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Published August 13, 2010, 07:54 AM

Cutting phosphorus key to helping rivers

County board member Clarence “Buck” Malick has more than a passing interest in clean rivers and he told members of the Thursday Noon Rotary Club last week that the key to healthy lakes and rivers is the reduction of phosphorus.

By: Doug Stohlberg, Hudson Star-Observer

County board member Clarence “Buck” Malick has more than a passing interest in clean rivers and he told members of the Thursday Noon Rotary Club last week that the key to healthy lakes and rivers is the reduction of phosphorus.

Malick, an attorney, is currently a board member of the St. Croix River Association and is the former executive director of the now defunct Minnesota-Wisconsin Boundary Area Commission.

Malick noted that the St. Croix River was listed as “impaired” in 2008. Since the watershed includes the rivers and streams that enter the St. Croix River, the designation includes the Kinnickinnic, Willow and Apple rivers in St. Croix County.

“When a river is designated as impaired, the federal government gives local authorities five years to come up with a plan to reduce phosphorous. That plan is currently being formulated by county, state and DNR officials.

Currently, the level of phosphorous (measured in tons per year) is well above the recommended 350 tons per year. The level was at 450-plus in 1990 and is expected to be at 550-plus by 2020. The 350 level would bring phosphorous back to the levels of the 1940s and 1950s.

“The amount of phosphorous essentially dictates the amount of algae in a lake or river — the more phosphorous, the more algae,” Malick said. “A little phosphorous can add lots of algae to a body of water.”

Contrary to popular belief, however, phosphorous in dishwashing soap adds very little to the phosphorous levels. Most phosphorous comes from farm runoff. Farmers fertilize fields and much of the chemicals wash into the streams and rivers.

In the Willow River for instance, the city of New Richmond has a water treatment facility on the river and the village of North Hudson is also on the waterway — yet the vast majority of phosphorous is caused by farm runoff. All water is also subject to a small percentage of natural sources of phosphorous, like leaves from trees; and urban sources, like grass clippings, etc.

Statistically on the Willow River watershed, phosphorous comes from the following sources: Agriculture, 73 percent; residential/urban, 15 percent; forest/grasslands, 10 percent and point sources (wastewater treatment plants), 2 percent – down from 20 percent about a decade ago.

In helping to devise a plan, however, Malick said it makes sense to spend the money on the greatest contributors – that being farm runoff.

“There are ways farmers can plow the fields and plant seeds to reduce runoff,” Malick said. “Also, farmers generally over-fertilize. Over-fertilization does not do any harm to the crops, yet under-fertilization can stunt the growth of crops. To them (farmers) it makes more sense, with less risk, to do a bit more fertilizing than is necessary.”

Some federal grant money is available to assist in developing a plan to cut phosphorous. What is undetermined is the funding to implement a plan when that time comes.

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