Title: Surface Water Improvement and Management (SWIM): Lake Apopka: Marsh Flow-way Project Removing Nutirents
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Title: Surface Water Improvement and Management (SWIM): Lake Apopka: Marsh Flow-way Project Removing Nutirents
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Language: English
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Spatial Coverage: North America -- United States of America -- Florida
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Abstract: Surface Water Improvement and Management (SWIM): Lake Apopka: Marsh Flow-way Project Removing Nutirents
General Note: Box 8, Folder 5 ( Vail Conference, 1995 - 1995 ), Item 33
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00001419
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
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Lake Apopka


Surface Water Improvement and Management


Fact Sheet


Marsh Flow-way Project removing nutrients


The St. Johns River Water
Management District's 1,850-
acre marsh flow-way project is
designed to filter suspended
sediments rich in phosphorus
and nitrogen from Lake
Apopka.
An overabundance of phos-
phorus and nitrogen in the
lake is the principal cause of
the lake's poor condition.
The lake's pea green color,
caused by chronic algal
blooms, has prompted many
to refer to Lake Apopka as a
f( "dead" lake. Actually, the lake
is much too alive. The profu-
sion of algae serves to choke
off many of the normal life
forms present in a healthy
lake system.
These algal blooms indicate
an overly-enriched condition in
the lake where phosphorus
and nitrogen, elements
common in fertilizer, serve to
feed the algae.
The flow-way, located on
the northwest corner of the
lake, is on a site where
vegetables were once grown.
Functioning much like a swim-
ming pool filter, it removes
phosphorus and nitrogen from
the lake as water passes
through the grassy marsh in a
shallow sheet flow.
The sediments contained in
the lake are constantly
re-suspended in its shallow,
turbulent basin. They will be
f filtered from the water as it
passes through the marsh
flow-way before returning to
the ApoDka-Beauclair Canal


and Lake Apopka. Rention
time of water in the flow-way
varys from 3-25:days to
determine optimum water
depth and flow rate for the
full marsh flow-way project.
Environmental scientists at
the District estimate 90 per-
cent of the phosphorus in the
lake is in particulate form and
that much of the suspended
sediments can be filtered out.
During the next two years,
the District will fine-tune the
flow-way process in prepara-
tion for expanding the project
to 5,000 acres.
Dr. Mike Coveney, techni-
cal program manager for
Lake Apopka's restoration,
predicts the full marsh flow-
way system will remove and


store 30 metric tons of
phosphorus per year from the
lake, and the total volume of
Lake Apopka could pass
through the marsh flow-way
twice each year.
In the final 5,000-acre
marsh flow-way, water from
Lake Apopka will be filtered for
10 days. Ninety percent of that
treated water will be returned
to the lake, while 10 percent
will go downstream. Only
treated water from the marsh
will be released to go down-
stream.
Land for the initial marsh
flow-way cost $5,000,000.
Construction on the 1,850-
acre project began in Decem-
ber 1989 and took one year to
complete.


I







Chronology of Lake Apopka
Restoration Efforts
June 1985
Lake Apopka Restoration Act passed,
directing SJRWMD to develop an envi-
ronmentally sound, economically feasible
method to restore Lake Apopka.

June 1987
Legislature passes SWIM Act, naming
Lake Apopka a priority for restoration.

August 1987
Marsh Flow-way concept formalized.

March 1988
Interim SWIM plan developed for Lake
Apopka.
June 1988
First $5,000,000 appropriated for
Marsh Flow-way land acquisition.

DER delegates to SJRWMD authority
to regulate agricultural discharges into
Lake Apopka.

June 1989
Second $5,000,000 appropriated for
Marsh Flow-way land acquisition.

September 1989
DER approves Lake Apopka SWIM
plan.

December 1989
Construction begun on Marsh Flow-
way Demonstration Project.

June 1990
Final $5,000,000 appropriated for
Marsh Flow-way land acquisition.

November 1990
Marsh Flow-way Demonstration
Project begins operation.


Lake Apopka Vital Statistics

Location: Approximately 15 miles north of Orlando in Lake and Orange counties.

Size: Fourth largest lake in Florida with a surface area of 30,800 acres and a volume
of 54 billion gallons.

Depth: Lake Apopka's water stage is 66.5 feet above sea level. The average depth
is 5.4 feet. Deepest point is 16 feet along south shore. Ninety percent of the flat and
shallow lake bottom is covered by a layer of sediment averaging 46 inches thick.
This black muck sediment is composed of dead algae and plant material.
These sediments are constantly stirred up by wave and wind action, reducing the
clarity of the water. This resuspension keeps the sediments in the lake water so that
they can be filtered out as the water passes through the marsh flow-way.
Lake Apopka is classified as "hypereutrophic" in that it has an average of .22 mg/l
of phosphorus and 4.5 mg/1 of nitrogen (typical level is .05 mg/1 for phosphorus and
1.0 mg/l for nitrogen).

Recreational Activity: Once heralded as one of the best bass fishing lakes any-
where, only one of 21 fish camps open in 1956 still remains open. Recreational
activity is nearly non-existent. There is little recreational fishing and swimming is
discouraged.

Marsh Flow-way Vital Statistics

Total Area: The Demonstration Project is 1,850 acres, including 950 acres of wet-
lands, of which 635 acres comprise the flow-way. The full marsh project will be 5,050
acres, including 4,150 acres of wetlands.

Water Flow: The Demonstration Project's rate of water flow from the lake varies
from 30-300 cubic feet/second. It takes 3-25 days for the water to pass through the
marsh flow-way. These flow rates will help determine the optimum nutrient storage
levels for the full marsh project. The full marsh project is designed for a water flow
from the lake of 510 cubic feet/second, with the water taking 10 days to make its way
through the flow-way. It is estimated the full marsh project will extract 30 metric tons
of phosphorus from the lake each year.

Land Cost: Land for the Demonstration Project cost $5,000,000. Land
acquisition for the full marsh project is estimated at $15,000,000.

Benefits: The Marsh Flow-way is designed to:
Reduce muck farm discharges through land acquisition;
e Restore fish and wildlife habitat;
Protect downstream lakes;
a Improve water quality.

Flow-way project's filtering improves water clarity


For more Information about the
Lake Apopka restoration project,
call Jim Conner at (407) 897-4347,
or the Public Information Division
at (904) 329-4500.


The Marsh Flow-way Demonstra-
tion project's natural filtering process
is having a visible effect on water
quality and clarity.
In initial tests, the marsh has
removing more than 40 percent of
phosphorus and 50 percent of
nitrogen from the water-exceeding
designers' projections.
More than 90 percent of all sus-
pended solids--which phosphorus
and nitrogen bind to-are removed
as the lake water passes through
the marsh.
The difference between water


entering the marsh flow-way and
that leaving it is startling.
District environmental scientists
use a black and white secchi disk to
measure water clarity. They record
the depth at which the disk is no
longer visible in the murky water.
Secchi comparisons between the
center of Lake Apopka and the
pump station at the end of the marsh
flow-way show water clarity at the
pump station is up to ten times
greater than at the center of the
lake. A




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