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Lake Winnipeg's dead zone expanding

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Pair of ducks
The Red River during flooding Wednesday, April 6, 2011. This view is from Fargo looking east toward downtown Moorhead.
MPR Photo/Ann Arbor Miller

Minnesota, North Dakota and Manitoba are planning to work together to fix an expanding dead zone in Lake Winnipeg.

The lake is a major fishery in Manitoba, but it's health is declining because of nutrients like phosphorus flowing in through the Red River. The nutrients cause large algae blooms.

The problem has been building for decades, said Lance Yohe, Red River Basin Commission executive director.  

"The new research is indicating we're getting closer and closer to a tipping point where the lake would start to deteriorate rather fast," he said. "If we solve the problem and make progress, this is the best tool to do that."

The Red River drains a large area, and the first step is to identify where nutrients are coming from, Yohe said.

"If you have a septic tank overflow in a rural area or along a lake or discharges from an urban area, you can measure the output coming from that point and say 'Okay, we've got too much of this or that or the other thing,'" he said. "Then you can target strategies at that location."

A nutrient reduction plan is critical because research indicates the lake is nearing a tipping point and water quality will begin to deteriorate much faster if nothing is done, Yohe said.

Minnesota's new basin-wide approach to monitoring the health of rivers should help identify where nutrients are coming from, he said.

Possible solutions include more natural buffers to filter farm field runoff, identifying and fixing failing septic systems, and using non-phosphorus detergents.