WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



33 



Heat 



Tremendous quantities of water are withdrawn 

 daily from streams and lakes for cooling in indus- 

 trial and processing plants. After use, these waters 

 are usually returned to the stream or lake from 

 which they were withdrawn. Large quantities of 

 heat are thus transferred to these water bodies. 

 Since the amount of oxygen that water can hold 

 decreases with increasing temperature, the intro- 

 duction of heat into water has the net effect of in- 

 troducing additional oxygen-demanding pol- 

 lutants. 



Added heat to streams and other water bodies is 

 adverse to fish life in terms of oxygen supply. Heat 

 also has a direct detrimental effect upon fish and 



other aquatic life because it changes their physical 

 environment. Some fish can stand only a few de- 

 grees increase in temperature. 



Forests providing recreational and fishing rights 

 on associated lakes and streams, rural area develop- 

 ment programs providing fishing opportunities, 

 and farmers and ranchers providing fishing oppor- 

 tunities in their ponds, lakes, and streams can be 

 and frequently are hurt by loss of fish life as a re- 

 sult of heat added to these waters. 



Although heat as a water pollutant is not a 

 waste having a major adverse effect on agriculture 

 and forestry, the growing interest in providing 

 recreational opportunities in rural and forested 

 areas indicates that the effect of added heat on fish 

 life will a.rouse mounting concern. 



