Environment and Natural Resources
NEWS RELEASE: October 18, 2002
For more information: Rich Hanson, 773-4216

Lake Oliver Treated with Alum to Improve Water Quality

PIERRE – An alum treatment project completed this week should produce noticeable water quality improvements in Lake Oliver. The project was carried out by the Deuel County Conservation District under a water quality project approved by the Department of Environment and Natural Resources (DENR).

A specially-designed barge with attached booms was used to apply more than 70,000 gallons of alum to the surface of Lake Oliver. Sweetwater Technology Corporation of Aitkin, Minn. owns the barge. Treatment of the lake began Tuesday, October 15, and was completed Thursday, October 17.

Alum, or aluminum sulfate, is a nontoxic material used to control algae by reducing the amount of phosphorus in the water. As the alum is applied and settles to the bottom, it collects suspended particles and traps nutrients at the bottom of the lake.

Alum treatment has been used successfully to improve water quality in several Minnesota lakes. DENR is not aware of its use on any lakes in South Dakota, although the city of Mitchell is considering alum treatment of Lake Mitchell.

Alum is used regularly in municipal water treatment plants to help treat water for human consumption. It is also harmless to fish and aquatic plants.

"Completing the first alum treatment of a lake in South Dakota was exciting," said DENR Secretary Steve Pirner. "DENR is proud to be able to work with the Deuel County Conservation District and their local sponsors that include the Lake Cochrane Improvement Association, East Dakota Water Development District, and local landowners to complete this water quality improvement project."

Lake Oliver is a shallow, 180-acre lake located east of Clear Lake just off Highway 22 near the South Dakota-Minnesota border. The lake has experienced water quality problems in recent years and was placed on the state’s 1998 303(d) Waterbody List of impaired waters along with neighboring Lake Cochrane. Lake Oliver was placed on the list because of excessive nutrients. Lake Cochrane was placed on the list because of the presence of fecal coliform bacteria; however, subsequent assessment monitoring in 1999 found low numbers of fecal coliform.

The alum treatment on Lake Oliver is part of a larger project designed to improve water quality on both Lake Cochrane and Lake Oliver. Sediment retention ponds adjacent to Lake Cochrane will also be cleaned out to ensure that sediment loadings to Lake Cochrane remain at a low level. 

The Deuel County Conservation District completed a total maximum daily load (TMDL) in 1999. The TMDL concluded that the major problem for the two lakes was excessive nutrients in Lake Oliver that lead to the growth of noxious aquatic plants including algae. Sediment in Lake Oliver is the primary source of nutrients within the lake, and that only minimal nutrients reach the lake from the watershed. The goal of the project is to reduce the phosphorus concentrations in Lake Oliver by 50 percent.

Governor Bill Janklow helped secure sufficient federal and state funding to complete the Lake Cochrane/Lake Oliver Watershed Improvement Project. The overall estimated cost of the project is $125,000. Grants include $75,000 from the U.S. Environmental Protection Agency through the 319 Nonpoint Pollution Control Program, $20,000 from the state’s Consolidated Program, and $7,225 from the state’s Coordinated Soil and Water Conservation Program. The remaining funds will come from the Deuel County Conservation District, Lake Cochrane Improvement Association, East Dakota Water Development District, and local landowners participating in the watershed project.

The Deuel County Conservation District is the project sponsor.

For more information on the TMDL conducted at Lake Oliver and Lake Cochrane, visit www.state.sd.us/denr/DFTA/WatershedProtection/TMDL/TMDL_CochraneOliver.pdf or contact Rich Hanson, DENR, at 605-773-4216.

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