to which a surface water body
shall be allowed to fluctuate without interference except as approved by the Board for the
purpose of conserving the waters in th State so as t realize their full bII eneficial use. Suh
level shall be expressed as an elevation, in feet above mean sea level.
(4) "Ten (10) year flood warning level" means that elevation in feet above sea
level, which approximates the level of flooding expected on a frequency of not less than
the ten (10) year recurring interval, or on a frequency of not greater than a ten percent
(10%) probability of occurrence in any given year, as determined fr om analysis of bet
available data.
(5) "Best surface water management practice" in the design, construction,
operation, and maintenanFe of structures or devices requires a consideration and
evaluation of both long term and short term effects of the activity upon the water resources
of the District. Factors to be considered include the following:
(a) Conservation and proper utilization of surface water.


(G) Preservation of natural res sources, fish, and wldllife.
(d) -Storage for aquifer recharge.
(e) Non consumptive uses, including but not limited to, navigation,
r.crea tin. and aesthetics.


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Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Amended 1-22-79, Formerly 16J-8.02,
Amended

40D-8.031 Implementation.
(1) The provisions of Chapter 40D-8 of these rules shall continue to be
implemented as of May 2, 1978, within the Hillsborough River, Northwest Hillsborough,
Green Swamp, Alafia River, Coastal Rivers, Manasota, Peace River, Withlacoochee River
and Pinellas-Anclote River Basins and shall be implemented immediately and shall apply
within the area annexed into the District by Chapter 78-65, Laws of Florida., and sha-l apply
as follows:
(a) Muanagement levels of lakes and other impoundments as prescribed
herein shall become effective immediately upon:
e i a Installation of a staff gauge in a prominent location on the water


-2. -Posting f .notice to the public pursuant to Rule 40D 8.6v6; and
a--1 I-,3a. Pu blicatieon f notice in a newspaper having general circulati;o
within the affected area.
(b) The extreme low management level as adjusted by the cyclic vacation
shall become effective when similar notice has been given.
(2) No Guidance management Levels shall be prescribed for any reservoir or
other artificial structure which is located entirely within lands owned, leased, or otherwise
controlled by the user, and which require water only for filling, replenishing, and maintaining
of the water level thereof, provided however:
(a) That Chapter 40D-2 rules shall apply to the use of water for such
filling, replenishing, and maintaining of the water level, and
(b) That the applicable minimum flood level pursuant to Rules I OD 8.02 n
and ODi 8.611 and the Ten Year Fflood Wwarning Llevel pursuant to Rules 40D-8.603024
and 4O- 8.613 may be established for any lake or other impoundment determined by the
Board to be in the public interest.
(3) No Guidance management Levels shall be prescribed for Lake Manatee in
Manatee County, Ward Lake in Manatee County, the City of Tampa Reservoir on the
Hillsborough River in Hillsborough County, and the Peace River/Manasota Regional Water
SupplyV Authority Reservoir General Development Utilities Reservoir constructed in
connection with the Southwest Florida Water Management District's Permit Numbers
7500016, 7- 172, and 75 290 in DeSoto County.
(4) The Governing Board shall establish minimum flows and levels based on a
scientific assessment of key ecological factors for the desired natural system and the
influence of unique factors that have a permanent effect on the desired natural system.
These unique factors are as follows:
(a) Recreation, navigation, or aesthetic and scenic attributes supported
by the natural system, including use of the water body for:
1. Powerboats:
2_. Boat docks:
3. Canoes, Kayaks and other paddle-propelled boats:


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4. Sailboats;
5_ Swimming:
6 Divinq;
7_ Snorkelinq;
8 Scuba Diving:
9. Fishing: or
10. Sensory beauty.
(b) Surface water alterations either natural, permitted under programs
authorized by Part 1 or Part 4 of Ch. 373, F.S. ,or exempt from permitting, where:
1. The alterations were not caused by water withdrawals, and
2_ The alterations have permanently changed the hydrology and
ecology of the waterbody, and
3. No other feasible means of offsetting their impact (e.g.
augmentation downstream of a dam) is foreseen, and
4_ The impacts of these alterations are scientifically established
to the satisfaction of the Governing Board;
(c) Unavoidable public health, safety and welfare problems that would be
created if the desired natural system is maintained.
(5) I I .- I .. i.

In such areas, the District
shall establish Recovery Flows or Levels which are I that
can be attained within a specific time period. These Recovery Levels will be a part of the
District's recovery strategy for the area. This strategy will be contained within the District's
Water Management Plan and the Regional Water Supply Plan for the Water Use Caution
Area within which the applicable waterbody is located. I l l. I I


(6) Unless otherwise provided for in the District's recovery strategy, where the
Existing flow or level is below the minimum flow or level, .-_' h i......1--i...
.................. ... I IIaB gieBa4i n i ii '---.

S-(7) Where the existing flow or level is above the minimum flow or level, gmft


{8) The Conditions for Issuance of 40D-2.301, 40D-4.301, and 40D-4.302 F.A.C.,
and all pertaining sections within the Bases of Review described in 40D-2.091 and 40D-
4.091, F.A.C. are required to be met irrespective of a permitted's demonstration of
compliance with the minimum flows and levels requirements established herein.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 120.53,
373.016, 373.023, 373.042, 373.0421, 373.044, 373.086, 373.103 FS. History New 6-7-
78, Amended 10-16-78, 1-22-79, Formerly 16J-8.03, Amended 3-23-81,


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40D-8.041 Minimum Rates of Flow and Levels.
(1) Minimum Flows For the Lower Hillsborough River including Sulphur Springs
(a) For the purposes of minimum flows the l is
defined as the The Lower Hillsborough River
includes Sulphur Springs, an artesian spring that enters the river via a short spring run
located 2.2 miles downstream of the reservoir dam. The determination of minimum flows
for the Lower Hillsborough River includes the establishment of minimum flows for Sulphur
Springs. Management options that involve diverting a portion of the flow from Sulphur
Springs to the base of the dam to provide minimum flows at that location were evaluated
in making the minimum flow determinations.
(b) The Minimum Flow established for the Lower Hillsborough River
accounts for the fact that this system has had M 1!__- of the type described
in 40D-8.031(4)(b). There are, however, IINL I IBMllNltlE
S-i. The relationships and dependence of these ecological communities with
freshwater flows from the reservoir and Sulphur Springs were key elements of the District's
minimum flow evaluation. Ecological factors utilized in determining minimum flows include:
1. The protection and enhancement of fish populations associated
with the Lower Hillsborough River;
2. Relationships of freshwater flows to potential fish habitat;
3_ The relationships of other biological parameters (e.g., benthic
invertebrates, shoreline plant communities) to freshwater inflows as they affect the overall
biological integrity and productivity of the system.
(c) The minimum flows determination has been based on an evaluation
of salinity and dissolved oxygen distributions in the Lower Hillsborough River as a function
of flow releases from the reservoir and Sulphur Springs, and the function of Sulphur
Springs for providing warm waters that serve as thermal refugia for the West Indian
Manatees in the lower river during winter months.
(d) The District determined minimum flows for the Hillsborough River by
comparing the quantity and quality of potential habitats to various releases from the
reservoir and Sulphur Springs, and included diversions of portions of the flow from Sulphur
Springs to the base of the dam to provide minimum flows at that location. The
improvements in environmental characteristics and potential biological utilization as a result
of increased flows were balanced with impacts to the water supply yield of the Hillsborough
River Reservoir.
(e) Based on the factors described above, r


... .. :lO during periods ********
and TO BE DETERMINED cfs when water surface
elevations at U.S.G.S. Gage ******* in the reservoir II .. Up to one-
half of this minimum flow may be provided by diversions of water from Sulphur Springs, but
a minimum flow of TO BE DETERMINED cfs from Sulphur Springs at its point of outflow
as of the effective date of this rule must be maintained during the months of December.
January, and February. A minimum flow of TO BE DETERMINED cfs must be maintained


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from Sulphur Springs at its point of outflow as of the effective date of this rule for the
remaining nine months of the year.
(2) Minimum Flows for the Tampa Bypass Canal
(a) The Tampa Bypass Canal was constructed between 1966 to 1982 in
the channel of former Six Mile Creek and the Palm River. The width, depth and volume
of the canal are much greater than the tributaries that were excavated. Structure 160
serves as the barrier between the freshwater and tidal portions of the Tampa Bypass
Canal.

(b) The determination of minimum flows for the Tampa Bypass Canal
accounts for the fact that this system has had extensive physical alterations of the type
described in 40D-8.031(4)(b). There are, however, viable ecological communities
associated with this watercourse. Minimum flows are based on the relationships and
dependence of these ecological communities with freshwater flows from the water control
structure (Structure 160).
(c) The minimum flows determination has been based on an evaluation
of salinity and dissolved oxygen distributions in the Tampa Bypass Canal as a function of
flow releases from the water control structure. Criteria utilized in the determination


included:
1. The protection and enhancement of fish populations in this
watercourse:


2_ The relationships of other biological parameters (e.g.. benthic
invertebrates, shoreline plant communities) to freshwater inflows as they affect the overall
biological integrity and productivity of the system.
(d) The minimum flow is designed to provide some flow to create some
net water movement through the canal to avoid excessive long residence times in the canal
and possible water quality problems. A minimum flow of TO BE DETERMINED cfs is
established to provide this flow. Structure S-160 can be operated to provide this flow
during periods when there are no inflows to the lower pool from Structure S-162.
(e) This minumum flow for the Tampa Bypass Canal is established
specific to the physical configuration and operational constraints on the Tampa Bypass
Canal as they occurred on October 1, 1997. If physical modifications to the Canal are
pursued at a future date, the District shall reevaluate minimum flows at Structure 160.
(1) In establishing minimum rates of flow and levels and regulatory levels, the
Board shall use the best information and method available and will consider the protection
of existing, as well as future consumptive uses of water so as to promote the conservation,
development and proper utilization of water while preventing damage from floods, soil
erosion, and excessive drainage. When deemed appropriate, a schedule of rates of flow
and levels may be established to reflect seasonal or cyclic variations. The Board will also
consider, and at its discretion may provide for, the protection of non- consumptive uses,
including navigation, recreation, and the preservation of natural resources, fish, and

(24 Unless otherwise deemed appropriate by the Board, the minimum rates of
flow at a given point on a stream or other watercourse shall be established by the Board
for each month, Januar' through December. Minimum rates of flow shall be established


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as follows: For each month, the five (5) .lowet monthly mean discharges for the preceding
twenty (20) years shall be averaged. Minimum rates of f3low shall be established 3
seveRty pcnt (370%) of thse value-S for -the foir (1) wettest months and ninety percent
(90%) of these values for the remaining eight (8) months. The detrmination shall be
basCd on available data, or in the absen; e of such data, it shall be established by
reasonable calculations approved byr the Board.
(3\ Inless otherwise demed appropriate by the Boardl the minimum m lel of the
watef- table at a given point shall be established by the Board and shall be three feet (3')
below the average f thae five (5) lowest levels in each calendar year (provided no .to (2)
levels shall be taken from the same calendar month) for the preceding ten (10) years. The
determination shall be based on available data, or in the absence of such data, it shall be
established by reasonable calculations approved by the Board.
(4) Unless otherwise deemed appropriate by the Board, a regulatory level for a
Seonfined aquifer at a gien point shall be established generally to limit the rate af
movement f water from the water table atl the b.oundar of the land owned, .eased, or
otherFwise controlled by an applicant for a consumptive use permit oF at the boundary of an
equivalent area based on the configuration of the o3ne of depression caused by the
proposed location and operation of the well or wells.
(a) Such regulatory level shall be determined by taking the minimum level
ef the water table plus three feet (3'), or such ether adjustment as deemed appropriate by
the BoaFd, and subtracting the head difference required to pass the water crop from th
water table to the confined aquifer. Such head difference is the water crop divided by the
leakance Acoefficient of the confining bed. The water crop, in the absence of data t t4he
contrary, is 0.0229568 gallons per day per square foot.
--- (b) The elevation of the potentiometric surface at such point shall-be
DRAFT IV; 8i '8" '
measured cumulatively throughout the production year. At no time shall the cumulative
wee kly average elevation be lower than the regulatory level and at no time shall the weekly
average elevations of the potentiometric surface of the Floedan Aquifer be more than five
feet (5') below the regulatory level.

Specific Authority 373.044, 373.133, 373.149, 373.171 FS. Law Implemented 373.042,
373.086, 373.339 FS. History Readopted 10-5-74, Amended 12-31-74, Formerly 16J-
0.15, 40D-1.601, Amended 10-1-84,

40D-8.091 Publications Incorporated By Reference
The determination of Guidance Flood Levels, Low Levels and Minimum Lake Levels
set forth in 40D-8.603(1),(2) and (3) are more particularly described in the Lake Level
Methodology Manual, dated 1997 which is hereby incorporated into this chapter.
This document is available from the District upon request.

Specific Authority 120.54, 373.016, 373.023, 373.044, 373.103, 373.113, 373.133,
373.149, 373.171 FS. Law Implemented 120.53, 120.54, 373.016, 373.023, 373.026,
373.0395, 373.042, 373.0421, 373.044, 373.086, 373.103, 373.171, 373.339 FS. History-
New


DRAFT I 8-8









40D-8.603 Managemet Guidance Levels for Lakes, Wetlands, and Other
Impoundments.
(1) In establishing minimum water levels, minimum flood levels and other
management levels for lake and other impundm ents, the Board shall Iue the best

(2) Data from technical publications, topographic maps, Geological Survey Water
Data Reports and other studies and records may be considered. Information may alsory
obtarporated froms the aleveial mappof flooding, ehydoxpectaphed bottom frequency fcontour mapping, than tage duten (10) year




recurring interval, frequency of noratified beater than a ten percent (10%) probability oth
occurrence in any ven year.
(3) Field investigation may be used to determine past surface levels from water



aks, wetland vegetative, and d d vegetation, akd testabis the elevation of septi




Lp""""l"~"p~l~~- '- I r". On lakes with control structures
or ditches, it may no longer be desirabd fle and/or possible to achieve the Pre-modification
11 Flood Levels
(al The a is provided as an advisory
guideline for lake shore development. The Ten (10) Year Flood Warning Level.
incorporates the level of flooding expected on a frequency of not less than the ten (10) year
recurring interval, or on a frequency of not greater than a ten percent (10%) probability of
occurrence in any given year.


or ditches, it may no longer be desirable and/or possible to achieve the Pre-modification
Flood Level without modification of the outfall feature. The Pre-modification Flood Level
shall be established from analysis of one or a combination of the following data, and the
Pre-modification Flood Level finally determined is a reconciliation of all the elevations
based on the following data:
1.


2, Elev
include the following if present:


nationss determined by biological indicators which may


i_ The average elevation of the soil at the base of the
lowest lakeward extent of the palmetto (Serenoa reopens) fringe;
ii_ The average elevation of the soil at the base of the
lowest lakeward extent of the mature wax myrtle (Myrica cerifera) fringe;
iii. The average elevation of the soil at the base of the
highest landward extent of the cypress (Taxodium sp.) fringe;
iv. The average elevation of the soil at the base of the
lowest lakeward extent of longleaf pine (Pinus palustrus) fringe;
v. The average elevation of the soil at the base of the
lowest lakeward extent of the live oak (Quercus virginiana) fringe (trees with diameter at
breast height greater than or equal to 24 inches);
vi. The average elevation of the lowest extent of lichen
growth.


DRAFT


8-9


8l~rrrlr"~l--pg)blsP~C-rCcLI L~C ~k-"' rlLCC;









3. Elevations determined by physical indicators which may include
one or a combination, of the following, if present:
i_ The average elevation of the toe of the highest landward
scarp line;
ii. Interpretation of historic aerial photography;
iii. Stratified beach deposits;
4_ Elevations indicated by the elevation of anthropogenic features.
(c) The for lakes with hydrology modified
by surface water conveyance systems or natural occurrences (e.g. sinkholes) is the highest
level to which a lake is expected to fluctuate on an average annual basis. The Post-
modification Flood Level for lakes with an operable structure is a peaking elevation and not
one which is maintained. The Post-modification Flood Level shall be determined from
analysis of one or a combination of the following data, and the Post-modification Flood
Level finally determined is a reconciliation of all the elevations determined based on the
following data.
1.

2_ The elevation of the lowest invert for the non-operable surface
water conveyance system.
3. The elevation of other anthropogenic features.
(d) If hydrologic modifications exist due to surface water conveyance
system modifications, or natural occurrences (e.g.. sinkholes), then the Governing Board
may pursuant to 40D-8.031(4) establish the Post-modification Flood Level as the Flood


Level using the methodology in subparagraph (1)(c) above.


(2) Low Levels
S(a is the of a lake.
This Level shall be established from analysis of one or a combination of the following data.
The Pre-modification Low Level finally determined is a reconciliation of all the elevations
based on the following data:


2_ Biological indicators may include the average elevation of the
soil at the base of the lowest lakeward extent of cypress (Taxodium sp.) fringe.
3. In the absence of biological indicators and stage duration data,
the Pre-modification Low Level is equal to the Pre-modification Flood Level minus the
Reference Low Value.
4_ Site specific hydrologic data can be used to determine a site
specific Reference Low Value for lakes without data that are connect and share the same
level pool as an adjacent lake with data. In this case, a site specific Reference Low Value
will be calculated using the hydrologic data for the adjacent lake and used in the same
manner as described 40D-8.603(2)(a)3. above.


DRAFT I


Q1 1 r1i1--I- i for lakes with hydrology modified by
anthropogenic activities excluding withdrawals or natural occurrences (e.g. sinkholes) is
the expected annual low level of a lake which has been influenced by such activities and
which no longer fully exhibits pre-modification fluctuations. The Post-modification Low


8-10









Level may be used as a guide to operate a lake control structure, for those lakes with
control structures.
1. The Post-modification Low Level finally determined is a
reconciliation of all the elevations based on the following data:
a...

b_ An elevation equal to the Post-modification Flood Level
minus the Reference Low Value.
c_ Site specific hydrologic data can be used to determine
a site specific Reference Low Value for lakes without data that are connect and share the
same level pool as an adjacent lake with data. In this case, a site specific Reference Low
Value will be calculated using the hydrologic data for the adjacent lake and used in the
same manner as described 40D-8.603(2)(b)2. above.
2. If hydrologic modifications exist due to surface water
conveyance system modifications, or natural occurrences (e.g., sinkholes), then the
Governing Board may pursuant to 40D-8.031(4) establish the Post-modification Low Level
as the Low Level using the methodology in subparagraph 40D-6.03(2)(b) above.
(3) Posted Notice
(a) Staff gauges will be installed in prominent locations on each lake,
wetland, or other impoundment for which Guidance Levels have been established. A
notice shall be posted in the immediate proximity of the staff gauge indicating that levels
have been established.
(b The notice shall indicate the elevations of the Flood Level and the
established Minimum Level.
(4) Renaming of Levels
(a) Levels previously established as Minimum Flood Levels shall now be
known as Flood Levels.
(b} Levels previously established as Minimum Low Levels shall now be
known as Low Levels.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044, 373.086 FS. History New 6-7-78, Formerly 16J-8.672, Paragraphs
(2)(h) and (i) Formerly 16J-8.6721, Paragraph(4) Formerly 16J-8.673, Amended


40D-8.605 Cyclic Variations for Minimum Water Level.
(4-) For lakes and other impoundments with a District-owned control structure the
elevation of the minimum water levels established for a lake or other impoundment shall
be lowered below the applicable low management level periodically to allow fluctuation
necessary for the preservation of natural resources, fish and wildlife, and for the protection
of non-consumptive uses. The lowered level is designated the extreme low management
level.
(2) The low management level shall be the applicable minimum water level for
such lake or other impoundment until four () consecutive years have passed during which


DRAFT I


8-11









event the eyreme low management level shall become the applicable minimum i water lvel
for the lake OF r ther impu indmnt Unil the atlual wateFr level reredes to or bew,,, t
erem. lo.w manaqmentF level. Whenever the acual water level r.eedes to or below the
exrCeme low management level, the applihable minimum \water level for the lake or other
impoundment shall immediately be raised one aain to the low managennmnnt level and the
cyclic variations shall continue.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044, 373.086 FS. History New 6-7-78, Formerly 16J-8.671. Amended


40D-8.611 Minimum Flood Levels
(1) The minimum flood level indiatesr the minimum level to which high water may
be expected to rise on a somewhat regular basis and will not necessarily correspond to an"
particular flood frequecRy. Flood wateFrs may often rise above the minimum flood level.
(2) .. ks, sea walls, septic tanks, drain fields, floor slabs, and other physical
improvements, On InRd near lakes anrd there impoundments for which management levels
have been established, should be so locatd and l constructed that their function will net be
impaired by rising water.


through the full management range established for such impoundment.
(4) Propety owners are hereby advised that compliance with District RulCes and
Regulations does not relieve owners of the responsibility of complying with other
fegultatiens and ordinances required by local governing bodies, e.g. as in connection with
the National Flood Insurance Program.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.672, Repealed

40D-8.613 Ten (10) Year Flood Warning Levels.
(1) Flood warning levels arc provided for a surface water body as an advisory
statement for the public interest. Property owners, public officials and the general public
are- advised that flooding on a frequency of not less than a ten (10) year recurring internal
is expected to occur at the indicated elevation. Flood waters may often rise above the
flood warning level.
(2) Floor slabs, septic tanks and drain fields, docks, sea walls and other physical
mpfrevements, on land near lakes and other impoundments for which flood warning levels
have -been established, should be so located and constructed sufficiently above the flood
warning level such that their functions will not be impaired by the rising water.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 1-22-79, Formerly 16J-8.6721, Repealed



DRAFT I 8-12









40D-8.616 Posted Notice.


pecitd in theo immediate prvxiit y 3f th7 staff gauge in3diatin7g that managemented 373
have been established.-
(2) The notiGe shall iRdicate the eleyatongS of the minimum flood level and the
applicable minimum water level.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.673, Repealed


40D-8.621 Operating Levels for Lakes, and Other Impoundments with
Structures.
(1) Schedules, levels, and procedures for operation of lakes and other
impoundments equipped with structures shall be established by the Board.
(2) The operating range for a structure of a lake or other impoundment shall be
prescribed as that between the high operating level and the low operating level.
(a) High operating level shall be established by the Board in consideration
of public testimony and in keeping with the best surface water management practices.
(b) Low operating level shall be established by the Board in consideration
of public testimony and in keeping with the best surface water management practices.
(3) A prescribed schedule for operation of all lakes and other impoundments with
structures shall be established by the Board. The schedule will contain time sequences
by which the levels of the water body will be maintained throughout the established
management range. While recognizing the difficulty of maintaining precise control of actual
levels, the schedule shall provide the guideline by which the operator of the structure will
attempt to maintain the prescribed levels insofar as he has control.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.677.

40D-8.624 Srhedule-ef Levels for Lakes, Wetlands, and Other Impoundments.
(1) Establishment of the Minimum Lake Level
For lakes which have low water levels adopted after October 1, 1997, the
Minimum Level shall be established by the Governing Board pursuant to 40D-8.031(4), and
400-8.603, F.A.C.
(2) Establishment of Minimum Wetland Levels
LL .(.- r-- .^.-^-.L I- .... A ---- II ... I .--


(b) The normal pool elevation shall be determined based on a
reconciliation of biological indicators of sustained inundation such as:


I nA


UArAF I


0-13









1L The lower limit of epiphytic mosses and liverworts intolerant of
sustained inundation;
2. The upper limit of the root crown on Lyonia lucida growing on


tree tussocks:
3.
and other species which


The upper limit of adventitious roots on Hypericum fasiculatum


exhibit this moroholoaic response to sustained inundation:


4_ Other indic
is milar period of sustained inundation.


:ators which can be demonstrated to represent a


(3) Levels for lakes, wetlands and other impoundments are hereby established
as follows*:

Lakes:
Location Name of Ten Year Minimum Low Level Minimum
Lake Flood Flood Guidance Level
Guidance Guidance (NGVD) (NGVD)
(NGVD) (NGVD)
Hillsborough County, in Sapphire 64.1 63.5 61.9 62.7
the Northwest Lake
Hillsborough Basin,
S-14,T-27,R-18
Hillsborough County, in Cypress 49.5 48.9 47.3 48.1
the Northwest Lake
Hillsborough Basin,
S-24,T-27,R-17
Hillsborough County, in Dosson 55.1 53.4 50.0 52.1
the Northwest Lake
Hillsborough Basin,
S-20,T-27,R-18
Hillsborough County, in Sunshine 55.1 52.8 50.6 51.7
the Northwest Lake
Hillsborouqh Basin,
S-20,T-27,R-18
Hillsborouqh County, in Lake 54.2 53.0 51.4 52.2
the Northwest Helen
Hillsborouah Basin,
S-19,T-27,R-18
Hillsborough County, in Lake Ellen 54.2 53.0 51.4 52.2
the Northwest
Hillsborouqh Basin,
S-19,T-27,R-18


DRAFT I


ei this morphologic response to susta d i


8-14









Location Name of Ten Year Minimum Low Level Minimum
Lake Flood Flood Guidance Level
Guidance Guidance (NGVD) (NGVD)
(NGVD) (NGVD)
Hillsborough County, in Lake 54.2 53.0 51.4 52.2
the Northwest Barbara
Hillsborough Basin,
S-19,T-27,R-18
Hillsborough County, in Little Moon 41.0 40.8 38.9 38.9
the Northwest Lake
Hillsborough Basin.
S-28,T-27,R-17
Pasco County, in the Big Fish 76.9 76.5 74.6 74.6
Coastal Rivers Basin. Lake
S-21,T-24,R-19
Hillsborough County, in Calm Lake To Be TBD TBD TBD
the Northwest Determin-
Hillsborough Basin, ed (TBD)
S-14,T-27,R-17
Hillsborough County, in Horse TBD TBD TBD TBD
the Northwest Lake
Hillsborough Basin.
S-26,T-27,R-17
Hillsborouqh County, in Starvation TBD TBD TBD TBD
the Northwest Lake
Hillsborough Basin.
S-21,T-27,R-18
Hillsborough County, in Lake Alice TBD TBD TBD TBD
the Northwest
Hillsborough Basin.
S-16,T-27,R-17
Hillsborough County, in Hobbs TBD TBD TBD TBD
the Northwest Lake
Hillsborouqh Basin,
S-1,T-27,R-18


DRAFT I


8-15









Location Name of Ten Year Minimum Low Level Minimum
Lake Flood Flood Guidance Level
Guidance Guidance (NGVD) (NGVD)
(NGVD) (NGVD)
Hillsborouqh County, in Platt Lake TBD TBD TBD TBD
the Northwest
Hillsborough Basin,
S-35,T-27,R-18
Pasco County, in the Camp TBD TBD TBD TBD
Pinellas-Anclote Basin, Lake
S-34,T-26,R18
Pasco County, in the Lake TBD TBD TBD TBD
Pinellas-Anclote Basin, Padgett
S-24,T-26,R-18
Hillsborouqh County, in Stemper TBD TBD TBD TBD
the Northwest Lake
Hillsborough Basin.
S-13,T-27,R-18
Hillsborough County, in White TBD TBD TBD TBD
the Northwest Trout Lake
HillsborouQh Basin.
S-22,T-27,R-18
Pasco County, in the Moon Lake TBD TBD TBD TBD
Coastal Rivers Basin,
S-28.T-25,R17
Hillsborouqh County, in Mound TBD TBD TBD TBD
the Northwest Lake
Hillsborough Basin,
S-11,T-27,R-17
* Existing adopted levels have not been repeated here.


DRAFT I


8-16









Specific Authority 373.044, 373.113, 373.171 FS. Law Implemented 373.016, 373.042,
373.103 FS. History New 6-7-78, Amended 1-22-79, 4-27-80, 10-21-80, 12-22-80, 3-23-
81,4-14-81, 6-4-81, 10-15-81, 11-23-81, 1-5-82, 3-11-82, 5-10-82, 7-4-82, 9-2-82, 11-8-82,
1-10-83, 4-3-83, 7-5-83, 9-5-83, 10-16-83, 12-12-83, 5-8-84, 7-8-84, 12-16-84, 2-7-85,
5-13-85, 6-26-85, 11-3-85, 3-5-86, 6-16-86, Formerly 16J-8.678, Amended 9-7-86, 2-12-
87, 9-2-87, 2-18-88, 6-27-88, 2-22-89, 3-23-89, 9-26-89, 7-26-90, 10-30-90, 3-3-91, 9-30-
91, 10-7-91, 7-26-92, 3-1-93, 5-11-94. 6-6-96, 2-23-97,

400-8.626 Minimum Aquifer Levels in Northern Hillsborough, Pasco, and Pinellas
Counties
(1) The minimum aquifer level shall be the elevation expressed in feet relative
to N.G.V.D. which represents the limit at which L.. .
..r... .. ....r.. This level shall be expressed as a and
shall be used when evaluating water use permit applications on a long-term average basis.
(2) Determination of the Minimum Aquifer Level '
Within the Northern Tampa Bay WRAP area. the Minimum Aquifer Level for the UDDer
Floridan Aquifer system (UFAS) shall be calculated based on the relationship between
water levels in the Upper Floridan aquifer and water levels in the surficial aquifer system
(SAS) and surface features, i.e. lakes or wetlands. Minimum Aquifer Levels in the Upper
Floridan aquifer shall be calculated adjacent to lakes or wetlands where minimum levels
have also been set per 40D-8.624(1) and 40D-8.624(2). The Minimum Aquifer level shall
be established at the location of nested well pairs (wells in both the surficial and Upper
Floridan aquifers) with sufficient period of record.
(a) Using the best available hydroqeologic data the leakance between the
surficial aquifer and the Upper Floridan aquifer shall be estimated for the area of the lake
or wetland and nested wells. Best available data with respect to the leakance value can
include aquifer performance test results or calibrated ground-water flow model leakance
parameter values, and head difference values from nested SAS and UFAS well pairs.
(b) For each location chosen for establishment of a Minimum Aquifer
Level, the drawdown in the UFAS is determined based on the allowable drawdown in the
SAS as determined in 40D-8.624(1) and 40D-8.624(2) for that area. The ratio of SAS to
UFAS drawdown is determined by ground-water flow modeling for the specific leakance
determined in paragraph (2)(a) above.
(c) The Minimum Aquifer Level in the UFAS is calculated using one of
the following:
1. If there is sufficient data to estimate the pre-withdrawal UFAS
water level:
al The long term average pre-withdrawal UFAS water level
is estimated using the best available data.
b) The drawdown for the UFAS calculated in paragraph
2(c) is subtracted from the pre-withdrawal water level giving the Minimum
Aquifer Level.
2_ If there is insufficient data to estimate the pre-withdrawal UFAS
water level:


DRAFT I


8-17































Where the
Where the


a_ The normal pool level for the surficial feature (lake or
wetland) is determined from the appropriate vegetation line per 40D-8.624(1)
or(2).
b] The offset from the normal pool level as determined in
40D-8.624(1) or (2) is subtracted from the normal pool resulting in the
Minimum level for the surficial feature.
c) The current long term average water level in the
surficial feature is estimated from the best available water level data.
d} The distance that the current level is below the minimum
level is calculated based on the difference between the minimum level and
the current average level. This is the recovery in the surficial feature needed
to attain the minimum level.
e) The current long-term average UFAS water level is
determined from water level hydrograph data. .
fl The recovery needed in the UFAS is estimated using the
relationship between the surficial and Floridan water levels determined in
paragraph (b) above.
g) The Minimum Aquifer level in the UFAS is determined
by adding the recovery needed in the UFAS to the current average level in
the UFAS.

Recovery Levels
existing aauifer level is below the Minimum Level, as part of the District's


recovery strategyav .Lu p
S. The Recovery Levels
are based on the reasonably-expected development and implementation of alternative
sources of water supply as well as resource-enhancement initiatives such as wellfield
K*tion. The Recovery Levels specified below are .r


(4 Minimum Aquifer Levels shall be established as follows:

Latitude Longitude Well Name SASIUFAS Minimum Recovery
Ratio Level Level
(NGVD) (NGVD)
280708 820748 T-1 0.4 84.59 TBD
280510 820438 T-2 0.4 94.92 TBD
280849 820537 T-3 0.4 89.56 TBD
282149 822815 A-1 0.7 66.3 TBD
282221 822419 CB3E 0.6 69.2 TBD
281719 822246 TMR1 0.9 65.9 TBD


DRAFT I


8-18










Latitude Longitude Well Name SAS/UFAS Minimum Recovery
Ratio Level Level
(NGVD) (NGVD)
281745 822342 TMR3 0.5 64 TBD
281204 822240 MW500 0.5 51.6 TBD
281019 822114 2-1000 0.7 59.8 TBD
280652 822042 MB1 0.4 31.8 TBD
280628 822007 MB6 0.4 25.6 TBD
280656 821751 MB13 0.4 29.2 TBD
280703 823027 HILLSB 13 0.4 44.2 TBD
280834 823435 CALM33 A 0.1 27 TBD
280653 823415 JAMES11 0.4 34.2 TBD
280608 823529 COSME3 0.2 26.1 TBD
281021 823956 EW005 0.6 22.7 TBD
280905 823905 EW 1 0.4 23.3 TBD
281018 823808 EW142 0.8 29 TBD
281102 822924 MATTS 0.8 62.5 TBD
281036 823056 SP42 0.2 49.5 TBD
281006 823852 1A EAST 0.4 42.4 TBD
280922 823955 1A WEST 0.8 30.9 TBD
281907 823344 NPMW-2 0.9 46.4 TBD

Specific Authority 120.54. 373.042. 373.044, 373.113. 373.171 FS. Law Implemented
120.54. 373.016. 373.023. 373.0395, 373.042. 373.171 FS. History New


DRAFT I


8-19









Lake Level Methodology Manual


I. Definitions and Standard Procedures Used throughout this Document

The procedures, conventions and definitions described in this section apply to the analyses
of all levels described in this document.

1_ Pre-modification period a period prior to when the lake level fluctuations were
altered by the construction of a surface water conveyance system.

2_ Post-modification.- refers to the period following the construction of surface water
conveyance systems (excluding water withdrawals) that had/have the potential to
alter the lake level fluctuations from their historic (pre-development) regimes.

3. P10 a percentile ranking defined as the elevation of the water surface of a lake
that is equaled or exceeded (greater than) 10 percent of the time as determined from
a stage duration analysis.

4. P50 a percentile ranking defined as the elevation of the water surface of a lake
that is equaled or exceeded (greater than) 50 percent of the time as determined
from a stage duration analysis.

5_ P90 a percentile ranking defined as the elevation of the water surface of a lake
that is equaled or exceeded (greater than) 90 percent of the time as determined
from a stage duration analysis.

6. Reference Lake Water Regimem, (RLWRI,) used to establish a range of lake level
fluctuations between the Minimum Flood Level and the Low Management Level for
lakes without stage duration data. The RLWRm is determined from the median of
the differences between the annual P10 and annual P90 values for reference lakes
in the same geographic region with similar hydrogeologic features as the subject
lakes. The reference lakes must have Pre-modification periods of record for at least
6 years.

7_ Stage Duration Curve a Stage Duration Curve is developed by plotting lake level
elevations against the cumulative frequency of occurrence of those elevations for
uniform increments of time (monthly readings). The stage duration curve shows the
percent of time the water surface is at a particular elevation.

8. Pre-modification Stage Duration Curve a stage duration curve for which the period
of record data must not be impacted by anthropogenic activities including alteration
of surface drainage and water withdrawals.


DRAFT I


8-20








9. Post-modification Stage Duration Curve A stage duration curve for which the
period of record data begins after the construction of anthropogenic alterations,
excluding water withdrawals.

10. Establishment of Biological Indicator Elevations Locations for measuring biological
indicators shall be chosen based on the presence of the plant species. Optimal
locations will have intact cypress wetlands around the lake, fringed by palmettos.
In these areas, A NUMBER TO BE DETERMINED of individual plants will be
measured. At least one transect shall be measured in each intact natural area
fringing the lake. Elevations of all biological indicators shall be established using
accepted survey practices. When more than one of each type biological indicator
occurs on each lake, the average elevation for each type of biological indicator shall
be calculated.

In the absence of intact fringing wetlands, elevations shall be measured for any
available biological indicators. Activities which may have impacted elevations, such
as, filling, soil subsidence, land clearing etc, shall be considered during evaluation
and analysis of the data.

11. Levels Expressed in Feet, NGVD All levels shall be expressed in feet relative to
National Geodetic Vertical Datum.

II. Ten (10) Year Flood Warning Level

The Ten (10) Year Flood Warning Level incorporates the level of flooding expected on a
frequency of not less than the ten (10) year recurring interval, or on a frequency of not
greater than a ten percent (10%) probability of occurrence in any given year.

The Ten (10) Year Flood Warning Level elevation shall be established using accepted
modeling practices. Input variables to the models may include, but not be limited to, the
following variables: rainfall, runoff, storage, soils and other factors affecting the response
of the lake elevation to a ten year storm event.

III. Minimum Flood Level

A. Determination of Historic Minimum Flood Level

The Historic Minimum Flood Level shall be established from analysis of, but not
limited to, one or a combination of the following methods:

1_ Analysis of Stage Duration Curves

The Historic Minimum Flood Level is equal to the elevation of the Pre-
modification Stage Duration Curve which occurs at the 10t percentile.


DRAFT I


8-21









2. Analysis of Elevations of Biological Indicators


The biological indicators and their relative elevations may include, but
not be limited to, the following:

a_ The average elevation of the soil at the base of the lowest
lakeward extent of the palmetto (Serenoa repens) fringe
b. The average elevation of the soil at the base of the lowest
lakeward extent of the mature wax myrtle (Myrica cerifera)
fringe
c. The average elevation of the soil at the base of the highest
landward extent of the cypress (Taxodium sp.) fringe
d_ The average elevation of the soil at the base of the lowest
lakeward extent of longleaf pine (Pinus palustrus) fringe
e_ The average elevation of the soil at the base of the lowest
lakeward extent of the live oak (Quercus viriniana) fringe
(trees with DBH greater than or equal to 24")
f. The average elevation of the lowest extent of lichen growth

Measurement of lowest lakeward extent of upland plant species shall
be made at the lakeward edge of the lowest rooted part of the plant
(e.g. the lowest rooted portion of the palmetto, live oak, wax myrtle or
lonaleaf pine). Measurement of the highest landward extent of the
wetland plant species shall be made at the highest rooted extent of
the plant (e.g. the landward side of the cypress tree).

The priority order for reconciling the elevations of biological indicators
is palmetto and cypress, followed by pine and/or live oak then lichens.
If both palmetto and cypress occur on the lake, then the Historic
Minimum Flood Level is equal to the average of the elevations of the
palmetto and cypress.

3. Analysis of Physical Indicators

Physical indicators may include, but not be limited to, one or a
combination, of the following:

a. The average elevation of the toe of the highest landward scarp
line.
b_ Interpretation of historic aerial photography
c_ Stratified beach deposits

4. Analysis of Other Features



DRAFT I 8-22









Other features may include, but not be limited to, the lowest average
lakeward elevation of cultivated crops. These measurements shall be
made at the waterward edge of the plants. Several measurements
should be made along the entire shoreline on which the crop occurs.

The Historic Minimum Flood Level finally recommended is a reconciliation of all the
elevations determined by the above analyses.

B. Determination of Post-modification Minimum Flood Level

The Post-modification Minimum Flood Level shall be established from analysis of,
but not limited to, one or a combination of, the following methods:

1. Analysis of Stage Duration Curves

The Post-modification Minimum Flood Level is equal to the elevation
of the Post-modification Stage Duration Curve which occurs at the
10't percentile.

2. Analysis of Outfall Elevations

Elevations of outfalls will be measured using accepted survey
practices. In the case of open ditches or canals, bottom elevations
shall be measured and the highest point of the solid ground in the
ditch or canal shall be the controlling elevation for the feature. For
culverts or pipes, the invert (lowest point) of the pipe or culvert shall
be measured and this will be the controlling point for this feature. For
weirs, the elevation of the top of the weir shall be measured and this
shall be the controlling elevation for this feature.

For lakes with more than one outfall, the elevation of the lowest outfall
shall be the controlling elevation of the lake and shall be considered
the Post-modification Minimum Flood Level.

3. Analysis of Other Features

Other features may include, but not be limited to, the lowest average
lakeward elevation of cultivated crops.

The lowest average lakeward elevation of cultivated crops shall be
determined using accepted survey practices. The lowest lakeward
elevation shall be measured at the waterward edge of the crop.
Several measurements should be made along the entire shoreline on
which the crop occurs.


DRAFT I 8-23









The Post-modification Minimum Flood Level finally recommended is a reconciliation
of all the elevations determined by the above analyses.

The Post-modification and Historic Minimum Flood Levels will be determined and
presented to the Governing Board, along with any other supporting information
gathered during the process of establishing lake levels. This information may
include elevations of low floor slabs, docks, septic tanks, and other cultural features.

III. Low Management Level

A. Determination of Historic Low Management Level

The Historic Low Management Level shall be established from analysis of, but not
limited to, one or a combination of the following methods:

1. Analysis of Stage Duration Curves

The Historic Low Management Level is equal to the elevation of the
Pre-modification Stage Duration Curve which occurs at the 90h
percentile.

2. Analysis of Biological Indicators

Biological indicators of the Historic Low Management Level may
include, but not be limited to, the average elevation of the soil at the
base of the lowest lakeward extent of cypress (Taxodium sp.) fringe.
The elevation of the lowest lakeward extent of cypress tress shall be
measured on the landward side of the tree using accepted survey
practices. When more than one cypress tree is found along the lake,
the average elevation of the measured trees shall be used to
determine the Historic Low Management Level.

3. Application of the Reference Lake Water Regime

In the absence of biological indicators or stage duration data for the
subject lake, the Historic Low Management Level may be calculated
from the Historic Minimum Flood Level using the Reference Lake
Water Regime (RLWRn,,). The RLWR is determined from the median
of the differences between the annual P10 and P90 values for
reference lakes in the same geographic region with similar hvdrologic
features.

To determine the annual P10 and P90 values for the reference lakes,
annual stage duration curves are prepared. The Stage Duration


DRAFT I


8-24









Curves must have a minimum Period of record of six years and must
not be impacted by pumDing.

The Historic Low Management Level finally recommended is a reconciliation of the
elevations determined by the above procedures.

B. Determination of Post-modification Low Management Level

The Post-modification Low Management Level shall be established from analysis
of, but not limited to, one or a combination of the following methods:

1. Analysis of Stage Duration Curves

The Post-modification Low Management Level is equal to the
elevation of the Post-modification Stage Duration Curve which occurs
at the 90" percentile.

2. Application of the Reference Lake Water Regime

In the absence of biological indicators or stage duration data for the
subject lake, the Post-modification Low Management Level may be
calculated from the Post-modification Minimum Flood Level using the
Reference Lake Water Regime (RLWR ,. The RLWR is determined
from the median of the differences between the annual P10 and P90
values for reference lakes in the same geographic region with similar
hydrologic features.

To determine the annual P10 and P90 values for the reference lakes.
annual stage duration curves are prepared. The Stage Duration
Curves must have a minimum Period of record of six years and must
not be impacted by DumDing.


' DRAFT I


8-25






PREVENTION AND
RECOVERY
STRATEGIES
FOR
MINIMUM FLOWS
AND LEVELS
DRAFT RULES
40D-80








RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-80
PREVENTION AND RECOVERY STRATEGIES
FOR MINIMUM FLOWS AND LEVELS

40D-80.011 Policy and Purpose
40D-80.073 Recovery Strategy For Pasco. Hillsborough and Pinellas Counties

40D-80.011 Policy and Purpose

This chapter sets forth the recovery or prevention strategies to achieve or protect.
as applicable, the minimum flows and water levels established for rivers, lakes, wetlands
and aquifers in Chapter 40D-8. F.A.C. as required by Section 373.0421(2). Florida Statutes
(1997).

Specific Authority 120.54. 373.0421. 373.044. 373.113. 373.113. 373.171 FS. Law
Implemented 120.54. 373.016. 373.023. 373.0395. 373.042. 373.0421. 373.171 FS.
History New

40D-80.073 Recovery Strategy For Pasco. Hillsborough and Pinellas Counties

(1 Chapter 96-339. Laws of Florida requires the District to establish minimum
flows and levels for priority waters within Pasco. Hillsborough and Pinellas Counties (the
Northern Tampa Bay Area or Area) by October 1. 1997. Those levels are contained within
Chapter 40D-8. F.A.C. In establishing those flows and levels, the District has determined
that the existing water levels in many of the priority waters are below the minimum levels.
The -is set forth in this Rule. This .WW
ig..s- the by permittees to offset existing
withdrawals which are causing unacceptable adverse environmental impacts within the
Area, and is This strateav
also incorporates .I.I -i I" of the recovery strategy so that mid-term
corrections can be accomplished, if needed.
(2) Recovery Strategy Elements Relating to West Coast Regional Water Supply
Authority and Member Governments
The West Coast Regional Water Supply Authority e and member
governments water supply facilities account for the majority of water withdrawals within the
Area. For this reason, these facilities are the 11r-a- gPa of the recovery strategy for the
Area. The v---" k ----.
(mgd) t.... ... .... .. ...... 4ir j to partially offset
withdrawal impacts caused by WCRWSA and member governments Central System
(defined below) facilities and to supply future water demand increases. The recovery
strategy is further predicated on the assumed continued withdrawal of 65 mgd annual


GOVERNING BOARD DRAFT








average daily quantities from the Hillsborough River Reservoir/Tampa Bypass Canal
system, and 24 mad annual average daily quantities from the South Central Hillsborough
Regional Wellfield.
a) Central System Facilities
The Central System Facilities are those facilities listed below owned
and operated individually or jointly by the WCRWSA and its member governments:
1. Cosme-Odessa Wellfield
2_ Eldridge-Wilde Wellfield
3. Section 21 Wellfield
4. South Pasco Wellfield
5. Cypress Creek Welifield
6. Cross Bar Ranch Wellfield
7. Starkey Wellfield
8. Morris Bridge Wellfield
9. Northwest Hillsborough Regional Wellfield
10. Cypress Bridge Wellfield
11. North Pasco Wellfield
b) Quantities Withdrawn from the Central System Facilities
1. The total quantity available to be withdrawn from the Central
System facilities, as limited by the specific terms and conditions of each of the Central
System facility's water use permits, is as follows:
i. Prior to 2007: Up to 140 million gallons per day (mad)
annual average daily quantity as limited by specific terms and conditions of each of the
Central System facility's water use permits:
ii. 2007-2010: Up to 90 mgd annual average daily quantity
as limited by specific terms and conditions of each of the Central System facility's water
use permits:
iii. 2010-2015: Up to 115 mgd annual average daily quantity
as limited by specific terms and conditions of each of the Central System facility's water
use permits.
2. Figure 80-1 depicts the Central System quantities available to
be withdrawn based on the recovery strategy. Figure 80-2 depicts the quantities to be
reduced over time based on the recovery strategy. For both Figures, the quantities other
than for years 2007 and 2015 are merely interpolations between points for illustrative
purposes and are not intended to be binding.
(c) Environmental Balancing
j1 The Central System facilities shall be operated in a coordinated
manner to optimize the environmental benefits of reduced withdrawals as new sources are
made available to offset water production from the Central System facilities. Water
production from the Central System facilities shall be reduced in accordance with the
recovery strateav. The
in withdrawn water quantities
which is to occur through the recovery strategy. The method must include consideration

GOVERNING BOARD DRAFT 2









i. the severity of the long term impacts associated with each
facility:
ii. environmental response to changing production quantities
of each facility;
iii. seasonal and annual drought conditions within the Central
System facilities;
iv. maintaining or improving operating flexibility for water supply
and minimum level recovery: and
v. any other factors considered critical to water supply and
minimum level recovery by the WCRWSA.
2. *ia, a -i -the ai to the
District Governing Board f
M W. The ROAM I-. "based on operating
xvn mrienc-,m onrc distrihbfion of th, redrlut-ion nf wnfithrawrin nlanfifiae arallh1l starts


@ Periodic Review of Recovery Strategy


The .... .. but not
limited to the dates by which the status reports described below are due, to assess the
progress of strategy elements and to determine whether changes to the strategy are
warranted. The District will evaluate the recovery attained in light of the reductions in
quantities withdrawn achieved by the due date of each status report described below.
These reviews shall be based, in part. upon reports generated by the WCRWSA describing
the status of all additional sources either developed or in development to offset withdrawals
from Central System facilities. ... .. .. i "- .
i ..Tb- e re orts shall inclu e:
1. A description of additional sources developed by the report
date:
2. Estimates of timing for completion additional sources and the
quantities associated with each source:
3_ A description of environmental balancing activities
accomplished as of the report date: and
4. A discussion of planned environmental balancing activities to
be accomplished within the next 5 year period based upon anticipated additional source
development.
Recovery Strategy Elements Relating To Other Water Use Permittees



lPIBW. The items that shall be considered in this determination include:
Ua The cost to the permitted to implement the measures;
( The time that it will take the permitted to fully implement the measures:


GOVERNING BOARD DRAFT








c) Any unavoidable public health, safety or welfare emergency that would
be caused by implementation of the measures:
(d. Whether the water resources benefits gained from implementation of
the permitted's measures to attain the minimum flow or level outweigh water resources
impacts that may result from the measures: and
(). Alternative actions or programs in lieu of or in combination with the
measures set forth above that will contribute to the attainment of the minimum flow or level
and will optimize the net positive effect on the impacted environmental systems.

Specific Authority 120.54. 373.0421. 373.044. 373.113. 373.113. 373.171 FS. Law
Implemented 120.54. 373.016. 373.023. 373.0395. 373.042. 373.0421. 373.171 FS.
History New


GOVERNING BOARD DRAFT

















Figure 80-1. WCRWSA Central System Quantities

Based On Recovery Strategy


97 98 99 0 1 2 3 4 5 6 7 8 9 1D 11 12 13 14 15
Year


Figure 80-2. Wellfield Reduction Quantities

WCRWSA Central System


140 -
120 -
100-
80-
so-
40-
20
0 7 9 2
97 98 99 0 1 2


I


3 4I
3 4 5


Year
See


1~U14U


8 9


4~IVI
-LJ-LF-


12 13 14 15


GOVERNING BOARD DRAFT


i


I






PREVENTION AND
RECOVERY
STRATEGIES
FOR
MINIMUM FLOWS
AND LEVELS
DRAFT RULES
40D-80









RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-80
PREVENTION AND RECOVERY STRATEGIES
FOR MINIMUM FLOWS AND LEVELS

40D-80.011 Policy and Purpose
40D-80.073 Recovery Strategy For Pasco. Hillsborough and Pinellas Counties

40D-80.011 Policy and Purpose

This chapter sets forth the recovery or prevention strategies to achieve or protect,
as applicable, the minimum flows and water levels established for rivers, lakes, wetlands
and aquifers in Chapter 40D-8. F.A.C. as required by Section 373.0421(2). Florida Statutes
(1997).

Specific Authority 120.54. 373.0421. 373.044. 373.113. 373.113. 373.171 FS. Law
Implemented 120.54. 373.016. 373.023. 373.0395. 373.042. 373.0421. 373.171 FS,
History New

40D-80.073 Recovery Strategy For Pasco. Hillsborough and Pinellas Counties

M11 Chapter 96-339. Laws of Florida requires the District to establish minimum
flows and levels for priority waters within Pasco. Hillsborough and Pinellas Counties (the
Northern Tampa Bay Area or Area) by October 1. 1997. Those levels are contained within
Chapter 40D-8. F.A.C. In establishing those flows and levels, the District has determined
that the existing water levels in many of the priority waters are below the minimum levels.
The recovery strategy for those waters through 2015 is set forth in this Rule. This strategy
includes the phased development of additional sources by permittees to offset existing
withdrawals which are causing unacceptable adverse environmental impacts within the
Area. and is based upon a certain quantity becoming available for this offset. This strategy
also incorporates periodic review of the effects of the recovery strategy so that mid-term
corrections can be accomplished, if needed.
(21 Recovery Strategy Elements Relating to West Coast Regional Water Supply
Authority and Member Governments
The West Coast Regional Water Supply Authority (WCRWSA) and member
governments water supply facilities account for the majority of water withdrawals within the
Area. For this reason, these facilities are the primary focus of the recovery strategy for the
Area. The recovery strategy is based upon the development of 85 million gallons per day
(mgd) annual average daily quantity of additional water supply sources to partially offset
withdrawal impacts caused by WCRWSA and member governments Central System
(defined below) facilities and to supply future water demand increases. The recovery
strategy is further predicated on the assumed continued withdrawal of 65 mad annual


GOVERNING BOARD DRAFT








average daily quantities from the Hillsborough River Reservoir/Tampa Bypass Canal
system, and 24 mad annual average daily quantities from the South Central Hillsborough
Regional Wellfield.
(a Central System Facilities
The Central System Facilities are those facilities listed below owned
and operated individually or jointly by the WCRWSA and its member governments:
1. Cosme-Odessa Wellfield
2. Eldridge-Wilde Wellfield
3. Section 21 Wellfield
4. South Pasco Wellfield
5_ Cypress Creek Wellfield
6. Cross Bar Ranch Wellfield
7. Starkey Wellfield
8. Morris Bridge Wellfield
9. Northwest Hilisborough Regional Wellfield
10. Cypress Bridge Wellfield
11. North Pasco Wellfield
(b. Quantities Withdrawn from the Central System Facilities
1_ The total quantity available to be withdrawn from the Central
System facilities, as limited by the specific terms and conditions of each of the Central
System facility's water use permits, is as follows:
L Prior to 2007: Up to 140 million gallons per day (mgd)
annual average daily quantity as limited by specific terms and conditions of each of the
Central System facility's water use permits:
ii 2007-2010: Up to 90 mgd annual average daily quantity
as limited by specific terms and conditions of each of the Central System facility's water
use permits;
iii. 2010-2015: Up to 115 mgd annual average daily quantity
as limited by specific terms and conditions of each of the Central System facility's water
use permits.
2. Figure 80-1 depicts the Central System quantities available to
be withdrawn based on the recovery strategy. Figure 80-2 depicts the quantities to be
reduced over time based on the recovery strategy. For both Figures. the quantities other
than for years 2007 and 2015 are merely interpolations between points for illustrative
purposes and are not intended to be binding.
(c) Environmental Balancing
1. The Central System facilities shall be operated in a coordinated
manner to optimize the environmental benefits of reduced withdrawals as new sources are
made available to offset water production from the Central System facilities. Water
production from the Central System facilities shall be reduced in accordance with the
recovery strategy. The WCRWSA. by July 1. 1998. shall develop and implement a method
to distribute among the Central System facilities the reduction in withdrawn water quantities
which is to occur through the recovery strategy. The method must include consideration


GOVERNING BOARD DRAFT









i. the severity of the long term impacts associated with each
facility;
ii. environmental response to changing production quantities
of each facility;
iii. seasonal and annual drought conditions within the Central
System facilities;
iv. maintaining or improving operating flexibility for water supply
and minimum level recovery: and
v. any other factors considered critical to water supply and
minimum level recovery by the WCRWSA.
2. Prior to its implementation, the WCRWSA shall submit to the
District Governing Board the document explaining the distribution methodology for
approval. The methodology can be modified by the WCRWSA based on operating
experience once distribution of the reduction of withdrawn quantities actually starts.
Modifications to the methodology shall be submitted to the District Governing Board for
approval prior to implementation.
() Periodic Review of Recovery Strategy
The District shall review the recovery strategy periodically, but not
limited to the dates by which the status reports described below are due, to assess the
progress of strategy elements and to determine whether changes to the strategy are
warranted. The District will evaluate the recovery attained in light of the reductions in
quantities withdrawn achieved by the due date of each status report described below.
These reviews shall be based, in part. upon reports generated by the WCRWSA describing
the status of all additional sources either developed or in development to offset withdrawals
from Central System facilities. Status reports shall be submitted by the WCRWSA to the
District by October 1 of the years 2002. 2007. and 2010. The reports shall include:
1 A description of additional sources developed by the report
date:
2. Estimates of timing for completion additional sources and the
quantities associated with each source;
3. A description of environmental balancing activities
accomplished as of the report date: and
4_ A discussion of planned environmental balancing activities to
be accomplished within the next 5 year period based upon anticipated additional source
development.
(3 Recovery Strategy Elements Relating To Other Water Use Permittees
Permittees whose water withdrawals impact established minimum flows and
levels will be evaluated upon permit renewal to determine the permitted's practical ability
to implement measures to reduce its impacts on the flow or level during the proposed
permit term. The items that shall be considered in this determination include:
(a The cost to the permitted to implement the measures:
(M The time that it will take the permitted to fully implement the measures:


GOVERNING BOARD DRAFT








(cl Any unavoidable public health, safety or welfare emergency that would
be caused by implementation of the measures:
dM Whether the water resources benefits gained from implementation of
the permitted's measures to attain the minimum flow or level outweigh water resources
impacts that may result from the measures: and
IM Alternative actions or programs in lieu of or in combination with the
measures set forth above that will contribute to the attainment of the minimum flow or level
and will optimize the net positive effect on the impacted environmental systems.

Specific Authority 120.54. 373.0421. 373.044. 373.113. 373.113. 373.171 FS. Law
Implemented 120.54. 373.016. 373.023. 373.0395. 373.042. 373.0421. 373.171 FS.
History New


GOVERNING BOARD DRAFT


















Figure 80-1. WCRWSA Central System Quantities

Based On Recovery Strategy


97 98 99 0 1 2 3 4 5 8 7 8 0 10 11 12 -13 14 15
Year


Figure 80-2. Wellfield Reduction Quantities

WCRWSA Central System
140-
120
100-
80



20-

97 98 99 0 1 2 3 4 5 8 7 8 9 10 11 12 13 14 15
Year


GOVERNING BOARD DRAFT





DATE: 08/19/97


OFFICE OF THE EXECUTIVE DIRECTOR
SWFWMD CORRESPONDENCE LOG # 12073-97


TIME: 09:15:16


DATE ASSIGNED:
SOURCE AND SUBJECT:


06/19/97
JERRY MAXWELL, WCRWSA/GRAPHIC OF 20 YEAR
RECOVERY PLAN


ASSIGNED TO: S. VERGARA
DATE REQUIRED: / /


ASSIGNED BY:
INSTRUCTIONS:

ACTION TAKEN:


PLM
FOR YOUR INFORMATION AND APPROPRIATE
DISPOSITION


COPIES TO: EBH/RVM/DLM/EAS/RTT
DATE COMPLETED: 06/19/97







:.. .-
.-^ .,"
s'\r -


t3


&41(97
VL7

lz/lq


~c~~c
F4~

















June 17, 1997


The Authorit in Water


E.D. "Sonny" Vergara
Executive Director
Southwest Florida Water Management District
2379 Broad Street
Brooksville, FL 34609

Sowdof Dear Sonny:
Directors


Ed Turanchik
David J. Fischer
Steen M. Seibert
R. Michael Salmon
Ed Collins


Attached is a graphic representation of the visual which you sketched at our meeting of
June 12. I asked my graphic staff to take your representation and attempt to replicate it
on 81/2" x 11". I believe it is essential to our cooperative efforts to agree on a
conceptual recovery plan as quickly as possible.


Wendy Brenner Sinc

General
Manager
Jerry L. Maxwell

.Generl General Manager
Counsel


Donald D. Conn


JLM:md
Attachment


2535 Landmark Drive
Suite 211
Clearwater FL 34621
Phone 813-796-2355
Fax 813-855-7479


t:\genmangr\maxwell\swfwmd\61797.doc


,Bt Mng 1

Cn~
Pse~-e m
~~ '

1 -- .





20 YEAR RECOVERY PLAN
11 WELLFIELDS IN NORTHERN TAMPA BA Y

1995 PERMITS (192)
190-



2015 FACILITIES NEED 531 _
PROJECTED USE INCLUDES 25% ROTATION
140-

MINIMUM RECOVERY
115


90 -90
9 MAXIMUM RECOVERY

PERMIT & IMPLEMENT MASTER WATER PLAN
PARTNERSHIP PLAN I

1995 2007 2010 2015

YEAR










Draft 40D-80, F.A.C.

Prevention and Recovery
Strategies for Minimum
Flows and Levels


July 16, 1997


_II








1 RULES OF THE
2 SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
3 CHAPTER 40D-80
4 PREVENTION AND RECOVERY STRATEGIES
5 FOR MINIMUM FLOWS AND LEVELS
6
7 40D-80.011 Policy and Purpose
8 40D-80.073 Recovery Strategy For Pasco, Hillsborough and Pinellas Counties
9
10 40D-80.011 Policy and Purpose
11
12 This chapter sets forth the regulatory portions of the recovery or prevention
13 strategies to achieve or protect, as applicable, the minimum flows and water levels
14 established for rivers, lakes, wetlands and aquifers in Chapter 40D-8, F.A.C. as required
15 by Section 373.0421(2), Florida Statutes (1997). The complete recovery strategy for a
16 given area will be set forth in the District Water Management Plan.
17
18 Specific Authority 120.54. 373.0421, 373.044. 373.113, 373.113, 373.171 FS. Law
19 Implemented 120.54, 373.016, 373.023, 373.0395. 373.042, 373.0421, 373.171 FS.
20 History New
21
22 40D-80.073 Phased Recovery Strategy For Pasco, Hillsborough and Pinellas
23 Counties
24
25 1, Chapter 96-339, Laws of Florida requires the District to establish Minimum
26 Flows and Levels for priority waters within Pasco, Hillsborough and Pinellas Counties (the
27 Northern Tampa Bay Area or Area) by October 1. 1997. Those minimum levels are
28 contained within Chapter 40D-8, F.A.C. In establishing those flows and levels, the District
29 has determined that the existing water levels in many of the priority waters are below the
30 minimum levels. In keeping with Section 373.0421 F.S., the District is expeditiously
31 implementing a recovery strategy for those waters, and this Rule comprises a portion of
32 that strategy. This Rule requires the phased development of additional sources by
33 permittees to offset existing withdrawals which have caused and are causing water levels
34 and flows to be below the Minimum Flow or Level, and is based upon a certain quantity
35 of additional water supply becoming available for this offset. This Rule also incorporates
36 periodic review of the effects of the recovery strategy so that mid-term corrections can be
37 accomplished, if needed. This strategy is in keeping with the District's efforts to resolve
38 the water supply and environmental impact concerns of the Northern Tampa Bay area in
39 a cooperative manner with the water suppliers and interested parties. The portion of the
40 District's recovery strategy embodied within this Rule is the first phase of a long-term
41 approach toward eventual attainment of the Minimum Flows and Levels established in
42 Chapter 40D-8, F.A.C.
43 (2) Recovery Strategy Elements Relating to West Coast Regional Water Supply
44 Authority and Member Governments


STAFF DRAFT C









1 The West Coast Regional Water Supply Authority (WCRWSA) and member
2 governments' water supply facilities account for the majority of water withdrawals within the
3 Area. For this reason, these facilities are the primary focus of the portion of the recovery
4 strategy encompassed by this Rule. This portion of the recovery strategy is based upon
5 the WCRWSA Master Plan, December, 1995, which provides for the development of 85
6 million gallons per day (mad) annual average daily quantity of additional water supply
7 sources. The 85 mgd will partially offset withdrawal impacts caused by WCRWSA's and
8 member governments' Central System (defined below) facilities and supply future water
9 demand increases. This portion of the recovery strategy is further predicated on the
10 assumed continued withdrawal of 65 mqd annual average daily quantities from the
11 Hillsborough River Reservoir/Tampa Bypass Canal system, and 24 mgd annual average
12 daily quantities from the South Central Hillsborough Regional Wellfield.
13 (a) Central System Facilities
14 The Central System Facilities are those facilities listed below owned
15 and operated individually or jointly by the WCRWSA and its member governments:
16 1_ Cosme-Odessa Wellfield
17 2_ Eldridge-Wilde Wellfield
18 3. Section 21 Wellfield
19 4. South Pasco Wellfield
20 5. Cypress Creek Wellfield
21 6. Cross Bar Ranch Wellfield
22 7_ Starkey Wellfield
23 8. Morris Bridge Wellfield
24 9. Northwest Hillsborough Regional Wellfield
25 10. Cypress Bridge Wellfield
26 11. North Pasco Wellfield
27 (b) Quantities Withdrawn from the Central System Facilities
28 1. The total quantity available to be withdrawn from the Central
29 System facilities, as further limited by the specific terms and conditions of each Central
30 System facility water use permit, is as follows:
31 i. 2002-2006: No more than 121 mgd;
32 ii. 2007-2010: No more than 90 mad:
33 iii. After 2010: Quantity will be determined based upon an
34 evaluation of the water resources recovery accomplished and the additional sources that
35 can be developed to offset further pumpage reductions, as necessary.
36 2_ Figure 80-1 is a graphic representation of the Central System
37 quantities available to be withdrawn based on the recovery strategy. The quantities after
38 2010 are displayed as a range to reflect the fact that these future quantities will be
39 developed based on information available in the 2007-2010 timeframe. The quantities
40 other than for years 2002 and 2007 are merely interpolations between points for illustrative
41 purposes and are not intended to be binding.
42 (c) Environmental Balancing
43 1_ The Central System facilities shall be operated in a coordinated
44 manner to optimize the water resources benefits of reduced withdrawals as new sources
45 are made available to offset water production from the Central System facilities. Water


STAFF DRAFT C









production from the Central System facilities shall be reduced in accordance with the
recovery strategy. The WCRWSA and member governments, by July 1, 1998, shall
develop and implement a method to distribute among the Central System facilities the
reduction in withdrawn water quantities which is to occur through the recovery strategy. The
method shall give first priority to water resources recovery in and around the Cross Bar
Ranch, Cypress Creek, and Starkey wellfields, followed by the remainder of the northwest
Hillsborough/southern Pasco/northeast Pinellas counties area wellfields, and must include:
i_ consideration of the severity of the long term impacts
associated with each facility;
ii. consideration of water resource response to changing
production quantities of each facility;
iii. consideration of seasonal and annual drought conditions
within the Central System facilities;
iv. consideration of maintaining or improving operating
flexibility for water supply and minimum level recovery;
v. consideration of any other factors deemed critical to
water supply and minimum level recovery by the WCRWSA and member governments:
vi. recovery levels, as defined in 40D-8.021, which result
from the quantity reductions related to the proposed distribution methodology: These
recovery levels shall be for the Floridan aquifer minimum level sites as specified in 40D-
8.626.
2_ Prior to its implementation, the WCRWSA and member
governments shall submit for Governing Board approval the document proposing and
explaining the distribution methodology. The methodology can be modified by the
WCRWSA and member governments based on operating experience once distribution of
the reduction of withdrawn quantities actually starts. Modifications to the methodology
shall be submitted to the District Governing Board for approval prior to implementation.
(d) Periodic Review of Recovery Strategy
The District shall review the recovery strategy periodically to assess
the progress of strategy elements and to determine whether changes to the strategy,
including the Central System quantities and time-periods stated above, are warranted. The
District will evaluate the water resource recovery attained in light of the reductions in
quantities withdrawn achieved based on the environmental performance standards set
forth in Section 4.2 of the Basis of Review for Water Use Permitting. These reviews shall
be based upon reports generated by the WCRWSA and member governments describing
the status of all additional sources either developed or in development to offset withdrawals
from Central System facilities as well as any other water supply and water resource
information available to the District. Status reports shall be submitted by the WCRWSA
and member governments to the District by October 1 of each year beginning in 1997. The
reports shall include:
1_ A description of additional sources developed by the report
date;
2_ Estimates of timing for completion of additional sources and the
quantities associated with each source;
3_ A description of environmental balancing activities


STAFF DRAFT C









1 accomplished as of the report date; and
2 4_ A discussion of planned environmental balancing activities to
3 be accomplished within the next 5 years based upon anticipated additional source
4 development.
5 (e) Implementation
6 The quantity reductions per wellfield resulting from that portion of the
7 recovery strategy set forth in 40D-80.073(2) shall be implemented through modification of
8 the WCRWSA and member governments Central System water use permits to reflect the
9 quantity reductions approved by the Governing Board following submission by the
10 WCRWSA and member governments of the distribution plan required by 40D-80.073(2)(c).
11 (3) Recovery Strategy Elements Relating To Other Water Use Permittees
12 Permittees whose water withdrawals impact established Minimum Flows and
13 Levels will be evaluated upon permit renewal to determine the permitted's practical ability
14 to implement measures to reduce its impacts on the flow or level during the proposed
15 permit term. The items that shall be considered in this determination include:
16 (a) The cost to the permitted to implement the measures;
17 (b) The time that it will take the permitted to fully implement the measures;
18 (c) Any unavoidable public health, safety or welfare emergency that would
19 be caused by implementation of the measures;
20 (d) Whether the water resources benefits gained from implementation of
21 the permitted's measures to attain the Minimum Flow or Level outweigh water resources
22 impacts that may result from the measures: and
23 (e) Alternative actions or programs in lieu of or in combination with the
24 measures set forth above that will contribute to the attainment of the Minimum Flow or
25 Level and will optimize the net positive effect on the impacted water resources.
26
27 Specific Authority 120.54, 373.0421, 373.044, 373.113, 373.113, 373.171 FS. Law
28 Implemented 120.54, 373.016, 373.023, 373.0395, 373.042, 373.0421, 373.171 FS.
29 History New


STAFF DRAFT C










Figure 80-1. Central System Quantities

Based On Phased Recovery Strategy


121


140 ^""

120

100

80

60-

40-

20

1998
1998


2002


2007-2010


Year


STAFF DRAFT C


115


2015


777 -77. 190









Draft 40D-8, F.A.C.

Minimum Water Levels
and Rates of Flow


July 16,


1997














40D-8.011
40D-8.021
40D-8.031
40D-8.041
40D-8.603
40D-8.605
4nD- I.


RULES OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
CHAPTER 40D-8
WATER LEVELS AND RATES OF FLOW

Policy and Purpose
Definitions
Implementation
Minimum Rates of Flow and-Levels
Management-Levels for Lakes and Other Impoundments
Cyclic Variations for Guidance Minimum Water Levels
Minimum Flnndrl I ev4lr.


10D 8.613 Ten (10) Year Flood Warning Levels
AnAr 0 CIC D +e.Ar KItf;e


40D-8.621

40D-8.624
40D-8.624


Operating Levels for Lakes and Other Impoundments with
Structures
Schedule f Guidance Levels for Lakes and Wetlands-,-and-Other


Impoundments
40D-8.626 Minimum Aquifer Levels in Northern Hillsborough, Pasco, and Pinellas
Counties

40D-8.011 Policy and Purpose.
(1) The purpose of Chapter 40D-8 is to establish minimum flows and levels at
specific locations throughout the District and to describe guidance levels for lakes and
other impoundments.
(2) Where appropriate, minimum flows and levels may reflect seasonal variations
and may include a schedule of variations and other measures appropriate for the
protection of non-consumptive uses andef the water resources.
(3) A further purpose of Chapter 40D-8 is to establish-minimum-flood levels and
warning levels for surface waters which are anticipated to occur on a somewhat regular
basis, and which shall serve as a precautionary warning to all persons who would propose
to construct facilities which may be damaged by periodic high water levels.
(4) Minimum flows and levels prescribed in Chapter 40D-8 are used as a basis
for imposing limitations on withdrawals of water and certain other activities. These
limitations are prescribed in this and other chapters pats of the rules of the District.
(5) Where existing flows or levels are below the established minimum flow or
level, the District shall address achieving the established flow or level via a recovery
strategy in accordance with Sections 373.0361 and 373.0421, F.S.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.026,
373.042, 373.044, 373.086 FS. History New 6-7-78, Amended 1-22-79, Formerly 16J-
8.01, Amended


DRAFT J


40D-8.021 Definitions.








The terms set forth herein shall have the meanings ascribed to them unless the
context clearly indicates otherwise, and such meanings shall apply throughout all District
these rules. To facilitate easier reference, certain terms defined by applicable statute have
been included verbatim ,with appropriate citation. The terms defined in Rule 40D-1.102
4-0D .02- shall also apply throughout Chapter 40D-8.
(1) "Guidance Levels" Levels, determined by the District using the best
available information and expressed in feet relative to National Geodetic Vertical Datum,
used as advisory information, including for the District, lake shore residents and local
governments or to aid in the control of operable structures. Guidance Levels include: Ten
Year Flood Warning Level: Pre-modification Annual High Level; Post-modification Annual
High Level: Pre-modification Annual Low Level; and Post-modification Annual Low Level.
(2) "Minimum Flow" means the level of flow for a surface watercourse at which
further withdrawals would be significantly harmful to the water resources or ecology of the
area.
4(1) "Management range" moans the difference bektwen the establishlo
minimum water levels and minimum flood levels, and reprOesents the capability of an
impoundment to receive, carry, or store wAater, to preserve non consumptive uses of a
surface water body, and within this range the District applies and requires best surface
water management practices.
(32) "Minimum water Level" means the level of surface water, water table, or
potentiometric surface at which further withdrawals would be significantly harmful to the
water resources of the area. Such level shall be expressed as an elevation, in feet relative
to National Geodetic Vertical Datum. A minimum level may be expressed as a
potentiometric surface. above mean sea and may incorporate a low management level and
an extreme low management level, which together establish the lower limits of the
management range, to which a water body shall be allowed to fluctuate naturally.
(41 "Long-term average" An evaluation period related to withdrawal impact
assessment that represents a situation which is insensitive to unstable fluctuations of the
variables utilized in the evaluation, and in which changes in withdrawal rates and
hydrologic conditions are balanced.
5 "Management range" means the difference between the applicable Low
Level and Flood Level pursuant to 40D-8.603.
6) "Pre-modification" a period prior to when the lake level fluctuations were
altered by anthropogenic activities.
(7) "Post-modification" a period after lake level fluctuations were altered by a
surface water conveyance system.
S8) "Recovery Flow or Level" a flow or level below the minimum flow or level
that is used as an interim level in areas where the existing flow or level is below the
minimum flow or level, as part of the District's recovery strategy set forth in Chapter 40D-
80, F.A.C.
(9) "Water Resources" waters in the state, including surface water and around
water, and associated natural systems.
(3) "Minimum flood level" means the highest level to which a surface water body
shall be allowed to fluctuate without interference except as approved by the Board for the
purpose of conseoring the waters in the State so as to realize their full beneficial use. Such
level shall be expressed as an elevation, in feet above mean sea level.


DRAFT J








(4) "Ten (10) yoar flood warning level" means that elevation in feet above sea
level, which approximates the level of flooding expected on a frequency of not less than



(5) -"Best surface water management practice" in the design, construction,
operation, and maintenance of structures or devices requires a consideration and
evaluat en of both Iong-trm and short term effects of the activity upon the water resource
of the District. Factors to be considered include the following:
(a) Conservation and proper utilization of surface water.
GenS p(b) A Preventiron of damage from floods, soiel erosion, and xco ssive
drainage.
() Preservation of natural resources, fish, and wildlife.
(d) Storage for aquifer recharge.
(e) Non consumptive uses, including but not limited to, navigation,


Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Amended 1-22-79, Formerly 16J-8.02,
Amended

40D-8.031 Implementation.
(1) The provisions of Chapter 40D-8 of these rules shall continue to be
implemented as of May 2, 1978, within the Hillsborough River, Northwest Hillsborough,
Green Swamp, Alafia River, Coastal Rivers, Manasota, Peace River, Withlacoochee River
and Pinellas-Anclote River Basins and shall be implemented immediately and shall apply
within the area annexed into the District by Chapter 78-65, Laws of Florida., aRd shall apply
as follows:
(a) Management levels of lakes and other impoundments as prescribed
herein shall become effective immediately upon:
1. Installation of a staff gauge in a prominent location on the water
bedYui
2. Posting of notice to the public pursuant to Rule 4ID 8.616; and
3. Publication of notice in a n-ws papnor having general circulation

(b) The xtreme low mIanagement level as adjusted by the cyclic variation
shall become effective when similar notice has been given.
(2) No Guidance Fnagoement LUevels shall be prescribed for any reservoir or
other artificial structure which is located entirely within lands owned, leased, or otherwise
controlled by the user, and which require water only for filling, replenishing, and maintaining
of the water level thereof, provided however:
(a) That Chapter 40D-2 rules shall apply to the use of water for such
filling, replenishing, and maintaining of the water level, and
(b) That the Pre-modification or Post-modification Annual High, as
applicable minimum flood level pursuant to Rules 40D 8.021 and 4OD 8.611 and the Ten


DRAFT J 8-3









1 Year Fflood Wwarning Lievel, all as determined pursuant to the procedures set forth in the
2 District's Lake Level Methodology Manual incorporated by reference in Rule 40D-8.091
3 pursuant to Rules '0D 8.021 and .OD 8.613 may be established for any lake or other
4 impoundment determined by the Board to be in the public interest.
5 (3) No Guidance management Lievels shall be prescribed for Lake Manatee in
6 Manatee County, Ward Lake in Manatee County, the City of Tampa Reservoir on the
7 Hillsborough River in Hillsborough County, and the Peace River/Manasota Regional Water
8 Supply Authority Reservoir Gencral nDovlopment Utilities Reservoir constructed ;n
9 connection with the Southwest Florida Water Managoment District's Permit Numbers
10 7500016, 7-1172, and 75 290 in DeSoto County.
11 () The Governing Board shall establish minimum flows and levels pursuant to
12 Sections 373.042 and 373.0421, F.S. considering the following factors which, if present,
13 are unique for each water body for which flows or levels are established:
14 (a) Recreation, navigation, or aesthetic and scenic attributes supported
15 by the water body, including use of the water body for:
16 1_ Powerboats;
17 2. Boat docks;
18 3. Canoes, Kayaks and other paddle-propelled boats:
19 4. Sailboats;
20 5. Swimming;
21 6. Diving;
22 7. Snorkeling;
23 8 Scuba Diving:
24 9. Fishing; or
25 10. Sensory beauty.
26 b) Alterations to hydrologic regimes, either natural, permitted under
27 programs authorized by Part 1 or Part 4 of Ch. 373, F.S., or exempt from permitting,
28 where:
29 1. The alterations were not caused by water withdrawals, and
30 2_ The alterations have changed the hydrologic characteristics and
31 ecology of the waterbodv and the impacts of these alterations are scientifically
32 established, and
33 3_ There is no other practicable means of offsetting their impact
34 (e.g. augmentation downstream of a dam).
35 (5) In areas where the existing flow or level is below the established minimum
36 flow or level:
37 a) Existing permits with withdrawals that impact such flows or levels shall
38 not be considered to automatically be in violation of the flow or level;
39 b) Pursuant to 373.042(2), F.S. the District shall develop a recovery
40 strategy. A portion of the recovery strategy will be contained within 40D-80, F.A.C., the
41 District's Water Management Plan and the Regional Water Supply Plan for the area within
42 which the applicable waterbody is located; and
43 (c) Permits affecting the established flows or levels will be adjusted
44 during the term of the permit or upon permit renewal in accordance with the recovery
45 strategy.


DRAFT J









1 (d Unless otherwise provided for in the District's recovery strategy, where
2 the existing flow or level is below the minimum flow or level, additional withdrawal
3 quantities that would contribute to violation of the flow or level and which are inconsistent
4 with the District's recovery strategy will not be allowed.
5 (6) Where the existing flow or level is above the minimum flow or level, permits
6 shall not be granted that would cause the actual flow or level to fall below the minimum flow
7 or level on a long-term average basis.
8 (7~ Establishment of a minimum flow or level shall not be deemed to be a
9 determination by the Governing Board that any quantity above the established minimum
10 flow or level is available for allocation to consumptive uses. Additionally, the Conditions
11 for Issuance of 40D-2.301, 40D-4.301, and 40D-4.302 F.A.C., and all pertaining sections
12 within the Bases of Review described in 40D-2.091 and 40D-4.091, F.A.C. are required to
13 be met irrespective of a permitted's demonstration of compliance with the minimum flows
14 and levels requirements established herein and in Chapter 40D-80, F.A.C.
15 (8) A portion of the regulatory element of the recovery strategy for Northern
16 Tampa Bay is contained within Chapter 40D-80, F.A.C. at section 40D-80.073.

17 Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 120.53,
18 373.016, 373.023, 373.042, 373.0421, 373.044, 373.086, 373.103 FS. History New 6-7-
19 78, Amended 10-16-78, 1-22-79, Formerly 16J-8.03, Amended 3-23-81,

2 0 40D-8.041 Minimum Rates of Flow and Levels.
21 (1) Minimum Flows For the Lower Hillsborough River
22 (a) For the purposes of minimum flows the Lower Hillsborouah River is
23 defined as the river downstream of Fletcher Avenue. The Lower Hillsborouah River
24 includes Sulphur Springs, an artesian spring that enters the river via a short spring run
25 located 2.2 miles downstream of the Hillsborough River.
26 (b) The Minimum Flow for the Lower Hillsborough River at the base of the
27 City of Tampa's dam shall be ten (10) cubic feet per second (cfs) when the surface water
28 elevation at USGS gage 02304500 is at or above 18.0 feet NGVD and 0 cfs when the
29 surface water elevation is below 18.0 feet NGVD. This minimum flow has been determined
30 based on the structural alterations in and along the River and the dependence of viable
31 ecological communities downstream of the dam with flows from the Hillsborough River
32 Reservoir and Sulphur Sprinqs.
33 (c) The District will establish a minimum flow for Sulphur Springs in the
34 future. As part of that process the District will evaluate if additional flows from Sulphur
35 Springs are available to supplement the minimum flow for the Hillsborough River at the
36 base of the City of Tampa's dam.
37 (2) Minimum Flows for the Tampa Bypass Canal
38 (a) The Tampa Bypass Canal extends 12 miles from above Fletcher
39 Avenue to McKay Bay. Structure 160 serves as the barrier between the freshwater and
40 tidal portions of the Tampa Bypass Canal.
41 (b) The Minimum Flow for the Tampa Bypass Canal at Structure 160 is
42 0 cfs. This Minimum Flow accounts for the structural nature of the Canal, its operational


DRAFT J


__









1 constraints and the relationship of ecological communities in the tidal reaches of the Canal
2 and McKay Bay with freshwater flows through Structure 160.
3 c) The Minimum Flow for the Tampa Bypass Canal at Structure 160 is
4 established specific to the physical configuration and operations constraints of the Tampa
5 Bypass Canal as they exist at the time of adoption. If physical modifications to the Tampa
6 Bypass Canal are made, the District shall reevaluate the Minimum Flow at Structure 160.
7
8 Specific Authority 373.044, 373.133, 373.149, 373.171 FS. Law Implemented 373.042,
9 373.086, 373.339 FS. History Readopted 10-5-74, Amended 12-31-74, Formerly 16J-
10 0.15, 40D-1.601, Amended 10-1-84,

11 40D-8.091 Publications Incorporated By Reference
12 The determination of Guidance Flood Levels, including the Annual High and Low
13 Levels, and Minimum Lake Levels set forth in 40D-8.603 and 40D-8.624 are more
14 particularly described in the Lake Level Methodology Manual, dated 1997 which
15 is hereby incorporated into this chapter. This document is available from the District upon
16 request.

17 Specific Authority 120.54, 373.016, 373.023, 373.044, 373.103, 373.113, 373.133,
18 373.149, 373.171 FS. Law Implemented 120.53, 120.54, 373.016, 373.023, 373.026,
19 373.0395, 373.042, 373.0421, 373.044, 373.086, 373.103, 373.171, 373.339 FS. History -
20 New

21 40D-8.603 Management Guidance Levels for Lakes and Other Impoundments.
22 M1 Guidance Levels and Minimum Levels adopted by the Governing Board in
23 August, 1997 or later and the method for calculating those levels are set forth in 40D-8.603
24 and 8.624(3) and (4). Guidance Levels adopted by the Governing Board prior to August
25 1997 are listed in 40D-8.624(5).
26 (2) Flood Levels
27 (a) The Ten (10) Year Flood Warning Level is provided as an advisory
28 guideline for lake shore development. The Ten (10) Year Flood Warning Level,
29 incorporates the level of flooding expected on a frequency of not less than the ten (10) year
30 recurring interval, or on a frequency of not greater than a ten percent (10%) probability of
31 occurrence in any given year. The Ten Year Flood Warning Level is calculated as
32 described in Chapter Two of the District's Lake Level Methodology Manual described in
33 40D-8.091.
34 (b) The Pre-modification Annual High Level for lakes is the highest level
35 to which a lake is expected to fluctuate on an average annual basis. The Pre-modification
36 Annual High Level is calculated as described in Chapter Three of the District's Lake Level
37 Methodology Manual described in 40D-8.091.
38 c) The Post-modification Annual High Level, for lakes with hydrologic
39 regimes modified by surface water conveyance systems or natural occurrences (e.g.
40 sinkholes) is the highest level to which a lake is expected to fluctuate on an average annual
41 basis. The Post-modification Annual High Level for lakes with an adjustable structure is
42 a peaking elevation and not one which is maintained. The Post-modification Annual High


DRAFT J









1 Level is calculated as described in Chapter Four of the District's Lake Level Methodology
2 Manual described in 40D-8.091.
3 (3) Low Levels
4 (a) The Pre-modification Annual Low Level is the expected annual low
5 level of a lake. The Pre-modification Annual Low Level is calculated as described in
6 Chapter Three of the District's Lake Level Methodology Manual described in 40D-8.091.
7 (b) The Post-modification Annual Low Level, for lakes with hydrologic
8 regimes modified by anthropogenic activities excluding withdrawals or natural occurrences
9 (e.g. sinkholes) is the expected annual low level of a lake which has been influenced by
10 such activities and which no longer fully exhibits pre-modification fluctuations. The Post-
11 modification Annual Low Level may be used as a guide to operate a lake control structure,
12 for those lakes with control structures. The Pre-modification Annual Low Level is
13 calculated as described in Chapter Four of the District's Lake Level Methodology Manual
14 described in 40D-8.091.
15 (4) Posted Notice
16 a) Staff gauges will be installed in prominent locations on each lake for
17 which Guidance Levels or Minimum Levels have been established. A notice shall be
18 posted in the immediate proximity of the staff gauge indicating that levels have been
19 established.
20 (b) The notice shall indicate the elevations of the Annual High Level and
21 the established Minimum Level.
22 (5) Renaming of Levels
23 (a) Levels previously established as Minimum Flood Levels shall now be
24 known as Annual High Levels.
25 b Levels previously established as Minimum Low Management or
26 Minimum Extreme Low Levels shall now be known as Low Levels and Extreme Low
27 Levels, respectively.
28 (1) In establishing minimum water levels, minimum flood levels and other
29 management levels for lakes and other impoundments, the Board shall usc thh best
30 informationn available.
31 (2) Data from technical publications, topographic maps, Geological Survey Water
32 Data Repors and other studies and records may be considered. Information may also be
33 obtained from aerial mapping, hydrographs, botto-m ,contour mapping, stage duration
34 curves, water quality records, stratified beach deposits, precipitation data and other
35 souFres.
36 (3) Field investigation may be used to determine past surface l vls from water
37 marks, wetland vIgntatin; and d- r land I gn tatin an d ton establish; h the elevatin If n.;.
38 tanks, docks, sea walls, roads, and floor slabs and to secure other pelincnt information.

39 Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
40 373.042, 373.044, 373.086 FS. History New 6-7-78, Formerly 16J-8.672, Paragraphs
41 (2)(h) and (i) Formerly 16J-8.6721, Paragraph(4) Formerly 16J-8.673, Amended
42

43 40D-8.605 Cyclic Variations for GuidanceMinimum Water Levels.


DRAFT J









{4-) For lakes and other impoundments with a District-owned control structure the
elevation of the minimum water levels established for a lake or other impoundment shall
be lowered below the applicable low management- level periodically to allow fluctuation
necessary for the preservation of natural resources, fish and wildlife, and for the protection
of non-consumptive uses. The lowered level is designated the extreme low management
Level
2)\ The low managrmoant laevl shall b the applicable minimum water lval for
such lake or othkr im poundmnt until flour (1\) aconsutiv years havo passed during wh;h
the actual water level has failed to recede to the extreme low management level; in which
event the extreme low management level shall become the applicable minimum water level
for the lake or otheFr impoundment until the actual wateFr level recedes to or below the
extreme low management level. Whenever the actual water level recedes to or below the
extreme low management level, the applicable minimum water level for the lake or other
impoundment shall immediatelyy ha raised onc again to the low management level and the
cyclic variations shall Rcontinue.
Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044, 373.086 FS. History New 6-7-78, Formerly 16J-8.671, Amended


40D-8.611 Minimum Flood Levels
(1) Th minimum flood level indicates, the minimum level to which high water m.ay
be expected to rise on a somewhat regular basis and willno not nessarily correspond to any
particular flood frequency. Fleed waters may often rise above the minimum flood levl.
(2) Docks, sea walls, septic tanks, drain fields, floor slabs, and other physical
;improvm~nts, on land na r lakes rd ether impoundments for which management levels
havo been established, should be so located and construted that thi r function will not be
impaired by rising water.
(3) No structure, improvement, or device shall be constructed or operated in
such a manner as to diminish the capability of a lake or other impoundment to fluctuate
through the full management range established for such impoundment.
(4) Property owners are hereby advised that compliance with District Rules and
Regulations does not relieve owners of the responsibility of complying with other

the National Flood Insurance Program.

Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.672, Repealed

40D-8.613 Ten (10) Year Flood Warning Levels.
(1) Flood warning Iev els are provided for a suface water body as an advisory
statement for the public interet. Property owners, publir.c officials and the general public
are advised that flooding on a frequency of not less than a ten (10) year recurrinFg interal
is expected to occur at the indicated elevation. Flood waters may often rise above- th
flood warning level.


DRAFTJ 8-8









1 -(2) Floor slabs, septic tanks and drain fields, docks, sca walls and other physical
2 improvemnts, on land near lakes and other impoundments for which flood warning levels
3 have been established, should be so located and constructed sufficiently above the flood
4 warning level such that their functions will not be impaired by the rising water.

5 Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
6 373.042, 373.044 FS. History New 1-22-79, Formerly 16J-8.6721, Repealed
7

8 40D-8.616 Posted Notice.
9 (1) Staff gauges w.Aill be installed in prominent locations on each lake or other
.0 impoun-dment for which a management rang has be-n established. A notice shall be
.1 posted in the immediate proximity of the staff gauge indicating that management levels

.3 L(2) Th notice shall indicate the elevations of the minimum flood level and the
.4 applicable minimum water level.

.5 Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
.6 373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.673, Repealed
.7

8 40D-8.621 Operating Levels for Lakes, and Other Impoundments with Structures.
9 (1) Schedules, levels, and procedures for operation of lakes and other
0 impoundments equipped with structures shall be established by the Board.
1 (2) The operating range for a structure of a lake or other impoundment shall be
2 prescribed as that between the high operating level and the low operating level.
3 (a) High operating level shall be established by the Board in consideration
4 of public testimony and in keeping with the best lake control management sufae-wate
5 (managemnt practices.
6 (b) Low operating level shall be established by the Board in consideration
7 of public testimony and in keeping with the best lake control management srface- water
8 management practices.
9 (3) Best lake control management practices in the design, construction,
0 operation, and maintenance of structures or devices requires a consideration and
1 evaluation of both long-term and short-term effects of the activity upon the water resources
2 of the District. Factors to be considered include the following:
3 ) Conservation and proper utilization of surface water.
4 (b) Prevention of damage from floods, soil erosion, and excessive
5 drainage.
6 c) Preservation of natural resources, fish and wildlife.
7 (d Storage for aquifer recharge.
8 (e) Non-consumptive uses, including but not limited to, navigation,
9 recreation, and aesthetics.
0 (43) A prescribed schedule for operation of all lakes and other impoundments with
1 structures shall be established by the Board. The schedule will contain time sequences


DRAFT J









1 by which the levels of the water body will be maintained throughout the established
2 management range. While recognizing the difficulty of maintaining precise control of actual
3 levels, the schedule shall provide the guideline by which the operator of the structure will
4 attempt to maintain the prescribed levels insofar as he has control.

5 Specific Authority 373.016, 373.023, 373.044, 373.103 FS. Law Implemented 373.016,
6 373.042, 373.044 FS. History New 6-7-78, Formerly 16J-8.677.

7 40D-8.624 Sehedule-of Levels for Lakes, and, Wetla nd d Other Impoundment.
8 ( Establishment of Minimum Wetland Levels
9 (al The minimum level for isolated, cypress dominated wetlands shall be
10 that level which is 1.7 feet below a reference elevation referred to as the normal pool
11 elevation. Wetland water levels are deemed to be below the Minimum Level when the
12 median stage is below the Minimum Level based on a six year monitoring period.
13 b The normal pool elevation shall be determined based on a
14 consideration, utilizing professional judgement, of biological indicators of sustained
15 inundation such as:
16 1_ The lower limit of epiphytic mosses and liverworts intolerant of
17 sustained inundation;
18 2. The upper limit of the root crown on Lyonia lucida growing on
19 tree tussocks;
20 3. The upper limit of adventitious roots on Hypericum fasiculatum
21 and other species which exhibit this morphologic response to sustained inundation;
22 4. Other indicators which can be demonstrated to represent a
23 similar period of sustained inundation.
24 (2 Minimum Levels for wetlands are hereby established as set forth in the
25 following table. For those wetlands whose Minimum Level elevation is followed by an
26 asterisk (*), it has been deemed that upon the effective date of the rule adopting the
27 Minimum Level that the wetland water levels are below the Minimum Levels as described
28 in 40D-8.624(1)(a) above.
29

30 Location Wetland Identification Minimum Level
(NGVD)

31 TBD TBD TBD

32 (3) Establishment of Minimum Lake Levels
33 a Pre-modification Lakes (PrM) the Minimum Level shall be the Pre-
34 modification Annual Low Level as calculated pursuant to 40D-8.603. The lake level is
35 deemed to be below the Minimum Level when the elevation representing the P50 is
36 depressed below the Annual Low Level for greater than 50% of the time for at least a six
37 year period.


DRAFT J


8-10









(b) Post-modification Lakes with at least six years of hydrologic data
(PMD) the Minimum Level is the P50 as determined from the stage data used to establish
the Post-modification Annual High and Low Levels pursuant to 40D-8.603. The lake level
is deemed to be below the Minimum Level when the elevation representing the P50 is
below the Minimum Level more than 50% of the time for at least a six year period.
(c) Post-modification Lakes with less than six years of hydrologic data or
lakes without six years of hydrologic data prior to impacts due to water withdrawals (PMND)
- the Minimum Level is the midpoint between the Post-modification Annual High and Low
Levels elevations as determined pursuant to 40D-8.603. The lake level is deemed to be
below the Minimum Level when the elevation representing the P50 is below the Minimum
Level more than 50% of the time for at least a six year period.
(d) If insufficient data exists to determine if the lake level is below the
Minimum Level pursuant to 40D-8.624(3)(a) (c) above, the lake level can be determined
to be below the Minimum Level based on a comparison with similar lakes by use aerial
photographs and evaluation of biological indicators.
(44) Levels for lakes and other impoundme ns are hereby established as set forth
in the following table .ellews- After the Minimum Level elevation for each lake an
abbreviation of PrM, PMD or PMND is listed. The abbreviation indicates which of the


methodologies described in 40D-8.624(3) above was used to calculate the Minimum Level.


Guidance Levels established prior to August 1997 are set forth in 40D-8.624(5) below.


For those lakes whose Minimum Level elevation is followed by an asterisk (*), it has been
deemed that upon the effective date of the rule adopting the Minimum Level for those lakes
the lake level is below the Minimum Level as described in 40D-8.624(3)(a)-(b) above.

Location by County and Name of Ten Year Annual Annual Minimum
Basin Lake Flood High Low Level
Guidance Guidance Guidance (NGVD)
(NGVD) (NGVD) (NGVD)
(a) In Charlotte County
Within The Peace River
Basin
(b) In Citrus County
Within The Coastal
Rivers Basin
(c) In Citrus County
Within The
Withlacoochee River
Basin
(d) In DeSoto County
Within The Peace River
Basin


DRAFT J


-~----- ~---~---~~- `~~- ~~~~~~~~~~~~`~ --~-~~


8-11









(e) In Hardee County
Within The Peace River
Basin
(f) In Hernando County
Within The Coastal
Rivers Basin
(a) In Hernando County
Within The
Hillsborough River
Basin
(h) In Hernando County
Within The
Withlacoochee River
Basin
(i) In Highlands County
Within The Peace River
Basin
(i) In Hillsborough
County Within The
Alafia River Basin
(k) In Hillsborouqh
County Within The
Hillsborouah River
Basin
(I) In Hillsborough Sapphire 64.1 63.5 61.9 62.7*
County, Within the Lake (PMND)
Northwest Hillsborough S-14,T-
Basin, 27,R-18

Cypress 49.5 48.9 47.3 48.1*
Lake (PMND)
S-24,T-
27,R-17
Dosson 55.1 53.4 50.0 52.1*
Lake (PMD)
S-20,T-
27,R-18


DRAFT J


8-12









Sunshine 55.1 52.8 50.6 51.7*
Lake (PMND)
S-20,T-
27,R-18
Lake 54.2 53.0 51.4 52.2*
Helen (PMND)
S-19,T-
27,R-18
Lake Ellen 54.2 53.0 51.4 52.2*
S-19,T- (PMND)
27,R-18
Lake 54.2 53.0 51.4 52.2*
Barbara (PMND)
S-19,T-
27,R-18
Little Moon 41.0 40.8 38.9 38.9*
Lake (PMND)
S-28,T-
27, R-17
(m) In Lake County
Within The Green
Swamp Basin
(n) In Levy County
Within The
Withlacoochee river
Basin
(o) In Manatee County
Within The Manasota
Basin
(p) In Marion County
Within The
Withlacoochee River
Basin
(a) In Pasco County Big Fish 76.9 76.5 74.6 74.6*
Within the Coastal Lake (PrM)
Rivers Basin, S-21,T-
24,R-19


DRAFT J


8-13









(r) In Pasco County
Within The Green
Swamp Basin
(s) In Pasco County
Within The
Hillsborough River
Basin
(t) In Pasco County
Within The Pinellas-
Anclote River Basin
(u) In Pasco County
Within The
Withlacoochee River
Basin
(v) In Pinellas County
Within The Pinellas-
Anclote River Basin
(w) In Polk County
Within The Alafia River
Basin
(x) In Polk county
Within The Green
Swamp Basin
(y) In Polk County
Within The
Hillsborough River
Basin
(z) In Polk county
Within The Peace River
Basin
(aa) In Sarasota
County Within The
Manasota Basin
(bb) In Sumter county
Within The Green
Swamp Basin


DRAFT J


8-14















the following
the following


Guidance Levels established for lakes prior to August, 1997 are set forth in


table:


*******CLAUDIA INSERT "OLD" TABLE HERE**********

Specific Authority 373.044, 373.113, 373.171 FS. Law Implemented 373.016, 373.042,
373.103 FS. History New 6-7-78, Amended 1-22-79, 4-27-80, 10-21-80, 12-22-80, 3-23-
81,4-14-81, 6-4-81,10-15-81, 11-23-81, 1-5-82, 3-11-82, 5-10-82, 7-4-82, 9-2-82, 11-8-82,
1-10-83, 4-3-83, 7-5-83, 9-5-83, 10-16-83, 12-12-83, 5-8-84, 7-8-84, 12-16-84, 2-7-85,
5-13-85, 6-26-85, 11-3-85, 3-5-86, 6-16-86, Formerly 16J-8.678, Amended 9-7-86, 2-12-
87, 9-2-87, 2-18-88, 6-27-88, 2-22-89, 3-23-89, 9-26-89, 7-26-90, 10-30-90, 3-3-91, 9-30-
91, 10-7-91, 7-26-92, 3-1-93, 5-11-94, 6-6-96, 2-23-97,

40D-8.626 Minimum Aquifer Levels in Northem Hillsborough, Pasco, and Pinellas
Counties

1} The minimum aquifer level shall be the elevation expressed in feet relative
to N.G.V.D. which represents the limit at which further withdrawals would be significantly
harmful to the water resources of the area. This level shall be a long-term average water
level and shall be used as a long-term average when evaluating water use permit
applications.
(2) Determination of the Minimum Aquifer Level
Within Hillsborough, North of U.S. Highway 60, Pasco and Pinellas Counties, the Minimum
Aquifer Level for the Upper Floridan aquifer system (UFAS) shall be calculated based on
the relationship between water levels in the Upper Floridan aquifer and water levels in the
surficial aquifer system (SAS) and associated wetlands. The minimum aquifer level is
determined using the following steps:
(a) Determine the pre-withdrawal level at the well;
(b Estimate the allowable Floridan aquifer water level drawdown at the
well;
(c) Subtract the allowable Floridan drawdown from the pre-withdrawal
water level to calculate the minimum level.
(3) The pre-withdrawal water level represents the level in a Floridan aquifer
monitor well before the existence of significant around water withdrawals in the vicinity of
the well. The pre-withdrawal water level is estimated for each site using the following
methods:
(a) If five years or more of the pre-withdrawal data for the well are
available, then the pre-withdrawal level is calculated by taking the average of the pre-
withdrawal water level data.


DRAFT J


(cc) In Sumter County
Within The
Withlacoochee River
Basin


I I F


8-15









1 (b) If one to four years of pre-withdrawal data are available, then the pre-
2 withdrawal level is calculated by taking the average of the pre-withdrawal water level data
3 and verifying that the available pre-withdrawal water level record represents average
4 climatic conditions. This is performed by assessing rainfall records of the area, or by
5 adding the long-term average cumulative drawdown at the well to the current long-term
6 average water level of the well, and comparing the result to the average of the available
7 pre-withdrawal water level record at the well. The current water level is the average water
8 level over a period when historic ground-water withdrawals near the well were nearly
9 constant (annual pumpage varied by less than 20 percent from the long-term average).
10 The long term average drawdown is estimated using the best available methodology.
11 (c) If no pre-withdrawal water level data for the well are available, then the
12 pre-withdrawal water level is determined by adding the long term average cumulative
13 drawdown at the well to the current long term average water level of the well.
14 (4 Allowable Floridan aquifer water level drawdown
15 (a For each location chosen for establishment of a Minimum Aquifer
16 Level, the allowable drawdown in the UFAS is determined based on the allowable
17 drawdown in the surficial aquifer system and associated wetlands. The ratio of surficial to
18 Floridan allowable drawdown is based on the Upper Floridan aquifer leakance coefficient
19 for the area surrounding the minimum aquifer level well.
20 b The wetland minimum level based on 40D8.624(2) is 1.7 feet below
21 the wetland normal pool. Because the median P50 wetland water level for healthy cypress
22 wetlands is 1.0 foot below normal pool, the wetland minimum level represents 0.7 feet of
23 long-term average drawdown in the wetland.
24 cl For the purpose of calculating the Floridan aquifer minimum level at
25 the locations specified in Chapter 40D-8.626(6), below, a drawdown of 0.7 feet in the
26 surficial aquifer is assumed to represent a drawdown of 0.7 feet in the wetland. The
27 following procedure outlines how the 0.7 foot drawdown in the surficial aquifer is used to
28 calculate the allowable Floridan aquifer drawdown:
29 1_ The Floridan aquifer drawdown that would cause 0.7 feet of
30 surficial aquifer drawdown is estimated from Figure 1, a type curve which was developed
31 using the Northern Tampa Bay Regional Ground-water Flow Model. For development of
32 the type-curve, the surficial and Floridan aquifers drawdown was determined for each
33 active cell in the model.
34 2. The ratio of surficial to Floridan aquifer drawdown was then
35 calculated and plotted against the value of leakance for that model cell.
36 3 To calculate the allowable Floridan aquifer drawdown at the
37 proposed minimum level well, the leakance between the surficial aquifer and the Upper
38 Floridan aquifer shall be estimated for the area of the minimum aquifer level well. Best
39 available data with respect to the leakance value can include aquifer performance test
40 results or calibrated ground-water flow model leakance coefficient data.
41 4. Using the site specific leakance determined in 40D8.626(4)(c),
42 the ratio of surficial to Floridan drawdown for the well site is determined from Figure 8-1 by
43 noting where the vertical line for a particular leakance coefficient intersects the type curve
44 and then reading across for the appropriate drawdown ratio value.


DRAFT J


8-16









) Minimum aquifer level calculation Once the pre-withdrawal level and the
allowable Floridan aquifer drawdown are determined, the allowable Floridan aquifer


3 drawdown is
4 (6)


subtracted from the ore-withdrawal level to determine the Minimum Level.


Minimum Aquifer Levels shall be established as follows:


Well Latitude Longitude SAS/UFAS Minimum
Name Ratio Level
(NGVD)
(a) T-1 280708 820748 0.4 84.59
(b) T-2 280510 820438 0.4 94.92
(c) T-3 280849 820537 0.4 89.56
(d) A-1 282149 822815 0.7 66.8
(e) CB3E 282221 822419 0.6 69.2
(f) TMR1 281719 822246 0.9 65.5

(g) TMR3 281745 822342 0.5 64.5
(h) MW500 281204 822240 0.5 51.6
(i) 2-1000 281019 822114 0.7 58.9
(j) MB1 280652 822042 0.4 31.8
(k) MB6 280628 822007 0.4 25.6
(I) MB13 280656 821751 0.4 29.2
(m) 280703 823027 0.4 46.4
HILLSB 13
(n) 280834 823435 0.1 27
CALM33 A
(o) 280653 823415 0.4 33.2
JAMES11

(p) 280608 823529 0.2 27.6
COSME3
(q) EW005 281021 823956 0.6 22.7
(r) EW11 280905 823905 0.4 24.5
(s) EW142 281018 823808 0.8 29


DRAFT J


i


8-17









(t) MATTS 281102 822924 0.8 62.6
(u) SP42 281036 823056 0.2 51.9
(v) 281006 823852 0.4 42.4
1A EAST
(w) 280922 823955 0.8 30.9
1A WEST
(x) 281907 823344 0.9 46.4
NPMW-2
(y) Debuel 55.4
(z) Lutz 57.6
Park
(aa) 42.2
Buchanan
(bb) 31.1
RMP8D1
(cc) 31.4
Hutchinson
#59
(dd) 45.0
Claywell
Elem.
(ee) N2 24.8
(ff) N4 32.0
(gg) Eagles 20.9
WRAP
(hh) Lutz 44.6
Lake Fern
(ii) 52.3
Ledantec
(jj) Starkey 35.2
Regional
(kk) Starkey 43.4
1A East


DRAFT J


8-18









(II) Starkey 28.7
707
(mm) MW1 34.4
(nn) Seven 21.0
Springs
Deep
(oo) Starkey 42.9
Ranch
WRAP

(pp) 44.5
NPMW-7

(qq) 41.7
NPMW-11
(rr) SR52 51.9
West
(ss) TMR4 60.5
(tt) SR52 73.2
East
(uu) WRW 52.9
(vv) CB1SE 72.5
(ww) FK6 70.7
(xx) Morris 28.8
Bridge 1
(yy) Morris 30.3
Bridge 13
(zz) DGW2 40.5
(aa) 51.2
DMW500


Snecific Authority 120354. 373.042. 373.044. 373.113. 373.171


FS. Law Imolemented


DRAFT J


120.54. 373.016, 373.023, 373.0395, 373.042, 373.171 FS. History New


8-19









1 Lake Level Methodology Manual
2

3 CHAPTER ONE INTRODUCTION

4 1.1 Objectives Under Part I of Chapter 373, Florida Statutes (FS) and Chapter 40D-8,
5 Florida Administrative Code (FAC), the District is responsible for establishing
6 minimum levels for lakes within its jurisdiction. Pursuant to Chapter 373.042, FS,
7 minimum levels shall be calculated using best available information, and may reflect
8 seasonal variations. The District shall also consider, and at their discretion may
9 provide for, the protection of non-consumptive uses in establishment of Minimum
10 Levels. The objective of this document is to identify and describe the usual
11 procedures and methods used by District staff in determining and proposing lake
12 levels to the Governing Board.

13 1.2 History of the Lake Levels Program Since the mid-1970's, the District has
14 maintained a program to adopt management levels for lakes throughout the District.
15 These management levels were selected to be representative of a healthy
16 fluctuation range for each lake and can be used for water management purposes.


17 Prior to 1996, management levels had been set on 397 lakes. However, in 1996,
18 revisions to Chapter 373, Florida Statutes resulted in changes to the Lake Levels
19 Program. The most substantial change to the program was the requirement that a
20 Minimum Level be established. This Minimum Level is the level of a lake at which
21 further withdrawals would be significantly harmful to the water resources of the area.
22 As a result of the 1997 rule revisions, the terms management levels, Minimum Flood
23 Level and Low Management Level were changed to guidance levels, Annual High
24 Level and Annual Low Level, respectively. The Extreme Low Level was deleted
25 from the methodology and will no longer be an adopted level.

26 1.3 Criteria for Inclusion of Lakes in the Lake Levels Program Historically, lakes were
27 included in the lake levels program based on several criteria. These criteria
28 included lakes with District water control structures, lakes with water use permits
29 and lakes 20 acres or larger with multiple owners. In response to legislative
30 mandates in 1996, criteria were added to the lake selection process which
31 emphasized lakes located in Water Resource Caution Areas, lakes in the vicinity of
32 major water withdrawals and lakes specifically identified by local governments or
33 other entities. The revisions to Chapter 373, F.S. also required that the District
34 adopt a Minimum Flows and Levels (MF/L) Priority List. The MF/L Priority List,
35 which identifies the lakes and the time frames for establishing levels, is included in
36 the District Water Management Plan.

37 1.4 Levels Established under the Lake Levels Program -The levels defined below will
38 be established based on the procedures and methods discussed in this document.

40D-8.J 8-20









1 All levels shall be expressed in feet relative to National Geodetic Vertical Datum
2 (NGVD) of 1929.

3 Guidance Levels, as described in section 1.4. below, are established for all lakes
4 in the Lake Level program as follows. Pre-modification Guidance levels will be
5 determined for all lakes included in the Lake Levels Program. For lakes with
6 modified surface conveyance systems, Post-modification Guidance levels also will
7 be determined. The levels finally recommended to the Governing Board will depend
8 on the type of lake system. For lakes without modifications to the surface
9 conveyance systems, Pre-modification Guidance Levels will be recommended to
10 the Governing Board. For lakes with modified surface conveyance systems, Post-
11 modification Guidance Levels will be recommended to the Governing Board. Pre-
12 modification Guidance Levels for these lakes may be provided to the Board for
13 informational purposes.

14 A Minimum Level based on lake type will also be determined and recommended to
15 the Governing Board for lakes included in the Lake Level Program.

16 1.4.1 Guidance Levels determined by the District using the best available information
17 and expressed in feet relative to National Geodetic Vertical Datum, used as
18 advisory information, including for the District, lake shore residents and local
19 governments or to aid in the control of adjustable structures. Guidance Levels
20 include: Ten Year Flood Warning Level; Pre-modification Annual High Level; Post-
21 modification Annual High Level; Pre-modification Annual Low Level; and Post-
22 modification Annual Low Level.


23 1.4.2 Ten (10) Year Flood Warning Level is an advisory level provided as a discretionary
24 guideline for lakeshore development. The Ten (10) Year Flood Warning Level,
25 incorporates the level of flooding expected on a frequency of not greater than ten
26 percent (10%) probability of occurrence in any given year.

27 1.4.3 Pre-modification Levels refer to lake water regimes before impacts by human
28 activities and includes modification of surface water conveyance systems and water
29 withdrawals.

30 1.4.3.1 Pre-modification Annual High Level the highest level to which a lake is
31 expected to fluctuate on an average annual basis.

32 1.4.3.2 Pre-modification Annual Low Level approximates the average annual low
33 level of a lake.

34 1.4.4 Post-modification Levels refer to lake water regimes resulting from alterations to
35 the lake's surface water conveyance systems.


40D-8.J


8-21









1 1.4.4.1 Post-modification Annual High Level lakes with water regimes resulting
2 from alterations to the lake's surface water conveyance systems. The Post-
3 modification Annual High Level is the highest level to which a lake is
4 expected to fluctuate on an average annual basis.

5 1.4.4.2 Post-modification Annual Low Level lakes with water regimes resulting
6 from alterations to the lake's surface water conveyance systems. The Post-
7 modification Annual Low Level approximates the annual low level of a lake.
8 The Post-modification Annual Low Level may be used as a guide to operate
9 a lake control structure for those lakes with existing control structures.

10 1.4.5 Pre-modification Minimum Level the Pre-modification Annual Low Level. Non-
11 conformance with the Pre-modification Minimum Level occurs when the P50 from
12 the previous six (6) calendar years of hydrologic data falls below the Pre-
13 modification Minimum Level.

14 1.4.6 Post-modification Minimum Level For lakes with hydrologic data, the Post-
15 modification Minimum Level is the P50 as determined from the stage data used to
16 establish the Post-modification Annual High and Annual Low Levels. For lakes with
17 less than six years of hydrologic data or lakes without hydrologic data prior to
18 impacts due to water withdrawals, the Post-modification Minimum Level is the
19 midpoint between the adopted Post-modification Annual High and Annual Low
20 Guidance elevations. Non-conformance with the Post-modification Minimum Level
21 level occurs when the P50 from the previous six (6) calendar years of hydrologic
22 data falls below the Post-modification Minimum Level.

23 1.5 Definitions The definitions in this section apply to the determination of all levels
24 described in this document.

25 1.5.1 P10 a percentile ranking defined as the elevation of the water surface of a lake
26 that is equaled or exceeded 10 percent of the time as determined from a stage
27 duration analysis.

28 1.5.2 P50 a percentile ranking defined as the elevation of the water surface of a lake
29 that is equaled or exceeded 50 percent of the time as determined from a stage
30 duration analysis.

31 1.5.3 P90 a percentile ranking defined as the elevation of the water surface of a lake
32 that is equaled or exceeded 90 percent of the time as determined from a stage
33 duration analysis.

34 1.5.4 Reference Lake Water Regime (RLWR) is a regional factor that approximates the
35 typical annual range of lake level fluctuations for lakes within a similar hydrogeologic
36 setting. The RLWR corresponds to the difference between the annual high and
37 annual low Levels. It is used to estimate the Annual High or Annual Low Level for

40D-8.J 8-22









1 lakes without hydrologic data and biological indicators of one of the levels. (See
2 Chapter Five.

3 1.5.5 Stage Duration Curve a graphic representation of the percent of time the water
4 surface of a lake equals or exceeds a particular elevation. A stage duration curve
5 is developed by plotting lake level elevations against the cumulative frequency of
6 occurrence of those elevations for uniform increments of time e.g., monthly
7 readings.

8 1.5.5.1 Pre-modification Stage Duration Curve a stage duration curve prepared
9 using a minimum of six years of Pre-modification hydrologic data.

10 1.5.5.2 Post-modification Stage Duration Curve a stage duration curve prepared
11 using a minimum of six years of Pre-modification hydrologic data which
12 begins after the construction/installation of surface water conveyance
13 systems.

14 1.5.6 Pre-modification period before lake water regimes were impacted by human
15 activities such as alteration of surface water conveyance systems and water
16 withdrawals.

17 1.5.7 Post-modification period after lake water regimes were impacted by human
18 activities, specifically alterations to the surface water conveyance systems.


40D-8.J


8-23









1 CHAPTER TWO DETERMINATION OF 10 YEAR FLOOD WARNING LEVELS

2 2.1 General The Ten (10) Year Flood Warning Level shall be established using
3 methods that correspond to the hydrology and type of conveyance system of the
4 lake being evaluated. Generally, lakes are classified as open basin lakes that
5 discharge and closed basin lakes. Open basin lakes that discharge are those lakes
6 that have a surface water conveyance system that by itself, or in series with other
7 lakes, connects to or is part of an ordered stream or creek. A closed basin lake,
8 has no outlet conveyance system, or has an outlet system that overflows only during
9 peak elevations. The methodology to be used for the determination of the 10-year
10 Flood Warning Level of these two lake types is given below.

11 2.2 Lakes that discharge 10 Year Flood Warning Levels for lakes that discharge shall
12 be established using numerical single storm event models. Rainfall depths shall be
13 taken from Part D of the Environmental Resources Permitting Information Manual
14 (SWFWMD, 1996). Runoff volumes shall be computed using conventional methods
15 such as the Soil Conservation Service (SCS) curve number method, or with
16 standard infiltration formulas (e.g. Hortons Equation, Green-Ampt Equation). Runoff
17 distributions shall be computed using conventional methods including the SCS
18 method or other unit hydrograph methods, or the kinematic wave overland flow
19 method. Modeling programs that account for tailwater and compute backflow are
20 preferred for the hydraulic routing. The initial water level elevation used in the
21 model of a lake with no significant alterations to its natural surface conveyance
22 and/or outlet configuration shall be the Pre-modification Annual High Level as
23 defined in Chapter 3. The initial water level elevation of a lake with significant
24 alterations to its natural surface conveyance and/or outlet configuration shall be the
25 Post-modification Annual High Level as defined in Chapter 4. Exceptions shall be
26 based on peer review by the appropriate District staff and their consensus and
27 thoroughly documented in a report or memorandum to the project file.

28 2.3 Closed Basin Lakes 10-Year Flood Warning Levels for closed basin lakes and
29 lakes that overflow only during peak elevations shall be derived using a frequency
30 analysis of lake stage readings, or lake stages predicted by a physically based
31 numerical "continuous simulation model", or an empirical simulation model derived
32 either by linear or non-linear regression methods. The choice to use a linear or non-
33 linear regression technique shall be based on engineering judgement. The
34 simulation periods for either numerical or empirical models shall be based on not
35 less than thirty years of contiguous rainfall record. A composite of more than one
36 rainfall station in the region in which the subject lake is located is acceptable.
37 Calibration of the simulation model shall be based on as many indicators as
38 possible including, but not limited to, stage records and biological ans physical
39 indicators referenced in other parts of this document. If stage records do not exist
40 or the record does not contain peak elevation readings, then particular attention
41 should be given to obtaining eye-witness accounts of peak stages. Model


40D-8.J


8-24









1 simulations to determine the 10-Year Flood Warning Level shall exclude effects of
2 water withdrawals.


40D-8.J


8-25









1 CHAPTER THREE DETERMINATION OF PRE-MODIFICATION LEVELS

2 3.1 General Pre-modification Levels refer to lake water regimes prior to impacts by
3 human activities including modification of surface water conveyance systems and
4 water withdrawals. Pre-modification levels may be determined from one or a
5 combination of the following procedures: analysis of stage duration data; and
6 analysis of biological and physical water level indicators. Other information used
7 to determine Pre-modification Levels may include, but not be limited to, survey data,
8 maps and hydrologic data from such sources as the United States Geological
9 Survey, the Army Corps of Engineers and General Land Office Notes. For lakes
10 without stage duration data and biological indicators, the Pre-modification Annual
11 Low Level may be determined using the Reference Lake Water Regime described
12 in Chapter 5. If Pre-modification Levels are determined using more than one
13 procedure, the Pre-modification Levels finally recommended will be a reconciliation
14 of the procedures used.

15 If Pre-modification Levels are determined using more than one procedure, the Pre-
16 modification Levels finally recommended will be a reconciliation of the procedures
17 used. Reconciliation involves comparing the levels determined by the various
18 methods. If the Pre-modification Levels determined by each of the methods are
19 similar, then the levels determined from analysis of stage duration data take
20 precedence unless the stage duration data are determined to be impacted by water
21 withdrawals. If the levels determined by each of the methods are not similar, then
22 possible reasons for the difference should be investigated. Physical indicators
23 should only be used to determine the Pre-modification levels if biological indicators
24 and hydrologic data are not available for the lake.

25 Biological and physical indicators have been used to determine water levels.
26 (Cooke, 1939; Davis, 1973; Florida Board of Conservation, 1969; Holcomb &
27 Wegener, 1971; Kenner, 1961). This approach has been used primarily to
28 determine high-water levels on lakes (Bishop, 1967; Knochenmus, 1967). Dooris
29 and Courser (1976) related both high and low water levels to various biological,
30 hydrological and cultural features.

31 3.2 Analysis of Stage Duration Data This method applies only to lakes which have a
32 minimum six years of Pre-modification stage data.

33 3.2.1 Pre-modification Annual High Level The Flood Annual High Level is equal to the
34 elevation corresponding to the P10 value on a Pre-modification Stage Duration
35 Curve.

36 3.2.2 Pre-modification Annual Low Level The Pre-modification Annual Low Level is
37 equal to the elevation corresponding to the P90 value on a Pre-modification Stage
38 Duration Curve.


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1 3.3 Analysis of Biological and Physical Indicators This method is applied to lakes for
2 which one or more biological and/or physical indicators are present. The
3 methodology is based on known relationships between the location of wetland and
4 upland plant species and Pre-modification water levels.

5 3.3.1 Methods for Site Selection and Measuring Indicator Elevations Elevations of the
6 indicators described in this section shall be measured using accepted surveying
7 practices.

8 Locations for measuring biological indicators shall be chosen based on the
9 presence of the indicator plant species. Preferred locations will have naturally
10 vegetated wetlands around the lake, fringed by palmettos or other upland plant
11 species. As many transects as practical should be measured in each of these
12 areas. If multiple specimens of each indicator species occur on the lake, then
13 elevations should be determined for as many specimens as practical.

14 In the absence of naturally vegetated wetlands and uplands, elevations shall be
15 measured for any available biological indicators included in this document.
16 Activities which may have impacted elevations, such as, filling, soil subsidence, land
17 clearing and similar activities shall be considered and accounted for during
18 evaluation and analysis of the data. If no biological or physical indicators are
19 present, proceed to Chapters Four and Five.

20 3.3.2 Pre-modification Annual High Level Biological indicators of the Pre-modification
21 Annual High Level may include, but not be limited to, the following: palmetto
22 (Serenoa repens); cypress (Tax odium sp.); longleaf pine (Pinus palustrus); live oak
23 (Quercus virginiana); and mature wax myrtle (Myrica cerifera); liGheRs.

24 The method for measuring elevations of the indicator plants is described below.
25 Data recorded includes the elevation of the indicator species and for trees, the
26 diameter at breast height (DBH).

27 a. The elevation of the soil at the base of the lowest lakeward extent of the
28 palmetto (Serenoa repens) fringe is measured at the lowest rooted extent of
29 the plant.
30 b. The elevation of the soil at the base of the highest landward extent of the
31 cypress (Taxodium sp.) fringe is measured on the landward side of the tree
32 at the base of the trunk.
33 c. The elevation of the soil at the base of the lowest lakeward extent of longleaf
34 pine (Pinus palustrus) fringe is measured on the lakeward side of the tree at
35 the base of the trunk. Note: Only longleaf pine shall be used to establish the
36 Annual High Level.
37 d. The elevation of the soil at the base of the lowest lakeward extent of the live
38 oak (Quercus virginiana) fringe is measured on the lakeward side of the tree


40D-8.J


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1 at the base of the trunk for trees with a minimum diameter at breast height
2 (DBH) of 24".
3 e. The elevation of the soil at the base of the lowest lakeward extent of the
4 mature wax myrtle (Myrica cerifera) fringe is measured on the lakeward side
5 of the tree at the base of the trunk.

6 If more than one specimen of each indicator species is measured, then the average
7 elevation and standard deviation are calculated for the indicator species. The average
8 elevations of the indicator species are used in the analysis of the Pre-modification Levels.
9 If multiple biological indicators occur on the lake, then the Pre-modification Annual High
10 Level may be determined from the biological indicators using best scientific judgement.
11 If more than one indicator plant species is present and measured, then typically the priority
12 order for use of biological indicators is palmetto, cypress, pine and/or live oak and mature
13 wax myrtle.

14 In the absence of, or in support of, biological indicators, physical indicators may be used
15 to determine the Pre-modification Annual High Level. Physical indicators may include, but
16 not be limited to, one or a combination, of the following:

17 a. The elevation of the toe of the highest landward scarp line. (Bishop, 1967
18 and Knochenmus, 1967).
19 b. Analysis of historic aerial photography, topographic maps, surveys, site plans
20 or other information that may identify locations or elevations of biological
21 indicators of the Pre-modification Annual Level.
22 c. The elevation of stratified beach deposits (Bishop, 1967 and Knochenmus,
23 1967).

24 If none of the above biological or physical indicators exist along the lake shore and
25 cultivated groves of perennial woody species (i.e. citrus trees, pine plantations) occur along
26 the shoreline, then the lowest lakeward elevation of the cultivated species may be used to
27 determine the Pre-modification Annual High Level. The lowest lakeward elevation of the
28 crop shall be measured at the lowest rooted extent of the crop. This method is not
29 applicable if the cultivated species is water dependent or water tolerant crop.

30 3.3.3 Pre-modification Annual Low Level Biological indicators of the Pre-modification
31 Annual Low Level may include, but not be limited to, the average elevation of the
32 soil at the base of the lowest lakeward extent of the cypress (Taxodium sp.) fringe.
33 The elevation of the lowest lakeward extent of the cypress trees shall be measured
34 on the lakeward side of the tree at the base of the trunk.

35 If other biological indicators of the Pre-modification Annual Low Level are proposed,
36 they must integrate water levels over a long period of time and must persist after
37 water levels have receded. For example, due to their rapid growth and colonization
38 rates, the lowest lakeward extent of emergent and floating aquatic plants such as
39 lotus (Nelumbo spp.), pickerel weed (Pontederia spp.), maidencane (Panicum


8-28


40D-8.J









1 hemitomon) and torpedo grass (Panicum repens) are not a suitable indicator of Pre-
2 modification Annual Low Levels.

3 3.3.4 Reference Lake Water Regime The RLWR is used only if stage duration data
4 and biological or physical indicators of the Pre-modification Annual High or Annual
5 Low Level are not available. The Reference Lake Water Regime (RLWR)
6 represents a lake level fluctuation range, and therefore cannot be used alone to
7 establish lake levels. The RLWR is used to calculate a Pre-modification Annual
8 High or Annual Low Level once a Pre-modification Annual High Level or Annual Low
9 Level has been determined from one or more of the biological and physical methods
10 described above.

11 3.3.4.1 The Pre-modification Annual High Level is equal to the Pre-modification
12 Annual Low Level plus the RLWR.

13 3.3.4.1 The Pre-modification Annual Low Level is equal to the Pre-modification
14 Annual High Level minus the RLWR.


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1 CHAPTER FOUR DETERMINATION OF POST-MODIFICATION LEVELS

2 4.1 General Post-modification Levels refer to lake water regimes impacted by human
3 activities, excluding water withdrawals. Post-modification levels may be determined
4 from analysis of stage duration data and analysis of modifications of the surface
5 water conveyance systems from the lake. Typically, biological indicators may not
6 be used to establish Post-modification levels. For lakes without stage duration data,
7 Post-modification levels may be determined by the application of the RLWR
8 described in Chapter 5.

9 If Post-modification levels are determined by more than one procedure, the Post-
10 modification levels finally recommended are a reconciliation of the procedures used.
11 Levels determined using analysis of stage duration data take precedence over the
12 levels determined from analysis of outfall elevations and the RLWR unless the
13 stage duration data is determined to be impacted by water withdrawals. Analysis
14 of outfall elevations and application of the RLWR is used only if sufficient stage
15 duration data are not available or if the lake is impacted by water withdrawals.

16 4.2 Analysis of Stage Duration Data This method applies only to those lakes with a
17 minimum of six continuous years of Post-modification stage duration data that have
18 not been impacted by water withdrawals.

19 4.2.1 Post-modification Annual High Level The Post-modification Annual High Level is
20 equal to the elevation corresponding to the P10 value on the Post-modification
21 Stage Duration Curve.

22 4.2.2 Post-modification Annual Low Level The Post-modification Annual Low Level is
23 equal to the elevation corresponding to the P90 value on the Post-modification
24 Stage Duration Curve.

25 4.3 Analysis of Outfall Elevations and Application of RLWR This method is applied to
26 lakes with modified surface water conveyance systems with less than six continuous
27 years of Post-modification stage duration data or lakes with stage data impacted by
28 water withdrawals. The method accounts for modifications to surface water
29 conveyance systems on the lake that does not allow water levels to be maintained
30 above the invert elevation of the outfall.

31 Elevations of outfalls will be measured using accepted survey practices. In the case
32 of open ditches or canals, bottom elevations shall be measured and the highest
33 legally existing and maintained stable point along the outlet profile shall be the
34 control point. For culverts or pipes, the invert (lowest point) of the pipe or culvert
35 shall be measured and this will be the control point. For fixed crest weirs, the
36 elevation of the top of the weir shall be measured and this shall be the control point.


8-30


40D-8.J









1 Elevations will be established for all outfalls on the lake using the above procedures.
2 If there is more than one outfall on the lake, then the lowest outfall will be
3 considered as the control point.

4 4.3.1 Post-modification Annual High Level, Non-operable structure/open conveyance -
5 The Post-modification Annual High Level is equal to the elevation of the lowest legal
6 flow line control. The lowest legal flow line control is the highest stable point along
7 the outlet profile.

8 4.3.2 Post-modification Annual Low Level, Non-operable structure/open conveyance -
9 The Post-modification Annual Low Level for lakes with less than six continuous
10 years of stage data or lakes with stage data impacted by water withdrawals must be
11 determined using the RLWR described in Chapter 5.

12 The Post-modification Annual Low Level is equal to the Post-modification Annual
13 High Level minus the RLWR.

14 4.3.3 Post-modification Annual High Level, Operable Structure The Post-modification
15 Annual High Level is equal to the highest elevation to which the structure can be
16 operated.

17 4.3.4 Post-modification Annual Low Level, Operable Structure The Post-modification
18 Annual Low Level is equal to the lowest elevation to which the structure can be
19 operated.


40D-8.J


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1 CHAPTER FIVE REFERENCE LAKE WATER REGIME


2 5.1 General In some cases there are little or no lake stage data or the existing lake
3 stage data reflects impacts due to human activities (e.g., water withdrawals). For
4 lakes which have sustained long-term water level declines, the P10 and P90 values
5 are generally uncorrelated to Pre-modification biological and physical indicators of
6 water levels. For the case where declines were caused by water withdrawals, the
7 P10 and P90 values can not be used to determine Guidance Levels because they
8 would grandfather effects of the water withdrawals into the adopted levels.

9 The Reference Lake Water Regime (RLWR) was developed to approximate the
10 annual range of lake level fluctuation that typically occurs and corresponds to the
11 range of fluctuation defined by the Annual High and Annual Low Guidance Levels.
12 The RLWR is a regional factor developed for lakes in the same hydrogeologic
13 region as the lakes for which levels are being established. It is applied to lakes with
14 less than six (6) years of stage data or where stage data have been significantly
15 influenced by water withdrawals. The District will continue to investigate methods
16 for calculating the RLWR and to estimate fluctuation ranges which can be used to
17 establish Guidance Levels.

18 Guidance Levels established by use of the RLWR are considered to be provisional
19 until six (6) years of lake stage data have been collected. Following collection of
20 sufficient data, an analysis of the adopted levels and stage data will be conducted
21 and a recommendation made as to whether the Governing Board should consider
22 re-establishing the levels.

23 In many areas of the SWFWMD there are few lakes that are unaffected by human
24 activities. To ensure that the RLWR is based on a representative number of lakes,
25 lakes that are in decline or that have experienced a decline in water levels, are
26 incorporated into the calculation of the RLWR. Though water withdrawals can
27 cause increases in annual lake water level fluctuations, long-term water level
28 declines are the cumulative result of these increases and typically do not occur in
29 a single year. Annual fluctuations in lake levels are still highly related to changes
30 in rainfall. In some instances lakes have experienced changes in annual
31 fluctuations of about 1 foot when comparing changes for different decades (e.g.
32 Horse Lake). A review of the data indicates that large annual fluctuations typically
33 occur in years of high rainfall following a period of low lake stage.

34 5.2 Calculation of RLWR Calculation and application of the RLWR is described in the
35 following sections. The District will continue to investigate methods for calculating
36 the RLWR and to estimate fluctuation ranges which can be used to establish
37 Guidance Levels.

38 5.2.1 CASE 1: Closed basin lake with less than six (6) years of stage data


8-32


40D-8.J









1 The RLWR is calculated from lakes in the same hydrogeologic region as the lake(s) for
2 which levels are being established. Following identification of representative lakes in the
3 region, the lake stage data are reviewed and lakes with less than six (6) years of data are
4 removed from the analysis. Annual stage duration curves are prepared for each of the
5 remaining lakes and differences between the annual P10 and P90 levels are calculated.
6 Next, for each lake the median of the annual differences is obtained to establish a median
7 range of fluctuation for the respective lakes. The RLWR is finally calculated as the median
8 of the individual lake medians.

9 5.2.2 Case 2 Lake without data connected to lake with data

10 If a lake for which levels are to be established is connected via a surface water conveyance
11 system to a lake with data, then the RLWR shall be calculated using data from the adjacent
12 lake. The criteria for applying this method are: the lakes must share the same level pool;
13 and the lake must have a minimum of six continuous years of stage data.

14 For example: Lakes Rainbow and Little Moon are connected above 34.67', NGVD and
15 Rainbow Lake has stage data from 1972 to 1996. Therefore, the RLWR used for Little
16 Moon Lake is equal to the median of the differences between annual P10 and annual P90
17 values for Rainbow Lake.

18 5.2.3 CASE 3: Lake impacted by water withdrawals

19 For lakes affected by water withdrawals and that have less than six (6) years of stage data
20 prior to the initiation of withdrawals a site specific RLWR is calculated. The site specific
21 RLWR is calculated using data collected for the lake of interest. Annual stage duration
22 curves are prepared and differences between the annual P10 and P90 levels are
23 calculated. The RLWR is calculated as the median of the annual differences to establish
24 a median range of fluctuation for the lake.

25 5.3 Application of RLWR The RLWR may be used to calculate either Pre-modification
26 Flood Levels or Low Levels depending upon the biological and physical indicators
27 present. The RLWR may also be used to calculate the Post-modification Low
28 Level.

29 5.3.1 Determination of Pre-modification Levels Using the RLWR

30 5.3.1.2 Pre-modification Annual Low Level If there are biological or physical
31 indicators of the Pre-modification Annual High Level then the Pre-
32 modification Annual Low Level can be calculated by subtracting the RLWR
33 from the Pre-modification Annual High Level elevation established by the
34 biological and/or physical indicators.

35 Pre-modification Annual Low Level = Pre-modification Annual High Level RLWR


40D-8.J


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1 5.3.1.3 Pre-modification Annual High Level If there are no unimpacted biological
2 or physical indicators of the Pre-modification Annual High Level, but there
3 are biological indicators of the Annual Low Level, then the Pre-Modification
4 Annual High Level can be calculated by adding the RLWR to the Pre-
5 modification Annual Low Level elevation established by the biological
6 Indicators.

7 Pre-modification Annual High Level = Pre-modification Annual Low Level +
8 RLWR

9 5.3.2 Post-modification Annual Low Level If the natural surface water conveyance of a
10 lake has been modified by construction of ditches or the installation of culverts and
11 there are no Post-modification data available, then the Post-modification Annual
12 Low Level must be determined from the RLWR. In this case, the Annual Post-
13 modification Low Level is determined by subtracting the RLWR from the Post-
14 modification Annual High Level elevation established by analysis of outfall
15 elevations.

16 Post-modification Annual Low Level = Post-modification Annual High Level RLWR

17 Note: To use the RLWR you must have a point at which to start. Either you have
18 a Annual High Level and work down or you have an Annual Low Level and work up.

19 5.4 Determining Effects of Water Withdrawals Before using period of record data to
20 establish Guidance Levels, it is necessary to determine whether the lake has been
21 or is potentially affected by water withdrawals. If lake levels are influenced by water
22 withdrawals, using the period of record data to establish Guidance Levels may
23 "grandfather" the effects of water withdrawals. Determine effects of water
24 withdrawals on lake levels can be accomplished using one or a combination of the
25 following methods:
26 Analysis of the hydrologic budget of the lake
27 Statistical regression analysis
28 Continuous simulation models
29 Groundwater flow models
30 Analysis of hydrographs
31 Analysis of existing studies










40D-8.J 8-34










1 CHAPTER SIX ADDITIONAL INFORMATION SUPPLIED TO THE GOVERNING BOARD
2 FOR ADOPTING LAKE LEVELS

3 6.1 General District staff may provide additional information to the Governing Board
4 when recommending Guidance and Minimum Levels to the Governing Board. This
5 information may include, but not be limited to, bathymetric maps, aerial
6 photographs, and elevations of docks, seawalls, house slabs and other structures.
7 Information regarding typical uses of the lake (i.e., recreational uses, irrigation,
8 potable water supply) and surrounding land uses also may be provided.


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1 BIBUOGRAPHY

2 Bishop, E.W. 1967. Florida Lakes. Part 1, A study pf the high water lines of some Florida
3 lakes. Division of Water Resources, Florida Board of Conservation. Tallahassee,
4 FL.

5 Cooke, C.W. 1939. Scenery of Florida: Interpreted by a geologist. Florida Geological
6 Survey. Tallahassee, FL.

7 Davis, Jr., J.H. 1973. Establishment of mean high water lines in Florida Lakes. Publication
8 #24. Florida Water Resources Research Center. Gainesville, FL.

9 Dooris, P.M. and Courser, W.D. 1976. Determining stages and fluctuation schedules for
10 regulated lakes in Central and South Florida. Florida Scientist. 39(1):14-18.

11 Florida Board of Conservation. 1969. Florida Lakes, Part Ill. Gazetteer. Division of Water
12 Resources. Tallahassee, FL.

13 Holcomb, D. and W. Wegener. 1971. Hydrophytic changes related to lake fluctuation as
14 measured by point transects. Proceedings of the Twenty-fifth Annual Conference
15 of Southeastern Association of Game and Fish Commissioners. Charleston, SC.

16 Kenner, W.E. 1961. Stage characteristics of Florida lakes, Informational Circular #31.
17 Florida Geological Survey. Tallahassee, FL.

18 Knochenmus, Darwin D. 1967. Shoreline features as indicators of high lake levels. U.S.
19 Geological Survey Professional Paper 575-C.

20 SWFWMD. 1996. Environmental Resources Permitting Information Manual. Southwest
21 Florida Water Management District. Brooksville, FL


40D-8.J


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Figure 8-1


Surfidal Aquifer Drawdown/Floridan Aquifer Draw wn

























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