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38 additional fish and wildlife habitat continue to increase, as evi- denced by the more intensive use of existing sites. Research programs by State and Federal agencies must focus their attention on developing benefit evaluation factors and identification of future needs of fish and wildlife. Other water resources functional needs such as water quality and outdoor recreation should be considered in conjunc- tion with minimum streamflow and flatwater needs for fish and wildlife, Irrigation Development Situation Statement During the last few years, not only the domestic but worldwide demands for American agricultural products have in- creased rapidly. One way in which crop and livestock agriculture in the Missouri River Basin has responded to the need for in- creased stability and productivity has been through the greater utilization of irrigation on croplands and pastures. Traditionally, irrigation has been used in this Basin mostly for reclamation of arid lands, increasing production, and helping alleviate the clima- tic variations in dryland crop and livestock agriculture. Since about 1950, however, with the expanding market for agricultural products, higher costs generally, and the need to assure produc- tion, irrigation has come to be used also as a supplemental water supply in marginal rainfall areas. Recently, even the States in higher rainfall parts of the Basin-Iowa, Missouri, Kansas, Nebraska, and Minnesota-have experienced significant in- creases in irrigated acreages. The development of center pivot sprinkler systems, which permit irrigation of much cropland with- out leveling, is another reason for the expansion of irrigation in many parts of the Basin. Coupled with these newer technologies, periodic droughts provide an unusually strong impetus to such development. Irrigation development in the Missouri Basin has been so extensive that the attendant water use accounts for close to 90 percent of the total water consumed. Irrigation water use is caus- ing stream depletion ranging from minor to complete dewatering for substantial periods in some areas, especially in parts of Mon- tana, North and South Dakota, Kansas, Wyoming, Nebraska, and Colorado. In other areas, particularly eastern Colorado, Kansas, and some parts of Nebraska and Wyoming, the ground water resources are being depleted at a rapid rate. This olten has the near- or long-term effect of depleting streamflow. Competition for water for irrigation and other uses is, in many places, becoming intense. Directions Projections indicate that national as well as worldwide demand for American food and fiber will continue to rise. To ensure that the Nation's productivity will keep pace with this demand, the Missouri Basin's agricultural output will have to expand steadily during the foreseeable future. In order to achieve such expansion, supplemental water sources will be required to protect the high capital investment costs necessary to assure stabilization of the agricultural economy. Continual development of both surface and ground water for irrigation will be required. The Basin's irrigation development must be based on careful and thorough knowledge of the interrelationship of ground and surface water and an analysis of the supply available, tem- pered to allow for the preservation of water of adequate quantity and quality for other recognized uses. Irrigatecl agriculture is greatly dependent on energy for pumping and distributing water to the soli to meet crop needs. The rapid expansion of high-pressure sprinkler irrigation systems dur- ing the past 10 years has accelerated agricultural demands for energy, because sprinklers require 10 to 20 times-more energy than open-channel or low-pressure surface systems. Research and development of more efficient, low-energy surface systems should 'be pursued. New basic concepts and technology are needed also to reduce evaporation losses from sprinkler sprays and soil surfaces that have been wetted by irrigation. In the case of ground water development, decisions re- garding depletion of this resource must be made on the basis of technical analyses, and local residents should understand the consequences of exhausting the resource. State direction will be required in most cases (Montana, Colorado, Nebraska and Kan- sas have already initiated measures of this type) to manage the resource in consonance with established goals. Land Conservation and Management Situation Statement Abundant clean water and productive land are the most important natural resources and the principal basis for the Basin's strong agricultural economy. The need for conservation of the land resource, both public and private, has been recognized and stressed since the Dust Bowl days of the 1930's, when wind erosion reduced much productive land to wasteland. Likewise, water erosion decreases farmland productivity, and the effects are often permanent and irreversible. Excessive sediment pro- duced by water erosion fouls streams through reduction in water quality and stream channel deterioration, and depletes valuable storage space in reservoirs. Rural flooding, erosion, sedimentation, and drainage prob- lems are serious throughout much of the Missouri Basin, but are particularly acute in central South Dakota, western Iowa, south- eastern Nebraska, and northwestern Missouri. Efforts of indi- viduals and local, State, and Federal agencies have produced advances in land conservation and management during the past four decades. Nevertheless, at the present rate of land treatment, it would take four more decades of proper conservation and management practices to bring the Basin's lands up to optimum stabilization and productivity. In addition, new farming techniques are making certain earlier conservation practices outmoded and requiring restructuring of some measures already installed and practiced.