Lake Winnipeg Blue Green Algae a lesson we need to learn

(Summary of a MacLean’s Magazine article Aug. 24th. 2009 edition).

Lake Winnipeg is an isolated prairie lake surrounded by forest and tucked away from industry and major population centers, yet it is dying. What was a small patch of algae, first noted in the early 1990’s has now grown to cover one half of the lakes 24,500 square kilometer area throughout most of the summer months. The green mat that covers the lake is twice the size of PEI and clearly visible from space.

The culprit is not global warming, oil spills, toxic or industrial waste but is nutrient overloading from fertilizers, human and animal waste.

Nutrients such as nitrogen and phosphorus do precisely in water what they do on land. They cause plant life to grow. This growth process is accelerated by tiling of farm land and clearing of ditches to allow runoff from fields. It comes from improperly operated and maintained sewage systems be they sewage treatment plants, sewage treatment lagoons or even home septic systems.

At the same time the destruction of wetlands and river bank areas, which are natures kidneys, has decreased these natural filters and nutrient traps by up to 70%. 

Although, nutrient loading is good to a point, there is a tipping point. When the organic material from excess weed growth dies over the fall and winter months it consumes oxygen and sinks to the bottom. It is during this period that bacteria go on an eating binge and consume oxygen and will eventually consume much of the available oxygen.

In the bottom sludge anaerobic bacteria which do not need oxygen begin to thrive and actually begin to generate their own phosphorus. Once this starts the food change in the lake will die from the bottom up.


Date Added: September 23, 2012 | Comments Off | Filed under: News — Tags: — webedit @ 8:27 pm



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