• TABLE OF CONTENTS
HIDE
 Title Page
 Introduction
 Table of Contents
 List of Tables
 List of Figures
 Executive summary
 Acknowledgement
 West coast inlets in their natural...
 West coast inlets in their modified...
 A comment on sand management capabilities...
 A case study - entrance to St....
 Information and recommendation...
 Pensacola Pass
 East Pass (Destin Harbor)
 St. Andrews Bay entrance channel...
 St. Andrews Bay (East Pass)
 Mexico Beach inlet
 Entrance channel to St. Joseph...
 West Pass
 Sikes Cut
 East Pass (Carrabelle Harbor)
 Hurricane Pass
 Dunedin Pass (Big Pass)
 Clearwater Pass
 Johns Pass
 Blind Pass (Pinellas County)
 Pass-A-Grille and Bunces Pass
 Tampa Bay entrance
 Longboat Pass
 New Pass (Sarasota)
 Big Sarasota Pass
 Midnight Pass
 Venice Inlet
 Stump Pass
 Gasparilla Pass
 Boca Grande Pass
 Captiva Pass
 Redfish Pass
 Blind Pass (Lee County)
 San Carlos Bay entrance
 Big Carlos Pass
 New Pass (Lee County)
 Big Hickory Pass
 Wiggins Pass
 Clam Pass
 Doctors Pass
 Gordon Pass
 Big Marco Pass
 Caxambas Pass
 References






Group Title: Paper - Coastal and Oceanographic Engineering Department, University of Florida ; UFL/COEL-87/018
Title: Florida's west coast inlets
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Permanent Link: http://ufdc.ufl.edu/UF00089992/00001
 Material Information
Title: Florida's west coast inlets shoreline effects and recommended action
Series Title: UFLCOEL
Physical Description: 100 p. : ill. ; 28 cm.
Language: English
Creator: Dean, Robert G ( Robert George ), 1930-
O'Brien, M. P
University of Florida -- Coastal and Oceanographic Engineering Dept
Florida -- Division of Beaches and Shores
Publisher: Coastal & Oceanographic Engineering Dept., University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1987
 Subjects
Subject: Inlets -- Florida   ( lcsh )
Coastal and Oceanographic Engineering thesis M.S
Coastal and Oceanographic Engineering -- Dissertations, Academic -- UF
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 98-100.
Statement of Responsibility: R.G. Dean, M.P. O'Brien ; prepared by Coastal and Oceanographic Engineering Department, University of Florida ; submitted to Division of Beaches and Shores, Department of Natural Resources.
General Note: "December, 1987."
 Record Information
Bibliographic ID: UF00089992
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 21025762

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Table of Contents
    Title Page
        Title Page
    Introduction
        Page 1
        Page 1a
    Table of Contents
        Page 2
        Page 3
    List of Tables
        Page 4
    List of Figures
        Page 5
    Executive summary
        Page 6
        Page 7
    Acknowledgement
        Page 8
    West coast inlets in their natural state
        Page 9
        Page 10
        Page 11
    West coast inlets in their modified state
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
    A comment on sand management capabilities and present efforts
        Page 17
    A case study - entrance to St. Andrews Bay
        Page 17
        Page 18
    Information and recommendation summary
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Pensacola Pass
        Page 24
        Page 25
    East Pass (Destin Harbor)
        Page 26
        Page 27
    St. Andrews Bay entrance channel (Panama City)
        Page 28
        Page 29
    St. Andrews Bay (East Pass)
        Page 30
        Page 31
    Mexico Beach inlet
        Page 32
        Page 33
    Entrance channel to St. Joseph Bay (Port St. Joe)
        Page 34
        Page 35
    West Pass
        Page 36
        Page 37
    Sikes Cut
        Page 38
        Page 39
    East Pass (Carrabelle Harbor)
        Page 40
        Page 41
    Hurricane Pass
        Page 42
        Page 43
    Dunedin Pass (Big Pass)
        Page 44
        Page 45
    Clearwater Pass
        Page 46
        Page 47
    Johns Pass
        Page 48
        Page 49
    Blind Pass (Pinellas County)
        Page 50
        Page 51
    Pass-A-Grille and Bunces Pass
        Page 52
        Page 53
    Tampa Bay entrance
        Page 54
        Page 55
    Longboat Pass
        Page 56
        Page 57
    New Pass (Sarasota)
        Page 58
        Page 59
    Big Sarasota Pass
        Page 60
        Page 61
    Midnight Pass
        Page 62
        Page 63
    Venice Inlet
        Page 64
        Page 65
    Stump Pass
        Page 66
        Page 67
    Gasparilla Pass
        Page 68
        Page 69
    Boca Grande Pass
        Page 70
        Page 71
    Captiva Pass
        Page 72
        Page 73
    Redfish Pass
        Page 74
        Page 75
    Blind Pass (Lee County)
        Page 76
        Page 77
    San Carlos Bay entrance
        Page 78
        Page 79
    Big Carlos Pass
        Page 80
        Page 81
    New Pass (Lee County)
        Page 82
        Page 83
    Big Hickory Pass
        Page 84
        Page 85
    Wiggins Pass
        Page 86
        Page 87
    Clam Pass
        Page 88
        Page 89
    Doctors Pass
        Page 90
        Page 91
    Gordon Pass
        Page 92
        Page 93
    Big Marco Pass
        Page 94
        Page 95
    Caxambas Pass
        Page 96
        Page 97
    References
        Page 98
        Page 99
        Page 100
Full Text






UFL/COEL-87/018


FLORIDA'S WEST COAST INLETS

SHORELINE EFFECTS AND RECOMMENDED ACTION










R. G. Dean

M. P. O'Brien






December, 1987






Submitted To:



Division of Beaches and Shores

Department of Natural Resources

Tallahassee, Florida 32399






Prepared By:


Coastal and Oceanographic Engineering

University of Florida

Gainesville, Florida 32611


Department







REPORT DOCUMENTATION PAGE
SReport No. 2. c3. Kcipiant's Accession No.


4. Title and Suotitle 5. Report Date
Florida's West Coast Inlets December 1987
Shoreline Effects and Recommended Action 6.

7. Author(s) 8. Performing Organization Report No.
R. G. iDean UFL/COEL-87-018
M. P. O'Brien
9. Performing Organizacion Nam and Address 10. Project/Task/Work Unit No.
Coastal and Oceanographic Engineering Department
University of Florida l. conctrct or Granc no.
336 Weil Hall C4348
Gainesville, FL 32611 13. Type of report
.2. Sponsoring Organization Name and Address
Division of Beaches and Shores
Department of Natural Resources Final
3900 Commonwealth Boulevard
Tallahassee, FL 32399 14.
15. Supplemetary Notes



16. Abstract
This report responds to the 1986 Beaches Bill which, in recognition of the
potential deleterious impact on Florida's beaches of inlets modified for navigation,
mandated a study of those inlets with identification of recommended action to reduce
the impacts. This report addresses West Coast inlets; East Coast inlets are the
subject of a companion report.

There are 37 inlets along that portion of Florida's West Coast commencing from
Pensacola Bay Entrance to Caxambas Pass at the south end of Marco Island. Compared to
those on the East Coast, most West Coast inlets have not had the deleterious effects
on the adjacent beaches, yet all modified inlets without proper management have the
potential of impacting unfavorably on the adjacent shorelines. Moreover, at present
there is interest in opening three West Coast entrances which either have been open
in the past (Midnight Pass) or which have opened occasionally (Navarre Pass and
Entrance to Phillips Lake).

A review of inlets in their natural condition demonstrates the presence of a
shallow broad outer bar across which the longshore transport occurs. These shallow
and shifting bar features were unsuitable for navigation which in many cases has led
to the deepening of the channels and fixing with one or two jetty structures. Inlets

Continued -

17. Originator's Key words 18. Availability Stateent
Bypassing
Entrances
Inlets

SL. S. Security Classif. of the Report 20. U. S. Security Classif. of This Page 21. No. of pages :2. Price

UNCLASSIFIED UNCLASSIFIED 100










in this modified state along with inappropriate maintenance practices have the
potential of placing great erosional stress along the adjacent beaches. Moreover,
channel dredging can reduce wave sheltering of the shoreline by ebb tidal shoals and
alter the equilibrium of the affected shoreline segments. The ultimate in poor sand
management practice is the placement of good quality beach sand in water depths too
great for the sand to reenter the longshore system under natural forces; depths of 12
ft. or less are considered appropriate for Florida in order to maintain the sand in
the system.

With the interference of the nearshore sediment transport processes by inlets
modified for navigation, if the adjacent beaches are to be stabilized there must be
an active monitoring program with commitment to placement of dredged material of
beach quality on shoreline segments of documented need. Several East Coast inlets
have such transfer facilities; however, the quantities of sand transferred should be
increased. Although an evolution and improvement in the technical capability to
manage sand resources in the vicinity of inlets is expected, an adequate capability
exists today and a concerted program should be made to commence a scheduled
implementation of this capability at those entrances causing greatest erosional
stress on the adjacent shorelines.

A brief summary review for each of the 37 West Coast inlets is presented
including: a scaled aerial photograph, brief historical information, several items
related to sediment losses at each inlet and special characteristics relevant to
State responsibilities. For each inlet, where appropriate, the above information is
utilized to develop a recommended action.

















-











TABLE OF CONTENTS


PAGE

LIST OF TABLES.............................................. 4
LIST OF FIGURES... ............. ........................................ 5
EXECUTIVE SUMMARY........ ................................................ 6
ACKNOWLEDGEMENTS...................................................... 8
INTRODUCTION. .................................. *.....* ................... 9
WEST COAST INLETS IN THEIR NATURAL STATE.................................. 9
WEST COAST INLETS IN THEIR MODIFIED STATE...................... .......... 12
Deeper Entrance Channels............................*................. 12
Effects of Jetties.................... ...*.... ......... *............. 13
Channel Maintenance Dredging............................................. 13
Fixed Channel Alignment............................ ....... ........... 14
Summary of Modified Channel Effects.........................*.......0 14

A COMMENT ON SAND MANAGEMENT CAPABILITIES AND PRESENT EFFORTS............ 17
A CASE STUDY ENTRANCE TO ST. ANDREWS BAY................. .............. 17
INFORMATION AND RECOMMENDATION SUMMARY................................... 19
Photograph.................... ** *... ************* ..... .............. 19
Brief Historical Information......... ...... ..................... ..... 19
Sediment Balance................................. *********** 21
Brief Dredging History..............*.................. ..... ......... 21
Special Characteristics Relevant to the State Responsibilities....... 21
Recommended Action ........... *0 ....... ..* .........*....... ..**** 22
PENSACOLA PASS............................... ............ ................ 24
EAST PASS (DESTIN HARBOR)................................................ 26
ST. ANDREWS BAY ENTRANCE CHANNEL PANAMAA CITY)........................... 28
ST. ANDREWS BAY (EAST PASS) .......... .......... ...... ... ... ......... 30
MEXICO BEACH INLET.................................. ................ .. ... 32
ENTRANCE CHANNEL TO ST. JOSEPH BAY (PORT ST. JOE)........................ 34
WEST PASS............................................***** ********. ..... 36
SIKES CUT..............*. ..... ................... ........** ............ 38
EAST PASS (CARRABELLE HARBOR) ................... ........................ 40
HURRICANE PASS................... .................................... .... 42
DUNEDIN PASS (BIG PASS) ............................. ...................... 44
CLEARWATER PASS ................ ........... .................... 46










JOHNS PASS...................... ................. ........ .. ...... 48

BLIND PASS (PINELLAS COUNTY) ...... ........**.......................... 50
PASS-A-GRILLE AND BUNCES PASS.......................................... 52
TAMPA BAY ENTRANCE ..........................**........................ 54

LONGBOAT PASS................. ........................................... 56

NEW PASS (SARASOTA) ..................................................... 58
BIG SARASOTA PASS......... ................................. .. ......... 60
MIDNIGHT PASS........................ ................................... 62
VENICE INLET ....................... .............*...................... 64
STUMP PASS........................ *.....*.. .... *........... ........... 66


BOCA GRANDE PASS*.................................................... ... 70

CAPTIVA PASS ......................................... ............... 72
REDFISH PASS................................................. ... 74

BLIND PASS (LEE COUNTY) .................................. ............ 76
SAN CARLOS BAY ENTRANCE .................................................. 78

BIG CARLOS PASS.........................**..................*.............. 80
NEW PASS (LEE COUNTY)........................................ ............ 82
BIG HICKORY PASS.......................... ......... ... ..... ........ 84

WIGGINS PASS.....................*........*......... ....... ......... ..... 86

CLAM PASS. ......... ............................ .. 88Q
DOCTORS PASS ....................... ................. .................. 90
GORDON PASS............. ........ ..................... ........ ......... 92

BIG MARCO PASS........................................................ 94

CAXAMBAS PASS............ ........................................... 96
REFERENCES............... ............ ...... ..... ........ ......... 98







LIST OF TABLES

TABLE PAGE

I. SUMMARY OF ANNUALIZED (1976-1986) QUANTITIES AND PERCENTAGES
FOR PLACEMENT OF BEACH QUALITY SAND (Federally Maintained West
Coast Inlets: Pensacola-Carrabelle) ................................... 15
II. SUMMARY OF ANNUALIZED (1980-1985) QUANTITIES AND PERCENTAGES
FOR PLACEMENT OF BEACH QUALITY SAND (Federally Maintained West
Coast Inlets: Hurricane-Caxambas).............................. .. 16
I

I

I










LIST OF FIGURES


FIGURE PAGE


1. Effects of Ebb Tidal Shoals Causing Wave Sheltering, Accretion

Adjacent to Inlets, Erosion Near Island Center and Possible
Breakthrough. Low Wave Conditions............................. 11
2. Effect of Cutting Entrance to St. Andrews Bay in 1934 on
Downdrift Shoreline (Shoreline Change Results Provided by
J. H. Balsillie) ................. ................................ 18
3. Locations of West Coast Inlets.................................. 20










EXECUTIVE SUMMARY


This report responds to the 1986 Beaches Bill which, in recognition of
the potential deleterious impact on Florida's beaches of inlets modified for
navigation, mandated a study of those inlets with identification of
recommended action to reduce the impacts. This report addresses West Coast
inlets; East Coast inlets are the subject of a companion report.

There are 37 inlets along that portion of Florida's West Coast commencing
from Pensacola Bay Entrance to Caxambas Pass at the south end of Marco Island.
Compared to those on the East Coast, most West Coast inlets have not had the
deleterious effects on the adjacent beaches, yet all modified inlets without
proper management have the potential of impacting unfavorably on the adjacent
shorelines. Moreover, at present there is interest in opening three West
Coast entrances which either have been open in the past (Midnight Pass) or
which have opened occasionally (Navarre Pass and Entrance to Phillips Lake).

A review of inlets in their natural condition demonstrates the presence
of a shallow broad outer bar across which the longshore transport occurs.
These shallow and shifting bar features were unsuitable for navigation which
in many cases has led to the deepening of the channels and fixing with one or
two jetty structures. Inlets in this modified state along with inappropriate
maintenance practices have the potential of placing great erosional stress
along the adjacent beaches. Moreover, channel dredging can reduce wave
sheltering of the shoreline by ebb tidal shoals and alter the equilibrium of
the affected shoreline segments. The ultimate in poor sand management
practice is the placement of good quality beach sand in water depths too great
for the sand to reenter the longshore system under natural forces; depths of
12 ft. or less are considered appropriate for Florida in order to maintain the
sand in the system.

With the interference of the nearshore sediment transport processes by

inlets modified for navigation, if the adjacent beaches are to be stabilized
there must be an active monitoring program with commitment to placement of
dredged material of beach quality on shoreline segments of documented need.
Several East Coast inlets have such transfer facilities; however, the
quantities of sand transferred should be increased. Although an evolution and
improvement in the technical capability to manage sand resources in the


6










vicinity of inlets is expected, an adequate capability exists today and a
concerted program should be made to commence a scheduled implementation of
this capability at those entrances causing greatest erosional stress on the
adjacent shorelines.

A brief summary review for each of the 37 West Coast inlets is presented
including: a scaled aerial photograph, brief historical information, several
items related to sediment losses at each inlet and special characteristics
relevant to State responsibilities. For each inlet, where appropriate, the
above information is utilized to develop a recommended action.














































7









ACKNOWLEDGEMENTS


Much of the data presented in this report were assembled by Professor
A. C. Hine, Mr. D. L. Mearns, Professor R. A. Davis, Jr. and Mr. M. Bland of
the University of South Florida under contract with the Division of Beaches
and Shores. That contract resulted in the University of South Florida report
"Impact of Florida's Gulf Coast Inlets on the Coastal Sand Budget". Captain
J. N. Marino, formerly of the University of Florida, participated in the early
stages of the present study in organizing much of the data contained in the
inlet summary forms. The contributions of Ms. Lethie Penquite of the Division
of Beaches and Shores in assembling and preparing the photographs for the
inlet summary forms is greatly appreciated. Ms. Cynthia Vey provided her
usual expert manuscript preparation including typing and checking.



































8p


,- ~~inmn










FLORIDA'S WEST COAST INLETS
SHORELINE EFFECTS AND RECOMMENDED ACTION


INTRODUCTION

At present, there are 37 inlets and channel entrances along Florida's
West Coast between the Florida-Alabama boundary and the southern end of Marco
Island. These inlets serve as navigational entrances and passageways for
renewal of water to the bays and lagoons behind the barrier islands. Many of
these inlets have been stabilized for navigational purposes by dredging and/or
construction of jetties. In their natural state, due to shallow and shifting
outer bars, most entrances were unsuited for the navigational roles they now
provide. In some cases, the deepening of the channels, the construction of
jetties for channel maintenance and the dredging to maintain channel depth
have had severe deleterious effects on the adjacent shorelines. The effects
are due primarily to the deprivation of the adjacent shorelines of the supply
of sand received in their natural conditions. Clearly, if these entrances are
to serve navigation without causing severe downdrift effects, the supply of
sand that has been interrupted by these entrances must be reinstated. At
present there is interest in opening three inlets on Florida's West Coast:
Midnight Pass, Navarre Pass and the entrance to Phillips Lake. The purpose of
this report is to provide a very brief historical review and assessment of the
effects of West Coast entrances on the adjacent shorelines and based on the
available information, to develop recommendations for remedial measures. This
report is a companion document to the report "FLORIDA'S EAST COAST INLETS -
SHORELINE EFFECTS AND RECOMMENDED ACTION".


WEST COAST INLETS IN THEIR NATURAL STATE

Under natural conditions, the West Coast inlets differed both in number
and in character from those currently present. These entrances and their
associated shoals achieved long-term equilibrium with the sandy transport
processes.

The natural longshore sand transport quantities and directions along the
West Coast are highly variable. In the Panhandle area, the transport is
toward the west and fairly large in magnitude, on the order of 200,000 cubic
yards per year. Along the South West Coast, in the vicinity of Venice, the


9






I
I

transport appears to be fairly consistently directed toward the south at
approximately 70,000 cubic yards per year. Along the remainder of the West
Coast, the transport is quite variable both in direction and magnitude and
depends substantially on the orientation of the shoreline which can vary
significantly. For example, Sand Key in Pinellas County is 14 miles long and I
extends from Johns Pass on the south to Clearwater Pass on the north. At the
north end, the transport is to the north at approximately 70,000 cubic yards
per year and at the south end, the transport is toward the south at about
50,000 cubic yards per year.

A feature which distinguishes portions of Florida's West Coast from the
East Coast is the generally weaker waves. On the East Coast, these waves tend
to limit more effectively the magnitudes and forms of the sand bodies jetted
seaward by the ebb tidal currents at inlets. These sand bodies, called ebb
tidal shoals, tend to be crescentic features in the presence of the higher
waves on the East Coast and exhibit near-symmetry relative to the inlet
axis. In the presence of the West Coast milder wave activity, these sand
bodies achieve greater volumes and can be much more irregular in shape and
variable in time, depending primarily on the tidal currents, the direction of
sand transport and the stage of evolution of the ebb tidal shoal. These
shoals can cause sheltering of adjacent island tips from wave action and thus
act as sand traps, resulting in the accretion of the island tips and an
associated erosion at the island centers, see Figure 1. In some cases the
shoal will eventually be driven shoreward causing the shoreline to accrete
initially and later erode. It is possible that under natural conditions, the
cycle could result in a breakthrough and formation of a new, more efficient
inlet near the island center, the closure of the two original inlets and then
a long-term repetition of this cycle (Figure Ic). Longboat Key is an example
of a barrier island which is eroding near the center with dominant shoals at
Longboat Pass to the north and New Pass to the south. In some cases, the ebb
tidal shoals can store tremendous quantities of sand. Dean and Walton (1975)
have estimated that the Boca Grande Pass shoals contain in excess of 200
million cubic yards of sand.

In their natural state, inlets will achieve a long-term equilibrium with
the natural sand supply and processes. This "equilibrium" may include fairly
severe fluctuations of the shoreline as the ebb tidal shoals wax and wane or











Shoals-


tzj 2}V' I
Waves
Not


Net /I
Transport






Waves
17 Z;(-


A 5

ffffs


Former Ebb
Tidal Shoals A 7
to be Driven
Ashore by
Waves



New
Shoals -a I/s.
Forming





^w r


S Location of
, Former Inlet




New Inlet




Location of
S Former Inlet

'N^


NOTE:
A = Accretion
E = Erosion


INCREASING


a) Ebb Tidal Shoals Provide
Local Wave Sheltering
and Sediment Deposition
Near Inlets


b) In Response to Sediment
Accumulation on Island
Tips, Erosion Occurs
Near Mid-Island Locations


c) Possible Breakthrough and
Inlet Formation at Location
of Eroding Center of Island.
Closure of Former Inlets.


Figure 1. Effects of Ebb Tidal Shoals Causing Wave Sheltering, Accretion Adjacent to Inlets, Erosion Near
Island Center and Possible Breakthrough. Low Wave Conditions.


TIME


MW










as the channel migrates through the bar to achieve transfer of the longshore U
transport. The ocean bar, its connection to the adjacent shorelines and the
adjacent shorelines have been termed by coastal geologists as a "sand sharing
system". It is important to recognize that the form and geometry of this sand
sharing system play a vital role in maintaining the continuity of longshore
sand transport processes along the West Coast. In areas of substantial
longshore sand transport, the broad shallow ocean bars function as "sand
bridges" across which the sediment transport occurred from the updrift to
downdrift beaches. The interference with or geometric modification of this
sand sharing system, particularly the ebb tidal shoal, can cause substantial
interruption of the sediment supply to the adjacent shorelines.


WEST COAST INLETS IN THEIR MODIFIED STATE

Entrances, constructed or modified for navigational purposes, differ from
natural inlets in four respects: (1) the entrance channels are deeper,
(2) jetties are generally present, (3) periodic dredging may be required to
maintain the design channel depth, and (4) the channel alignment is fixed.
The effects of each of these differences are discussed below. Dean (1987)
presents a more detailed discussion of the effects of modified inlets on
adjacent shorelines and recommended measures for improvement.


Deeper Entrance Channels

As noted previously, to accommodate the longshore sediment transport,
inlets in their natural state included shallow ocean bars and these shallow,
broad bars functioned as "bridges" for sediment transport around the inlets.
Even if the net longshore sediment transport were non-existent (zero), the bar
would exist and be part of the equilibrium sand sharing system. A dredged
channel deeper than the natural shallow depth over the bar interrupts this
system. The system responds by attempting to rebuild the bridge through
deposition. If no attempts are made to maintain the channel depth, the
channel will fill, approaching the natural depth after which the transport
processes will resume. It is important to recognize that if a quantity of
sediment is removed from the sand sharing system by dredging the navigational
channel; and if the channel is allowed to fill, the fill volume will result in
the adjacent beaches suffering a volumetric deficit consistent with that



12









required to fill the channel. In a more likely case, dredging is carried out
to maintain the channel at the desired depth. If this dredged sediment is not
reintroduced into the system at the proper locationss, erosion will occur at
these locations. Particularly with respect to West Coast inlets, a deeper
channel will result in less wave sheltering and thus greater wave attack on
portions of the shoreline and associated erosion at these locations.


Effects of Jetties

The purposes of jetties at navigational entrances are twofold. First,
the jetties are designed to prevent or reduce the amount of sand which would
enter a channel, primarily in the more active nearshore region. Secondly, as
the origin of the term suggests, jetties are intended to "jet" sand that would
otherwise tend to be deposited within the region of natural sediment motion
including the outer bar to water depths in excess of that desired for
navigation. This explains the rule of thumb that jetties should be
constructed out to the desired navigational depth. On shorelines with
substantial longshore sediment transport magnitudes, jetties can cause adverse
effects to the downdrift beaches simply by impounding sand which must be
manifested as downdrift erosion. The aforementioned jetting of material an
additional distance offshore such that it no longer is part of the sand
sharing system results in a loss to the nearshore system in general and
adjacent shorelines in particular.


Channel Maintenance Dredging

Sand dredged from navigational channels to maintain their depths, if not
placed at the appropriate locations on the adjacent beaches, will cause a
deficit of sediment to be manifested as erosion. In the simplest case of a
unidirectional sediment transport and in which only the net transport enters
the channel, obviously placement of the dredged material on the downdrift
beaches is appropriate. In more realistic cases, the proper placement
location may be determined best by monitoring the adjacent shorelines to
determine need. A modified inlet may result in the transport and deposition
in an inlet channel of substantially greater quantities than the net longshore
sediment transport. The legacy of offshore placement in deep water of large
quantities of beach quality sand dredged from inlets has caused a serious










erosional stress on Florida's east and West Coast beaches. As shown in Tables I
I and II, recent records document that substantial amounts of West Coast
entrance dredge material are still being placed in water too deep for return I
to and benefit of Florida's beaches. Table I summarizes the results for the
period 1976-1986, for the four channels under the jurisdiction of the Mobile
District of the Corps of Engineers. For the material disposition that can be
accounted for, an average of 37% (192,400 yd3/yr) has been placed in water too
deep to return to the shoreline. Table II presents a similar summary for the
eight West Coast entrances under the jurisdiction of the Jacksonville District
of the Corps of Engineers. For the material disposition and quality that can
be accounted for definitely, 33% (230,400 yd3/yr) has been placed in water
depths too great to return to shore. Although it is encouraging that
substantial quantities of sand are being returned to the shoreline, the loss
of more than an average of 400,000 cubic yards per year can still cause
substantial shoreline erosion. To compensate for this loss through beach
nourishment would cost in excess of $3,000,000 per year and it is doubtful if
comparable quality sand could be located for this price. Tables I and II also
demonstrate the need to better document the quality of material dredged and
the placement locations.


Fixed Channel Alignment

Although the character of channel alignment differs for modified and
natural channels, the fixed alignment per se is not responsible for adverse
effects to adjacent shorelines. It is the previously discussed measures that
are taken to maintain the alignment that cause these adverse shoreline
effects.


Summary of Modified Channel Effects

In summary, there are two types of potential adverse effects that a
modified channel entrance can have on adjacent beaches: (1) a distribution
effect, i.e. accretion in one location and corresponding erosion in another,
and (2) a net erosion. Jetty impoundment is an example of the former in which
the volumetric increase of sand on the updrift side of the inlet is balanced
(in volume) by a corresponding erosion on the downdrift side. In this case,
there is no net loss of sand to the system. The offshore deposition of









TABLE I


SUMMARY OF ANNUALIZED (1976-1986) QUANTITIES AND PERCENTAGES
FOR PLACEMENT OF BEACH QUALITY SAND
(Federally Maintained West Coast Inlets: Pensacola-Carrabelle)

Amount Amount
Amount Placed on Placed Depth of
Dredged Beach/Upland Offshore Placement
Inlet (yd3/yr) (yd3/yr) (yd3/yr) (ft.)

Pensacola Channel 373,700 218,200 155,500 30+
(0%) (100%)

East Pass1 86,100 19,700 9,200 30+
(Destin) (23%) (11%)

St. Andrews Bay 78,000 50,300 27,700 30+
(64%) (36%)

Sikes Cut2 35,700 35,700 0 -
(100%) (0%)

Totals3 572,800 323,900 192,400
(63%)4 (37%)

REMARKS: 157,700 yd3/yr have disposal areas which are unaccounted for.


2Records indicate material has been placed
landward ends of jetties.

3Data taken from "Impact of Florida's Gulf
Coastal Sand Budget," Hine et al., 1986.

4Percentages based on quantities placed in
total of 516,300 cubic yards per year.


in erosional areas at


Coast Inlets on the


known areas, i.e. a








TABLE II
SUMMARY OF ANNUALIZED (1980-1985) QUANTITIES AND PERCENTAGES
FOR PLACEMENT OF BEACH QUALITY SAND
(Federally Maintained West Coast Inlets: Hurricane-Caxambas)
Amount Amount
Amount Placed on Placed Depth of
Dredged Beach/Upland Offshore Placement
Inlet (yd3/yr) (yd3/yr) (yd3/yr) (ft.)
Johns Pass 38,500 38,500 0
(100%) (0%)
Blind Pass 141,700 141,700 0
(Pinellas) (100%) (0%)
Tampa Harbor1 2,489,000 0 2,489,000 16-19
(0%) (100%)
Longboat Pass 55,000 55,000 0 -
(100%) (0%)
New Pass 71,700 71,700 0 -
(Sarasota) (100%) (0%)
Boca Grande 266,400 36,000 230,400 40
(Charlotte Harbor) (14%) (86%)
San Carlos Bay 56,200 56,200 0 -
(Ft. Myers Beach) (100%) (0%)
Gordon Pass 72,600 72,600 0 -
(100%) (0%)

Totals2,3 3,191,100 471,700 2,719,400
(15%) (85%)
REMARKS: tAverage of 6 261,700 yd3/yr of sand, shell and silts were dredged,
3,772,700 yd /yr of that was disposed of within Tampa Bay.
Percentage of sand vs silt in remaining 2,489,000 yd3/yr is unknown.
2Data taken from COE Jacksonville District, 2 May 86, printout.
3Totals exclusive of Tampa: 702,100 yd3/yr; 471,700 yd3/yr (67%);
230,400 yd3/yr (33%).


p

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dredged sand or the jetting of sand to water depths greater than those of the
sand sharing system will result in a net and permanent loss to the nearshore
system. Although both of these types of effects are serious, the net loss of
sand to the nearshore system is more detrimental and will appear as a net
erosion of the shoreline.


A COMMENT ON SAND MANAGEMENT CAPABILITIES AND PRESENT EFFORTS

From the preceding discussion, it is clear that generally improved sand
management practices will be required at entrances if the adverse effects on
adjacent shorelines are to be reduced. Undoubtedly, considerable innovation
must be accomplished to minimize costs and maximize future efficiency. The
need for development of improved capabilities should not serve as a reason to
delay implementation of needed management practices as both the need and an
adequate (albeit imperfect) capability exist.

There are no established continuous programs of sand bypassing on
Florida's West Coast similar to those on the East Coast. The two entrances
causing greatest downdrift effects are the St. Andrews Bay Entrance Channel
and Venice Inlet. For other modified entrances, monitoring of the adjacent
shorelines should be conducted and beach quality sand derived from channel
dredging should be placed on those shorelines where monitoring has documented
the need. All beach quality material dredged should be returned to the active
beach system.


A CASE STUDY ENTRANCE TO ST. ANDREWS BAY

This entrance is an example of very severe effects to the downdrift
shoreline. Additionally the entrance is relatively young (constructed in
1934) and the shoreline impact has been documented rather completely.

The entrance to St. Andrews Bay is an artificial entrance and was cut and
lined with two jetties in 1934. Prior to this time, navigation was through
East Pass around the eastern end of the barrier island. Shoreline change data
are available as presented in Figure 2 for the intervals 1855-1934 (79 years)
before the entrance was cut and 1934-1984 (50 years) after the entrance was
cut. Figure 2 presents the average shoreline change rates over a shoreline
segment of approximately 20 miles. Prior to the entrance, portions of the
shoreline were eroding; however, accretion was predominant with an average










dredged sand or the jetting of sand to water depths greater than those of the
sand sharing system will result in a net and permanent loss to the nearshore
system. Although both of these types of effects are serious, the net loss of
sand to the nearshore system is more detrimental and will appear as a net
erosion of the shoreline.


A COMMENT ON SAND MANAGEMENT CAPABILITIES AND PRESENT EFFORTS

From the preceding discussion, it is clear that generally improved sand
management practices will be required at entrances if the adverse effects on
adjacent shorelines are to be reduced. Undoubtedly, considerable innovation
must be accomplished to minimize costs and maximize future efficiency. The
need for development of improved capabilities should not serve as a reason to
delay implementation of needed management practices as both the need and an
adequate (albeit imperfect) capability exist.

There are no established continuous programs of sand bypassing on
Florida's West Coast similar to those on the East Coast. The two entrances
causing greatest downdrift effects are the St. Andrews Bay Entrance Channel
and Venice Inlet. For other modified entrances, monitoring of the adjacent
shorelines should be conducted and beach quality sand derived from channel
dredging should be placed on those shorelines where monitoring has documented
the need. All beach quality material dredged should be returned to the active
beach system.


A CASE STUDY ENTRANCE TO ST. ANDREWS BAY

This entrance is an example of very severe effects to the downdrift
shoreline. Additionally the entrance is relatively young (constructed in
1934) and the shoreline impact has been documented rather completely.

The entrance to St. Andrews Bay is an artificial entrance and was cut and
lined with two jetties in 1934. Prior to this time, navigation was through
East Pass around the eastern end of the barrier island. Shoreline change data
are available as presented in Figure 2 for the intervals 1855-1934 (79 years)
before the entrance was cut and 1934-1984 (50 years) after the entrance was
cut. Figure 2 presents the average shoreline change rates over a shoreline
segment of approximately 20 miles. Prior to the entrance, portions of the
shoreline were eroding; however, accretion was predominant with an average





N

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0 5 10 15 20
DISTANCE EAST FROM BAY COUNTY LINE (miles)
a)Shoreline Change Rates Prior to Cutting Entrance to
St. Andrews Bay, 1855-1934 (79 Years).


0 5 10 15
DISTANCE EAST FROM BAY COUNTY LINE (miles)
b)Comparison of Shoreline Change Rates Prior to Cutting
Entrance to St. Andrews Bay, 1855-1934 (79 Years) and
Subsequent to Cutting Entrance, 1934-1984 (50 Years).


Effect of Cutting Entrance to St. Andrews Bay in 1934 on Downdrift
Shoreline (Shoreline Change Results Provided by J. H. Balsillie).


-10


Figure 2.










accretion rate of approximately 1 ft/yr. Immediately west (downdrift) of the
entrance location, the shoreline was accreting at approximately 3 ft/yr. For
the 20 year period after cutting the entrance, the erosion was dramatic
downdrift of the entrance. The maximum erosion was approximately 7 ft/yr,
tapering to the natural changes some nine miles west of the entrance. Erosion
over this 50 year interval amounted to a maximum of 350 ft. in an area that
was accreting prior to cutting of the entrance channel. Using conventional
rules of thumb, the erosion depicted in Figure 2 is equivalent to 13 million
cubic yards. Much of the material dredged from this entrance (9 million cubic
yards) has been disposed of in deep water and an ebb tidal shoal of 2.8
million cubic yards has developed since the entrance was cut. Since 1972,
some of the maintenance material has been placed on the downdrift (west)
shoreline. It is believed that the large quantities of maintenance dredging
required are due in part to the permeable jetties which allow sand to leak
through from the adjacent beaches to the entrance channel. This possibility
should be evaluated and if found to be significant, the jetties should be
sand-tightened to prevent further losses. Also, all future dredging of beach
quality sand should be placed on the downdrift shoreline.


INFORMATION AND RECOMMENDATION SUMMARY

This section presents for each inlet information and recommendations in a
two-page summary form. The order of presentation of the inlets is from west
to east to south commencing with Pensacola Bay Entrance to the west to
Caxambas Pass at the south end of Marco Island. Figure 3 presents the
locations of the 37 West Coast entrances summarized in this report. The items
presented for each entrance and some background as to their relevance is
discussed briefly below.


Photograph A scaled aerial photograph is presented to illustrate the
character of the inlet including modifications if present. In
some cases, the relative effects of the entrance on the downdrift
and updrift shorelines are evident.


Brief Historical Information Provides background, including whether inlet is
natural or constructed and the timing of modifications.





















'm





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or








I tWOLuS4A
r- r --- -- --
I^ WEL f '4 *



, <>, a '-,u 1 R A N E ,


-at / P ,- .SC --

JQ. 4 ,s I IT
JOhn8 ass83




Big Sarasota PaQ sA,-- or "" ---'-_
w p dnss. Sarasota CO. .- \ ,-e I E
Big Sarasota Pass L C
SVenic nlet .ri .
Stumip^U -- T pass ''. off



O 'Pas's oIoaN
"k






D,,_
mo iLo








Figure 3. Locations of West Coast Inlets

20~, a_1


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Sediment Balance Several items are presented relevant to adjacent shoreline
stability. Increases in volumes of sand in the ebb tidal shoal
generally represent good quality sand removed from the beach
system and in most cases sand suitable for shoreline nourishment.

Net littoral transport rates provide a measure of the net
amount of sand moving under natural action along the shoreline.
Where inlet modifications have altered the system through channel
deepening, jetty construction, etc. to a degree that natural
transport is interrupted, it is this quantity that must be
transferred by engineering measures to ensure stability of the
downdrift shoreline. The estimates of net longshore sediment
transport indicated "Walton" were developed by T. L. Walton
(1973) based on observations of wave characteristics made by
ships at sea.

Shoreline volume changes provide a measure of the impact of
the entrance on the adjacent shoreline. The usual pattern in
areas of large net longshore sediment transport is accretion
updrift of the entrance and erosion of the downdrift shorelines.
However, if the updrift jetties allow sand to drift through them,
it is possible that the updrift shorelines will accrete at lower
rates than the net longshore transport, or in the limiting case,
erosion of the updrift shorelines can occur.


Brief Dredging History Provides information relevant to adjacent shoreline
impact. In particular good quality sand disposed in deep water
usually represents sand from the longshore transport system and
therefore will result, on a per unit volume basis, in erosion of
the adjacent shoreline(s).


Special Characteristics Relevant to the State Responsibilities Identifies
those technical, operational or jurisdictional features that are
relevant to the State's responsibility to providing maximum
stability of the beach resource.





21






Recommended Action All available information is synthesized into concise
recommendations which are in accord with requirements of the 1986
Beaches Bill. Because of the importance of these
recommendations, they are highlighted inside a rectangular
enclosure.

I



*
*


*






PENSACOLA PASS


) 1000 2000 3000 4000
SCALE IN FEET


(Date of Photography: September 22, 1985)

Brief Historical Information
Natural entrance.
Federal navigation project since 1881.
Channel 800 ft. wide and 37 ft. deep.
Channel schedule to be deepened to 48 ft. within next two years.






24


I










PENSACOLA PASS


Sediment Balance


Ebb shoal:
1984 Caucus shoal
Middle ground
East bank

Net littoral transport rate:


12 million cubic
3.7 million cubic
2.4 million cubic


yards
yards
yards


240,000 cubic yards per year (Westward)
300,000 cubic yards per year (Westward-Walton)


Shoreline volume changes, 1877-1984:
+4.3 million cubic yards over 1,750 ft. east of inlet
+1.7 million cubic yards over 1,000 ft. west of inlet


Brief Dredging History


Total dredged volume, 1883-1985:


Dumped at sea


Placed on beach or upland
(Santa Rosa Island)

Maintenance dredging 1976-1985


Amount dredged


Placed on Perdido Key


35.6 million cubic yards

28.7 million cubic yards


6.9 million cubic yards


4.1 million cubic yards

2.4 million cubic yards


Special Considerations Relevant to State Responsibilities


In conjunction with designation of Pensacola Bay as homeport for the
aircraft carrier, Kitty Hawk, construction excavation of more than 6
million cubic yards of beach quality sand is planned within the next
two years.


Recommended Action



Monitor beaches east (Santa Rosa Island) and west (Perdido
Key) to determine effects of dredging at Pensacola Pass.

Place as much beach quality sand available from
construction and maintenance dredging on Santa Rosa Island
and Perdido Key as required to maintain beaches there.







EAST PASS (DESTIN HARBOR)


(Date of Photography: February 8, 1985)


Brief Historical Information

Breach through eastern end of Santa Rosa Island formed new East Pass in
1928.

Old East Pass closed naturally in 1938.

Twin jetties completed in 1969.


urn









EAST PASS (DESTIN HARBOR)


Sediment Balance


Ebb shoal: 1877-1984

Flood shoal: 1905-1984

Net littoral transport rate:


+8.2 million cubic yards

18.3 million cubic yards


270,000 cubic yards per year (Westward-Walton)


Shoreline volume changes, 1877-1981:
+1.74 million cubic yards over 6,700 ft. east of inlet
-8.54 million cubic yards over 14,200 ft. west of inlet


Brief Dredging History

From 1931-1984, total dredged volume: 4.4 million cubic yards of which
2.1 million cubic yards were placed nearshore and 1.3 million cubic
yards were used for dike construction or placed on beach.




Recommended Action






ST. ANDREWS BAY ENTRANCE CHANNEL PANAMAA CITY)


1000 2000 3000
SCALE IN FEET


(Date of Photography: September 23, 1983)

Brief Historical Information
Entrance dredged in 1934.
Two jetties constructed in 1934.
Present channel authorized to 42 ft. depth.

Sediment Balance

Ebb shoal: 1882-1983 2.8 million cubic yards

Net littoral transport rates:
110,000 cubic yards per year (Westward-Walton)

Shoreline volume changes:
1882-1983: +1.1 million cubic yards over 5,400 ft. east of inlet
1934-1984: -13 million cubic yards over 10 miles west of inlet


28


U -










ST. ANDREWS BAY ENTRANCE CHANNEL PANAMAA CITY)



Brief Dredging History

Since entrance construction, in 1934, in excess of 9 million cubic
yards of maintenance dredging material has been disposed of in deep
water (42 ft.). An additional 3.8 million cubic yards has been placed
on the beaches.


Special Characteristics Relevant to State Responsibilities

This entrance has caused an erosion of the downdrift (west) shoreline
of approximately 13 million cubic yards, extending some eleven miles to
the west.

Starting in 1972, some of the maintenance dredging has been placed on
the downdrift shoreline. In the period 1976-1986, 128,000 cubic yards
per year was dredged and all was placed on the beach.

The available information suggests that the jetties at this entrance
may be quite permeable allowing sand to enter the channel at rates
greater than the net longshore sediment transport.


Recommended Action


Evaluate whether the permeability of the jetties is
detrimental to the stability of the adjacent beaches. If
so, sand tighten jetties.

Continue to place all maintenance dredging on the downdrift
shoreline. The placement area should serve as a feeder
beach to the downdrift shoreline.

To partially compensate for the net loss of approximately
13 million cubic yards since inlet construction, develop
plans to place at least 7 million cubic yards of sand at
selected locations within the downdrift segment of
approximately seven miles.






ST. ANDREWS BAY (EAST PASS)


3" *hl."


(Date of Photography: September 23, 1983)


Brief Historical Information

Natural inlet. First channel to St. Andrews Bay.

Maintenance by Corps of Engineers discontinued, in 1934.

Sediment Balance

Ebb shoal:
1882 29.1 million cubic yards

Net littoral transport rate:
150,000 cubic yards per year (Westward-Walton)

Shoreline volume changes, 1882-1983:
+3.7 million cubic yards over 4,000 ft. west of inlet

Area in state of rapid change










ST. ANDREWS BAY (EAST PASS)


Brief Dredging History

From 1911-1934, total dredged volume was 6.1 million cubic yards.
Dredging dumped in open water.


Recommended Action



S If channel is dredged, place material on the west beach.






MEXICO BEACH INLET


"4; a


(Date of Photography: October 20, 1986)


Brief Historical Information

Originally a small creek draining a low marshy area.

Stabilized with short jetties when interior lowland was developed into
a canal system in the 1940's to 1950's.

West jetty 150 ft. long, east jetty 130 ft. long.

West jetty extends 100 ft. farther offshore than east jetty.

Channel dimensions: 4 ft. deep by 60 ft. wide.





32


mu










MEXICO BEACH INLET



Sediment Balance

Ebb shoal: Small

Flood shoal: Insignificant

Net littoral transport rates:
140,000 cubic yards per year (Eastward-Walton)

Shoreline volume changes:
Poorly documented, although a substantial erosional stress on
the downdrift (eastern) beach is evident. Wind-blown sand over
west jetty and bulkhead are substantial.


Brief Dredging History

Sand transfer has been required to maintain channel navigable by small
craft.

From 1971 to 1975, a drag line was used to maintain channel open.

S From 1973-1974 and 1976, jet pump systems were used to bypass sand.

Bypassed quantities by drag line and jet pump are not known.

At present (1987), a small floating dredge is being used for bypassing.


Recommended Action



Encourage installation of an effective bypassing system to
transfer at least 40,000 cubic yards per year.







ENTRANCE CHANNEL TO ST. JOSEPH BAY (PORT ST. JOE)


(Date of Photography: November 21, 1983)


Brief Historical Information

S Federal navigation project authorized for channel 300 to 500 feet wide
and 35 to 37 ft. deep, from St. Joseph Bay to Gulf plus a silting
basin.










ENTRANCE CHANNEL TO ST. JOSEPH BAY (PORT ST. JOE)


Sediment Balance


Ebb shoal:
1984 -


145.0 million cubic yards


Net littoral transport rate:


175,000 cubic yards per year (Eastward-Walton)


Sediment transport locally variable due to the unusual configuration of
its locality.

Shoreline volume changes, 1882-1984:
+13.4 million cubic yards over 4,500 ft. east of inlet

Point St. Joe has grown approximately 4,000 ft. in the period of study;
involving 13 million cubic yards.


Brief Dredging History

Approximately 12.4 million cubic yards have been dredged from this
channel and silting basin.

Until 1970, all material dredged was disposed in the Gulf. In 1970 and
1973, 1,150,000 cubic yards placed on Point St. Joe. In 1981, 332,000
cubic yards disposed in the bay.


Special Characteristics Relevant to State Responsibilities

A portion of the present channel runs very close to St. Joe Spit.
Naturally this is one of the areas of greatest shoaling. Dredging and
removal of this material increases erosion on St. Joe Spit.


Recommended Action



Examine the possibility of relocating a portion of the
navigational channel to the northeast to reduce erosion of
St. Joe Spit.







WEST PASS


(Date of Photography: December 8, 1984)


Brief Historical Information

S Maintenance discontinued, Sikes Cut became the navigation channel in
1948.

Sediment Balance

Ebb shoal:
1984 62.0 million cubic yards

Net littoral transport rate:
115,000 cubic yards per year (Westward-Walton)

Shoreline volume changes, 1882-1984:
+0.8 million cubic yards over 1,000 ft. east of inlet
+0.7 million cubic yards over 1,500 ft. west of inlet


36


0 0 0 0 EA










WEST PASS



Brief Dredging History

Between 1900 and 1948, 466,000 cubic yards dredged and disposed
offshore.


Recommended Action



S If pass is dredged in future, place material on adjacent
beaches.







SIKES CUT


I :1000SC I fN


(Date of Photography: December 8, 1984)


Brief Historical Information

Channel cut through St. George Island by local interests, in 1954.

Two jetties built by Corps of Engineers in 1956 to stabilize channel
200 ft. by 10 ft. in 1956.

Sediment Balance

Ebb shoal:
1970 0.6 million cubic yards

Net littoral transport rate:
175,000 cubic yards per year (Westward-Walton)

Shoreline volume changes, 1882-1980:
-0.1 million cubic yards over 1,800 ft. east of inlet

Brief Dredging History

From 1956-1986, 885,000 cubic yards disposed in bay or Gulf, 393,000 to
eroded areas at landward termini of jetties, none to beach.


38


a


m










SIKES CUT



Special Characteristics Relevant to State Responsiblities

State Park at west end of St. George Island.


Recommended Action



Place all dredged material on west beach or at landward
termini of jetties if needed to prevent flanking.







EAST PASS (CARRABELLE HARBOR)


(Date of Photography: December 7, 1984)


Brief Historical Information

Natural inlet.

Federal navigation project; channel dimensions: 200 ft. by 12 ft.

Sediment Balance

Ebb Shoal:
1984 42.1 million cubic yards

Net littoral transport rate:
175,000 cubic yards per year (Westward-Walton)

Shoreline volume changes, 1882-1984:
+3.9 million cubic yards over 3,500 ft. east of inlet
+6.0 million cubic yards over 7,500 ft. west of inlet


Brief Dredging History

From 1905 to 1963, one million cubic yards disposed offshore.








EAST PASS (CARRABELLE HARBOR)


Recommended Action


I* If this channel is dredged, place spoil on the east beach.







HURRICANE PASS


1000 2000 3000 4000
SCALE IN FEET


(Date of Photography: February 7, 1984)


Brief Historical Information

Pass breached by hurricane in 1921.

Clearwater Causeway constructed between 1923-26.

Honeymoon Causeway constructed between 1900-63.

Dredging and filling began for Island Estates Development in 1958.

In 1970, rip-rap placed on north side to stablize south end of
Honeymoon Island.

Pass not maintained federally or locally; channel: 1,800 ft. wide by
6 ft. deep.










HURRICANE PASS


Sediment Balance

Ebb shoal: 1984 -

Flood shoal: 1926 -

Net littoral transport rate:


0.1 million cubic yards

2.6 million cubic yards


75,000 cubic yards per year (Southward-Walton)


Brief Dredging History

Total 1.14 million cubic yards, all placed on beach or upland.


Special Characteristics Relevant to State Responsibilities

Honeymoon Island to the north of Hurricane Pass is a State park and the
south end of this island is eroding.


Recommended Action


Place all dredged material on the north beach.






DUNEDIN PASS (BIG PASS)


0 1000'SCN'


(Date of Photography: February 7, 1984)

Brief Historical Information


* From 1883-1921, Big Pass was the predominant influence on Clearwater
Bay-St. Joseph Sound area.

* Hurricane Pass formed by storm diverted flow from Big Pass in 1921.

* Clearwater Causeway constructed between 1925-26.

* Dredging for Island Estates Development started in 1958.

* Honeymoon Island Causeway constructed between 1960-63.

* Jetty construction at north end of Sand Key in 1974.

* Not Federally or locally maintained; channel dimensions: 1,800 ft. wide
by 6 ft. deep.


m










DUNEDIN PASS (BIG PASS)


Sediment Balance

Ebb shoal: 1984 -
Flood shoal: 1957 -

Net littoral transport rate:


4.8 million cubic yards
2.4 million cubic yards


100,000 cubic yards per year (Southward-Walton)


Brief Dredging History

Volumes unknown.


Recommended Action


S Place dredged material on the north beach.




CLEARWATER PASS


I


(Date of Photography: February 7, 1984)


Brief Historical Information
Natural inlet.
Construction of causeways: Clearwater, 1925; Honeymoon, 1964.
Became Federal navigation project in 1960; channel 150 ft. wide by
10 ft. deep.
Construction of jetties: south, 1975; north, 1981.
City of Clearwater purchased a dredge and began dredging in the pass.
Deauthorized as a Federal project in 1983.

46


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CLEARWATER PASS



Sediment Balance

Ebb shoal:
1984 7.0 million cubic yards
Flood shoal:
1957 0.9 million cubic yards
Net littoral transport rate: highly variable (Estimates encompass wide
range)
100,000 cubic yards per year (Southward-Walton)
76,000 cubic yards per year (Northward)
38,000 to 76,000 cubic yards per year (Southward)
Shoreline volume changes, 1950-1985:
+1.8 million cubic yards over 4,750 ft. north of inlet
+2.6 million cubic yards over 6,600 ft. south of inlet

Causeways may have altered the effective tidal prism and the
sedimentary regime


Brief Dredging History

S Sand Key and Clearwater Beach have received 1,602,600 cubic yards of
dredged material since 1950.

S Corps of Engineers maintenance dredging:
1960 1977
321,000 cubic yards disposed in Gulf or Bay
312,000 cubic yards to north end of Sand Key
1980 1985
970,000 cubic yards on Sand Key and Clearwater Beach

A total of 1.3 million cubic yards has been placed on the beach.


Special Characteristics Relevant to State's Responsibilities

Federal project discontinued.
S City of Clearwater maintains channel by dredging.


Recommended Action



Continue placing dredged sand on the beach to the north and
to eroding areas on Sand Key to the South.






JOHNS PASS


(Date of Photography: February 7, 1984)


Brief Historical Information

Blind Pass and Johns Pass connect Boca Ciega Bay to the Gulf of Mexico.

Johns Pass formed by a hurricane in 1848; became a Federal project in
1964.

North jetty 460 ft. long built in 1962; south bank reveted 920 ft. in
1966.





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Sediment Balance
Ebb shoal:
1984 5.0 million cubic yards
Flood shoal:
1976 0.5 million cubic yards
Net littoral transport rate:
50,000 cubic yards per year (Southward-Walton)
Changes in Blind Pass have affected the flow area, tidal prism and
sedimentary regime of Johns Pass
Ebb shoal has been used as a borrow area for several beach nourishment
projects.

Brief Dredging History
S 94,000 cubic yards dredged from channel and placed on outer bar in
1960.
S 30,000 cubic yards dredged from Johns Pass and placed on beach north in
1961.
78,000 cubic yards dredged from channel and placed offshore in 1966.
231,000 cubic yards dredged and placed on Treasure Island from 1979 to
1983.

Recommended Action


Continue placing dredged material on the adjacent beaches
in accordance with documented erosion areas.


JOHNS PASS






BLIND PASS (PINELLAS COUNTY) I


(Date of Photography: February 7, 1984)

Brief Historical Information

Johns Pass and Blind Pass both connect Boca Ciega Bay to the Gull
Mexico.

Low jetty built on north side, in 1937.

Jetty built on south side, 425 ft. long, in 1962.

South jetty extended in 1986.

Not a Federal project, but designated as a borrow area for beach
replenishment.
Sediment Balance

Ebb shoal:
1984 1.7 million cubic


f of


VRrdsa


Net littoral transport rate:


50,000 cubic yards per year (Southward-Walton)


TOAM


. .







BLIND PASS (PINELLAS COUNTY)


Brief Dredging History
10,000 cubic yards dredged and placed on Sunset Beach in 1964.
100,000 cubic yards dredged and placed on Treasure Island in 1969.
This material was too fine for use as beach replenishment.
550,000 cubic yards dredged offshore and placed on Treasure Island in
1972 and 1976.
75,000 cubic yards dredged from Blind Pass and used for beach fill in
1975.
950,000 cubic yards to be removed from Blind Pass and placed on
Treasure Island and Long Key in 1986 (planned).

Special Characteristics Relevant to State Responsibilities
The partial removal of the once extensive ebb tidal shoals has altered
the equilibrium planform of the north end of Long Key (Upham Beach).

Recommended Action


* Conduct study to determine the effects of removal of
additional material from the ebb tide shoals on the
adjacent beaches.


I

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PASS-A-GRILLE AND BUNCES PASS


auu
0 1000 2000 3000
SCRLE IN FEET


laO


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N


(Date of Photography: February 7, 1984)


Brief Historical Information
Pass-A-Grille has two entrances, separated by Shell Key. Between 1926
and 1948, Shell Key, between these entrances, migrated 1,800 ft.
northward and was reduced substantially in volume.
Jetty built on south tip of Long Key in 1959; extended in 1962.
Federal navigation project authorized in 1964.
Jetty rehabilitated in 1984.
In 1986, north channel 3,400 ft. wide by 14 ft. deep; south channel
(Bunces) 1,200 ft. wide by 18 ft. deep.
No Federal or other maintenance at this time.

52









PASS-A-GRILLE AND BUNCES PASS


Sediment Balance

Ebb shoal:
1979 43.0 million cubic yards

Net littoral transport rate:
100,000 cubic yards per year (Southward-Walton)


Dredging Record

160,000 cubic yards dredged from Pass-A-Grille channel and deposited
offshore, in 1960. No other dredging.

Bunces Pass has not been dredged.


Special Characteristics Relevant to State Responsibilities

The sand in the ebb tidal shoal is ideal for beach nourishment.

Removal of excessive amounts of ebb tidal shoal sand could jeopardize
the stability of adjacent shorelines.


Recommended Action



S Place sand dredged from channel on adjacent beaches.

Conduct study to establish limits on removal of ebb tidal
shoal sand.


I





TAMPA BAY ENTRANCE


I


N


Brief Historical Information


* Available surveys date from 1877.
* Federal navigation project.


* There
Corps
4,900
depth


are three channels: Egmont. Main shipping channel. Maintained by
of Engineers. Width 4,200 ft., depth 48 ft. Southwest. Width
ft., depth 21 ft. Not maintained. Passage Key. Width 1,500 ft.,
17 ft. Not maintained.


.-MM OMMM










TAMPA BAY ENTRANCE



Sediment Balance

Ebb shoal (3 channels):
1979 401.0 million cubic yards
1885 350.0 million cubic yards

Net littoral transport rate: variable but predominantly southward

110,000 cubic yards per year (Southward-Walton)


Brief Dredging History

Since 1951, 13.5 million cubic yards have been dredged from the Egmont
channel.

All dredged material has been placed in the Gulf.


Recommended Action



Place beach quality dredged material on adjacent eroding
beaches according to documented need.







LONGBOAT PASS


(Date of Photography: April 25, 1986)


Brief Historical Information

Longboat Pass separates Anna Maria Island (north) from Longboat Key
(south).

Surveys since 1876 show many changes in the location of this inlet and
the two adjacent islands.

Longboat Pass became a Federal project in 1977.

S Width, 750 ft.; depth, 11 ft.


-- ~--~~ .. ~~










LONGBOAT PASS


Sediment Balance


Ebb shoal:
1982 -

Flood shoal:
1951 -


Net littoral transport rate:


8.1 million cubic yards


1.5 million cubic yards


60,000 cubic yards per year (Southward-Walton)


Shoreline volume changes, 1946-1985:
+3.9 million cubic yards over 9,000 ft. north of inlet
-0.5 million cubic yards over 9,700 ft. south of inlet


Brief Dredging History

304,000 cubic yards dredged and placed on north end of Longboat Key and
south end of Anna Maria Key in 1977.

200,000 cubic yards dredged and placed on adjacent islands in 1982.

148,000 cubic yards dredged and placed on Anna Maria Key in 1985.


Special Characteristics Relevant to State Responsibilities

The area immediately south of Longboat Pass was badly eroded in the mid
1970's. Beach nourishment projects have now alleviated the erosion in
the immediate vicinity of the pass (Whitney Beach), but severe erosion
persists farther south.


Recommended Action


S Continue practice of placing dredged material on the
adjacent beaches on the basis of documented erosion.




NEW PASS (SARASOTA)


II
II

I




I
I
I!
I
II
I

[1",
Li
lI


D O
SCALE IN FEE


(Date of Photography: January 15, 1986)


Brief Historical Information
New Pass separates Longboat Key (north) and Lido Key (south).
Became a Federal navigation project in 1964 with planned dimensions of
450 ft. by 15 ft.





58


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I


124,000 cubic yards dredged and placed on North Lido Key beach in 1964.
246,000 cubic yards dredged and placed on Central Lido Key beach in
1974.
400,000 cubic yards dredged and placed on Central Lido Key beach in
1977.
185,000 cubic yards dredged and placed on Lido Key and Longboat Key
beaches in 1982.
S 239,000 cubic yards dredged and placed on Lido Key beach in 1985.

Special Characteristics Relevant to State Responsibilities
S The placement of sand on Longboat Key in 1982 in combination with a
relocation of the outer end of the channel by 300 feet southward appear
to have caused severe erosion of the south bank of New Pass.

Recommended Action


* Continue practice of placing dredged material on the south
beach.
* Develop a plan for placement of dredged material that will
enhance stability of channel and adjacent beaches.


^ ______ **-


NEW PASS (SARASOTA)


Sediment Balance
Ebb shoal:
1982 4.4 million cubic yards
Flood shoal:
1951 6.2 million cubic yards
Net littoral transport rate:
60,000 cubic yards per year (Southward-Walton)
Shoreline volume changes, 1883-1956:
+0.5 million cubic yards over 4,000 ft. north of inlet
+0.5 million cubic yards over 6,000 ft. south of inlet

Brief Dredging History





BIG SARASOTA PASS


U500
0 1000 2000 3000
SCALE IN FEET


(Date of Photography: January 15, 1986)
Brief Historical Information
Big Sarasota Pass separates Lido Key (north) from Siesta Key (south).
No dredging to date.
Adjacent south shoreline has been hardened.
Not maintained by either Federal or local agencies.

60


K

K

K

U

K

K

K

K

KI

K







BIG SARASOTA PASS


Sediment Balance
Ebb shoal:
1982 -
Flood shoal:


13.6 million cubic yards


1984 7.1 million cubic yards
Net littoral transport rate: variable in direction and net annual volume
60,000 cubic yards per year (Southward-Walton)


Brief Dredging History
No dredging to date.

Special Characteristics Relevant to State Responsibilities
Sand transport southward has caused a large shoal to grow from Lido Key
toward Siesta Key. This shoal has resulted in a deep channel adjacent
to and an erosional tendency on the north end of Siesta Key.

Recommended Action


I[
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I


Monitor adjacent beaches by surveys. If pass is dredged,
place material on Siesta Key.


~ ---





MIDNIGHT PASS


I


OUU
0 1000 2000 3000
SCALE IN FEET


(Date of Photography: January 15, 1986)
Brief Historical Information
Surveys show that by 1888, Midnight Pass had migrated several miles
north to Point of Rocks on Siesta Key.
In 1921, severe hurricane opened new inlet south of old position and
both inlets remained open for a time.
In 1924, old inlet at Point of Rocks closed naturally.
In 1960, dredging of Intracoastal Waterway altered tidal flow and
channels.
In 1983, channel very narrow and shallow. Homeowners obtained
permission to dredge new channel; this channel closed the day after
opening completed.
Midnight Pass has been closed since 1983.


S

i

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MIDNIGHT PASS



Sediment Balance

Ebb shoal:
1982 0.6 million cubic yards

Flood shoal:
1957 1.3 million cubic yards

Net littoral transport rate: variable in direction and annual rate

70,000 cubic yards per year (Southward-Walton)


Brief Dredging History

There has been no appreciable dredging to date.

Special Characteristics Relevant to State Responsibilities

There is substantial local interest to reopen Midnight Pass for
navigation and improvement of water quality in Little Sarasota Bay.


Recommended Action



Monitor changes in adjacent beaches by surveys.

If a decision is made to reopen pass, require provisions to
monitor and ensure stability of adjacent beaches.







VENICE INLET


M


zUU

0 1000 2000 3000 4000
SCALE IN FEET


(Date of Photography: December 20, 1985)


Brief Historical Information

Venice Inlet is a natural channel originally known as Casey's Pass;
separates Casey's Key (north) and Manasota Key (south).

Between 1937-1938, Corps of Engineers constructed twin jetties and
dredged a channel 100 ft. by 9 ft.

In 1983, jetties repaired.

Maintenance by Corps of Engineers.

Sediment Balance

Ebb shoal:
1982 0.4 million cubic yards

Net littoral transport rate :
70,000 cubic yards per year (Southward-Walton)

Shoreline Volume changes, 1883-1956:
+0.2 million cubic yards over 1,350 ft. north of inlet
+0.1 million cubic yards over 2,350 ft. south of inlet

Commencing about one-half mile south, the inlet has caused severe erosion.







VENICE INLET


Brief Dredging History
Between 1937-1938, initial dredging of 70,000 cubic yards used as
backfill of bulkheads.
S In 1964, 22,000 cubic yards dredged; 19,000 cubic yards to Venice
Beach.


Special Characteristics Relevant to State Responsibilities


Venice Inlet has caused severe erosion to the beaches to the south. A
road has been abandoned and portions of a sewage treatment facility are
jeopardized.


Recommended Action


* Monitor adjacent beaches in surveys.
S Develop a concerted effort to implement some sand transfer
at Venice Inlet.


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STUMP PASS


M


M


M


U


(Date of Photography: December 7, 1985)


Brief Historical Information
Stump Pass separates Manasota Key (north) from Knight Island (south).
Inlet natural until 1980, when it was dredged by Charlotte County to
provide a channel 150 ft. by 10 ft.
Not a Federal navigation project.
Sediment Balance
Ebb shoal:
Substantial in volume; however, no reliable data available
Net littoral transport rate:
40,000 cubic yards per year (Southward-Walton)

66










STUMP PASS



Brief Dredging History

In 1980, 140,000 cubic yards dredged and placed on beach at Port
Charlotte State Park.

Not Federally maintained. Charlotte County has requested a permit for
dredging.


Special Characteristics Relevant to State Responsibilities

S Port Charlotte State Park is badly eroded and sand placed on beach
tends to be drawn back into inlet.

S The stability of the park beaches would be enhanced considerably by the
presence of a relatively short terminal structure at the south end of
Manasota Key.


Recommended Action


S Place any dredged material on the adjacent beaches.

* Consider the possibility of placing a relatively short
terminal structure at the south end of Manasota Key to
enhance the stability of the beaches of Port Charlotte
State Park.





GASPARILLA PASS


100
ET


(Date of Photography: December 7, 1985)
Brief Historical Information
There has not been any dredging or modification due to construction
works to date.
The pass is approximately 1,800 ft. wide and 13 ft. deep.
No significant erosion has been recorded updrift or downdrift of the
pass.



68


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UI

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GASPARILLA PASS


Sediment Balance


Ebb shoal:
1982 -
1951 -


3.5 million cubic yards
2.4 million cubic yards


Net littoral transport rate:
100,000 cubic yards per year (Southward-Walton)


Recommended Action


No action recommended unless modification of channel or
beaches is proposed.





BOCA GRANDE PASS


) 2000 3000 4000
SCRLE IN FEET


(Date of Photography: February 25, 1986)
Brief Historical Information
Boca Grande separates Gasparilla Island from Cayo Costa.
Until 1912, a stable natural inlet with a depth of 19 ft.
In 1924, channel dredged to 24 ft; in 1927, to 27 ft; and in 1937, to
30 ft.
Present Federal project, 3,000 ft. wide by 32 ft. deep.
From 1930 to 1970, the southwest tip of Gasparilla Island eroded more
than 1,500 ft.
Small terminal structure constructed at south end of Gasparilla Island
in early 1970's. Has been effective in reducing erosion to the north.


N


U


M


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BOCA GRANDE PASS


Sediment Balance


Ebb shoal:
1985 -


160 million cubic yards


Net littoral transport rate:
110,000 cubic yards per year (Southward-Walton)
Shoreline volume changes, 1909-1985:
-17.5 million cubic yards over 17,000 ft. north of inlet
+17.6 million cubic yards over 22,000 ft. south of inlet


Brief Dredging History

From 1912 to 1984, 8.8 million cubic yards dredged.

All dredged material dumped at sea except 264,000 cubic yards placed in
1981 on Gasparilla Island.


Special Characteristics Relevant to State Responsibilities

The modifications (deepening) of this entrance have placed great
erosional stress on Gasparilla Island to the north.

Sand dredged for channel maintenance is believed to be beach quality.


Recommended Action



Develop plans to place sand economically on eroding beaches
to the north.







CAPTIVA PASS


(Date of Photography: February 25, 1986)


Brief Historical Information

Captiva Pass separates Cayo Costa from North Captiva Island.

Not Federally or locally maintained.

Channel 2,400 ft. wide by 15 ft. deep with no structures.






CAPTIVA PASS

I Sediment Balance
IEbb shoal:
1982 12.0 million cubic yards
Flood shoal:
1958 2.7 million cubic yards
Net littoral transport rate:
S100,000 cubic yards per year (Southward-Walton)
SBrief Dredging History
None

Recommended Action
I
Monitor adjacent beaches by surveys. If there is dredging,
Place material on the south beach.


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I 73





REDFISH PASS


(Date of Photography: February 25, 1986)

Brief Historical Information
Redfish Pass separates North Captiva Island from Captiva Island.
Formed by a severe hurricane in 1926.
This pass has not been dredged or altered.
Some limestone rip-rap has been placed at north end of Capitiva Island.
No provision for Federal or local maintenance.
A short terminal structure was constructed on the north end of Captiva
Island in conjunction with the 1981 beach restoration project.
74


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II










REDFISH PASS



Sediment Balance

Ebb shoal:
1982 2.8 million cubic yards

Flood shoal:
1958 2.6 million cubic yards

Net littoral transport rate: variable in direction and probably small

100,000 cubic yards per year (Southward-Walton)


Brief Dredging History

In 1981, 765,000 cubic yards dredged from offshore borrow area in ebb
shoal and placed on Captiva Island over a beach length of 4,000 ft.
extending south from Redfish Pass.


Recommended Action



S Place any dredged channel material on adjacent beaches.





N


BLIND PASS (LEE COUNTY)


M


M


N


(Date of Photography: February 25, 1986)

Brief Historical Information


* Blind Pass separates Captiva Island (north) from Sanibel Island. It is
not Federally or locally maintained. The pass has no dredging history.
Blind Pass now (December 1987) closed.
* Blind Pass was opened by Hurricane Agnes in 1972 and a small terminal
structure was constructed on the north side by the Department of
Transportation to protect a bridge abutment.


-E


h Itrn ~trd









BLIND PASS (LEE COUNTY)


Sediment Balance

Ebb shoal: insignificant

Flood shoal:
1979 4.0 million cubic yards

Net littoral transport rate:
110,000 cubic yards per year (Southward-Walton)

1859 to 1944 2,000 ft. of progradation of southern tip of Captiva
Island. North end of Sanibel Island gained considerable area by the
migration of this entrance.


Special Characteristics Relevant to State Responsibilities

In conjunction with a planned nourishment of Captiva Island, there is
interest in providing stability to the south end of the fill through
extension of the Blind Pass terminal structure or by other means.


Recommended Action



Give consideration to one or more adjustable structures at
the north end of Turner Beach to provide stability to
Captiva Island beach restoration project, thereby reducing
potential for affecting Sanibel Island.





SA. CARLOS BAV -XTRANC:


(Date of Photography: February 25, 1986)


Brief Historical Information
Entrance separates Sanibel Island (north) from Ft. Meyer's Beach
(south).
Not maintained Federally or locally.
Channel dimensions: 17,500 ft. wide by 12-18 ft. deep.
Sediment Balance
Ebb shoal:
1982 26.1 million cubic yards
Net littoral transport rate:
35,000 cubic yards per year (Northward-Walton)


N


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SAN CARLOS BAY ENTRANCE


Brief Dredging History

Between 1980 and 1985, 56,000 cubic yards placed on Ft. Myers Beach.


Recommended Action



I* If channel is dredged, place material on the south beach.






BIG CARLOS PASS


(Date of Photography: February 25, 1986)


Brief Historical Information

This pass has remained unchanged during the last century.

There has been no dredging or construction of training works (jetties).

Channel dimensions: 1,500 ft. by 11 ft.

In 1963, tidal prism increased when several small inlets to the south
were closed by construction of a causeway.
Not Federally or locally maintained.


U










BIG CARLOS PASS


Sediment Balance

Ebb shoal:
1982 -

Flood shoal:
1979 -

Net littoral transport rate:


8.0 million cubic yards


4.2 million cubic yards


55,000 cubic yards per year (Southward-Walton)


Recommended Action


If this pass is dredged, place dredged material on the
south beach.





NEW PASS (LEE COUNTY)


5007
1000 2000 3000 1000
SCALE IN FEET


(Date of Photography: December 25, 1986)

Brief Historical Information
S From 1963 to 1965, construction of a causeway between Fort Meyers and
Bonita Beach caused closure of several small inlets between Big Carlos
Pass and New Pass and increased the tidal prism of the two adjacent
inlets.
There has been no dredging or construction of training works (jetties).
Not a Federal navigation project.


S Channel dimensions: 1,350 ft. wide by 7 ft. deep.



82


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NEW PASS (LEE COUNTY)


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Sediment

I Ebb sh
19
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19

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IRecommend




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I


Balance

oal:
82 -

shoal:
53 -

ttoral transport rate:
55,000 cubic yards per


0.4 million cubic yards


0.3 million cubic yards


year (Southward-Walton)


ed Action


If channel is dredged, place material on the south beach.





BIG HICKORY PASS


(Date of Photography: December 25, 1986)


Brief Historical Information
Big Hickory Pass is not open at this time.
Pass is not maintained Federally or locally.
Pass closed and re-opened by dragline in 1976.
Pass closed again in 1979.
Sediment Balance
Ebb shoal: insignificant
Flood shoal:
1953 -
Net littoral transport rate:


p

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II


0.7 million cubic yards


55,000 cubic yards per year (Southward-Walton)










BIG HICKORY PASS


Brief Dredging History


Pass opened by dragline in 1976. Unknown volume of material placed on
south beach.


Recommended Action



If a decision is made to reopen pass, conduct a study of
prior history to establish appropriate measures to ensure
stability of adjacent beaches.





WIGGINS PASS


500
SCALE IN FEEP


(Date of Photography: December 14, 1985)
Brief Historical Information
Prior to 1952, pass experienced frequent closures and was not navigable
throughout most of the year.
In 1952, changes in connecting channels increased the tidal prism by 50
percent; this change caused throat area to increase and closures were
eliminated.
S Tidal prism further increased in the period 1960 to 1970; ebb shoal
well-developed by 1974 and navigable channel was migrating.
In 1983, pass dredged, channel dimensions: 200 ft. wide by 8 ft. deep.
Pass is not Federally or locally maintained.
Sediment Balance


Ebb shoal:
1982 -


Flood shoal:
1952 -
Net littoral transport rate:


0.8 million cubic yards
0.1 million cubic yards


85,000 cubic yards per year (Southward-Walton)


13

Ip
IN


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p

p










WIGGINS PASS


Brief Dredging History


S In 1983, 48,000 cubic yards dredged and placed on adjacent state park
beach.


Recommended Action



Place dredged material of beach quality on adjacent beaches
according to documented erosional areas.





CLAM PASS


500
0 1000 2000 3000 00
SCALE IN FEET


(Date of Photography: December 14, 1985)


Brief Historical Information
Clam Pass is a very small, shallow natural pass.
Not maintained Federally or locally.
Between 1954 and 1970, migrated almost 600 ft. north.
Closed naturally in 1976 and in 1981; re-opened each time by
Channel 100 ft. wide by 4 ft. deep.


Sediment Balance
Ebb shoal: insignificant
Net littoral transport rate:


85,000 cubic yards per year (Southwar


p

p
















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d-Walton) p


p









CLAM PLASS


Brief Dredging History


S When pass was opened in 1976 and 1981 by dragline, sand was placed on
south beach; but quantities were not documented.


Recommended Action



Continue to place material removed from the channel on the
south beach.





DOCTORS PASS P


m


M


M


3UU
0 1000 20 3000 000
SCALE IN FFET


(Date of Photography: December 14, 1985)

Brief Historical Information
In the years around 1960, the pass tidal prism was enlarged.
From 1959-60, pass straightened and jetties constructed. Rock removed
from channel in late 1960's.
In 1984, pass dredged to remove shoals; channel 150 ft. wide by 4-6 ft.
deep.

Sediment Balance
Ebb shoal: insignificant
Net littoral transport rate:
85,000 cubic yards per year (Southward-Walton)


P



P

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p

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DOCTORS PASS



Brief Dredging History

Pass dredged twice in 1960s; amount of material removed unknown.

In 1984, 13,000 cubic yards dredged; material deposited offshore.


Recommended Action



Beach compatible dredged material should be placed on the
south beach.






GORDON PASS


I


500

1000 2000 3
SCALE IN Fl


(Date of Photography: December 14, 1985)


Brief Historical Information

Gordon Pass separates Naples Beach (north) from Keewaydin Islanc
(south).

Gordon Pass became a Federal navigation project in 1963.

Channel dimensions: 540 ft. wide by 8 ft. deep.

South jetty constructed in 1969.


E E T aO








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GORDON PASS


Sediment Balance


Ebb shoal:
1982 -

Flood shoal:
1952 -


0.6 million cubic yards

0.1 million cubic yards
0.1 million cubic yards


Net littoral transport rate:
70,000 cubic yards per year (Southward-Walton)

Shoreline volume changes, 1961-1985:
+1.0 million cubic yards over 3,900 ft. north of inlet
Little change over 3,600 ft. south of inlet


Brief Dredging History

Between 1963 and 1985, dredging from the channel amounted to 1,100,000
cubic yards; dredged material placed on Keewaydin Island to the south.


Special Characteristics Relevant to State Responsibilities

Based on shoreline change history, it appears that the channel traps
more than the net longshore sediment transport and that maintenance
dredging material should be placed both on north and south beaches on
the basis of documented erosion.


Recommended Action



Conduct monitoring of adjacent beaches before and after
each maintenance dredging to determine proper apportionment
for placement of beach quality sand.


-- --------~,~uul-rsn~l.r;~-~:-n Irrr-






BIG MARCO PASS


(Date of Photography: December 14, 1985)


Brief Historical Information

Big Marco Pass is a natural inlet which has not been dredged or
modified.

Channel dimensions: 1,140 ft. wide by 10 ft. deep.

Sediment Balance
Ebb shoal:
1982 15.3 million cubi
Flood shoal:
1952 3.4 million cubi
Net littoral transport rate:
70,000 cubic yards per year (Southward-


.c yards

ic yards i

-Walton) *
tp






















.c ard










BIG MARCO PASS


Brief Dredging History

None


Recommended Action


S No action recommended, except to monitor adjacent beaches
to obtain a better understanding of the system for
background in the possible eventuality of interest in
modification.






CAXAMBAS PASS


(Date of Photography: December 14, 1985)


Brief Historical Information

Prior to 1952, pass was stable with no changes occurring in
configuration.

Between 1967 and 1976, portions of the Marco Island shoreline retreated
up to 330 ft.

Pass not Federally or locally maintained.










CAXAMBAS PASS



Sediment Balance

Ebb shoal: poorly defined due to shifting hydrography


Flood shoal:

Net littoral transport rate:


0.3 million cubic yards


55,000 cubic yards per year (Southward-Walton)


Shoreline volume changes, 1958-1985:
+0.2 million cubic yards over 7,200 ft. north of inlet
+5.9 million cubic yards over 8,100 ft. south of inlet


Brief Dredging History

S In 1982, 320,000 cubic yards dredged from the ebb tidal delta and used
to nourish the south end of Marco Island.


Recommended Action



Place any available beach quality dredged material on Marco
Island beach in areas of documented erosion.




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