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Show main-line levees protecting rural areas upstream from Albuquerque are breached. Zoning by local authorities could and should be used to prohibit the creation of residential subdivisions in the existing rural areas upstream from the tie-back levees where only limited protection is or will be afforded. At Hot Springs, N. Mex., the authorized project plan for the river basin provides for urban protec- tion by improvement and extension of an existing levee and by channel rectification. Certain low areas adjacent to a slough comprising a segment of an old river channel are subject to inundation by backwater from the Rio Grande at infrequent pe- riods of spillway discharge from Elephant Butte Dam. Normally the slough provides an outlet for local storm runoff and its closure would involve unjustifiable expenditures in interior drainage. The reduced frequency and magnitude of spillway discharge from Elephant Butte Dam after comple- tion of planned upstream reservoirs may encourage urban development in the area which would be subject to damage from intense local storm runoff or backwater inundation when spillway discharge from Elephant Butte does occur. Flood plain zoning here would serve not only to prevent future overflow damage but also materially assist the proper functioning of the project. Com- pliance with this zoning need may well be made a Federal requirement in connection with the actual accomplishment of that improvement. Conclusions Application of flood plain zoning is restricted to a few isolated urban areas. Full consideration should be given to the advisability of sound flood plain zoning to prevent flood damages. 5. Redistribution of Water Rights To Permit Re- tirement of Inferior Lands and the Substitution of Higher Water Use The Problem To what extent should water rights be trans- ferred from inferior lands with prior water rights to better lands with junior or no water rights? The Situation In considering this problem, it must first be recog- nized that water rights are established for existing developments; that the development of irrigation over the past many years has resulted in the estab- lishment of farming and urban centers, which to- gether constitute the economy of an area; and, that in preparing plans for future development these factors require thorough consideration, not only from an economic but also from a sociological standpoint. In view of the above, existing develop- ment must be incorporated into future plans to the fullest extent practicable. It has always been the practice of the Bureau of Reclamation to make full allowance for existing water use for irrigation and municipal water supply in determining the water supply available for new development. Only in rare instances where these priorities con- flict with State laws is there any departure from this practice. Reclamation principles, of course, re- quire that water use developments give full consid- eration to the laws of the State in which the projects lie. In the Rio Grande Basin, the present pattern of irrigation does not provide for optimum use of available water. This is the case for several rea- sons, including the historical growth pattern of water rights in the area, lack of knowledge of requirements at the time irrigation developments were initiated, and lack of proper facilities or ade- quate planning. One of the problems found is the assignment of water rights and application of water to poor classes of land which under present conditions and knowledge would not be consid- ered suitable for irrigation. Recent land classifications reveal that about 20 percent of the approximately 1,270,000 acres of water-right lands included in irrigation projects are nonirrigable. These lands are in the Valley Gravity area in Texas, the Carlsbad and the Mid- dle Rio Grande Projects in New Mexico, and the San Luis Valley Project in Colorado. Inasmuch as water rights are generally pertinent to specific tracts of land and because of long established farms on those lands, it has been difficult and, in most cases, impossible, short of condemnation, to provide for their transfer to lands better suited to irrigation. Hence, there is not a generally satisfac- tory solution, at present, to removing water from poorer classes of irrigated lands to obtain optimum use. Conclusions In this area, where water rights have been estab- lished for many years and where many uses antedate the so-called Anglo-American influx, it would be extremely difficult to attempt a readjustment. Be- 323 |
