In this section
- History of Lake Apopka
- Lake Apopka Marsh Flow-Way
- Lake Apopka North Shore
- Gizzard shad harvesting at Lake Apopka
- Continuous sensor-based water quality data
- Map of the regions (flood control areas) where water control structures operated by the district are designed to reduce flood impacts
Lake Apopka shad harvesting
- Setting Water Quality Goals for Restoration of Lake Apopka: Inferring Past Conditions (technical report)
- Total Maximum Daily Load for Total Phosphorus for Lake Apopka, Lake and Orange Counties, Florida (technical report)
- Florida Fish and Wildlife Conservation Commission aquatic plant management strategy for Lake Apopka
Lake Griffin is one of nine lakes in the Harris Chain of Lakes.
Located in northwest Lake County, the 9,400-acre Lake Griffin is one of nine lakes that make up the Harris Chain of Lakes — Apopka, Beauclair, Carlton, Dora, Eustis, Yale, Little Lake Harris and Harris. These lakes all drain into Lake Griffin, then into the Ocklawaha River and into the St. Johns River. Lake Griffin is fed by rainfall and water flowing from the upstream lakes through a dam on Haynes Creek. A dam on the Ocklawaha River downstream of Lake Griffin controls water levels in Lake Griffin.
Until the early 2000s, Lake Griffin was considered one of Florida’s most polluted lakes. It was plagued for decades by discharges of phosphorus from farms along its northeastern shore and discharges of wastewater and industrial outfalls. Farming and sewage discharges into upstream lakes, particularly Lake Apopka, also contributed to Lake Griffin’s deterioration.
With the increase in nutrients and subsequent algal blooms, water clarity deteriorated. The cloudy water prevented sunlight from reaching underwater vegetation critical to fish and wildlife habitat, and the continual settling of dead algae created several feet of soupy sediment on the lake bottom.
Beginning in 1996, chlorophyll levels in Lake Griffin noticeably increased, and the lake became greener. Chlorophyll levels in lake water indicate algal growth is fed by excess phosphorus. Surveys by the St. Johns River Water Management District of Lake Griffin’s algal communities revealed that a new, nonnative species of blue-green algae, Cylindrospermopsis raciborskii, made up 95 percent of the algae in the lake.
The district is moving forward to restore the entire Harris Chain of Lakes. The restoration of Lake Griffin has focused both on the lake itself and on upstream Lake Apopka. The district is now developing a plan to establish minimum flows and levels and to return more natural flows and levels to the lakes. Three dams built within the Harris Chain of Lakes and on the Ocklawaha River to prevent flooding have slowed water flows and stabilized lake levels since the 1960s. More continuous flows and more natural fluctuations in levels are critical to healthy water bodies and marshes in Florida.
Great blue heron
Other work in the basin has included:
- Eliminating sewage discharges into the Harris Chain in the 1980s, and beginning steps to control stormwater discharges into the lakes.
- Sponsoring studies to develop management plans for the Lake Griffin algal blooms.
- Purchasing 7,000 acres of former muck farms along the northeastern shore of Lake Griffin between 1991 and 1993 to decrease nutrient discharges to the lake. Total phosphorus discharges from the former muck farm area have decreased by more than 90 percent. Low-elevation areas of the former farms are being restored to aquatic and wetland habitat, while uplands are being managed as natural areas.
- Adopting an interim lake level fluctuation plan in 2002 to enhance fluctuation of water levels in Lake Griffin.
- Reconnecting Lake Harris and Lake Griffin via a wetland area called the Harris Bayou. This represents a major step in providing the structure needed to improve flood management and allow more desirable fluctuation along the Chain of Lakes.
- Harvesting gizzard shad, removing more than 2.7 million pounds from the lake since 2002. The harvests reduces the cycling and re-suspension of phosphorus-laden sediments associated with the feeding behavior of these fish. Scientists believe that the shad harvesting has contributed to the improvements in water quality in Lake Griffin, although reduction in external nutrient loading has been the major factor affecting the lake.
As water quality in the lake improves, fish and wildlife habitat also has begun to recover and surveys in the lake show establishment of numerous beds of desirable submersed vegetation. This habitat provides primary spawning and nursery area for game fish species. The wetlands already provide diverse habitat for wildlife. Since 1997, numerous wading birds and waterfowl, including more than 1,000 endangered wood storks and more than 500 white pelicans, have fed in the restored marshes.
Updated on 1-28-2013