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<br />Lake ,Eutrophication Problems and Progress--A Panel
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<br />Dr. Alfred C. Fox, Leader of the South Dakota Cooperative Fishel'ies
<br />Unit, South Dakota State University, at Brookings, South Dakota, told
<br />the Committee that all of our lakes are transitory ~n nature. Their
<br />longevity is dependent upon their size., depth, and the rate at which
<br />silt and nutrient materials enter their basins. Eventually they Hill
<br />all fill up and disappear.
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<br />As the eutrophication process continues, plankton populations
<br />begin and increase; then green algae appears; and finally the blue-green
<br />algae appear s and the tremendous "b looms" occur "hie h are often the
<br />first sympton to alarm us. They alarm us because the recreational
<br />value or the lake, the prime ingredient of "hich is the fishery, begins
<br />to be affected.
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<br />Many of the most desirable sport fishes are found in Haters that
<br />are generally classified as oligotrophic. These are typical trout
<br />waters. As these lakes age, trout are replaced by pike, bass, perch,
<br />and many species of panfish. Further aging brings on a predominance
<br />or rough fish such as: carp, buffalo, and other species.
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<br />Although the eutrophication process cannot be stopped; ic can be
<br />slowed down. If we are to slow dOlvn this process, it would seem that
<br />our first line of attack should be directed at arresting nutrient and
<br />silt inflows Co lakes. Once we have done all that is possible to
<br />decrease nutrient inflo'tV into a lake, we can thinlc about removing
<br />excess nutrients already in the lake.
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<br />Mr. Robert G. Lipscomb, Hydrologist, U. S. Geological Survey,
<br />Fort l-layne, Indiana, discussed "Some Natural Aspects of Eutrophication."
<br />Mr. Lipsconrn told the Connnittee that eutrophication is defined as the
<br />natural process of maturing in a lake. There is no common index to
<br />eutrophication by which lakes may be compared. Most productivity in
<br />lakes occurs during the warmer part of the annual cycle and it is the
<br />rate of biological turnover which is important in eutrophic ation.
<br />Present rates of eutrophication are accelerating in many of our lakes
<br />and the evidence leads one to believe that man's activities 'are
<br />responsible for this premature aging.
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<br />Dr. A. F. Bartsch, Chief of the National Eutrophication Research
<br />Pro~ram, Federal Water Pollution Control Administration, Pacific
<br />Northwest Water Laboratory at Corvallis, Oregon, told the Committee
<br />eutrophication is the sum of the processes by which ~akes mature,
<br />grow old, and finally disappear. The national problem of eutrophication
<br />already involves in varying degrees m<1ny of the 100,000 small lakes of
<br />the United States. In many lakes eutrophication is brought on and
<br />accelerated by acts of man. These include: (1) Increasing the input
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