The Florida atlas of lakes
 What about bulkheads?
 Volunteer bulletin board
 Outstanding Lakewatch voluntee...
 Why do we collect the brown bottle...
 Back Cover


Florida Lakewatch newsletter
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00055470/00030
 Material Information
Title: Florida Lakewatch newsletter
Physical Description: v. : ill. ; 28 cm.
Language: English
Creator: Florida LAKEWATCH
Publisher: Dept. of Fisheries and Aquatic Sciences of the Institute of Food and Agricultural Sciences (IFAS) at the University of Florida (UF)
Place of Publication: Gainesville FL
Creation Date: 2007
Frequency: irregular
completely irregular
Subjects / Keywords: Lakes -- Periodicals -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
periodical   ( marcgt )
serial   ( sobekcm )
General Note: Description based on v. 9 (spring 1997); title from caption.
General Note: Latest issue consulted: v. 33 (2006).
 Record Information
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 65383070
lccn - 2006229159
System ID: UF00055470:00030


This item has the following downloads:

FLWVol39 ( PDF )

Table of Contents
    The Florida atlas of lakes
        Page 1
        Page 2
    What about bulkheads?
        Page 3
        Page 4
        Page 5
    Volunteer bulletin board
        Page 6
    Outstanding Lakewatch volunteer
        Page 7
        Page 8
        Page 9
    Why do we collect the brown bottle samples?
        Page 10
        Page 11
    Back Cover
        Page 12
Full Text

F or da


The Florida Atlas of Lakes

Florida LAKEWATCH, the
Florida Center for Community
Design and Research at the
University of South Florida and the
Florida Lake Management Society
have teamed up to provide easy
access to data for all
LAKEWATCH lakes. This new
service will soon be implemented
as the "Florida Atlas of Lakes"
found at the Water Atlas website
The existing Water Atlas
Program from the University of
South Florida provides water
resource data via the World Wide

Web for a nine county region
stretching between Pinellas County
on the west coast and Seminole
County and, soon, Volusia County
on the East Coast and Leon County
in the Florida Panhandle. The
extension of the coverage of the
Water Atlas to anyone with a web
browser has always been a major
goal of the Water Atlas program.
Until recently the program has not
had the manpower, funding or
technology to achieve this goal.
However, a combination of new
designs and new technologies has
now made this goal possible. This

Figure 1. Arclms map page showing themes, Florida Lake Regions and Counties and
various lake locations with LAKEWATCH data.

year we will make a step in that
direction with the Florida Atlas of
Lakes. While this new statewide
atlas will not have the full
comprehensive functionality of the
existing county Water Atlases, it
will have the key water chemistry
data that is generated by the Florida
LAKEWATCH program.
The Water Atlas project manages
and delivers data through a map
interface. LAKEWATCH sites are
matched to map themes based on
the 1:24,000 scale National
Hydrology Database (NHD).
Additional map themes are then
added to the base map to create the
map that is used as a key element
of the database. Figure 1 shows
Water Atlas web-based map with
the Florida Atlas of Lakes Themes
added. Additional themes,
including the 2004 aerial
photographs for lakes, will be
added as the project matures. Data
is managed and displayed on water
resource pages.


The Florida Atlas of Lakes (continued from page 1)

The Alas I Rese.ach I Diga Lbiay Educalloni News & Evrver About nhe Awla Hlp Contact Us

I' da Atlas of Lakes Ent Al
I Ilk % 1r I'A ., .
tLMEff Adopt-A-Pond Progam


Florida LAKEWATCH is a volunteer citizen lake monitoring
program that facilitates "hands-on" citizen participation in the
management of Florida lakes through monthly monitoring
Coordinated through the University of Florida's Institute of
Food and Agricultural SciencesDepartment of Fisheries and
Aquatic Sciences, the program has been in existence since
1986. In 1991 the Florida Legislature recognized the
importance of the program and established Florida
LAKEWATCH in the state statutes (Florida Statute 1004.49.).
LAKEWATCH is now one of the largest lake monitoring
programs in the nation with over 1800 trained citizens
monitoring 600+ lakes, in more than 40 counties.
Why Do We Have ftorida LAKEWATCH?
HI.:'.. D Flonda LAh.EWATCH WI iPP ?
Figure 2. Florida Atlas of Lakes program page.

The Florida Atlas of Lakes web
page structure will include over
600 resource pages and program
pages (Figure 2). Page types are
managed through a web page
administration function which will
allow volunteers and staff to
personalize text, add photos and

communicate via announcements
and web-based forms.
When implemented in October
2007, the Florida Atlas of Lakes will
allow the citizens of Florida to better
understand and appreciate the
important work that is done on their
behalf by Florida LAKEWATCH

volunteers. Users will be able to
view data for any of the
waterbodies in the Florida
LAKEWATCH program. Look
for future announcements in our
newsletter and website as the atlas
release date nears.


The fulownlg is a list f currently
accessible project wpsites, please click
on one of tnhie hnks to x'giore thr
compr n svc and userl-frndly Water

* Lake County Water Atlas
* Manatee County Water Atlas
* Orange County Water Atlas
hIp :www angf w"r"rr, Ii c

Florida Center for Community Design +
5 -Ul I At~ilt, At- + C- ,tv D-c il
Uivi-y Siith ,itBda
3650 Spectru Blvd Suite IBS
Tamrpa, FL 33612

If ywo are interested n knowing more about thi
Water Atlas Pr,&am, pease contact Stan- Landry
at The Fltida CeLter for Commun ity Design +
Give us a cati at 813-974-4042 or If yV prefer to

The home page for the wateratlas web site (www. wateratlas.usf.edu).

To view an

existing county

water atlas or for

more information

about the family

of water atlas

web sites visit


Drkt l MM


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What About Bulkheads?

One of the major topics at the Florida
LAKEWATCH regional meetings
concerns the use of erosion control
structures such as bulkheads, seawalls,
riprap, and retaining walls. The questions
usually deal with the pros and cons of
the structures and how they may affect
the plant and animal life associated with
the shoreline as well as permitting

What are bulkheads?
The Florida Department of
Environmental Protection (FDEP)
defines a bulkhead or seawall as a man-
made wall or encroachment, designed to
protect upland property and structures
from the force of waves that
create shoreline erosion.

What are the effects of
bulkheads on the habitat and
the organisms that utilize that
There is a lot of
information on the
installation of bulkheads, the
materials used in their
construction, and many site
specific engineering reports.
However, there has been
limited research concerning
the effects of such structures .. .
on the habitat and the -
community of aquatic
Scientist in 1998 A vinyl sea
compared the complexity of
communities utilizing the littoral zones of
The study was designed to compare
riprap, vertical retaining seawall, and
natural shoreline. Wire baskets were used
to simulate riprap and concrete blocks to
simulate retaining seawall. Higher
numbers of organisms and more species
were found colonizing baskets than
blocks, however, neither abundance nor
number of species differed statistically
among substrate types. The scientist
concluded that riprap, being a 3-
dimensional artificial substrate, would
offer more surface complexity and
interstitial space for macroinvertebrate
communities than would a 2-dimensional
artificial substrate like a sea wall.

The Texas Parks and Wildlife
Department also did a study concerned
with the number of bulkheads being
placed on Lake Conroe in Texas which
was published in the Reservoir
Newsletter Volume 2, Issue 1 March
1994 Southern Division, American
Fisheries Society. It compared
electrofishing samples between cleared,
bulkhead, and riprap shoreline
treatments. They observed that juvenile
fish were more common in the riprap
shoreline and as a result were able to
convince the Army Corp of Engineers to
require riprap in at least 50% of any
bulkhead structures on Lake Conroe.
Two additional studies investigated

wall constructed on a lake in Michigan.

copper arsenate (CCA), which has
become a concern in regard to human
health. In these 1993 studies scientist
collected oysters, fish, and worms from a
canal that was lined with CCA treated
wood. These organisms had elevated
levels of copper and arsenic in their
tissues compared to organisms collected
at a reference site without treated wood.
Worms with the elevated metal
concentrations in their tissues were then
fed to fish in a controlled study. After
one month the fish showed no significant
trend in survival or growth when
compared to fish fed uncontaminated
worms. Since the study showed that these
metals can bioaccumulate in the tissues
of animals, more research is warranted.

Subsequently, these same scientists in
1994 evaluated the fine particle fraction
of sediment collected near CCA treated
wood. They found high levels of the
metals in the fine particle fraction of
sediment, but also pointed out that fine
particles made up only 1% of the
sediment samples and that the sediments
did not show consistent copper and
arsenic levels. Benthic community
analysis showed reduced species richness
and diversity when compared to
uncontaminated reference sites. The
results of these studies indicate that
materials without CCA should be used if
possible or that materials should be
treated with less toxic wood preservatives
that is available on the

Permitting Procedures
The FDEP is
responsible for
permitting bulkheads
and/or seawalls. This
state agency recognizes
E the need to protect
8 structures from the
effects of erosion while
I' also acknowledging that
bulkheads may have
negative impacts on the
environment. The
Installation of seawalls
Should be designed to
minimize damage to the
shoreline habitat.
Bulkheads should only
be placed where the soil composition and
water activities are susceptible to erosion
and shoreline damage.
There are two basic types of
regulations for bulkheads or seawalls:
permits and exemptions. Exemptions for
installation and repair of bulkheads of set
lengths and orientations are defined in
Section 403.813 of the Florida Statues.
Exemptions as listed in this chapter do
not have to seek authorization from the
FDEP because of their nature and scope.
Going outside these specified
exemptions require permitting from state
and local government.

Continued on page 4.

What about Bulkheads? (continued
Need a permit?
In order to get a permit to protect
habitable structures, the following criteria
must be met:

The structure should not be on a
foundation designed to withstand
undermining by storm erosion.
Non-inhabitable structures can
also be protected if their failure
would damage a habitable
structure or cause major damage to
public infrastructure.
The structure should be vulnerable
to at least a 15-year interval storm.
The bulkhead structure shall not
result in loss to public access if
The construction will not cause
significant adverse impact.

Exemptions to the above criteria:
If there are existing bulkheads on
either side of a property and the
gap between the bulkheads does
not exceed 250 feet (coastal), then
an authorization can be given to
close the gap.
If there is going to be a shoreline
restoration project within nine
months that has been permitted
and funded, then the construction
of a bulkhead cannot be

A bulkhead in a marina in Lake County Florida

When is a permit not required?
A permit is not required for
activities associated with the
following types of exempt projects:

Restoration of seawalls at their
previous locations or upland
of, or within one-foot water
ward of, their previous
locations. This paragraph does
not affect the permitting
requirements of Chapter 161.
Construction of private
seawalls in wetlands or other

A bulkhead located in Naples, Florida.

surface waters where such
construction is between and
adjoins at both ends
existing seawalls; follows a
continuous and uniform
seawall construction line
with the existing seawalls;
is no more than 150 feet in
length; and does not violate
existing water quality
standards, impede
navigation, or affect flood
control. This paragraph
does not affect the
permitting requirements of
Chapter 161.

Additional restrictions
Notice that there are additional
restrictions placed on structures
placed in estuaries and lagoons
as cited in Chapter 373.414(5)
F.S. as follows:

(a) It is the intent of the
Legislature to protect
estuaries and lagoons from
the damage created by
construction of vertical
seawalls and to encourage
construction of
environmentally desirable
shore protection systems such
as riprap and gently sloping
shorelines which are planted
with suitable aquatic and
wetland vegetation.

r- W7,

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A bulkhead located in Tampa, Florida.
(b) No permit under this part to create a
vertical seawall may be issued by the
governing board or the department
unless one of the following
conditions exists:
1. The proposed construction is
located within a port as defined in s.
315.02 or s. 403.021;
2. The proposed construction is
necessary for the creation of a
marina, the vertical seawalls are
necessary to provide access to
watercraft, or the proposed
construction is necessary for public
3. The proposed construction is
located within an existing man-made
canal and the shoreline of such canal
is currently occupied in whole or in
part by vertical seawalls; or
4. The proposed construction is to
be conducted by a public utility
when such utility is acting in the
performance of its obligation to
provide service to the public.
(c) When considering an application for
a permit to repair or replace an
existing vertical seawall, the
governing board or the department
shall generally require such seawall

to be faced with riprap material, or
to be replaced entirely with riprap
material unless a condition specified
in paragraph (b) exists.
(d) This subsection shall in no way
hinder any activity previously
exempt or permitted or those
activities permitted pursuant to
Chapter 161.
This legislation is intended to discourage
the placement of seawalls in areas where
habitat loss can have significant impacts.
Suggested alternatives include sloping
riprap or native vegetation. If seawall
repair is allowed, the permit may specify
that the seawall be faced with riprap. No
permit or exemption may violate state
surface water quality standards and the
Federal Clean Water Act provides the
statutory basis for these standards. The
above state statutes indicate that it is
possible to get a permit and/or an
exemption to construct a bulkhead.
However, these are State of Florida
regulations and it is also possible that
local governments may have additional
regulations. It is the property owner's
responsibility to secure permitting at all

How can I get information
from the FDEP, from rules
to literature?

There are several ways:

General to Specific Questions: Call
the FDEP Office of Citizen
Services at (850) 2-5-2118, or
contact your local FDEP
District Office.

For publications: Call the FDEP's
Office of Environmental
Education at (850) 2-5-2130,
and ask for the Publications List.

Rules can be found on the FDEP
web page under the "Index by
Subject" drop down box.

Rules, Statutes and Publications
also are available at the FDEP
Library, first floor, FDEP Twin
Towers Office Building,
Tallahapsse (R95M 24-5-RSfl

Vounee BltBa

Good Bye Sky!
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/.1 i hl l [ m .I the. Ind lI' .h. -

will mi. eky nd t, llo te ctrent, her rou
w hi.mlill wl on hl. I cre patl.i Goo.d|

stant Director I i F LAKEWATCHn i.

New Regional Du h ties
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I know I speak for everyone when I say we
will miss Sky and all of the talents he brought
to the LAKEWATCH program and that we
wish him well on his new career path. Good
luck Sky!!!!
Mark Hoyer
Assistant Director Florida LAKEWATCH

New Regional Duties
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We Need To Know!

If you are unable to sample your lake due to low water
please let us know. You can call the toll free number
or e-mail us at

2008 Florida LAKEWATCH Calendar Update

Work on the 2008 Florida LAKEWATCH calendar is
progressing and we are excited about the more than 200
great photos we have received from our volunteers. For
updates on the availability of the calendar and to see which
photos have been included in the calendar check the
LAKEWATCH website (http://lakewatch.ifas.ufl.edu) in late
September or early October. Thanks to everyone who
submitted entries and Good Luck!

Jackson ('ountv

///L' t' t l II 1 /0 'lI L LL//L'C II I u 'lll/l.'\ II // l. t /l lllltl
1) Elder Care Services Marianna Office
4297 Liddon ST. larianna, FL 32446
Hours: 8 AN1-12 Noon, Monday Friday
Call ahead to be sure. It is next to the old high school.
2) Silver Lake Reality Offices
Jim Garrett Realty
132 Fairview Road
Marianna, FL 32448
Contact: Beverly Schollian

Missing Your Quarterly Summary?

Florida LAKEWATCH head chemist Mary Stonecipher would like you to know
that due to health reasons she has not been able to keep up with the
quarterly data summaries, as she would like. She is doing much better now
and is looking forward to getting your quarterly data summaries out to you as
soon as possible. Thank you for your understanding!

Some of Jerry Jaillet's fondest
childhood experiences come from the
shores of Lake Ola in Orange County.
Even today he spends many hours of
recreation on the lake working to
protect it for others. Naturally, when
Jerry learned about our organization
he thought that it would be a great way
to preserve this unique resource. Jerry
was trained to collect water samples
for LAKEWATCH on Lake Ola on
October 7, 1990 and has remained a
dedicated volunteer for over 16 years.
During this time he has sampled for
approximately 200 months. On top of
this impressive achievement, Jerry
also started sampling Lake Jem in
Lake County on September 17, 1997.
This is an extraordinary example of
dedication and one that we can all find
inspiration from. Way to go Jerry!
Lake Ola is a 446-acre lake located
in the town of Tangerine at the corer
of US 441 and Hwy 448. The lake is
classified as a mesotrophic lake
located in the Apopka Upland Region,
an area of residual sand hills
overlaying karst limestone bedrock.
Lakes in this region are variable. Some
are acidic, clear, soft water lakes with
low mineral content and some are
clear lakes with moderate nutrients
and some are darker water lakes.
Jerry is an avid outdoorsmen,
which makes a good match with a long
career working in the nursery
business. One thing we have learned
about Jerry is that when a concern
comes up on the lake, he will take the
time to learn all about that issue before
making a decision. Yes, we understand
that lake management can lead to
touchy debates, but keeping an open
mind and getting the data to address
the issues can lead to a better
understanding of lake ecosystems and
help make management decisions.
We give a heart-felt appreciation
for Jerry's time and effort he has
shared with the LAKWATCH
program. Jerry' s dedication to his
lakes goes


~~j :i


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Jerry Jaillet displaying his Outstanding Volunteer paddle
for more than 15 years dedication to the LAKEWATCH
program at the Lake County regional meeting in Tavares.

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mi[ W 'I Most p'Jopl etIh i lovre Io Shl~r aau S ate aem

Domesticated ducks are ducks that are
bred in captivity and have been "tamed"
from the wild. They are often raised as
pets, for consumption, and for
aesthetically pleasing purposes.
Domesticated ducks often depend on
humans for survival but can become quite
adept at fending for themselves in the
wild if need be. Common domesticated
ducks observed on lakes include the
Green-headed Mallard, White Peking,
and the ubiquitous and often maligned

having domesticated ducks in your lake,
there are also good reasons for not
releasing our domesticated feathered
friends into the wild.

Let's face it, most people don't mind
a few ducks in the lake. However, as you
know it doesn't take long for a pair of
ducklings to become a small family and
before you know it there are flocks of
ducks all over the lake! The problems

they happen to be at the time. Areas
that we human beings like to frequent,
such as swings, tables, chairs, water
slides, benches, boats and docks are all
favorite spots for ducks to leave there
little calling cards.

Bacteria/Swimmers Itch
Some studies have shown that lakes
and ponds with large populations of
ducks and geese may also have high

A mother Florida mottled duck with her ducklings in south central Florida in May 2006. Photograph copyrighted by Bob Paty, and
used with permission.

Homeowners may intentionally
release domesticated ducks on their
lakefront property for numerous
reasons. Some people like to see
living things around their lake, some
have memories of feeding the ducks
when they were kids, and others just
like having a few ducks hanging
around for good measure. Just as
these may be good reasons for

begin when the ducks start visiting places
where they don't belong. They love
swimming pools, backyards, docks,
boats, driveways, roadsides, and just
about anywhere you can imagine.
They also love to eat and have been
known to chase people down to beg for
snacks. Because they eat, they eventually
have to defecate and will do so wherever

fecal coliform bacteria concentrations.
These bacteria can cause and
gastrointestinal distress in swimmers
who ingest the contaminated water.
Some people who are more sensitive
can develop rashes when they come
into contact with the bacteria.

Also associated with ducks and
aquatic birds are certain parasites
including the swimmer's itch organism
that requires birds as intermediate host.
When a duck defecates into the water it
releases the parasites from its body,
which then seek to find another host. One
part of the life cycle of this parasite is a
free-swimming form that attaches itself
to swimmers and causes irritation that is
known as swimmer's itch.

The waste produced by ducks contains
both phosphorus and nitrogen. When
their feces enter a water body it can
elevate nutrient levels and cause higher
algae concentrations. So if you have a
large population of ducks on a small
water body there is the potential for an
increased chance of algae blooms when
they defecate in or near the lake and in
turn fertilize it.

The Florida Fish and Wildlife
Conservation Commission (FFWCC)
enforces a state law that prohibits the
release of domestic ducks into the wild
because these ducks can compete with
native wildlife for food and habitat and
may transmit diseases. Another potential
problem with releasing domestic ducks
also involves genetic issues.
Domesticated Green-headed Mallard
ducks can hybridize with the native
Florida Mottled Duck and reduce their
genetic integrity. There are documented
cases where store-bought domestic
Green-headed Mallard ducks were
released into the wild. These ducks then
bred with the native Florida Mottled
Duck and created a hybrid that diluted
the genetic pool of this unique species
that occurs no where else in the world.
The Florida Mottled Duck does not
migrate and spends all of its life in the
peninsular area of Florida. Wild Green-
headed Mallards, however, do not
hybridize with the native Florida Mottled
Ducks because by the time breeding
season rolls around they will have
migrated north, out of Florida, and
therefore do not mate with the Florida
natives. But the domesticated Green-
headed Mallard ducks that are released to
the wild do not migrate north and stay in

A green headed mallardpairfloating in the lake.
Florida year round. As a result, they are
available to breed and hybridize with the
Florida Mottled Duck.
So what should one do? First off, do
not release, feed, or shelter domesticated
Green-headed Mallard ducks. Tell your
friends and neighbors the problems
associated with releasing or supporting
domesticated mallards as well as other
breeds of domesticated ducks. Educate
your environmental managers about
problems with these ducks. Get a
commitment from the people who live on
lakes or have lake access to not release
them. All in all, the lakes will probably
be better off with the native wildlife that
normally uses the lakes.
If you would like additional
information about the feral mallard

A Florida mottled duck in its native habitat.

hybridization problem or would like
more information about the removal of
mallards, please contact one of the FWC
waterfowl offices at (850) 488-5878 or
(321) 726-2862; or visit the FWC Web
site at www.MyFWC.com/duck and
click on "mallard control permit."
Licensed, permitted trappers may
assist you with the removal of mallards.
A list of trappers is available by visiting
The U.S. Department of Agriculture's
Wildlife Services also has the authority
and can assist you with such removal
efforts. Their services are available year-
round and they can be contacted at (352)


Why do We Collect the Brown Bottle Samples?

During training sessions, our
volunteers may have noticed their
regional coordinator collecting some
additional water. These one-liter brown
bottles are used by Florida
LAKEWATCH to provide additional
water for supplemental chemistry
analysis. The additional testing for total
alkalinity, pH, specific conductance,
color and chloride concentrations
provides insight into basic biological and
chemical processes in lake systems.
However, tests for these parameters must
be completed in a shorter time window
from un-frozen water, therefore they are
only collected when the regional
coordinator can turn them in quickly to
the LAKEWATCH laboratory.

Total alkalinity is a measure of the
water's capacity to neutralize acids. Total
alkalinity is often abbreviated TALK.
The unit of measure for total alkalinity is
milligrams per liter of total alkalinity as
equivalent calcium carbonate
(abbreviated mg/L as CaCO ). Even
though alkalinity is expressed in units
that reference calcium carbonate,
alkalinity levels of natural water are
generally the result of bicarbonates.
Total alkalinity of a lake is
influenced by the soils and bedrock
minerals found in its watershed and by
the amount of contact the water has had
with them. For example, lakes in
limestone regions, which are rich in

LAKEWATCH staff collecting supplemental
water samples from a lake in South Florida.

calcium carbonate, often tend to have
higher values for alkalinity. Those in
sandy soil regions, which lack
calcium carbonate, often tend to have
lower values.
High alkalinity waters are more
biologically productive than low
alkalinity waters. Consequently, total
alkalinity was once used as an
indirect measure of a lake's
productivity. In general, soft water
lakes have lower alkalinity values
ranging from 0 to 60 mg/L CaCO
and hard water lakes alkalinity values
are greater than 62 mg/L as CaCO.
Total alkalinity concentrations from
1120 Florida lakes sampled range
from 0 to 391 mg/L as CaCO with
over 75% having total alkalinity
values less than 42 mg/L as CaCO .
This means the majority of lakes in
the Florida LAKEWATCH program
are considered soft water lakes.

The pH is a measure of hydrogen
ions in solution. It is measured on a
log scale of 1 (acid) through 14
(alkaline or basic), which means a
change of one pH unit represents a
tenfold change in hydrogen ion
content. A measure of 7.0 is
considered neutral. The pH of most
natural waters ranges from 4.0 to 10.0
with most waterbodies falling in a
narrower range of 6.5 to 8.5. For
comparison, stomach acid has a pH
around 2.0, human blood is around
7.0 and saliva around 7.5, while
rainfall tends toward the acid side
ranging from 4.5 to 5.7.
The pH of hard water lakes is
generally stable due to the high
amount of bicarbonate in the water.
The pH values of these lakes range
vary over a narrow range from 7.5 to
8.5. The pH of soft water lakes by
comparison is much more variable
ranging from 5.0 to over 9.0 due to
lower concentrations of bicarbonate
ions in the water. Photosynthesis and
respiration are the driving forces for

the change in pH over the course of a
day in lake water. Photosynthesis
removes CO2, which is acidic, from
the water leading to an increase in
pH. Respiration dominates during the
night when there is no photosynthesis
leading to increases in CO2 and a
corresponding decrease in pH. The
pH values from 1120 Florida lakes
sampled ranged from 3.9 to 11.7,
with approximately 50% of the lakes
sampled having pH values between
5.8 to 7.8.

Specific conductance
Specific conductance is a
measure of the capacity of water to
conduct an electric current and is
representative of the total amount of

1 *

LAKEWATCH lab assistant Wanda Garfield
analyzes water samples.
ions or salts in the water. A higher
value of conductance means that the
water is a better electrical conductor.
Generally, specific conductance of a
lake is determined by the geology of
the land surrounding the lake.
Conductivity can become elevated
as a result of human activities. For
example, effluent from septic systems
or wastewater treatment plants can
have high solute levels that raise the

specific conductance above natural
levels. Natural factors can also
cause higher conductance values in the
open water. For example, drought
conditions can increase the salt
concentrations in a lake as the heat and
low humidity can increase the rate of
evaporation in open water, leaving the
lake with a higher concentration of salt.
Specific conductance values of 1120
lakes sampled in Florida ranged from
11 to 20233 iS/cm @ 25 C with over
75% of the values less than 220 iS/cm
@ 25o C.

Color of a water sample is comprised
of two components. Apparent color is
the color of a water sample that has not
had particulates filtered out and true
color is the color of a water sample that
has all particulates filtered out of the
The measurement of true color is the
one most commonly used by scientists
and the value reported by
LAKEWATCH. Color is expressed in
platinum-cobalt units (abbreviated as
either PCU or Pt-Co units) and a
higher PCU value represents water that

The presence of color can reduce both
the quantity and quality of light
penetrating into the water column and in
turn, will influence the growth of plants
and algae, the types of aquatic plants and
the depth they will grow to. An
acceptable level of color depends on
personal preference. Water clarity
becomes noticeably reduced in highly
colored waters (greater than 50 PCU) to
the point where underwater hazards may
be concealed, creating a potentially
dangerous situation for swimmers, skiers,
and boaters. The color values of 1120
lakes sampled in Florida were highly
variable and ranged from 0 to 700 PCU
with 75% of the color values less than 68

Chloride Concentration

Chloride is a substance found in all
natural waters. Chloride levels in lakes
are affected by several factors with
climate being a major influence. For
example, chloride concentrations in lakes
in humid regions tend to be low, whereas
those in semi-arid and arid regions may
be hundreds of times higher because of
higher rates of evaporation.

LAKEWATCH head chemist Mary Stonecipher pours up water for chemical analysis.

The activities of people and
animals can also affect chloride
concentrations. Common table salt,
sodium chloride, is a necessary part of
human and animal diets. Chloride is
found in all animal and human wastes,
septic systems and areas where animal
wastes are deposited and can be
sources of chlorides entering lakes.
Home water softening systems and
fertilizers are also potential sources of
chlorides. For these reasons, the
presence of high levels of chlorides
can sometimes be used as an indicator
of pollution from these sources.
Many coastal waters have high
concentrations of chloride, because
they are close to marine (i.e.,
saltwater) systems. In these
waterbodies, seawater can seep
underground, called saltwater
intrusion, or flow directly into them
through tidal flow. Also, sea spray
carries chloride into the air where it
can then enter lakes as part of rainfall,
even far from coastal areas. Chlorides
are not dangerous themselves, but may
signal the possibility of contamination
from human or animal wastes that
contain bacteria and other substances
of health concerns. For this reason, it
is important to investigate sources of
high chloride concentrations in inland
waters. The chloride concentrations of
1120 lakes sampled in Florida range
from 1.7 to 7500 mg/L, with over 75%
of the lakes having chloride
concentrations less than 28 mg/L.

As you can see, a great deal of insight
into a waterbodies condition can be
determined from the results of this
supplemental water chemistry.

For additional
information please refer
to Florida LAKEWA TCH
Circular 101,

A Beginner's Guide to
Water Management: A
Description of
Commonly Used Terms.

Department of Fisheries and Aquatic Sciences
7922 NW 71st Street
Gainesville, FL 32653

TForT1al Fundraiser Update!
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