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One of the most persistent ecological problems
in agricultural areas is non-point source nutrient pollution. Nutrient
rich runoff from fields and feedlots ends up in streams and lakes, fertilizing
the growth of nuisance algae. This image shows an algal bloom on Lake
Winnebago in July, 1992. Algae bloom like this in lakes when the nutrient
concentrations are high (especially phosphorus since lakes tend to be
phosphorus limited) and the wind speed is relatively low. Winds the day
before this image was taken were blowing from the west at less than 6
miles perhour. If you had driven your boat through this bloom you probably
would have seen large floating rafts of foul smelling blue-green algae.
Lake Winnebago, a shallow lake near Oshkosh Wisconsin,
sits in the middle of a heavily agricultural area and so receives a substantial
amount of non-point source nutrient pollution from the farms upstream.
Riparian buffer strips, fertilizer control policies and manure containment
units are just a few of the solutions that farmers, managers and policy
makers are working on to reduce non-point source nutrient pollution.
This image was taken by the Landsat-7 satellite which
takes high resolution spectrum enhanced photos of the entire planet over
16 day periods. Landsat data is collected and maintained through a cooperative
effort between the USGS and NASA.
Text contributed by UW Green Bay professor Dr. Tara Reed
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