Big lake in peril

(The following was written as a sidebar to my recent feature story on water in Manitoba Farmers' Voice. It wasn't published. Now I've decided to make it available to all five [or whatever] of my blog's readers.)
Algae blooms are choking life in Manitoba’s biggest lake, and farms are a major source of the problem.
Phosphorus and nitrogen, found in manure and chemical fertilizers, have fuelled the growth of huge clusters of algae in Lake Winnipeg. That algae has forced the closure of beaches and presents a toxicity problem for animals. Commercial fishermen’s catches have shrunk because algae uses too much of the lake’s oxygen.
David Schindler, a professor and research scientist at the University of Alberta, says phosphorus is the root of the problem. Nitrogen levels increased in the 1990s and this decade, too, but he says phosphorus has the more deleterious effect.
Causes of the problem include sewage discharges, land-use change (from forest to farm), manure and fertilizer use.
While farmers are part of the problem, Schindler says they can be part of the solution through simple changes in what they do.
Excess phosphorus is being applied to soil in the Red River Valley, he says, so one simple measure farmers can take is soil testing, to see what types and what levels of phosphorus and nitrogen are needed, before applying fertilizer.
Manure has too little nitrogen in proportion to phosphorus, he says, so boosting nitrogen levels likely would make sense for most farms’ needs.
“Very archaic” sewage systems prevalent outside major urban areas often pump untreated waste into rivers, he says, adding those “Stone Age” municipal systems must be upgraded to remove more phosphorus.
One controversial measure the Manitoba government has taken is a moratorium on hog facility expansion in much of the province. Schindler says that “probably was” the right move because hog manure has rather high phosphorus content. “A hog barn with 25,000 animals is equivalent to a city of 250,000 people (in phosphorus output).”
Other parts of the province’s save-the-lake strategy include the establishment of Nutrient Buffer Zones (effective January 2009) wherein nutrients from manure, fertilizer, wastewater sludge or biosolids cannot be applied, and the establishment of a Lake Winnipeg Water Stewardship Board.
But Manitoba can’t cure the ailing lake by itself, as a great deal of the problem originates from places outside its jurisdiction. Lake Winnipeg’s watershed includes large parts of Minnesota, North Dakota, Saskatchewan, Alberta and northwestern Ontario. About half – some say most - of the phosphorus in the lake comes from those places.
North of the border, a federal-provincial Lake Winnipeg Implementation Committee has been working on the matter since 2005. Manitoba is working with southern neighbours through the International Red River Board.