As the Alexandria Lake Area Sanitary District moves forward with plans to reduce pollution in Lakes Winona, Henry and Agnes, it will hold a public hearing to explain its plans to treat Lake Agnes with alum.

The hearing is set for 5 p.m. Tuesday, June 18, at the Douglas County Public Works building.

Lake Agnes is downstream from Lake Winona, which takes treated water from the sewer plant. The Minnesota Pollution Control Agency has given all three lakes a "caution" designation for overall condition, clarity and recreation use. Lakes that are analyzed for meeting water quality standards receive either a "good" if they meet standards or "caution" if they don't.

Agnes, it says, is "not always suitable for swimming and wading due to low clarity or excessive algae caused by the presence of nutrients such as phosphorus in the water."

Alum is supposed to bind to the phosphorus and sink it to the bottom, where it will remain.

Sanitary District Executive Director Scott Gilbertson called the treatment a "successful, proven technology to restore lake water quality."

"It's been done throughout the state and country for many years," he said. "You're going to see a large increase in lake clarity."

Alum, a liquid, would be applied to Lake Agnes sometime in mid-September, during a time recreational users will most likely not be fishing or boating on it, he said. The district has not yet sought bids for the project.