The biota of the mid-water area of Lake Michigan reflects an unpolluted environment. Free floating algal populations were less than 500 per milliliter. Pollution-sensitive scuds predominated in the bottom associated organism population. Sludgeworm populations were less than 1,000 per square meter and midges were principally of the clean water variety. Extensive inshore areas of pollution totaling 3,475 square miles were found along the entire southern perimeter of Lake Michigan specifically Milwaukee, Racine and Chicago-Calumet and in Green Bay. The loss of the Green Bay fly, a fish food organism, and other detrimental pollution associated conditions have impaired commercial fishing in Green Bay. Swimming beaches have been closed in Milwaukee, Chicago and other areas when large mats of foul smelling algae have been deposited on the beaches. Aesthetic values associated with water have been impaired by algae on many occasions. Short filter runs and taste and odors resulting from high.