The volume of sewage and other wastes discharged into our waters has 

 increased with growth in population and the construction of sewage 

 systems. This enrichment plus detergent carriers, certain industrial 

 wastes, and runoff from heavily fertilized agricultural lands has produced 

 large algal populations and the eutrophication of many lakes and reser- 

 voirs. These growths cause serious problems for water-treatment-plant 

 operators because of the clogging of filters. In some localities at 

 certain times backwashing requires one-fourth of the time of operation. 

 This procedure greatly increases costs and reduces the volume of finished 

 water produced. Known and suspected filter-clogging algae were cultured 

 for screening tests in an effort to determine the species causing the 

 trouble and to find a better and more selective algicide than copper 

 sulphate. 



Series of screening tests were made with new materials that were 

 rapidly appearing on the market in the 1950's. We wanted to find algicides 

 that were specific for the target species and nontoxic to the others. Al- 

 though several good algicides were found, specific materials were not found 

 before the research work was discontinued when biological research was 

 transferred to the new national water quality laboratories. 



In conjunction with the algicidal studies, research was carried out for 

 the development of biological controls. We found that several algae pro- 

 duced materials that inhibited the growth of other algae. We also found 

 that several algae produced antibiotics. In the course of these studies a 

 virus that destroys some bluegreen algae was discovered. Studies of this 

 virus have continued at the Cincinnati laboratory. 



POLLUTION SURVEYS AND STUDIES OF NATURAL PURIFICATION AND BIOLOGICAL 

 INDICATORS OF POLLUTION 



The establishment of the American Fisheries Society in 1870 and the 

 beginning of trout culture and the creation of the U.S. Commission of Fish 

 and Fisheries in the early 1 870' s indicated a national awakening of 

 interest in our fisheries and their protection. It had been noted that 

 fishing was greatly reduced or eliminated in many streams receiving sewage 

 or industrial wastes, or both. Fishermen began to complain and to point 

 out the need for pollution abatement. As a result of these complaints, 

 studies to determine the effects of pollution were undertaken. 



In the 1870 ' s Stephen A. Forbes of the Illinois State Laboratory of 

 Natural History began investigations of the Illinois River, which later 

 established a firm base for the comparison of stream conditions before and 

 after pollution. The study of the Illinois River by the Illinois Natural 

 History Survey is a classical study of the effects of stream pollution, 

 natural purification, and biological indicators of pollution. As sewage 

 from the city of Chicago was added to the river through the Chicago 

 Drainage Canal, the pollution moved progressively down the river as the 

 city and the waste load grew. This provided an excellent opportunity to 

 observe and study the progressive chemical, physical, and biological 

 effects of increasing pollution. Changes in color, turbidity, dissolved 



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