Table 4.18 — Relative importance to wildlife and fish of water-related activities and conditions in the 



contiguous States and Hawaii, by region, 1975^ 



Source of concern 



Northeast 



North 

 Central 



Southeast 



South 

 Central 



Rocky Mountains- 

 Great Plains 



Pacific 

 Coast 



Hawaii 



Pollution, sedimentation, 

















and eutrophication 



1 



1 



2 



3 



1 



2 



— 



Residential, commercial. 

















industrial development 



2 



1 



2 



1 



3 



4 



1 



Dams, irrigation, navigation 

















and channelization projects 



3 



2 



1 



3 



1 



3 



3 



Volumes and fluctuations 

















of streamflows 



4 



— 



3 



4 



2 



1 



— 



Agriculture activities 



3 



3 



— 



2 



4 



— 



2 



Mining activities 



4 



4 



3 



— 



3 



- 



— 



'"1" means of greatest importance. No entry means not of major concern. 

 Source: US, Department of tfie Interior, Bureau of Outdoor Recreation 

 Nationwide analysis ol outdoor recreation. 1975, In U.S. Water Resource Council. 



The Nation's water resources — Part III, Chapter 8. Water requirements for 

 recreation and related resource considerations (review draft), p. 203, 1978. 



Free-flowing streams and rivers have been physi- 

 cally changed for many purposes, including power 

 generation, flood control, and transportation routes 

 for barges. While most hydroelectric construction has 

 been centered in the West, channelization continues 

 as a major activity in the East, and particularly along 

 the Mississippi River and its tributaries. 



The damming of rivers, reductions in the flow of 

 freshwater, and dredging of navigation waterways in 

 coastal zones change water circulation patterns and 

 the volumes of sediment entering estuaries. The sedi- 

 ments themselves are important, for they are sites for 

 microbial activity responsible for the decomposition 

 of organic matter. Substantial reductions in sediment 

 loads lead to the erosion of tidal shores, beaches, and 

 the deltas themselves. 



Leveeing of the Mississippi River has altered the 

 distribution of silt-laden freshwater to such an extent 

 that the Louisiana coastline is subsiding rapidly. Salt- 

 water intrusions are dramatically altering the fresh- 

 water and brackish marshes. On the Texas Gulf 

 Coast, predicted increases in freshwater consumption 

 may well lead to increased salinity, which would have 

 a serious impact on the shrimp and shellfish indus- 

 tries and on fishery habitats. The diversion of fresh- 

 water supplies through the cross-Florida navigation 

 system to Lake Okeechobee has reduced the extent of 

 the Everglades and of the estuarine ecosystem off 

 south Florida, and has increased the adverse impacts 

 of normal dry years. Finally, massive diversions of 

 water from the Sacramento and San Joaquin Rivers 

 to supply southern California cities with water 

 threaten to change San Francisco Bay from an estua- 

 rine to a marine environment; the anadromous fish 

 and waterfowl populations of central California also 

 have been affected. 



Pollution and Sedimentation 



Pollutants from a variety of sources, including 

 agricultural and industrial chemicals, pose a threat to 

 populations of wildlife and fish. Perhaps best known 

 has been the sometimes devastating impact on large 

 birds of prey, which accumulate some of the chemi- 

 cals assimilated by organisms that are at lower levels 

 in their food chains. The brown pelican, bald eagle, 

 and peregrine falcon are species that have suffered 

 from contamination of their food chains. 



Pollution can have devastating effects on scenic beauty and on 

 wildlife and fish habitat. 



138 



