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Show In a few cases wildlife interests in the West have been able to obtain water to irrigate land for wild and cultivated wildfowl food crops. Prob- ably as a direct result of the rapid preemption of natural wildfowl feeding land, California farmers have suffered extensive crop damage from wildfowl depredation. In 1941, 1942, and 1943, crops destroyed averaged over $2,200,000 annually. Congress voted $250,000 in 1949 to acquire and develop waterfowl management areas in California for feeding and rest areas for the wintering waterfowl population. In view of the fact that depriving waterfowl habitats of the necessary water results in Federal expenditures and commercial losses, and that the Government is bound by treaty to protect and preserve the flights of migratory birds on the North American Continent, there is a need for adjustment of State laws which do not recognize maintenance of wildlife as a beneficial water use. Certain minimum waterflows for migratory bird habitats must be provided in those areas definitely shown to play a role in the annual migratory flights of internationally protected wildfowl. Aquatic Life and Pollution When rivers, lakes, or bays are loaded with excessive quantities of sewage, sediment, or certain industrial wastes, the aquatic life of these waters is obliged to escape or die. Organisms at every level may be killed outright by toxic substances or by lack of oxygen. Aquatic plants, dependent on sunshine, will cease to grow in muddy water. Spawning beds and important bottom-dwelling life may be smothered under a blanket of silt or sewage sediment. As organic materials decay, vital dissolved oxygen is consumed. Vigorous organic decomposition or caustic pollutants may change the chemical reaction of the water to such an extent that the protective mucous membranes of fish are dissolved or the oxygenation of blood through their gills is prevented. Poison pollutants from industrial plants are often difficult to isolate or eliminate, but when efforts are finally successful the results in terms of fish recovery are very satisfying. It was re- cently found that zinc poisoning had killed many fish for 60 miles below a large rayon plant on the Shenandoah River. As a result of corrective action taken in 1948, the fish population is now increasing. Other encouraging signs are the recent re- appearance of a few oysters within a stone's throw of the Statue of Liberty and the partial restoration of the Hudson River shad run. Both of these events suggest that the pollution abatement pro- gram in New York is beginning to make some progress. Plainly, a pollution abatement program is essential to the future of our wildlife resources. The abundance of wild animals and fish that might result from such a program stirs the imagination. Impoundments and Wildlife The effects of dams on wildlife cannot be de- termined hastily or on a purely economic basis. Many variables, such as those of dam design and operation, time, weather, wildlife habits, hunting and fishing preferences, commercial value, and relative abundance of the species involved, all have to be considered. Basic biological facts are often lacking and can be obtained only through careful research. The Salmon Story.-Where there are estab- lished economic interests which depend on the wildlife or fish resources of a river system, the development of a program involving large mul- tiple-purpose reservoirs becomes especially diffi- cult. This is notably true in the Columbia Basin, where fishermen exploit the salmon runs. As the reservoirs are filled, spawning banks along the streams are submerged. The dams in- terfere with the migrations of adult fish upriver to spawn and with downstream movements of small fish returning to tjie sea. Unless effective fish ladders or fish locks can be designed, adult fish may never arrive at spawning areas. If penstocks and spillways are not provided with some kind of screen, young salmon may be killed as they pass through the dam. 261 |