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The State of the Lakes

The state of the lakes
By Karla Wennerstrom, Eden Prairie News, September 14, 2006

Eden Prairie’s lakes and creeks will be under scrutiny in the coming months, according to a report to the City Council presented by Eden Prairie’s Environmental Coordinator Leslie Stovring.

Eden Prairie is one of the “dirty 30,” 30 cities with the highest growth rate since 1988 that will have to provide reports detailing the effect development has had on their cities’ waters.

Eden Prairie is fifth on the list behind Rochester, Woodbury, Maple Grove and Lakeville.

“ In 1988, the state wrote some rules that basically say the waters of this state are not to be impacted,” Stovring said. “When we say nondegradation, we are looking at how things were in 1988 and we’re supposed to have not degraded the waters since that time.”

Joe Bischoff, a consultant with Wenck Associates, said the group will be compiling information for the Minnesota Pollution Control Agency on what effect development has had on water quality since 1988. Information will include the difference in impervious surface in the city and phosphorus levels in its lakes, for example.

The requirement is a result of the MPCA being sued by the Minnesota Center for Environmental Advocacy, Stovring said. “A result of that was that they needed to address nondegradation. What happened is they kind of worked out a deal with the League of Cities, the MCEA, the Pollution Control Agency and our water resource coordinators group – to work out a reasonable solution.”

Eden Prairie is one of the first five cities that will have to submit a nondegredation plan to the MPCA.

“ We’re going to be under scrutiny,” Stovring said.

“ We have a lot of concerns with it,” she said. “This is almost 20 years of development that’s occurred.” She said the city has been progressive with stormwater ponding and previously many sites were row crop, so, “In some ways, we might have better quality than we might have had under agriculture.”

The financial impact of any corrective measures won’t be known for several months, Bischoff said, but it could be costly.

“ It could end up requiring some costly projects to help correct some of the water quality issues in parts of the city,” Stovring said. Projects could include restoring banks and adding infiltration areas.

Stovring said costs would be shared with the watershed district and some costs could also be covered by the stormwater utility fund, which totals about $1.6 million.

“ We do know that we will have to do some projects,” Stovring said. “I know there are areas of the creek that will need stabilization. I’m sure we will need to retrofit some areas that were built without adequate stormwater ponding. … There may be some pond cleaning we need to do, which is not cheap either.”

However, “We’re holding out hope that we’ve improved water quality,” said Public Works Director Gene Dietz.

Public hearings will be part of the process. Stovring said it’s important to remember that everyone is responsible for the city’s water quality.

“ It’s not just the city, it’s the individual practices of the people who live and work in the city,” she said. “That’s what contributes to the water quality in our city. The way you fertilize your lawn, raking up leaves and grass, picking up litter and dog waste. All of those things contribute to the quality of our lakes and creeks.”

Anderson Lakes

The City Council was also updated on the status of several lakes in the city that have projects planned with local watershed districts.

At Anderson Lakes, a proposed water level drawdown during the next two winters would allow the bottom sediments to freeze to help control invasive species and make room for native plants, providing habitat for wildlife. Snow melt and spring runoff help refill the lakes during the summer, Stovring said. “We’re hoping the teals and ducks and everything comes back because of this. … By bringing back this habitat it should only be an improvement in what they see out their window.”

A public hearing process is planned before the drawdown, which would be a Nine Mile Creek Watershed District Project. Steve McComas of Blue Water Science is also doing plant surveys in Eden Prairie’s Anderson Lakes. He said drawing down the lake level should control curly leaf pondweed and improve native plants for wildlife habitat.

The lake level would be brought back to the historic level of about 1 to 1.5 feet lower than it is now.

Birch Island Lake

Water levels are to be restored to what they were before the construction of Highway 62 over the next two to five years. A stormwater pond would be upgraded and one new stormwater pond would be built.

Stovring said the water level is anticipated to go up about seven feet. She said drain tile would have to be installed along the Crosstown corridor. “They will be boring under the freeway to connect some stormwater and surface water drainage from the upper watershed back into Birch Island Lake.”

“ When they put Crosstown through, they cut off the natural flow pattern to the lake,” she explained. She said this would bring groundwater back to the lake. She said work on the project could start as early as this year.

Bryant Lake

Whole lake alum treatment would be set in 2008 or 2009. Alum interacts with phosphorus in the water, causing it to settle into the sediments at the bottom of the lake, Stovring said.

“ It will just make it clearer so it’s more comfortable for swimming and boating,” she said. She said the alum helps clean the lake while waiting for stormwater improvements to work.

Mitchell Lake

Listed as an impaired body of water. Stovring said improvements at Round Lake will help water coming in to Mitchell.

Recommendations include herbicide treatment to reduce curlyleaf pondweed and Eurasion watermilfoil for four years plus alum treatment for six years.

Stovring said that because Mitchell Lake is so shallow, when water is more clear, native species start growing. “There will be plant growth still,” she said, “just a more diverse variety of native species and a better fish habitat.

Rice Marsh and Riley Lakes

Alum treatment set for 2007 or 2008.

Round Lake

Alum treatment would be set after stormwater pond construction finished.

Monitoring of Round Lake over the summer has yielded positive results, according to Steve McComas of Blue Water Science, a consultant. “It’s about the best it’s been in the last 15-20 years,” he said. He said that assuming September is OK, “Round Lake will not be an impaired lake.” He said the clarity, phosphorus and algae levels meet criteria for an unimpaired lake. And bacteria levels have been low enough to be at safe swimming levels.

McComas will continue to monitor the lake through September. The beach is expected to be open for swimming next year.

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