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Group endorses alum treatments: Lake committee makes recommendations to City Council

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Mitchell, 57301
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Mitchell South Dakota 120 South Lawler 57301

The city's Lake Development Committee recommended Thursday that the City Council continue funding aluminum sulfate treatments to combat algae blooms this summer in Lake Mitchell.

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The group, which met at City Hall, also recommended that the council budget additional money for treatments in 2007, adopt an ordinance banning lakeside residents from using fertilizers that contain phosphates, and investigate a state loan fund and other programs to accelerate cleanup efforts in the Firesteel Creek watershed.

The city has provided funding for alum applications each of the past three years. The treatments were recommended and overseen by a paid consultant who conducted a study of the lake in 2001.

There has been some debate about the efficacy of the project, and the City Council recently heard an alternative proposal to attack the algae with underwater circulators.

Committee members unanimously preferred continued alum treatments over circulators. They said they did not believe that circulators would work, despite the claims of two men who said circulation had worked in other lakes.

"They didn't present any scientific evidence," committee member John Iverson said of the circulation proposal. "All they did was put pictures of other lakes on the screen."

Iverson and other committee members said the alum has been more effective than some people have claimed. City Councilman Britt Bruner, an ex-officio member of the committee, said the alum treatments are a work in progress.

"If we stop after three years, we'll be throwing away money and we won't see the full effect," Bruner said.

The next application of alum, according to the city's paid consultant, Dick Osgood, of Minnesota, will target the phosphorus produced by sediments on the lake bottom. Once the lake bottom is "sealed," future alum applications will still be needed to combat the phosphorus that flows in from the lake's only tributary, Firesteel Creek.

Alum works to neutralize phosphorus, which fuels algae growth. Much of the phosphorus is carried into the Firesteel Creek watershed and then the lake by runoff from agricultural sources such as fertilizers and manure.

Osgood has shown that alum applications during the previous three years reduced phosphorus levels in the lake. Some people noticed a difference in water quality, but others said there was no noticeable difference.

Some committee members said Thursday that the public's expectations for the alum project were beyond the actual scope of the work. The first three applications, committee members said, were supposed to seal the phosphorus on the lake bottom and provide data to determine alum dosages in the future.

The dosage required to finish sealing the phosphorus on the bottom of the lake will cost a projected $250,000 to $352,000 if applied in one summer, or $117,000 to $200,000 per year if the dosage is split between two summers.

The city budget already contains $130,000 for alum treatments this year, so the dosage apparently will be split over two years if the Council decides to continue the project. The committee recommended that the City Council budget $200,000 for next year.

Osgood also recommended, in a report filed in January, that the city install a low-dose injection system for future alum treatments. The system would save the city from hiring a barge operator every summer, but the system would cost a projected $400,000 to install. The system also would allow the city to adjust its alum treatments based on the amount of phosphorus flows coming in from Firesteel Creek.

If alum is applied this summer, it will presumably be done by barge. The committee's recommendation does not address an injection system, and the city has not budgeted for one. Some committee members suggested Thursday that the city could save money by building or buying its own barge.

Osgood's report also recommends the hiring of a full-time lake manager. The committee's recommendation does not address that issue either, but committee members speculated that Dave Kringen, who is currently managing the Firesteel Creek watershed cleanup, would be the perfect person for the job.

Kringen attended Thursday's meeting and updated committee members on the watershed project. He has implemented 13 animal waste management systems with farmers and ranchers; written 15 nutrient management plans covering 17,000 acres; built water pipelines, water tanks, ponds, dams and dugouts to minimize the number of livestock that drink and graze along Firesteel Creek; installed fences and implemented grazing systems to eliminate heavily grazed, high runoff areas; planted buffer strips and grass seed on 1,002 acres; and conducted shoreline stabilization efforts around the lake.

Kringen said much work remains to be done over many decades. Committee members said Thursday that they would investigate methods to "ratchet up" the watershed cleanup, which is viewed as the only long-term way to reduce algae in Lake Mitchell.

The proposed ordinance to ban lakeside residents from using fertilizers that contain phosphates is viewed by many committee members as more of a public relations move than an enforceable law. The impact of lawn fertilizers around the lake is small when compared to the pollutants that flow in from the 350,000-acre watershed, but committee members reasoned that people throughout the watershed might be more apt to participate in the cleanup if they know people in Mitchell are doing their part.

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