zones similar to those in sewage-polluted streams developed. This 

 artificial stream was observed year round, and it supplied valuable data on 

 natural purification; the role of different organisms in the purification 

 process; seasonal changes in the pollution zones and the purification 

 process; and the populations characteristic of the different pollutional 

 zones. 



During the period from 1914 until the Second World War, pollution sur- 

 veys were made of many streams throughout the country by state and federal 

 agencies. Several universities conducted related biological studies or co- 

 operated with the state surveys. Birge and Juday of the University of 

 Wisconsin made limnological studies in the lakes of the state. The New 

 York Stream Survey under the direction of Emaline Moore (1926-1939) 

 supplied valuable data on aquatic populations living in organically 

 enriched streams and lakes. This survey was planned and carried out so 

 that one or more river basins were surveyed each year. Special attention 

 was given to polluted waters, the cause of pollution, and its effect. 



In 1917 Weston and Turner at the Sanitary Research Laboratory and the 

 Sewage Experiment Station of the Massachusetts Institute of Technology 

 published a paper entitled, "Studies on the Digestion of a Sewage Filter 

 Effluent by a Small and Otherwise Unpolluted Stream." This investigation 

 was noteworthy because they studied in a natural stream the development of 

 pollutional zones, the natural purification process, and the development of 

 the aquatic biota characteristic of each of the zones of pollution. 



As data on the extent of pollution and its effects became know, an 

 ever-increasing demand developed from fishermen, sportsmen's clubs, civic 

 groups, and fish and game departments for strong federal laws to control 

 pollution. Early in the 1920 ' s the Isaac Walton League initiated a 

 national program for pollution abatement. This campaign was more effective 

 than the former attempts. The passage in 1948 of Public Law 845 was due in 

 part to the efforts of this group. 



The U.S. Bureau of Fisheries and its successor, the U.S. Fish and 

 Wildlife Service, conducted surveys in several areas. In 1927 a biological 

 survey of the upper Mississippi River with special reference to pollution 

 was carried out under the direction of A.H. Wiebe. Several very productive 

 surveys were made by M.M. Ellis, Chief of the Fish and Wildlife Service 

 field station at the University of Missouri. He approached the problem 

 from the viewpoint of a physiologist and made many important contributions 

 on the environmental requirements of aquatic organisms. 



Ruth Patrick of the Philadelphia Academy of Natural Sciences made exten- 

 sive studies of the role of plankton, especially diatoms, as indicators of 

 stream health or pollution. In connection with these studies the 

 "diatometer" was developed for the sampling of certain elements of the 

 plankton population. 



In 1949 the Biology Section of the Environmental Health Center in 

 Cincinnati initiated the Lytle Creek study. This stream was selected for 

 special study after an extensive search for a stream with one source of 



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