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Leon County
Board of County Commissioners Cover Sheet for Agenda #18 March 21, 2023 |
| To: | Honorable Chairman and Members of the Board |
| From: | Vincent S. Long, County Administrator |
| Title: | Lake Munson Status Report |
| Review and Approval: | Vincent S. Long, County Administrator |
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Department/Division Review and Approval: |
Alan Rosenzweig, Deputy County Administrator Ken Morris, Assistant County Administrator Brent Pell, Director, Public Works Charles Wu, Director, Engineering Services |
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Lead Staff/ Project Team: |
Anna Padilla, Stormwater Management Coordinator |
This item provides a six-month status update on the implementation and ongoing efforts related to the Lake Munson Action Plan, as approved by the Board at the October 11, 2022 meeting, including a recommendation to extend the drawdown through Spring 2024 to further dry out the exposed areas of the Lake and promote sediment capping to enhance water quality.
This item has no fiscal impact.
Option #1: Accept the status report on Lake Munson.
Option #2: Approve the extension of the Lake Munson drawdown through Spring 2024.
Report and Discussion
This item provides a six-month status update on the implementation and ongoing efforts related to the Lake Munson Action Plan, as approved by the Board at the October 11, 2022 meeting, including a recommendation to extend the drawdown through Spring 2024 to further dry out the exposed areas of the Lake and promote sediment capping to enhance water quality.
Execution of the Action Plan began immediately following approval by the Board. An aggressive schedule was implemented preparing for the drawdown with public notification and outreach as well as pre-drawdown data collection. Notable activities and findings include:
On September 13, 2022, the County Administrator advised the Board that staff was preparing an agenda item for the October 11th meeting that would seek Board approval to proceed with a temporary drawdown of Lake Munson and provide recommendations for any additional short- and long-term best management practices that may be advisable for the Lake. At that time, the Board directed staff to meet with a Lake Munson citizens group (Workgroup) to address their concerns about the Lake as part of the October 11th agenda item.
On October 11, 2022, a status report on the Best Management Practices for Lake Munson was presented to the Board which provided background information on Lake Munson including the millions of dollars the County has made and continues to make in investments in watershed planning, major project implementation, and follow-up studies throughout the basin since the 1990s. Despite the better water quality, in-lake mitigation, and the magnitude of investments in upstream infrastructure, during the summer of 2022 Lake Munson continued to experience occurrences of fish kills, algal blooms, invasive vegetation and snails, low game fish productivity, and depressed oxygen levels. The October 11th item presented the ongoing efforts and lake management best practices to address the challenges associated with Lake Munson including a planned drawdown with more frequent water quality testing, an aerial topographic survey of Lake Munson to measure elevations of compacted sediment, a new vegetation management program for treating invasive plants, and implementation of periodic drawdowns in consultation with Florida Fish and Wildlife Conservation Commission (FWC) to eliminate the need to mechanically remove organic-rich sediment. And finally, the item provided information on the County’s cooperative efforts with a group of local residents to address their concerns surrounding present day lake challenges.
This status report advances the following FY2022-FY2026 Strategic Initiatives:
These particular Strategic Initiatives aligns with the Board’s Environment Strategic Priorities:
Lake Munson has historically been subjected to drainage with high nutrient loads and wastewater discharges to the tributary system, which has resulted in the embedding of legacy nutrients in the lake-bottom soil. The Lake receives surface water flow from a 32,000-acre basin, much of which is located in the City of Tallahassee (Attachment #1). In the early 1980s the effluent from the City of Tallahassee T.P. Smith Water Reclamation Facility was redirected from Munson Slough to the Tram Road Sprayfields and since then, effluent from T.P. Smith does not discharge into Lake Munson (neither directly nor indirectly). Decades of development in the Tallahassee red-clay hills, wastewater treatment facilities discharging to the tributary system, and drainage activities focused on flood reduction contributed high nutrient loads entering Lake Munson resulting in poor water quality.
Efforts to improve the water quality and reduce the nutrient loading in Lake Munson have been ongoing since the 1990s. Leon County Government, the City of Tallahassee, and the Blueprint Intergovernmental Agency have dedicated hundreds of millions of dollars for projects in the Lake Munson basin and prioritized upstream improvements which provide water quality treatment, reduce the transport of sediment, collect trash, and benefit the Lake water quality. Since 2019, two studies have been completed on sediment contamination in Lake Munson which have guided the evaluation and analyses of future restoration projects. While the Lake continues to improve, undoing decades of damage will take continuous commitment to in-lake and upstream best management practices. The lake activity in summer 2022 including algal blooms, a fish kill, and rapid growth of an invasive aquatic vegetation (hydrilla), provided an opportunity to articulate the ongoing and planned strategies to enhance water quality, reassess the best management practices for the Lake, and explore opportunities to enhance the Lake conditions.
During development of the 2022-2023 Action Plan, staff sought input on the current water conditions, quality and ecology of Lake Munson from subject matter experts across County departments, Blueprint, State agency partners, consultants, and the Leon County Science Advisory Committee (SAC). Through the years, Leon County has coordinated with State agency partners such as Florida Department of Environmental Protection (FDEP), FWC, and Florida Department of Health (FDOH) for management of Lake Munson. The SAC is a citizen committee appointed by the Board and City Commission and is composed of credentialed scientists, University faculty, and local engineering and science professionals, many of whom have served multiple four-year terms (Attachment #2). The SAC has a great deal of institutional knowledge on Lake Munson and has provided input over the years on lake management best practices, operating under the general guiding principle of “First Do No Harm”. And finally, the County coordinated with the Workgroup, made up of residents who live near Lake Munson and other citizen stakeholders, to address area resident concerns.
Coordination with the Workgroup consisted of several meetings as well as an evaluation of ten specific requests made by the Workgroup to the Board. Staff listened to residents’ experiences and concerns, and engaged subject matter experts on issues related to water quality conditions, marine life, prudent health precautions related to algal blooms, and the projects and programs designed to enhance Lake Munson. These meetings also included State-agency partners from FWC and FDOH, County Department staff, SAC members, and Blueprint staff. While several of the Workgroup’s requests were incorporated into the Action Plan, all 10 were thoroughly addressed in the October 11th agenda item explaining where there is agreement or disagreement on certain mitigation techniques and best practices for Lake Munson.
As part of the 2022-2023 Action Plan, this item serves as the status report on Lake Munson to be provided to the Board every six months over the two-year drawdown and enhanced monitoring of Lake conditions.
Leon County Government, the City of Tallahassee, and the Blueprint Intergovernmental Agency have dedicated hundreds of millions of dollars for projects in the Lake Munson basin and prioritized upstream improvements which reduce the transport of sediment and benefit the Lake water quality. Munson Slough and Lake Munson are exceeding their State-mandated nutrient levels for nitrogen while phosphorus levels have declined significantly over the last ten years and are now approaching the target levels. While the Lake continues to improve, undoing decades of damage will take continuous commitment. The 1994 Lake Munson Action Plan has been used as the basis to guide watershed and stormwater improvements, regular testing and monitoring of water quality, and regulatory actions to limit pollutants and protect natural resources. Since 2019, two studies have been completed on sediment contamination in Lake Munson which will guide the evaluation and analyses of future restoration projects. As a result of these studies and the analysis presented to the Board in its adoption of the 2022-2023 Lake Munson Action Plan, in-lake sediment removal is no longer a viable mitigation option to reduce nutrient levels in Lake Munson at this time; however, as new technologies and information become available, dredging will continue to be evaluated as an option in the future.
Water quality improvements are not always immediately noticeable or profound and sometimes waterbodies experience setbacks as the system stabilizes with the improving conditions. Despite the better water quality, in-lake mitigation, and investments in upstream infrastructure, in recent years Lake Munson has continued to experience occurrences of fish kills, algal blooms, invasive vegetation and snails, low game fish productivity, and depressed oxygen levels. Several of these conditions were experienced by Lake Munson residents during the summer of 2022, providing an opportunity to hear directly from residents and other stakeholders. The County’s goals for the Lake include the water quality exceeding the State standards, a healthy ecosystem with native vegetation, a healthy and beneficial fish and wildlife habitat, and fewer algal blooms. While nothing in nature can truly be the same after outside influence, as a result of the active efforts discussed here the Lake has, and will continue to, recover from its chronic history of poor water quality due to wastewater discharges and drainage with high nutrient loads.
On October 11, 2022, the Board approved the 2022-2023 Lake Munson Action Plan which was prepared based on input from the Lake Munson Workgroup, State agency partners, and the SAC with a focus on water conditions, quality and ecology of Lake Munson. The 2022-2023 Lake Munson Action Plan provides a holistic approach to quickly mitigate the rapid growth of hydrilla and algal blooms while also providing long-term strategies aimed to supplement the State’s in-lake vegetation management activities and provide a higher level of service to County residents. As part of the approved Action Plan, this six-month status update provides an update on the progress of the Lake drawdown, an opportunity to articulate the major infrastructure projects planned and designed to benefit the Lake Munson basin, an update on the in-lake management actions to treat exotic vegetation and algal blooms, and the ongoing engagement over the next two years to evaluate the Lake’s response to the drawdown. The following is an outline of the Action Plan and the information provided in this status report:
Since adoption of the Action Plan at the October 11th meeting, the drawdown and enhanced monitoring have begun, as well as preparations for the long-term lake management actions and, as requested by the Board, staff continue to monitor the State’s study of health-related issues related to algal blooms. Engagement with the SAC and Workgroup has also continued with an update on the Action Plan presented to the SAC members and the Workgroup at the December and March SAC meetings. And finally, staff has joined the FAMU-Lake Munson Environmental and Health Group (FAMU Study Group), consisting of FAMU faculty engaged by the Workgroup who will be conducting scientific-based research into the ecological health and best practices for the Lake.
A quarterly update on the Action Plan was provided to SAC at its December and March meetings. At the request of the Workgroup, the SAC also discussed the Action Plan at its January meeting, outside of the quarterly schedule. Feedback from SAC and the Workgroup on the progress of the drawdown and Action Plan are provided throughout this item.
Lake Munson Drawdown & Extension
On November 1, 2022, three weeks after the presentation of the 2022-2023 Action Plan to the Board, Public Works staff opened the gate on the Lake Munson Dam and began the drawdown. While the Lake drained, staff monitored downstream conditions and the gate opening size was adjusted based on the downstream response. Ultimately the gate was fully opened and has stayed fully open since. By November 10th the Lake had substantially drained. As a result of several rainfall events since the drawdown began, the Lake has retained water on several occasions but with the gate fully open, eventually receded (Attachment #3). The Action Plan specified a drawdown period of 3-5 months, depending on the weather, and in consultation with FWC. The five-month mark for the drawdown is March 31st.
The higher than anticipated rainfall this winter has led to discussions on the appropriate time to refill the Lake. During their March meeting, the SAC discussed extending the drawdown beyond the 3-5 months. The initial conversation included extending the drawdown into this summer and evolved into extending for one to several years, allowing more time for the Lake sediment to dry out and oxidize. The concept of an extended drawdown is not new and has been discussed previously by the SAC. In conjunction with the Lake Munson Restoration Project in the early 2000s, the Lake was drawdown for 2 years and benefited greatly. The 2010-2011 Lake Munson drawdown, originally planned for 3-5 months, was extended to 8 months to allow additional drying time of the Lake bottom. Longer drawdowns provide more time and opportunity for the sediment to dry out, ultimately providing more benefit to the Lake. As outlined in the Action Plan, as a State-managed waterbody, staff has been working closely with FWC to determine the optimal time to begin refilling the Lake. In early March, staff met with representatives from FWC’s Invasive Plant Management, Aquatic Habitat and Conservation Restoration, Fish and Wildlife Research Institute, Freshwater Fisheries Management, and Hunting and Game Management Divisions to discuss the appropriate time to refill the Lake. FWC recommended continuing the drawdown until summer 2024 to allow additional time for the Lake to dry and promote sediment capping to improve water quality. FWC advised there would be additional benefits to the ecosystem and wildlife habitat. Without water in most of the Lake, terrestrial plants, which are plants that live on land, have filled in and are growing in the Lake. These plants provide an excellent benefit for wading birds as well as providing fish habitat when the Lake refills.
Based on the guidance from FWC for the State-managed waterbody and input from the SAC, this item recommends extending the drawdown through Spring of 2024. Staff will meet with FWC regularly to discuss progress of the drawdown, the SAC will continue to receive quarterly updates on the drawdown to review with the Lake Munson Workgroup, and the Board will continue to receive updates every six months.
The Workgroup, which championed the calls for the drawdown in the Fall, has shifted its position over the last few months. The Workgroup now questions the effectiveness of the drawdown based on water levels remaining in the North Lobe of the Lake, the rainfall over the winter, a City of Tallahassee Sanitary Sewer Overflow in mid-January, and concerns for the water quality leaving the Lake.
North Lobe Water Levels
As described in the October 11th item and further explained in an email to the Board on January 6th the length of time needed to dry out the sediments is dependent on nature and the weather. A majority of the bottom of the Lake has been exposed during the drawdown, but several areas such as the north lobe (bunny ear) and the southwest portion (back foot) have retained water, but at shallower depths than normal. This is due to the differences in the elevation of the lake bottom, as it relates to the elevation of the dam gate. These two areas have a lower lake bottom elevation creating pools of water that cannot drain and are located off the main flow through channel line, making it more difficult for the water to flow out of them to the dam. In addition, the north lobe is separated from the rest of the Lake by a sill, a naturally occurring higher elevation between two lower areas. In response to calls by the Workgroup to channel or pump the remaining water, staff advised that the sill separating the north lobe is considered an original feature of the Lake and currently has large 100-year old cypress trees.
This topic was discussed by the SAC at their January meeting. The SAC concluded that pumping of this area would create an unnatural condition, and would not provide an ecological benefit to the Lake given the relatively small size of the northern lobe. The goal of the drawdown is to mimic the natural draining and refilling cycle that keeps lakes in a healthy state. Channeling or pumping to drain these areas would be altering a historic, natural condition and could be counterproductive to the expected benefits of the drawdown. In addition, water remaining in this portion of the Lake provides ecological benefits by providing refuge for fish and other organisms and will retain establishment of the native aquatic vegetation.
As the Lake drains, the fish and other living organisms are forced to the areas that hold water. These areas serve as a place the fish and invertebrates can retreat to and survive during the drawdown, which will aid in quicker re-establishment upon refill of the lake. In addition, within the northern lobe, the submerged aquatic vegetation is predominantly native species. The remaining water will allow the native species to survive and give them a head start when the Lake is refilled. These areas will be well established with native vegetation so invasive exotic species will have a difficult time growing and the native vegetation will provide a seed source for areas that dried out. The water remaining in low areas of the Lake will offer a quicker and healthier response following the drawdown.
Workgroup Requests
On September 12, 2022, members of the Workgroup attended the Board meeting and provided a list of requests in writing and seeking a drawdown of Lake Munson. The Workgroup was supportive of the inclusion of the drawdown in the Action Plan and urged the County to initiate immediately. During the Fall meetings with staff, members of the workgroup expressed support for more frequent, annual, and extended drawdowns to benefit the Lake. The Workgroup continued to be vocal supporters of the drawdown until the beginning of the year. On January 28, 2023, staff received an email from the Workgroup stating they “determined the drawdown to be a failure” based on the amount of rain that had been received and associated stormwater runoff. The Workgroup stated that “our scientists reported scraping sediments flowing to the out flow and on to Wakulla Springs” and that the sanitary sewer overflow of a City facility on January 22nd negated any hope for the drawdown. The Workgroup recommended that “given the failure of the drawdown,” the gates on the dam be closed to “prevent further damage to the springs” and suggested that prolonging the drawdown will not be feasible due to Spring rains.
During the March 3rd SAC meeting and discussion about an extended drawdown limiting the use of the Lake, members of the Workgroup did not raise objections and noted that they were unable to use the Lake at that time and last summer given the conditions of the waterbody. However, on March 9th the Workgroup conveyed in writing its opposition to extending the drawdown and the need to close the gates on the dam due to impacts to Wakulla Springs. The issues raised by the Workgroup related to the sanitary sewer overflow and drawdown impacts on Wakulla Springs are addressed in the next two sections of this item.
Most recently the Workgroup has raised concern over the phosphorus reductions associated with drawdowns, claiming drawdowns have no effect on phosphorus levels in the Lake. While drawdowns result in smaller phosphorus reductions than nitrogen reductions, the drawdown can still provide a benefit to phosphorus reduction and removal from the system. The differences between the nitrogen reduction and the phosphorus reduction are related to the useable forms of the two and the cycles they each go through. Nitrogen takes several forms, and cycles between the different forms. Not all forms of nitrogen are available to plants. Nitrogen can also be converted to a gas and released into the atmosphere. Phosphorus forms are divided into organic and inorganic phosphorus. Inorganic phosphorus includes phosphorus that can be used by plants and organisms, while the organic phosphorus is the material that is incorporated into the tissues of plants and animals. The drawdown will provide some inorganic phosphorus reduction as the plant roots will take up phosphorus out of the sediment and animals eat the plants. Lake Munson is a nitrogen-limiting system, meaning the plant and algae growth is limited by the amount of nitrogen in the system. Additional phosphorus added to the system, or less phosphorus removed than nitrogen during the drawdown, will not result in increased vegetation or algae growth.
Sanitary Sewer Overflow
On Tuesday, January 22nd just before 6 pm, the City was alerted to a wastewater pump failure at Pump Station (PS) 12 – Orange Ave, which is located on West Orange Avenue, adjacent to Black Swamp, between Lake Bradford Road and Springhill Road. Upon investigation, crews discovered a large amount of debris (primarily rags) had clogged the pumps. The City crews worked for several hours to clear out the pumps and restore the normal operation of the system. The City conducted a follow-up inspection the next morning and observed a sanitary sewer overflow (SSO) approximately 250 feet west of the pump station that was not visible the night before due to heavy rain and darkness. Approximately 40,000 gallons of untreated domestic wastewater discharged from the system into Black Swamp due to its proximity, some of which ultimately flowed downstream to Lake Munson. When the SSO occurred, the City followed FDEP standard protocol, notified FDEP and FDOH, vacuumed up and recovered approximately 4,000 gallons of wastewater from low lying depressions, disinfected the impacted areas, and began ongoing water quality sampling for e-coli, the parameter which is the State’s regulatory standard for bacteria in Class III waterbodies, including Black Swamp. The City collected and tested samples daily at four stations, one upstream at Lake Bradford Road, one at the point of discharge, and two downstream locations along Munson Slough (one at Springhill Road and one at Capital Circle SW). The locations were chosen using FDEP standard practice and based on the proximity of the spill to Lake Henrietta and Lake Munson. The initial water quality samples taken immediately upstream of the Lake Henrietta stormwater facility and park at Springhill Road indicated impacts at that location. Although Lake Henrietta is a stormwater management facility, the City placed two spill notification signs within the Lake Henrietta parking area.
The results of the daily water quality sampling for e-coli at the four stations were provided daily to FDEP and FDOH as part of the State’s regulatory responsibilities in monitoring the incident. As a courtesy, the daily sampling data was also shared with County staff to analyze the conditions on the ground. The e-coli sampling is an effective indicator of the pathogens that can be present in wastewater. The natural environment is not a suitable living condition for the e-coli and pathogens, resulting in its reduction with time. The water quality samples track the transport of any unrecovered wastewater downstream, as well as any potential health concerns and indicate when the potential pathogens are no longer present. The City continued daily water quality sampling to track the reductions in e-coli concentrations at the established stations. On the seventh day the e-coli levels in the samples were still detected but reduced and were below the required water quality standards for SSO compliance set by FDEP. Consistent with FDEP standard protocol, because the water quality standards were met, the City ceased sampling. The City followed all FDEP requirements throughout the process and went above and beyond by facilitating the cross-jurisdictional partnership, keeping the County well-informed and updated, providing daily sampling results.
In addition to the immediate mitigation steps taken by the City, the subject pump station is scheduled for replacement through a $12 million capital improvement project with construction of a new station expected to begin this spring. The new pumps will be more resistant to clogging from rags and debris and the increased number of pumps will provide additional resiliency. Until completion, City crews plan to increase maintenance frequency of pump station.
Despite the City’s response to the SSO and adherence to FDEP’s requirements, the Workgroup issued multiple emails expressing dissatisfaction with the response by both the City and County. The Workgroup wanted to expand the e-coli testing to include additional parameters such as “nutrients and toxic contaminants” and sought additional testing sites to track the discharge downstream in Lake Munson at the Lake outfall. The Workgroup also suggested in emails that “the City and County Commissions should require testing of all water bodies affected by any sewage spill,” the County should conduct its own extensive tests when sewage spills enter waterbodies within the County’s jurisdiction, and for the “County to hold the City accountable and further require the City to initiate any additional cleanup or address resident health issues, now or in the future.” However, in addition to protecting public health, one of the reasons why the State has a regulatory role in the cleanup and response to an SSO is to mitigate local jurisdictional disputes.
As the system operator, the City is responsible for any SSOs and is required to follow Florida Administrative Code and State protocols as determined by FDEP and FDOH. Both agencies have established operating procedures and protocols to protect human health and safety and the environment. As cross-jurisdictional partners, the City and County remained in regular communication, and the County thoroughly monitored the situation and reviewed sampling results provided by the City. Based on the daily sampling results provided by the City, e-coli likely would have been detected in Lake Munson and further south in the Slough downstream of the Lake following the SSO; however, any e-coli downstream would be at lower concentrations than at the stations tested. Sample results are provided to FDOH daily for review and issuing health-related advisories and warnings. Had the levels been of concern with risk of human contact, additional steps would have been taken, such as additional signage like was posted at Lake Henrietta or health warnings issued by FDOH. As with any potential danger in a County facility, including waterbodies, the County facilities would be closed to the public.
Members of the Workgroup have long pursued more widespread and frequent testing of everything from the types of facilities being tested, enhancing the frequency of the County’s quarterly sampling, to the City’s response to SSOs despite the local governments’ adherence to State requirements and without a scientific rationale for the expanded testing. Further, the Workgroup has made claims about the quality of water leaving Lake Munson having a negative impact on Wakulla Springs. The January SSO incident resulted in the repeated calls for additional testing sites, more testing for nutrients and toxic contaminants, and concerns about the impact to Wakulla Springs. Additional testing is not warranted as determined by scientific, statistical analysis, as described in further detail later in the Analysis. In recent months, the Workgroup has claimed that the water leaving Lake Munson is negatively impacting Wakulla Springs as a result of the drawdown followed by the SSO. The Lake’s connection and conveyance of water to Wakulla Springs, including during the drawdown and following the SSO, is explained in the next section of the Analysis.
Connection to Wakulla Springs
The Workgroup have been vocal supporters of the drawdown until the beginning of the year, when they called for an end to the drawdown based on a belief that Lake Munson was directly and negatively impacting Wakulla Springs. The Workgroup has taken issue with the quality of water leaving Lake Munson claiming the conveyance of the wastewater from the SSO, the belief that sediments on the Lake bottom are being picked up and transported downstream, and overall poor water quality that is ruining Wakulla Springs. The drawdown has been discussed with various State agency partners and there have been no concerns with negative water quality impacts at Wakulla Springs.
Water in Lake Munson has, and will continue to, leave the Lake and flow downstream. The drawdown does not prevent outflow from the Lake, it merely changes the amount of time water is held in the Lake after a rain event. The SSO occurred during a rainfall event and at a time when water levels in the Lake were higher. When this occurs, the water coming in does not entirely pass through the Lake, and instead, some water is held in the Lake by the dam before discharging. Any pathogens that may have been transported downstream from the SSO would continue to die off before reaching Wakulla Springs.
The Workgroup claims that rainfall on the Lake is disturbing the lakebed sediment and then washing it downstream to Wakulla Springs. They have observed dark water flowing through the dam and believe this to be sediment from the lakebed. Rainfall events all generate some level of runoff in which sediments can be picked up and washed downstream. However, it is unlikely that stormwater flow through the Lake is stirring up the sediments on the bottom. Staff has conducted field inspections throughout the drawdown and while water discharging through the dam is brown in color, it appears to the be the same quality of water entering the Lake. The water flowing through the Lake follows a channel, which is also the primary path through the Lake when it is holding water. As water flows through the Lake, it is not digging a new channel and picking up sediment. Outside of the primary channel, the bottom of the Lake is covered with vegetation, which prevents the disturbance of sediment. The roots of the vegetation keep the sediment in place both when the bottom is exposed, and when the Lake has water.
The Workgroup raised this issue during the March SAC meeting. The SAC discussed the matter and reinforced that the sediments are not being resuspended during the drawdown. Staff and SAC agree that dark water flowing over the dam is not an indication of sediment from the lakebed or poor water quality. While Lake Munson usually has clear water, waterbodies upstream such as Black Swamp, Lake Bradford, and Cascade Lake are usually dark due to tannins, caused by decaying organic matter in the water that turns it dark, which does not correlate to poor water quality. Depending on water levels, this tannic water can be noticeable in Lake Munson. With low levels of water in the Lake during the drawdown, this tannic water would be noticeable flowing over the dam and downstream.
Although flow leaving Lake Munson does ultimately reach Wakulla Springs, this connection is several miles long and travels through an extensive surface and groundwater system before reaching the Springs. After discharging from Lake Munson, flow travels through Munson Slough approximately 2.5 miles, predominantly through the Apalachicola National Forest, before reaching Eight Mile Pond, an approximately 120-acre wetland and waterbody, that provides storage and water quality benefits. After some time in Eight Mile Pond, the water flows an additional half-mile to Ames Sink, where the water slowly enters the Upper Floridian Aquifer. Traveling through the aquifer system underground (straight line distance of over 5.75 miles), the flow from Ames Sink joins with three other underground streams and eventually emerges at Wakulla Springs. With four counties (Gadsden, Jefferson, Wakulla, and Leon) contributing flow to Wakulla Springs, these four streams combined contribute less than 11% of the flow discharging from the spring vent.
The drawdown presents other opportunities to enhance Lake Munson and stormwater facilities upstream while the water levels remain low including Clean-Up Events that will engage the community, provide education and outreach, and improve water quality with the removal of litter and debris from the system.
Clean-up Events
Due to the ongoing drawdown at Lake Munson, the County has a unique opportunity to conduct two water cleanup events in April. First, and most importantly, the County will conduct a focused service-learning engagement event in for local area volunteers in coordination with a Boy Scout troop. The drawdown has exposed litter along the shoreline and also presented an opportunity to educate and engage the public. The shoreline cleanup demonstrates the County's continued commitment to preserving our natural resources and protecting and ensuring Lake Munson's water quality and health. Second, the lake drawdown also presents an opportunity to cleanup Lake Henrietta on April 22 in celebration of Earth Day. Lake Henrietta provides an important water management function for Lake Munson, filtering trash and pollutants from the water before entering into Lake Munson. The drawdown has exposed the banks of Lake Henrietta, leading to a unique community engagement clean-up event.
Enhanced Monitoring
The Leon County Water Quality Monitoring Program performs quarterly water quality sampling and annual sediment and biological assessments of 12 lakes, 27 streams and 2 river systems at a total of 70 stations throughout the County. The County’s Water Resources Scientist, Water Resources Limnologist, and Engineers review and analyze the data for trends in the system and summarizes the information in the Annual Water Quality Report. The County has water quality data dating back to its inception in 2001 and the Program continues to demonstrate the County’s ongoing efforts as a responsible environmental steward of our natural resources and environmental beauty. As part of the Water Quality Monitoring Program, Leon County samples Lake Munson quarterly with two stations located in the Lake, one upstream in Munson Slough, and one downstream in Munson Slough (Attachment #4). Sampling is not conducted in Lake Henrietta because it is stormwater management facility. The Action Plan expands upon the existing Program to provide for enhanced monitoring of Lake Munson to include: a Water Quality Study, Point-Source Testing for PCBs and other contaminants, and an Aerial Topographic Survey.
The three components of the enhanced monitoring of Lake Munson are described in the following subsections. However, it is important to first recognize how water quality standards are assigned to waterbodies in Florida, how testing occurs, and the tremendous progress that has been made with regard to Lake Munson.
Lake Munson is designated by State Statute as Class III – Fish Consumption, Recreation, Propagation and Maintenance of a Healthy, Well-Balanced Population of Fish and Wildlife waterbody. Waterbodies designated as Class III are those where a person can engage in recreational activities or consume the fish they caught. A waterbody is considered impaired once the water quality criteria, or limits on physical and chemical parameters, have been exceeded and the waterbody no longer supports the designated uses or activities without posing a health or safety risk. The County’s Scientists monitor the quality of our water resources through field sampling to analyze the chemical makeup and assess the biological health of our waterbodies to ensure that waterbodies are within acceptable nutrient levels. Quarterly water quality samples are collected by certified County staff and analyzed for approximately 39 water quality parameters by laboratories that are accredited through the National Environmental Laboratory Accreditation Program (NELAP). After collection, the data is entered into the Florida Watershed Information Network (WIN) database for use by local, state and federal agencies. Should a waterbody exceed the water quality thresholds established by the State and become impaired, FDEP and the County would prepare a restoration plan to identify programs and improvements designed to reduce nutrient levels to meet the state standards. In most cases, the FDEP develops a Total Maximum Daily Load (TMDL) for the waterbody to achieve restoration.
The TMDL is a report, adopted by State rule, outlining the scientific determination of the maximum amount of pollutant a waterbody can absorb and still meet the water quality standards for the designated use. A TMDL also determines a pollutant reduction target and allocates necessary load reductions in the sources of the pollutant. In 2013, TMDLs were adopted for Lake Munson and Munson Slough, both upstream and downstream of the Lake. The TMDL included target concentrations for nutrients (nitrogen and phosphorus) and necessary load reductions. Waterbodies with a TMDL can be restored over time with upstream water quality investments and on-going waterbody management strategies and Lake Munson has made measurable improvement.
As a result of the significant investment in upstream improvements by the County, City, and Blueprint, substantial water quality achievements within the Lake Munson drainage basin have been achieved, thereby improving the water quality entering the Lake and in the Lake. The nutrient concentrations in Munson Slough (above the Lake) are lower than the target levels established in the TMDL. Based on available information, this is the first time in the data history of Munson Slough, which dates back more than 50 years to 1971 (one year prior to of the enactment of the Clean Water Act), that nutrient-based water quality standards have been met. Since the early 1970’s both nitrogen and phosphorus have been reduced by more than 95%. The water quality in Lake Munson has also experienced measurable improvements. Within the Lake, the nitrogen concentrations have been consistently below the TMDL limit since 2017 and the phosphorus concentrations have steadily declined (24% reduction since 2013) such that it is approaching the TMDL standard. Graphs of Munson Slough and Lake Munson’s nitrogen and phosphorus concentrations are included in Attachment #5.
Achieving the target levels of a TMDL is rare, but achievable with commitment and investment from multiple jurisdictional and agency partners. Within Northwest Florida, Munson Slough (above the Lake) is the only waterbody to achieve a nutrient-based TMDL and no longer be considered as impaired for the applicable nutrient parameters. The data collected through the Program provides a holistic approach to evaluating and monitoring the ecosystem health of the waterbodies of Leon County including Lake Munson. The Action Plan and enhanced monitoring expands upon the existing Water Quality Monitoring Program to provide a greater frequency of nutrient testing around Lake Munson, testing of the water column for metals and relic contaminants, and gather new sediment data from an aerial survey of the Lake.
Water Quality Study/Monthly Testing
As part of the drawdown, a Water Quality Study is being conducted to supplement the County’s routine quarterly Water Quality Monitoring sampling. The study will collect flow readings and standard water quality parameter samples at four locations (two immediately upstream of Lake Henrietta, one in Munson Slough immediately upstream of the Lake, and one in Munson Slough downstream of the Lake). The sampling plan was developed based on feedback and recommendations from the SAC. The Workgroup agreed with, and was supportive of, the monthly sampling for nutrients and requested testing at locations entering and leaving Lake Munson. An added benefit of the Water Quality Study and sampling locations is the valuable information it will provide on the efficiency of Lake Henrietta and can be used to quantify the water quality benefits of the Lake Henrietta Sediment Removal Project, discussed later in the item.
An initial sample event was planned prior to the drawdown; however, due to limited rainfall in October and the aggressive timeline to begin the drawdown by November 1st, conditions in the slough were not favorable for sampling. When the drawdown is complete, the remainder of the Study will begin, consisting of monthly sampling to collecting flow data and water quality samples at the four locations, for a period of two years. In-lake water quality samples will be collected separately during the County’s Water Quality Monitoring Program routine quarterly testing. In addition, the City has recently expanded their water quality monitoring sampling locations and will be sampling quarterly at one location in the Lake.
Since late December, the Workgroup is no longer supportive of the Water Quality Study developed in coordination with the SAC and now maintains that “at least weekly testing for nutrients and toxins” should be conducted at the Munson outfall to alert County staff of water quality conditions. This issue was discussed by the SAC at its January and March meetings and determined weekly testing to be unwarranted, which has long been the standpoint of County staff. The SAC determined that the confounding of nutrients, metals, and other toxins in statements by the Workgroup is counterproductive and these are not interchangeable properties. SAC members reiterated that the water has been tested. Quarterly water chemistry samples consistently have low nutrient concentrations and historical nutrient data from Wakulla Springs does not indicate any significant input from Lake Munson outflow. Further, the two in Lake Point-Source Testing samples (described further in next section) collected in late October show very little metals and no detectable toxins in the water in Lake Munson. The SAC confirmed that weekly sampling will not provide any more actionable information and would waste limited resources. County staff concur that the water chemistry in the Lake will not drastically change from week to week and collecting samples monthly will provide a clear picture of the health and trends of the Lake.
Once the Lake begins to refill, it will take time for the nutrient levels and ecosystem to stabilize. The monthly sampling of the inflow and outflow water following the drawdown is sufficient to capture fluctuating nutrient values. The SAC suggested that the Workgroup provide scientific evidence that weekly sampling of nutrients is necessary. Similar scientific evidence could be provided for toxins, including which specific toxins should be included in the testing. No scientific information supporting the calls for the more frequent nutrient or contaminant testing has been provided by the Workgroup. Most recently, the Workgroup points to the periods of low flow, when samples cannot be collected, and the TMDLs on Lake Munson and Wakulla Springs as the basis for more sampling. Again, these requests are unsubstantiated by scientific evidence. As discussed and supported by SAC during their March meeting, the County’s Water Quality Monitoring Plan has accounted for the low flow periods by establishing back up stations and protocols, consistent with FDEP requirements. While a TMDL is in place for Lake Munson and Wakulla Springs, this does not necessitate more frequent sampling. The quarterly sampling meets the State requirements and provides enough information to evaluate and monitor the Lake and track progress with the TMDL.
The Workgroup has often routinely confused nutrients in the water with PCBs and other contaminants in the sediment. The Water Quality Study and monthly sampling will test the water for nutrients. Independently, the 2022-2023 Action Plan includes Point-Source Testing to address concerns of the Workgroup surrounding the contaminants in the sediment.
Point-Source Testing
Members of the Workgroup have long advocated for the County and City to conduct Point-Source Testing to measure concentrations of polychlorinated biphenyls (PCBs) and metal contaminants upstream of Lake Munson. At issue were the findings and interpretations of two studies from 2019 and 2021 which also provide the basis against dredging Lake Munson. In an effort to resolve the concerns raised by the Workgroup, Point-Source Testing was incorporated into the Action Plan and welcomed by the Workgroup. The goal of the Point-Source Testing is to validate the 2019 sediment study conducted by the Florida Geological Survey (2019 FGS Sediment Study), a division of FDEP, and the associated review by Terracon Consultants, Inc. (2021 Terracon Report) to show that the sediment contaminants are not resulting in water column contamination. The studies found that although the Lake contains contaminated sediment, that PCBs and other contaminants are tightly attached to the sediment particles and are not leeching off into the water.
At its September 2022 meeting, the SAC discussed and provided guidance on sampling the water flowing into Lake Munson for dissolved concentrations of contaminants. Throughout development of the Action Plan, the Workgroup agreed with the methodology of the Point-Source Testing to sample in the water column during high flow and agreed on the four locations in and around the Lake. However, the Workgroup sought reoccurring Point-Source Testing and wanted to sample further upstream into the City limits. The Action Plan included one-time Point-Source Testing at the County’s two Water Quality Monitoring stations in the Lake and the Munson Slough upstream and downstream stations to determine whether PCBs and other contaminants in the sediments had transferred to the water column.
Contaminant sampling at the two stations in Lake Munson was taken the last week of October in conjunction with the County’s routine Water Quality Monitoring Program quarterly sampling. The results from these in-lake samples support the 2019 FGS Sediment Study and the 2021 Terracon Report to show that the PCBs and other contaminants in the sediment are not contaminating the water column. In short, of the 115 contaminants analyzed, only four were detected in the Lake water samples, all of which were metals (Arsenic, Barium, Iron, and Selenium). Of the four metals detected, three were well below the State’s water quality standards. Iron concentrations in the water were also below the State water quality standards but had higher concentrations than the other metals. Despite the higher concentration than the other metals, iron is naturally occurring so there is not cause for concern.
Due to limited rainfall in October and the aggressive timeline to initiate the drawdown by November 1st, conditions in the slough were not favorable for sampling prior to the drawdown. However, samples were subsequently collected in Munson Slough upstream and downstream of the Lake in early March. The results of the water column samples collected in the Slough will be presented and reviewed at the next quarterly update meeting with the SAC and Workgroup, and will be included in the next six-month status update to the Board.
During the December SAC meeting to review the results of the in-lake contaminant testing, the SAC explained that the contaminants are bound to the sediment and are not transferring through the water and into the air. The Workgroup continued to present alternative, unsubstantiated theories about the contaminants in the sediment such as their transfer to the water or air, and a link to the algal blooms. The Workgroup has raised concerns over the possibility of microorganisms “absorbing the contaminants, thereby, initiating a food chain reaction to be absorbed by fish consumption and airborne toxins distributed among residents and recreational use of the Lake.” In addition, they questioned why FDEP does not test fish for all toxic contaminants, but instead tests for PCBs and mercury. These issues were discussed further by the SAC at its January meeting. All contaminants in the sediment can be taken up by microorganisms, and then passed into the fish; however, PCBs will be detected in the fish tissue before other contaminants. Therefore, FDEP tests for PCBs and mercury but not additional contaminants. The last Lake Munson fish study conducted by FWC, FDEP, and FDOH in 2019 shows low levels of PCBs, even decreased from previous samples, which indicated this process of transfer from sediment to microorganisms to fish is becoming less of a threat.
The County will review the results of the Munson Slough PCB and contaminant testing and will provide the results to the SAC for review and discussion. In the unlikely event that elevated dissolved concentrations are found, additional sampling or an investigation into the upstream sources may be warranted.
Aerial Topographic Survey
The Action Plan calls for an aerial topographic survey to be conducted two times, once immediately after the lake bottom has been fully exposed and again immediately prior to refilling the Lake. This information will provide data on how much the sediment compacted, as well as information on the elevations of the current lake bottom. Data quantifying the amount of compaction is useful in evaluating the effectiveness of the drawdown. It also provides information on the responsiveness of the Lake during a drawdown which is beneficial in determining future drawdown timing. This component was included in the Action Plan based on findings from the 2010 drawdown.
The survey flight requires good weather, low Lake levels, and a preceding period of no rain. The first aerial survey was completed on November 29, 2022. At the time of the first survey, water had vacated approximately 205 acres, or 70% of the Lake. The County’s Survey Consultant will conduct the second aerial survey at the conclusion of the drawdown. After the County has received the final survey, County Water Resources and GIS staff will analyze the data to determine the amount of compaction and compare water depths to historical information.
Ongoing and Planned Infrastructure Projects
Since the 1990s, the County, City, and Blueprint have invested hundreds of millions of dollars in upstream infrastructure project to provide water quality treatment, reduce sediment transport, and collect trash (Attachment #6). As our community has continued to make so many investments over the last 30 years on these upstream improvements to ensure that clean water is flowing downstream, the County has also prioritized the importance of addressing household septic systems to reduce nitrogen loading to area waterbodies. According to the Comprehensive Wastewater Treatment Facilities Plan (CWTFP) approved by the Board earlier this year, approximately 34% of the nitrogen contribution to Wakulla Springs comes from septic systems in the four-county area and the southeastern portions of Leon County contribute more nitrogen to surface and groundwater than other parts of the County. Through the implementation of Leon County Strategic Initiatives and Bold Goals since 2017, the County has aggressively and successfully pursued state grant funds to eliminate and/or upgrade conventional septic tanks in the Primary Springs Protection Zone (PSPZ).
Based on the shared desire to enhance water quality in our region through nitrogen reduction projects, Leon County and FDEP jointly adopted the Leon County Water Quality and Springs Protection Infrastructure Improvement Plan (Springs Improvement Plan) in FY 2018. This first of its kind multi-year agreement between the State and a county was the result of Leon County’s strong commitment to reducing nitrogen levels in the PSPZ and FDEP’s willingness to provide a dollar-for-dollar match toward projects in Leon County. Both parties committed over $34 million through FY 2024 for water quality and springs protection infrastructure projects, subject to annual appropriation by the Board and Florida Legislature.
At present, there are several ongoing and planned infrastructure projects within the Lake Munson Basin which will have a direct benefit to the water quality of Lake Munson (Attachment #7), including:
Lake Henrietta is a constructed regional stormwater management facility that slows the rate of stormwater flowing to Lake Munson and provides a place to collect nutrient-rich sediment and floating trash before it can enter Lake Munson. Since construction in the early 2000s, the stormwater management facility has captured over 53,000 cubic yards of sediment and trash. Leon County was recently awarded a $2 million grant by the U.S. Environmental Protection Agency (EPA) for the Lake Henrietta Sediment Removal Project. The design of the project is anticipated to commence later this spring with construction to follow in FY 2024. This project will remove the material accumulated in Lake Henrietta and will restore the function of the facility, thereby reducing the amount of sediment flowing downstream to Lake Munson and improve the water quality of the Lake.
As part of the ongoing efforts to reduce the nitrogen output associated with household septic tanks, the County and FDEP have invested millions of dollars for the construction of the Northeast Lake Munson Septic to Sewer Project. This $15.6 million investment, funded in part by an FDEP Springs Protection Grant, brings sewer to neighborhoods immediately adjacent to Lake Munson and will remove up to 220 septic systems. Construction commenced in late February 2023.
Lake Munson, and portions of the Munson basin, are within the PSPZ which makes residents eligible for voluntary programs which offer financial incentives to homeowners that wish upgrade their conventional septic tank to an advanced nitrogen-reducing system.
On January 24, 2023, the Board accepted additional funding for the Septic Upgrade Incentive Program bringing the total available grant funding to $2.22 million which will provide incentive payments to nearly 300 property owners. The County is currently accepting applications for the project which opened earlier this month (March 2023).
The Capital Cascade Segment 4 improvements include stormwater improvements to enhance water quality in the Lake Munson basin and address sediment loads and trash accumulation in Lake Henrietta and Munson Slough.
This Spring, the City will replace PS12 – Orange Avenue, through a $12 million capital improvement project with construction of a new station. The new pumps will be more resistant to clogging from rags and debris and the increased number of pumps will provide additional resiliency.
Long-Term Lake Management Actions
The Action Plan calls for an expanded role of the County in managing Lake Munson as it continues to coordinate with state agencies on long-term restoration opportunities. As a State-managed waterbody, the County historically relied on the State for in-lake management such as the treatment of aquatic vegetation and sediment removal projects. The Action Plan includes supplementing the State’s lake-management efforts and responsibilities by implementing an enhanced vegetation management program, algal bloom treatments, initiating periodic drawdowns in consultation with FWC, and exploring new and innovative methods for in-lake management. The following sections summarize ongoing efforts related to these initiatives.
Invasive Exotic Vegetation Management Program
Invasive exotic plants adversely impact native plant communities and, if left untreated, will rapidly colonize and take over a waterbody. Native species create a healthier ecosystem; they allow a variety of plants to grow and serve as food and nesting habitat for fish and wildlife. As a State-managed waterbody, FWC’s Aquatic Plant Management Program provides for treatment of exotic vegetation for area lakes. The 2022-2023 Action Plan approved by the Board Plan calls for the County to implement an Invasive Exotic Vegetation Management Program to supplement the State’s treatment efforts on Lake Munson. Staff, in conjunction with FWC will monitor the Lake through the extended drawdown and will coordinate treatment efforts, if needed prior to refill of the Lake.
Algal Blooms Management Program
One of the requests by the Workgroup was a peroxide treatment of the algal blooms. Peroxide treatment methods on algal blooms are very new to Florida. Staff will continue to review the results of peroxide treatment on algal blooms state-wide and will evaluate the use on future blooms on Lake Munson, as well as continuing to explore the best treatment method for Lake Munson. Staff is reviewing what aspects of this component may be needed over the summer during the extended drawdown and are initiating contract development for potential use this summer and upon refill of the Lake.
Innovative Technology Exploration
And finally, staff will continue to explore new and innovative methods for lake management, and any potential strategies and technologies will be presented to the SAC and state agency partners for discussion and analysis. On August 15, 2022, the County applied for an FDEP Innovative Technologies Grant for a pilot project on Lake Munson utilizing Biochar, a charcoal-like substance capable of removing the dissolved nutrients that facilitate algal blooms. This grant will explore the effectiveness of the Biochar and determine scalability if implemented in a larger setting. The successful outcome from this and other Innovative Technologies Grants could be used on Lake Munson in the future. As of this writing, the FY 2022-2023 awardees for the FDEP Innovative Technology grants have not been announced. Staff will continue to follow the grant award status. As the FY 2022-2023 and future FDEP Innovated Technology grants are awarded, innovative projects are completed, and new strategies are proven to be effective, the best practices in lake management and restoration will continue to evolve.
State Health-Related Studies
The Florida Department of Health (FDOH) is the lead agency to address the health effects of cyanobacteria algal blooms throughout the State. FDOH has a process and procedures in place for assessing public health conditions related to algal blooms, and a dedicated web page providing information about their natural occurrence in Florida, precautions residents should take for themselves and their pets, and FAQs. While FDOH’s position at this time is that exposure to algal blooms may result in nuisance health effects, including temporary respiratory issues and irritations of the eyes, nose, and skin, it is important to note that additional research is underway at the federal and state levels to better understand this issue. The U.S. Centers for Disease Control is conducting surveillance studies on human and animal illnesses that are associated with exposures to cyanobacteria algal blooms, and the State of Florida is utilizing four universities to improve the understanding of potential human health impacts of algal blooms and red tide. Through FDOH, the State provided $650,000 to four universities in 2019 for ongoing studies on the prevention of toxic algal blooms, treatment for exposed individuals, health disparities related to the exposure of toxins, and better screening to quickly detect toxic blooms. At this time, the studies are ongoing, and no information has been published. Staff will continue to follow the progress of the studies and provide updates to the Board, as available, with the future six-month Action Plan updates.
Sediment Removal Impacts
The long-term goal of contaminated sediment management is risk reduction. Management strategies for contaminated sediments in waterbodies primarily focus on either removing the contaminated material (i.e., dredging) or reducing the availability of contaminants to pose an ecological or human health risk over time, which can include capping or monitored natural recovery (MNR). Sediment management through MNR involves leaving contaminated sediments in place and allowing natural processes to contain, destroy, or otherwise reduce the contaminants so they continue to pose less and less of a risk.
Dredging or excavation is a common sediment management strategy in highly contaminated areas that pose a substantial risk to ecological and human health. The EPA uses the Superfund program, in collaboration with other EPA programs, to clean up sediment sites that present unacceptable risks to human health and the environment. These sites are most often a result of hazardous waste being dumped, left out in the open, or otherwise improperly managed, and include manufacturing facilities, processing plants, landfills, and mining sites. These sites are often dredged or excavated, and many are done as a result of a lawsuit against a corporation accused of deliberate environmental pollution. In early December, the Workgroup provided a list of seven sites with contamination that have been remediated using dredging. The sites provided by the Workgroup are not directly comparable to Lake Munson. Many of the sites were remediated over 30 years ago. Since then, technology has changed, as well as the philosophy on what management strategies are best. Some of the sites were severely contaminated Superfund sites with groundwater and vapor contamination that were remediated as a result of a lawsuit against a large industrial corporation. At its January 2023 meeting, the SAC discussed this issue and pointed out that Lake Munson is under a TMDL and making progress toward achieving the State water quality standards. The conditions of the Lake are nothing like the contamination levels associated with Superfund sites that necessitate urgent dredging or the involvement of the EPA.
In areas of low to moderate levels of contamination, such as Lake Munson, alternative strategies to dredging, such as MNR, are more advantageous and applicable. The natural processes through MNR can include allowing the contaminants to naturally break down over time or capping and the natural benefits of drawdowns. Applying amendments or additives to the sediment, which can target and contain contaminants, has worked in some areas with contaminated sediment. Also, activated carbon (similar to Biochar) has been used to amend the sediment and reduce the availability of the contaminants to be taken in by organisms, plants, or fish. In these lower risk waterbodies, it is predominantly found that the risk of causing more damage than good associated with dredging outweighs the risk the contaminants pose as is, making natural processes the preferred option.
The contamination management strategies vary depending on the associated risk to ecological and human health. Significantly contaminated sites primarily use dredging or excavation, whereas sites that present a lower risk to ecological and human health tend to rely on MNR or similar strategies. There continues to be research and innovated solutions surrounding alternatives to dredging. Staff continues to explore in-lake management options to provide the best overall benefit to the Lake.
Conclusion
Lake Munson is a state-managed waterbody with a history of chronic water quality and ecological problems including fish kills, algal blooms, exotic vegetation and snails, high nutrient levels, low game fish productivity, sediment contamination, and depressed oxygen levels. The Lake receives surface water flow from a 32,000-acre basin, much of which is located in the City of Tallahassee and has historically been subjected to drainage with high nutrient loads and wastewater discharges to the tributary system, which has resulted in the embedding of legacy nutrients in the lake-bottom soil.
Significant efforts to improve the water quality and reduce the nutrient loading in Lake Munson have been ongoing since the 1990s and requires the continuous coordination among governmental partners to protect the natural resource. The 1994 Lake Munson Action Plan has been used as the basis to guide watershed and stormwater improvements, regular testing and monitoring of water quality, and regulatory actions to limit pollutants and protect natural resources. Leon County Government, the City of Tallahassee, and the Blueprint Intergovernmental Agency have dedicated hundreds of millions of dollars for projects in the Lake Munson basin, and prioritized upstream improvements which reduce the transport of sediment and benefit the lake water quality. While the Lake continues to improve, undoing decades of damage will take continuous commitment. After a series of lake challenges last summer, including algal blooms, a fish kill, and rapid growth of an invasive aquatic vegetation (hydrilla), staff sought input from subject matter experts across County departments, Blueprint, state agency partners, consultants, and the SAC. The current water conditions as well as quality and ecology of Lake Munson were evaluated to determine the best lake management strategies. The next steps to address the lake condition were presented to the Board as the Lake Munson Action Plan in 2022.
At the October 11, 2022 meeting, the Board approved a Lake Munson Action Plan, which provided an opportunity to better articulate the magnitude and duration of past, ongoing, and long-term infrastructure projects to benefit the basin, the planned drawdown with more frequent water quality testing, an aerial topographic survey of Lake Munson to measure elevations of compacted sediment to evaluate for future in-lake mitigation strategies, a new vegetation management program for treating invasive plants, and implementing periodic drawdowns in consultation with FWC to eliminate the need to mechanically remove organic-rich sediment. The Action Plan captured recommendations sought by the Workgroup including the deployment of hydrogen peroxide to treat algal blooms and point-source testing for PCBs. The plan also includes ongoing engagement over the next two years to evaluate the Lake’s response to the drawdown, quarterly coordination with SAC to review available enhanced monitoring data, and regular status updates to the Board every six months. This holistic approach provided immediate strategies to quickly mitigate the rapid growth of hydrilla and eliminate the algal bloom experienced at the time, while the long-term actions were aimed to supplement the State’s in-lake vegetation management activities and provide a higher level of service to County residents.
Since adoption of the Action Plan at the October 11th meeting, the drawdown and enhanced monitoring have begun as well as preparations for the long-term lake management actions and, as requested by the Board, the State’s study of health-related issues related to algal blooms has also been monitored. Ongoing engagement has been implemented with an update on the Action Plan presented to the SAC members and the Workgroup at the December and March SAC meetings. In response to higher than anticipated rainfall through the winter and based on the recommendation by the SAC and FWC, the drawdown will be extended through Spring of 2024. The extended drawdown will provide additional time for Lake sediments to dry out and oxidize and terrestrial vegetation in the Lake will provide beneficial habitat wildlife habitat. Staff have joined the FAMU-Lake Munson Environmental and Health Group (FAMU Study Group), consisting of FAMU faculty engaged by the Workgroup who will be conducting scientific-based research into the ecological health and best practices for the Lake. And finally, staff will continue to provide six-months updates to the Board on the progress of Lake Munson throughout the extended drawdown and Enhanced Monitoring phase.
Options #1 and #2