Lakes

 

There are sixteen lakes in the Shingle Creek watershed.  They are Bass, Curtis, Pomerleau, and Schmidt in Plymouth; Cedar Island and Eagle in Maple Grove; Crystal and Lower Twin in Robbinsdale; Magda and Success in Brooklyn Park; Meadow in New Hope; Palmer in Brooklyn Center and Brooklyn Park; Pike in Maple Grove and Plymouth; Ryan in Minneapolis and Robbinsdale; Middle Twin in Brooklyn Center, Crystal and Robbinsdale; and Upper Twin in Brooklyn Center and Crystal.  There are no lakes in the West Mississippi watershed.

 

TMDLs

 

Every two years, the Minnesota Pollution Control Agency (MPCA) releases the 303(d) list of impaired waters in Minnesota.  Named after the section of the Clean Water Act in which the impaired waters law is found, this list includes lakes, rivers and streams known to exceed water quality standards.  In 2002, twelve of the 16 lakes in the Shingle Creek watershed were included on the list for excessive nutrients.  In 2004 Cedar Island Lake, was added to the list and Shingle Creek was listed impaired by low dissolved oxygen levels.

 

In 2006 a TMDL was prepared by Wenck Associates Inc. for Ryan Lake and the three basins of Twin Lake to address nutrient impairment in the Twin Lake chain of lakes.  The goal of this TMDL is to quantify the pollutant reductions needed to meet State water quality standards for nutrients in South Twin, Middle Twin, North Twin and Ryan Lakes.  The final document was approved by the Environmental Protection Agency on November 9, 2007.  It can be viewed on the MPCAs website:  http://www.pca.state.mn.us/water/tmdl/tmdl-approved.html.

 

The Twin Lake chain of lakes, supports fishing and swimming as well as provides other aesthetic values. The drainage area to the lake chain is 5,550 acres of fully developed urban and suburban land. The lakes are connected by channels of varying lengths. The lake system discharges into Shingle Creek, which ultimately discharges into the Mississippi River. Water quality in North and South Twin Lakes are considered poor with frequent algal blooms while Ryan and Middle Twin Lakes have more moderately degraded water quality.

 

Monitoring data in the Twin Lake chain of lakes suggest that the chain is a highly productive system, with the greatest water quality problems occurring in North Twin Lake.  The uppermost lake in the chain, North Twin Lake, is a hypereutrophic lake where both internal and watershed loading appear to be significant sources of phosphorous. The majority of phosphorous in Middle Twin Lake is from water coming from North Twin Lake and the watershed. South Twin Lake is a eutrophic lake where internal loading has the potential to increase algal productivity throughout the season. Ryan Lake, the last lake in the chain, is a deep, mesotrophic lake that has relatively good water quality for an urban lake.

 

The final step in the TMDL process is the approval of an Implementation Plan that sets forth the activities the cities, Hennepin County and MnDOT will undertake to reduce phosphorus loading to the four lakes.  The Implementation Plan was reviewed by the member cities and approved by the MPCA in November 2007.

 

The member cities that are MS4s have until August, 2008 to revise their Stormwater Pollution Prevention Plans (SWPPPs) to incorporate nutrient reduction activities.  Six of the nine member cities drain to the Twin Lake Chain.  They are:  Brooklyn Center, Brooklyn Park, Crystal, Minneapolis, New Hope and Robbinsdale.

 

 

Cedar Island, Pike and Eagle Lakes TMDL

 

The Cedar Island, Pike and Eagle Lakes TMDL was undertaken in 2005 to address a nutrient impairment in the Eagle Lake chain of lakes.  The goal of this TMDL is to quantify the pollutant reductions needed to meet State water quality standards for nutrients in Cedar Island, Pike and Eagle Lakes.  Pike Lake was placed on the 2002 State of Minnesota’s 303(d) list of impaired waters, Cedar Island on the 2004 list and Eagle Lake on the 2008 list.  Each was identified for impairment of aquatic recreation (swimming).

 

The Eagle Lake chain of lakes is located in the cities of Maple Grove and Plymouth.  Eagle Lake is a highly used recreational water body that supports fishing and swimming as well as provides aesthetic values.  The drainage area to the lake chain is 2,880 acres of fully developed urban and suburban land.  Pike and Eagle Lakes are connected through a channel that has been dredged through a large wetland.  Cedar Island has no natural outlet.  A pumped outlet discharges into Eagle Lake.  The lake system discharges into Eagle Creek, a tributary of Shingle Creek, which ultimately discharges into the Mississippi River.

 

Cedar Island Lake is approximately 81 acres in size with an average depth of five feet.  Pike Lake is approximately 58 acres in size and has an average depth of seven feet.  Approximately 95% of the surface area is littoral.  Eagle Lake is approximately 291 acres in size with an average depth of 12 feet.  Approximately 68% of the surface area is littoral.  Aquatic vegetation in littoral lakes has considerable impact on the water quality of a lake.

 

Water quality in Cedar Island and Pike Lakes is considered poor with frequent algal blooms while Eagle Lake has more moderately degraded water quality.  Both Cedar Island Lake and Pike Lake drain into Eagle Lake and likely have a large influence on water quality in Eagle Lake.  The most severe algal blooms in Eagle Lake occur in late summer.  Cedar Island Lake is shallow and has extremely high total phosphorous concentrations and extremely severe algal blooms.  Cedar Island Lake has a large internal load that is exacerbated by the presence of curly leaf pondweed in nuisance densities.  Pike Lake is also shallow and has high total phosphorus concentrations throughout the summer with severe algal blooms.

 

A 67 percent decrease in phosphorus load would be required for Cedar Island Lake to consistently meet water quality standards.  Pike Lake would require a 29 percent decrease and Eagle Lake a 26 percent decrease.  Since Pike Lake contributes a substantial load downstream to Eagle Lake, improvements to that lake should result in improvement in Eagle.  Internal load management, biologic management and reduction of non-point sources of phosphorus in the watershed by retrofitting BMPs would have the most impact on reducing phosphorus load and improving water quality in the chain of lakes.

 

Aquatic plant management will target in-lake sources of nutrients, and fishery management will be coordinated with the DNR to manage and maintain a beneficial community.  The Shingle Creek Commission will work in partnership with the cities and other agencies with land that drains to the lakes to prepare a more detailed Implementation Plan that will set forth specific strategies and priorities for achieving nutrient load reduction goals.  The draft Cedar Island, Pike and Eagle Lakes Nutrient TMDL was submitted to the MPCA and EPA for their initial review and comment in March 2008.

 

Bass, Pomerleau and Schmidt Lakes TMDL

 

The Bass, Pomerleau and Schmidt Lakes TMDL study addresses a nutrient impairment of the lakes.  Located in the city of Plymouth, the three lakes were placed on the 2002 State of Minnesota’s 303(d) list of impaired waters.  Bass and Schmidt Lakes are highly used recreational water bodies that support fishing and swimming as well as provide aesthetic values, while Pomerleau has limited public access.  The drainage area to the lakes is 3,200 acres of mostly developed suburban land, with numerous large wetlands and a small remnant of agricultural land.  The lake system discharges into Bass Creek, a tributary of Shingle Creek, which ultimately discharges into the Mississippi River.

 

Monitoring data indicate that the lakes are eutrophic and experience significant algal blooms in late summer.  Both Schmidt and Bass Lakes appear to be impacted by significant internal phosphorus loading, while the water quality in Pomerleau appears to be primarily driven by phosphorus loading from the watershed.  A 22 percent decrease in phosphorus load would be required for Bass Lake to consistently meet water quality standards.  Schmidt Lake would require a 12 percent reduction, and Pomerleau a 65 percent reduction.

 

Because the watershed that drains to Schmidt and Bass Lakes is almost completely developed, there are limited options for reducing external load.  The area draining to Pomerleau Lake is undergoing development.  Development rules require new development or redevelopment to provide treatment and manage stormwater volume.  Additional BMPs to treat stormwater will be incorporated where opportunities such as street reconstruction arise and small practices such as rain gardens, native planting and reforestation will be encouraged to limit runoff and nutrient conveyance.

 

Aquatic plant management will target in-lake sources of nutrients and fishery management will be coordinated with the DNR to manage and maintain a beneficial community.  The Shingle Creek Commission will work in partnership with the cities and other agencies that drain to these lakes to prepare a more detailed Implementation Plan that will set forth specific strategies and priorities for achieving nutrient load reduction goals. 

 

The draft Bass, Pomerleau and Schmidt Lakes TMDL was submitted to the MPCA and EPA for their initial review and comment in March 2008.

 

Crystal Lake Nutrient TMDL

 

The Crystal Lake Nutrient TMDL study addresses a nutrient impairment in Crystal Lake.  Located in the City of Robbinsdale, Crystal Lake is a highly used recreational water body with an active fishery and provides other aesthetic values as well.  The drainage area is almost entirely in the City of Robbinsdale, with some contribution from the City of Minneapolis.  Crystal Lake does not have a natural outlet; a pumping station is used under high water conditions to discharge into the City of Minneapolis storm sewer system.  The storm sewer discharges into Shingle Creek, and ultimately into the Mississippi River.  Water quality is considered poor and not supportive of recreational activities, with frequent algal blooms.

 

Wasteload and Load Allocations to meet State standards indicate that nutrient load reductions ranging from 64 percent to 76 percent would be required to consistently meet standards under average precipitation conditions.  Internal load management and reduction of non-point sources of phosphorus in the watershed by retrofitting BMPs would have the most impact on reducing phosphorus load and improving water quality in Crystal Lake.

 

The draft Crystal Lake Nutrient TMDL was submitted to the MPCA and EPA for their initial review and comment in March 2008.