TMDLs
A Total Maximum Daily Load (TMDL) is a regulatory term in the U.S. Clean Water Act (CWA), describing a value of the maximum amount of a pollutant that a body of water can receive while still meeting water quality standards.A Total Maximum Daily Load (TMDL) and Implementation Plan must be prepared for each Impaired Water, identifying the contributors to the excessive loads of pollutants and outlining a plan for returning the water to an unimpaired state. Funding to undertake the TMDL studies has been provided by grants from the MPCA.
Shingle Creek Chloride TMDL
The Shingle Creek Chloride TMDL study began in 2002. The study and its attendant Implementation Plan were approved by the Environmental Protection (EPA) and Minnesota Pollution Control Agency (MPCA) in 2007.
This TMDL, the first for chloride in Minnesota, was based largely on in-situ measurements of chloride and of conductivity as a surrogate for chloride. The study showed that the majority of chloride in the Shingle Creek watershed is derived from nonpoint sources, primarily road deicing, as well as commercial and industrial deicing and groundwater. A load allocation of percent reduction was set and requires an overall reduction of 71% to meet State water quality standards.
Stakeholders have 18 months in which to update their Stormwater Pollution Prevention Plans (SWPPPs) to address the TMDL allocations. Although the Commission will be the lead on the implementation of the Chloride TMDL, individual stakeholders will ultimately be responsible for implementing the identified BMPs. These activities will be included in the National Pollutant Discharge Elimination System (NPDES) Phase II Permits held by the stakeholders and reported annually.
The Commission continues to collect road salt application data from road authorities in the watershed, as well as perform chloride and conductivity monitoring as part of its annual stream monitoring program. As road authorities implement best management practices (BMPs) to reduce salt use, additional analysis will evaluate BMP effectiveness and progress toward the load reduction goals set in the TMDL.
Dissolved Oxygen/Biotic Integrity TMDLs
The Shingle and Bass Creek Biota and Dissolved Oxygen TMDL is currently under public notice from June 20, 2011 to July 20, 2011. Due to the imminent State shutdown, the draft TMDL is being posted on the Shingle Creek Watershed Management Commission’s website, www.shinglecreek.org, for your convenience. During this official 30 day notice period, any interested party is welcome to submit comments on the TMDL. Following the public notice period, the Minnesota Pollution Control Agency (MPCA) will respond to comments received, make final revisions, and submit the TMDL to the Environmental Protection Agency (EPA) for final approval.
Dissolved oxygen impairment. Shingle Creek (reach 07010206-506) was placed on Minnesota’s 2004 303(d) list because it is impaired for aquatic life due to low dissolved oxygen (DO) levels. The monitoring data indicates that Shingle Creek frequently has DO concentrations below the state water quality standard of 5 mg/L.
Macroinvertebrates are organisms that are large (macro) enough to be seen with the naked eye and lack a backbone (invertebrate).
Biotic impairment. In 2006, Shingle Creek was placed on Minnesota’s 303(d) list because it is impaired for aquatic life due to stressors impacting the aquatic macroinvertebrate community. Bass Creek was placed on Minnesota’s 2002 303(d) list because it is impaired for aquatic life due to stressors impacting the fish community. The Minnesota Pollution Control Agency (MPCA) uses an Index of Biotic Integrity (IBI) to evaluate the biological health of streams in the state.
The Clean Water Act requires a Total Maximum Daily Load (TMDL) report to be completed for each impaired waterbody. The main objectives of this project are to determine the causes of the dissolved oxygen and biotic impairments and estimate the pollutant reductions needed in order for Shingle and Bass Creeks to meet state water quality standards. The main project deliverables are a stressor identification report for the Shingle and Bass Creek biological impairments and a Shingle and Bass Creek TMDL that addresses the pollutants causing both the DO and biological impairments.
Shingle and Bass Creeks are located in the Twin Cities metro area in Hennepin County. The creeks are in the Mississippi River - Twin Cities watershed of the Upper Mississippi River basin. The creeks are also within the Shingle Creek watershed which includes the municipalities of Brooklyn Center, Brooklyn Park, Crystal, Maple Grove, Minneapolis, New Hope, Osseo, Plymouth, and Robbinsdale. Lower Bass Creek starts at the outlet of Bass Lake in Plymouth and travels about 2.4 miles before it flows into Shingle Creek. Shingle Creek begins at the junction of Bass Creek and Eagle Creek in Brooklyn Park, flows easterly, then southerly for about 11 miles through Brooklyn Center and Minneapolis before discharging into the Mississippi River.
Commission Staff are currently developing a draft Implementation Plan to accompany the TMDL. This Implementation Plan breaks down the implementation activities shown in the TMDL by individual stream reach. The draft Implementation Plan will be distributed to the Shingle Creek Commission’s member cities and the MPCA for their review and comments. Following final commission review and approval, it will be submitted to the MPCA for final approval following EPA’s approval of the TMDL document.
Public Notice
DRAFT Shingle Creek-Bass Creek TMDL
Upper Mississippi River Bacteria TMDL
The Minnesota Pollution Control Agency (MPCA) and the Minnesota Department of Health are currently developing a work plan for a bacteria Total Maximum Daily Load for the Mississippi River from St. Cloud to St. Paul. The focus of the TMDL is on the main stem of the Mississippi River and its direct drainages and not necessarily on the tributaries. However, the tributaries, including Shingle Creek and West Mississippi, will be an important part of the study. At least six Mississippi River reaches will be addressed in this TMDL although, after an analysis of existing data is conducted, additional reaches may be added.
The goal of this project is to describe the reduction in pollutant loading and implementation activities needed so that Upper Mississippi River reaches can meet the water quality standard for bacteria (E. coli). In meeting this goal, the implementation of BMPs in critical areas could help meet the requirements of both the Clean Water Act and the Safe Drinking Water Act.
To date, the Commission has not pursued development of a bacteria TMDL for Shingle Creek due to limited knowledge on bacteria sources and BMPs in urban areas. Shingle Creek may become one of the studied reaches because of its size, land use and location upstream of the Minneapolis Water Treatment Plant intake.
This TMDL will be an opportunity for the Commission to begin developing an understanding of urban bacteria sources by monitoring potential source areas. For example, partnering with the MPCA to monitor outfalls from subwatersheds with only one land-use type, such as commercial, can help improve understanding of bacteria sources in the watershed.
The second is that Shingle Creek will likely be given a wasteload allocation based on the TMDL, which is essentially a TMDL for the watershed that Municipal Stormwater permits would need to address. The Commissions may consider pursuing a TMDL for the watersheds to make sure that the allocations are reasonable and practical.
The first meeting of the Upper Mississippi Bacteria TMDL stakeholder group occurred in July 2008. One of the first tasks was to identify stakeholders to serve on three committees that will provide comments on the TMDL process and draft documents. They are a Technical Advisory Committee (TAC), Stakeholder Advisory Team (SAT), and Policy Advisory Committee (PAC). At least one or two meetings will be held annually with each group at key points during the project.
Shingle Creek Corridor Study
The Corridor Study was undertaken to provide a coordinated vision for the future of Shingle Creek and its tributaries, a capital improvement plan that outlines projects for the restoration of Shingle Creek, and a program of management activities. The study encompassed all of Shingle Creek in Brooklyn Center and Brooklyn Park as well as Ryan Creek in Robbinsdale.
In 2005 the City of Brooklyn Park formally requested the Commission to draft a minor amendment to its Watershed Management Plan for the creek restoration project under design in that city. The city has an ecological concept to restore the creek in the reach from Brooklyn Boulevard crossing west of Zane Avenue to the Hampshire Avenue footbridge. With a low flow channel and native streambank plantings and remove the dam at Brooklyn Boulevard and replace it with rock vanes riffle/pool sequences. Later, the City expanded the project to include the subreach of Hampshire to Candlewood Drive. The study was approved by the Commission at its September 2005 meeting, where the Commission also adopted a resolution ordering the Shingle Creek Restoration Improvement project. Construction began in 2006.
A review draft of the Shingle and Bass Creeks Stressor ID Study is now available. This study was presented to the Technical Advisory Committee (TAC) and the Commission a few months ago. The Minnesota Pollution Control Agency (MPCA) has reviewed the Stressor ID and the draft incorporates their comments. Their comments did not change the findings or the conclusions previously presented. The Stressor ID is intended to be an appendix to the Dissolved Oxygen/Biotic Integrity TMDL, which is now being finalized for submittal to the MPCA. This Stressor ID will be included on the Commission’s August 12, 2010 agenda for review and approval.
Lake TMDLs
In 2003 the Commission began developing TMDLs for the thirteen lakes included on the 303(d) list. The Twin and Ryan Lakes Nutrient TMDL and companion Implementation Plan, which cover Upper, Middle, and Lower Twin Lake as well as Ryan Lake, were approved by the EPA and MPCA in 2007.
Twin Lakes/Ryan Lake TMDL
The Twin Lake chain of lakes is located in the cities of Brooklyn Center, Crystal, Minneapolis, and Robbinsdale. They are highly-used recreational water bodies that support fishing and swimming as well as provide aesthetic values. The drainage area to the lake chain is 5,550 acres of fully developed urban and suburban land.
Connected by channels of varying lengths, the lake system discharges into Shingle Creek, which ultimately discharges into the Mississippi River. Water quality in Upper and Lower Twin Lakes is considered poor with frequent algal blooms while Ryan and Middle Twin Lakes have more moderately degraded water quality. Upper and Lower Twin Lakes do not currently support recreational activities while Ryan and Middle Twin Lakes partially support recreational activities.
Based on the current State narrative standard for nutrients, the TMDL establishes a numeric target of 40 µg/L total phosphorus concentration for all lakes in the North Central Hardwood Forest ecoregion. According to the TMDL, to meet state water quality standards the phosphorus load to Upper Twin Lake must be reduced by 16-76%, depending on annual hydrologic conditions. This is a load reduction in an average precipitation year of approximately 800-900 pounds. Since Upper Twin contributes a substantial load downstream to the other lakes, improvements to that lake should result in improvement to the lower lakes in the chain.
The individual stakeholders (the Commission, Hennepin County, Minnesota DNR, MnDOT, Metropolitan Council, USGS, and the cities of Brooklyn Center, Crystal, Minneapolis, and Robbinsdale) will ultimately be responsible for implementing the identified BMPs and including them in their NPDES-II Permits.
In a previous study, DNR wetland 639W, just upstream of the lake, was found to export a significant phosphorus load. Improvements to wetland 639W would have the most impact on reducing phosphorus load and improving water quality in the chain of lakes. (See discussion on pages 8-9 of this report.) Other activities identified as most effective in restoring water quality to the chain of lakes include:
- Treatment options such as street reconstruction and development/redevelopment projects
- Increased infiltration
- Shoreline management and restoration
- Wildlife management
- Street sweeping
- Road salt reductions
- Chemical treatment
- Lake drawdown
- Aquatic plant management
- Rough fish management
Crystal Lake TMDL
Crystal Lake is an 89 acre lake within a 1,237 acre watershed. 887 acres are in Robbinsdale, the remaining 350 acres are in Minneapolis. The entire lakeshed is developed and has been for some time.
Most of the stormwater discharge into the lake is untreated, although there have been several improvements made in the past few years to add treatment, including shoreline buffers, pollutant traps in the storm sewer outfalls, and new ponds and underground treatment devices installed as part of the County Road 81 (Bottineau Boulevard) reconstruction. The lake has a pumped outlet into the Minneapolis storm sewer system.
The TMDL, on Public Notice at year-end, determined a 72% overall load reduction in phosphorus is needed. The average total phosphorus concentration during the summer growing season is 100µg/L compared to the 40 µg/L standard. The TMDL Implementation Plan calls out principles to guide development and implementation of the load reduction plan for Crystal Lake.
The City of Robbinsdale has undertaken a feasibility study to consider improvements to Crystal Lake. The study evaluated both internal load reduction and options to incorporate external load reduction into a comprehensive project.
The study identifies a proposed “Crystal Lake Improvement Project” that includes three potential components: 1) treatment of stormwater from a trunk storm sewer that drains about 350 acres with little to no treatment; 2) an alum treatment to reduce internal load and improve water clarity; and 3) the infrastructure to implement a future hypolimnetic withdrawal project.
The focus of this project centers on treating the internal load because, in the experience of the scientists and engineers preparing the report, the most cost-effective, immediate and guaranteed treatment methods are to address the in-lake source. Although the watershed load is larger than the internal load, the complexity, cost, timing and predictability of treatment methods make the implementation of management options on the watershed more suitable for installing treatment as opportunities arise with an overall goal of ultimately having stormwater treatment for all of the runoff.
The project would divert discharge from the 38th Avenue trunk storm sewer into a treatment system to be constructed in Lakeview Terrace Park. The stormwater would be treated with alum, then routed through a new pond and wetland system before being discharged into Crystal Lake. Facilities in the park would be relocated and upgraded, and currently untreated runoff would be routed into the pond and wetland system or into a pair of rain gardens to be constructed in the redesigned parking lot. It is estimated that if the alum injection system can achieve 90% phosphorus reduction efficiency, the annual external load reduction from this component of the project could be about 70 kg/year Total Phosphorus (TP). The external load reduction required in the TMDL is about 144 kg/year TP.
The project proposes to address internal load in two ways. First, an alum treatment would be applied to the lake to reduce sediment load release and improve water clarity. It is estimated that the alum treatment could achieve a 90 percent internal load reduction, or about 116 kg/year TP. The project also includes installation of the infrastructure necessary to install hypolimnetic withdrawal and treatment in the future if lake conditions warrant.
The hypolimnetic withdrawal system would pump phosphorus-rich water from the hypolimnion, or bottom layer, of the lake to the pumphouse being constructed to house the storm sewer alum injection system. The hypolimnetic water would be treated with alum and the discharge would be routed through the new pond and wetland system where it would eventually be discharged back into the lake. The necessary infrastructure would be incorporated as part of the proposed project. However, the hypolimnetic withdrawal system would not be implemented until the Commission’s Technical Advisory Committee determines that it is necessary as part of the Adaptive Management process.
Cedar Island-Pike-Eagle Lakes TMDL
Almost the entire drainage area of these lakes is located within the city of Maple Grove with a small area located in the city of Plymouth. Cedar Island Lake outlets through a pumped outlet into storm sewer that is conveyed to Eagle Lake, while Pike Lake is connected to Eagle by a channel through a shared riparian wetland.
Cedar Island Lake is approximately 81 acres in size with an average depth of 4.6 feet. The entire surface area is littoral (less than 15 feet in depth) and, therefore, biological communities have a significant impact on the in-lake water quality. The residence time indicates that runoff from the watershed displaces the lake volume approximately once per year.
Pike Lake is approximately 58 acres in size with an average depth of seven feet. Approximately 95% of the surface area is littoral. The residence time indicates that runoff from the watershed displaces the lake volume about once every eight months, providing a significant regular supply of nutrients to the lake.
Eagle Lake is approximately 291 acres in size with an average depth of 12.5 feet. Approximately 68% of the surface area is littoral. Residence time indicates that runoff from the watershed displaces the lake volume approximately once every four years.
Eagle Lake is moderately impaired while the other lakes are severely impaired. All experience late summer algal blooms. Cedar Island Lake and Pike Lake are considered shallow lakes, that is, 85 percent of the lake is less than 15 feet deep, while Eagle is considered a deep lake.
Modeling data was used to develop a phosphorus budget for each lake. The budget suggests that both internal and external load are significant factors in these lakes, although less so in Eagle. Internal loading can be a result of sediment anoxia where poorly bound phosphorus is released in a form readily available for phytoplankton production. Internal loading can also result from sediment re-suspension that may result from rough fish activity or propeller wash from boat activity.
Additionally, curly-leaf pondweed can increase internal loading because it senesces and releases phosphorus during the summer growing season. A survey of Cedar Island Lake conducted in 1999 found that about 74 percent of the lake bottom was colonized with submerged aquatic plants, with curly-leaf pondweed the dominant plant. Chemical treatments for curly-leaf pondweed have been applied in Cedar Island Lake for several years.
Common carp and other rough fish can also affect internal loading. Carp feeding and spawning re-suspends bottom sediments and nutrients. DNR surveys find that there are carp present in Pike and Eagle Lakes. The carp are large and could significantly disturb the lake bottom sediments. There are no DNR survey data available for Cedar Island Lake, but anecdotal information suggests there is a substantial rough fish population in that lake as well. Black bullhead, present in large numbers in Pike Lake, could also potentially disturb macrophyte beds and nutrient rich sediments.
Cedar Island has a large and variable internal load that is exacerbated by the presence of curly-leaf pond weed and rough fish. The TMDL estimated the potential for internal loading to account for up to 70% of the overall load in Cedar Island Lake. These loads can be partially mitigated through targeted aquatic plant and rough fish management. Because the total phosphorus concentrations in Cedar Island are so high, reducing the internal load will be a significant effort and will require whole-lake solutions. Wasteload and load allocations to meet State standards indicate that a phosphorus load reduction of 72% in Cedar Island Lake would be required to consistently meet standards under average precipitation conditions.
Pike Lake water quality is also dominated by internal phosphorus load. Pike Lake experiences long periods of sediment anoxia extending into the spring and fall and very severe algal blooms throughout the summer. Because Pike Lake is directly connected to Eagle Lake by a short channel, water quality in Pike Lake influences Eagle Lake. Wasteload and load allocations to meet State standards indicate that a phosphorus load reduction of 34% in Pike Lake would be required to consistently meet standards under average precipitation conditions.
Eagle Lake has reasonably good water quality, yet experiences algal blooms in late summer. The lake demonstrates some internal loading; however it is difficult to determine its role in water quality. Consequently, restoration efforts should focus on controlling the external load while improving water quality in the upstream lakes. Wasteload and load allocations to meet State standards indicate that a phosphorus load reduction of 72% in Eagle Lake would be required to consistently meet standards under average precipitation conditions.
Bass-Schmidt-Pomerleau Lakes TMDL
The entire drainage area of these lakes is located within the city of Plymouth except for a fraction located in the city of Maple Grove. The Pomerleau Lake and Schmidt Lake subwatersheds drain through the Bass Lake subwatershed to Bass Lake. Bass Lake outlets through Bass Creek to Shingle Creek, which outlets into the Mississippi River. The area is almost fully developed, with a 2000 Census population of about 20,000.
Bass Lake is approximately 175 acres in size with an average depth of 10 feet. Approximately 82% of the surface area is littoral (less than 15 feet in depth) and, therefore, biological communities have a significant impact on the water quality in this lake. Runoff from the watershed displaces the lake volume approximately twice per year which provides a significant regular supply of nutrients to the lake.
Pomerleau Lake is approximately 30 acres in size with an average depth of 11 feet. Approximately 66% of the surface area is littoral. Runoff from the watershed displaces the lake volume a little more than once per year.
Schmidt Lake is approximately 37 acres in size with an average depth of 5.5 feet. Approximately 92% of the surface area is littoral. Runoff from the watershed displaces the lake volume approximately twice per year which provides a significant regular supply of nutrients to the lake.
The lakes are moderately impaired and all three experience late summer algal blooms of varying intensity. Bass Lake and Schmidt Lake are considered shallow lakes – that is, 85 percent of the lake is less than 15 feet deep – while Pomerleau is considered a deep lake.
The phosphorus budgets developed for each of these lakes suggest that both internal and external loads are significant factors. Internal loading can result from sediment anoxia or from sediment re-suspension from rough fish or boat activity. In addition, curly-leaf pondweed can increase internal loading because it senesces and releases phosphorus during the summer growing season.
The Bass Lake Improvement Association routinely contracts for aquatic plant chemical treatment to target curly-leaf pondweed, Eurasian water milfoil, and filamentous algae. A survey for Schmidt Lake conducted in 2004 found that about 66 percent of the lake bottom was colonized with submerged aquatic plants, with curly-leaf pondweed and coontail the dominant plants in the early summer. By late summer Eurasian water milfoil was more abundant, but at low to moderate density. Chemical treatments for curly-leaf pondweed have been applied in Schmidt Lake for several years. No aquatic vegetation data is available for Pomerleau Lake.
There are carp present in Bass Lake, and DNR survey data indicate that the carp are large and could significantly disturb the lake bottom sediments. Carp may be present in either Schmidt or Pomerleau Lakes but none were collected from either lake during the most recent population survey. Black bullheads are present in large numbers in Schmidt Lake and could potentially disturb macrophyte beds and nutrient rich sediments. Residents have observed a reduction in the bullhead population in recent years.
The TMDL estimated the potential for internal loading to account for up to 50% of the overall load in Schmidt Lake. These loads can be mitigated through targeted aquatic plant management and rough fish management. Only small phosphorus load reductions are required for the Schmidt Lake watershed and management should focus on in-lake controls such as rough fish control and invasive species control. Internal loads should be evaluated further to determine their role in lake phosphorus cycling.
Pomerleau Lake water quality is likely controlled by watershed runoff, however, the lake does have the potential for internal loading. Presently, the internal load appears to be minimal. An imbalanced fishery is likely contributing to the algal blooms, which are often higher than expected based on the total phosphorus concentrations. Restoration efforts should focus on the external loads and restoring a balanced fishery.
Bass Lake has reasonably good water quality, yet experiences severe algal blooms. Although watershed controls will be necessary, the biggest need is in-lake controls including aquatic plant management and rough fish control. The lake demonstrates some internal loading; however it is difficult to determine its role in water quality. Consequently, restoration efforts should focus on controlling the external load while reestablishing the biological integrity of the lake.
Wasteload and load allocations to meet State standards indicate that phosphorus load reductions of 12% in Schmidt, 65% in Pomerleau, and 22% in Bass would be required to consistently meet standards under average precipitation conditions. The Implementation Plan details the activities the stakeholders plan to undertake to attain that reduction.
Magda Lake TMDL
At year-end, the Magda Lake TMDL was being readied for submittal to the MPCA for its initial review and comment. A stakeholder meeting will be scheduled following the initial comments. It is anticipated that the TMDL and Implementation Plan will complete the review process and be approved by the EPA and MPCA in 2009.
Meadow Lake TMDL
Likewise, the Meadow Lake TMDL is expected to complete the review process and be approved by the EPA and MPCA in 2009.
The entire drainage area of these lakes is located within the city of Plymouth except for a fraction located in the city of Maple Grove. The Pomerleau Lake and Schmidt Lake subwatersheds drain through the Bass Lake subwatershed to Bass Lake. Bass Lake outlets through Bass Creek to Shingle Creek, which outlets into the Mississippi River. The area is almost fully developed, with a 2000 Census population of about 20,000.
Bass Lake is approximately 175 acres in size with an average depth of 10 feet. Approximately 82% of the surface area is littoral (less than 15 feet in depth) and, therefore, biological communities have a significant impact on the water quality in this lake. Runoff from the watershed displaces the lake volume approximately twice per year which provides a significant regular supply of nutrients to the lake.
Pomerleau Lake is approximately 30 acres in size with an average depth of 11 feet. Approximately 66% of the surface area is littoral. Runoff from the watershed displaces the lake volume a little more than once per year.
Schmidt Lake is approximately 37 acres in size with an average depth of 5.5 feet. Approximately 92% of the surface area is littoral. Runoff from the watershed displaces the lake volume approximately twice per year which provides a significant regular supply of nutrients to the lake.
The lakes are moderately impaired and all three experience late summer algal blooms of varying intensity. Bass Lake and Schmidt Lake are considered shallow lakes – that is, 85 percent of the lake is less than 15 feet deep – while Pomerleau is considered a deep lake.
The phosphorus budgets developed for each of these lakes suggest that both internal and external loads are significant factors. Internal loading can result from sediment anoxia or from sediment re-suspension from rough fish or boat activity. In addition, curly-leaf pondweed can increase internal loading because it senesces and releases phosphorus during the summer growing season.
The Bass Lake Improvement Association routinely contracts for aquatic plant chemical treatment to target curly-leaf pondweed, Eurasian water milfoil, and filamentous algae. A survey for Schmidt Lake conducted in 2004 found that about 66 percent of the lake bottom was colonized with submerged aquatic plants, with curly-leaf pondweed and coontail the dominant plants in the early summer. By late summer Eurasian water milfoil was more abundant, but at low to moderate density. Chemical treatments for curly-leaf pondweed have been applied in Schmidt Lake for several years. No aquatic vegetation data is available for Pomerleau Lake.
There are carp present in Bass Lake, and DNR survey data indicate that the carp are large and could significantly disturb the lake bottom sediments. Carp may be present in either Schmidt or Pomerleau Lakes but none were collected from either lake during the most recent population survey. Black bullheads are present in large numbers in Schmidt Lake and could potentially disturb macrophyte beds and nutrient rich sediments. Residents have observed a reduction in the bullhead population in recent years.
The TMDL estimated the potential for internal loading to account for up to 50% of the overall load in Schmidt Lake. These loads can be mitigated through targeted aquatic plant management and rough fish management. Only small phosphorus load reductions are required for the Schmidt Lake watershed and management should focus on in-lake controls such as rough fish control and invasive species control. Internal loads should be evaluated further to determine their role in lake phosphorus cycling.
Pomerleau Lake water quality is likely controlled by watershed runoff, however, the lake does have the potential for internal loading. Presently, the internal load appears to be minimal. An imbalanced fishery is likely contributing to the algal blooms, which are often higher than expected based on the total phosphorus concentrations. Restoration efforts should focus on the external loads and restoring a balanced fishery.
Bass Lake has reasonably good water quality, yet experiences severe algal blooms. Although watershed controls will be necessary, the biggest need is in-lake controls including aquatic plant management and rough fish control. The lake demonstrates some internal loading; however it is difficult to determine its role in water quality. Consequently, restoration efforts should focus on controlling the external load while reestablishing the biological integrity of the lake.
Wasteload and load allocations to meet State standards indicate that phosphorus load reductions of 12% in Schmidt, 65% in Pomerleau, and 22% in Bass would be required to consistently meet standards under average precipitation conditions. The Implementation Plan details the activities the stakeholders plan to undertake to attain that reduction.
Magda Lake TMDL
At year-end, the Magda Lake TMDL was being readied for submittal to the MPCA for its initial review and comment. A stakeholder meeting will be scheduled following the initial comments. It is anticipated that the TMDL and Implementation Plan will complete the review process and be approved by the EPA and MPCA in 2009.
Meadow Lake TMDL
Likewise, the Meadow Lake TMDL is expected to complete the review process and be approved by the EPA and MPCA in 2009.