However, when a lake is subjected to heavy pollution and other forms of 

 human population pressure, eutrophication proceeds much more rapidly. This 

 accelerated process has been termed "cultural" eutrophication. 



THE PAST (1850-1967) 



Cultural eutrophication was recognized as a problem in this country at 

 least as early as 18b0 when complaints about unpleasant odors from Lake 

 Monona that assailed the citizens at Madison, Wisconsin, were published in 

 local newspapers. Eutrophication research in this country appears to have 

 started in the early 1900's with the work of Birge and Juday at the Univer- 

 sity of Wisconsin. Because eutrophication is fundamentally an expression 

 of the metabolism of lakes, studies of limnology and eutrophication go hand 

 in hand. 



In these early years limnology centered around the taxonomy, and to a 

 lesser degree, the ecology of the zooplankton and around descriptive 

 investigations of lake phenomena. Included particularly were the areal and 

 seasonal distributions of temperature, dissolved gases, and solar radiation. 

 Increased interest in the chemistry of lake waters developed during the 

 second quarter-century. There was special interest in nutrients, pH, Eh, 

 organic matter, and oxygen consumed, all parameters related directly to 

 lake productivity and trophic state, and hence eutrophication. 



In the 1930's and 1940's more attention was given to cycling of nutri- 

 ents in lakes. The awareness, for example, that algal populations could be 

 maintained or increased with no apparent changes in lake-water concentra- 

 tions of available phosphorus, or in the presence of no detectable avail- 

 able phosphorus (or nitrogen), led to renewed investigations in these areas. 

 It then became evident that in many lakes the nutrient elements were under- 

 going very rapid cyclical changes, moving between bottom sediments and over- 

 lying water, from dead organic matter to the water, from the water to 

 actively photosynthesizing plants and to bacteria. These precepts are 

 fundamental to an understanding of the eutrophication process and are basic 

 to the concept of limiting nutrients. 



Following World War II increased attention was devoted to the accele- 

 rated eutrophication of lakes by nutrients from cultural sources. For 

 example, experience with the Madison, Wisconsin, lakes, Lake Washington at 

 Seattle, and a number of European lakes (particularly Zurichsee) made it 

 increasingly evident that nutrients introduced by numerous activities of 

 man--from both point and non-point sources--could lead to rapid and serious 

 deterioration of water quality. As a consequences, a number of remedial 

 approaches were taken to curb nutrient contributions to lakes. At Madison, 

 where municipal sewage had long been discharged into the chain of lakes, 

 the following diversions took place: (a) from Lake Mendota in 1899, (b) 

 from Lake Monona in 1936, and (c) from Lake Waubesa in 1958. At Seattle's 

 Lake Washington, effluents from 11 treatment plants were diverted to Puget 

 Sound between 1963 and 1968. After the first diversion the lake's condi- 

 tion began to improve and has continued to do so. The abundance of phyto- 



