Table 2 



OCCUBRENCE OF AlGAE IN FoUR WISCONSIN HaRD WaTER LaKES 



(From Sawyer, Lackey, and Lenz, 1943) 



remains low during the spring and summer months but increases 

 during the fall and winter periods when there is a reduction in the 

 plankton. In general, where the total phosphate and nitrate con- 

 tent of drainage lakes is high, the algal flora is abundant. This 

 relationship is clearly demonstrated by the higher productivity of 

 plankton bulk in such lakes as Jordan in Michigan and Wingra in 

 Wisconsin when compared with the productivity of lakes in the 

 northern areas. It is noteworthy that in some of the Yahara River 

 lakes near Madison there is a significant relationship between exces- 

 sive growths and blooms of algae and the high phosphate-nitrate 

 content resulting from sewage efiluents and run-off water from 

 populated areas. A similar condition is observable in Jordan Lake, 

 Michigan, and in some of the eutrophic lakes in northwestern Iowa 

 which have received a continuous flow of fertilizing elements during 

 the past few decades. 



Lake Mendota, Dane County, Wisconsin, in the Yahara River sys- 

 tem, is a typical hard water drainage lake. The pH ranges from 7.4 



[17] 



