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Show Programs for the Future The programs of State game departments and the Fish and Wildlife Service for refuges and fish cul- ture stations will continue probably at a somewhat expanded pace in an effort to meet the increasing demand of sportsmen in the area. Present coop- erative river basin studies in which State game de- partments and the Fish and Wildlife Service de- termine means of obtaining maximum fish and wildlife values will be continued. Proper range and other land use practices needed for watershed protection also can enhance wildlife resources. The National Park Service will continue to study potential projects of other Federal agencies in its river basin study program and will recommend desirable recreation developments. Pollution Abatement Present Situation Pollution from domestic sources and industries in urban areas is usually treated in municipal sewage- treatment plants. Some of these plants are over- loaded and local nuisance conditions exist. Industry in the basin consists of mining and the processing of agricultural products. Industrial wastes from mining operations have not harmed many streams. Occasional abandoned milling op- erations have left residual mine tailings which have caused pollution damage. Extensive citrus can- ning waste has created a pollution problem in the lower Rio Grande Valley for which no economic solution is yet known. A great number of the necessary treatment works for handling domestic sewage have been built. However, a large percentage of these is overloaded and requires additions and enlargements. Treat- ment of industrial wastes has been less satisfactory. State agencies are aware of the problem and are taking steps to correct unsatisfactory conditions. Many of the rural communities and rural areas have primitive sanitary disposal systems. These are a source of widespread pollution of minor streams and of canals, many of which are a source of domestic water supply. Salt pollution of surface and ground waters in- creases with irrigation. Opportunities for evapo- ration and transpiration are increased by spreading water over the land. Progressive concentration of dissolved solids takes place and requires the application of relatively more irrigation water to keep concentrations down within tolerable limits for domestic uses and crop growth. Generally this aspect of water pollution is not adequately consid- ered in planning irrigation projects, but the salting of ancient irrigation projects in some other parts of the world should be taken account of and avoided in the Rio Grande Basin. Where saline pollution of water results from its rapid dissolving of salts in extensive deposits, as in parts of the Pecos Valley, little can be done except to keep the fresh waters from these salt beds or to prevent the salt water from contaminating the fresh by keeping fresh and salt waters apart. Program for the Future State water pollution control agencies will deter- mine waste treatment facilities required to meet needs of industrial operations, new military installa- tions, or new nuclear energy plants, so that the quality of the relatively small amount of water avail- able in this area will be impaired as little as possible for domestic, agricultural, or industrial use. They should undertake programs to reduce pollution in rural areas as well as in areas of greater concentra- tion. Mosquito Control Measures Except for the lower 200 miles of the Rio Grande, mosquito-borne malaria is practically unknown in this basin. However, mosquitoes are common in marshes, and seepage of irrigation water gives rise to breeding grounds for pest mosquitoes. In the El Paso area, campaigns for partial control of pest mosquitoes cost thousands of dollars annually. At Las Cruces, N. Mex., a continuing mosquito con- trol campaign is carried out. Any river develop- ment program should take into account the mos- quito problems which might arise from impounded water. Further studies are needed. Multiple-Purpose Aspects of Federal Program Major works have been constructed in the Rio Grande Basin for irrigation and related drainage, flood control, and compliance with international obligations. Other functions include sediment con- 311 |
