Lake Munson will be drained as efforts to mitigate pollution, algal bloom continue
In order to address harmful algal blooms and ongoing issues with pollution, the county is planning to draw down Lake Munson in the next month.
Effectively draining the lake will dry out and kill invasive aquatic plants such as hydrilla and compact years of polluted sediments that have settled on the lake bed.
Leon County commissioners got an update on the efforts of county and state officials to address Lake Munson, which has endured a toxic algal bloom over the past few months that has resulted in fish kills and the closure of the lake.
Work on Lake Munson has been a several-decades endeavor. Much of the city's stormwater runoff flows through the lake via Munson Slough as it passes south into the Wakulla Spring Basin.
The previous times the lake was drawn down were in 2000 and again in 2010.
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What will happen to the fish?
An action plan specifically focused on the lake was established in 1994 and since then there has been more than $285 million in stormwater investments by the county, the city of Tallahassee and the Blueprint Intergovernmental Agency
The target drawdown date is Nov. 1, said Anna Padilla the county’s stormwater management coordinator. She said the lake would remain dry for as long as it takes for it to respond to the efforts.
During the three to five-month period when water levels are being reduced by closing off an upstream dam, fish and other aquatic animals will follow the water into a sinkhole at the southwest corner of the lake.
County staff, however, note that many of the fish in the lake would not survive a complete draw down.
Populations could be re-established when those in the sinkhole or from upstream re-enter the lake or through stocking efforts by the Florida Fish and Wildlife Conservation Commission.
“The primary goal of the drawdown is to improve sediment quality, and thereby water quality, improving the long-term health of the entire lake ecosystem,” staff wrote in agenda materials. “Creatures that live naturally in Lake Munson have recovered from past drawdowns. The current condition of the lake, including an abundance of hydrilla and warm temperatures, threaten the entire fish population and can cause fish kills.”
Advocates fear effort will fall short
In recent months, citizens concerned about environmental impacts and quality of life for people who live around the lake have sounded the alarm.
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Terry Ryan, a co-founder of the Tallahassee Sewage and Wakulla Basin Advocacy Group, noted several concerns with the project moving forward, including no mention by county staff about removal of harmful sediments from the lake bed once its dried.
He detailed concerns sent to the county in the 90s by former chief of the city-county Environmental Planning Division, Craig Diamond.
“Continual drawdowns without removing dead vegetation, legacy muck and addressing legacy sediment will soon create an unusable lake of continual drawdowns and recoveries,” Ryan wrote in an email.
He also said he would have liked to have seen dedications to upstream and downstream testing to better identify pollution sources.
A short-term solution
The entire lake is not expected to dry up. There are portions of the lake where water would remain due to topography. There are no plans to dredge the top layer of sediment from the lake bed once it is dried.
However, Lake Henrietta, a stormwater pond along Springhill Road will be dredged. The pond is designed to catch water and sediments before they get into Lake Munson. The county has secured a federal grant to dredge Henrietta.
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The drawdown is a short term effort to address pollution.
Long-term efforts include treatments of algal blooms with peroxide, implementing an invasive aquatic vegetation management program alongside the FWC and a reoccurring draw down schedule every five to 10 years. Additionally, monthly water quality sampling will be done for the next two years.
The emerging efforts are more targeted at Lake Munson itself rather than addressing upstream issues that have been a focus for years, said Assistant County Administrator Ken Morris.
“Our focus has been we want the water that’s coming into the lake to be as clean as it can be and that will improve the overall quality of Lake Munson. The water going into the lake is much cleaner than the water in the lake.”
Contact Karl Etters at ketters@tallahassee.com or @KarlEtters on Twitter.
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This article originally appeared on Tallahassee Democrat: Lake Munson will be drained as efforts to mitigate pollution continue
