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Show Still more in contrast to the deep, relatively stable power reservoirs, are most irrigation reservoirs, wherein the maximum drawdown usually occurs in the middle of the growing season for aquatic plants. The amount of drawdown may depend on year- to- year variations in rainfall and in the resulting storage capacity, and therefore may be less excessive during the wetter years. Nevertheless, the general operational cycle of irrigation reservoirs usually is characterized by far greater extremes of fluctuation than is the case with power reservoirs. Production of plant and animal life, therefore, is far from stable, while in extreme cases, which unfortunately are numerous, water levels drop so far that the reservoirs are biological deserts. Convenience of access is an important factor in determining the value of an area for recreational use. Reservoirs on or near high- standard roads are likely to receive a much larger use than those reached by mountainous, narrow, rough, sandy, or otherwise difficult approach roads. In the case of the smaller reservoirs where the bulk of the use comes from the neighboring communities and farms, travel distance is a prime consideration. If the area is within an hour's drive, the day use may be expected to be of importance; if more than 2 hours' driving distance away, the area probably will not be used extensively unless overnight accommodations are available. Population of region.- In general, the recreational use of a reservoir is in proportion to the population density of the region in which the reservoir is located, but a number of limiting factors enter into the picture, such as the character of the population, climate, nature of site, operation of the reservoir, type and quality of the facilities provided, administration, and maintenance. It has been found that a larger percentage of the urban than the rural population may be expected to use the reservoirs for recreation; also that reservoirs located in the recognized vacation regions as, for example, the winter vacation region of southern Arizona and the summer vacation region of Colorado, will have a greater use due to the number of people in the region primarily seeking recreation. NATURE OF SITE The topography of the reservoir area determines to a considerable degree the amount of recreational use that can be made of the area. Reservoirs situated in open valleys usually offer more and better opportunities than those located in steep- sided canyons, where access to the water is difficult and sites for recreational facilities are limited. On the other hand, a very flat slope is also objectionable because of the wide shift of the water line between high and low water levels, frequently leaving unsightly mud flats exposed between the usable land above high water and the lake. The ideal situation is where the top of the dam is determined by a flattening of the topography so that there are gentle slopes adaptable to recreational development near both the high and low water lines. Sandy soil along the shore line and the presence of trees and shrubs for shade and stabilization of the soil are other assets. Freedom from mosquitoes and other annoying insects is an important consideration in selecting sites for camping, swimming, and other activities. Outstanding land forms, colored rock, interesting plant growth, or historic and scientific features in the vicinity of a reservoir tend to increase the attendance at the area. Especially are visitors from a distance attracted to the area by the publicity given these special features. Although the recreational use of a reservoir will depend to a large extent upon the quality of fishing that can be maintained, the adaptability of the reservoir area to a diversity of recreational activities will increase its use and value. As with fishing, however, the quality and adequacy of the recreational facilities will have much to do with the amount of use a reservoir area will receive. Among the requisites for a successful swimming area are: A comfortable surface underfoot, sandy and free from mud, rocks, and weeds, both above and below the shore line; water temperature about 70° F. or above; protected shallow areas for small children and nonswimmers; and deep- water diving areas. Camping areas are more popular when some privacy is offered between camp sites, which means the presence of adequate plant growth for screening. Parking spaces convenient to the boat docks, beach, and picnic areas contribute to the success of the development. 104 |