Lower Colorado River Basin

Presented at River basin management to meet competing needs: proceedings from the USCID conference on shared rivers held on October 21-31, 1998 in Park City, Utah.Specific entities in Arizona, California, and Nevada, (herein referenced as the Lower Basin states), are entitled to use in the aggregate either more than, an amount equal to, or less than 7.5 million acre-feet (maf) of Colorado River water in a year depending upon a determination to be made by the Secretary of the Interior (Secretary). In 1996, net water diversions from the Colorado River in the Lower Basin states exceeded 7.5 maf for the first time after accounting for unmeasured return flows. Net diversions in the Lower Basin states also exceeded 7.5 maf in 1997. It is projected that net diversions will exceed 7.5 maf in 1998 as well. Although entities in each state are entitled to use a certain yearly apportionment in the aggregate, entities in a Lower Basin state can utilize the unused apportionments of another Lower Basin state, subject to the approval of the Secretary. Also, entities in each state can use surplus Colorado River water when water in excess of 7.5 maf is available, as determined by the Secretary. No doubt, improved management of Colorado River water in each of the Lower Basin states is a challenge and a key element in meeting future demands to ensure economic stability and sustained development. Capital expenditures are necessary to improve water use efficiency by agricultural and urban users, and to facilitate cooperative programs in which agricultural users reduce their use of water to permit urban users to maintain their level of use. For several decades, California has been exploring and implementing a spectrum of programs aimed at improving the management of its water supplies and reducing its dependence on Colorado River water. A brief description of several of these programs is presented. To date, major progress has occurred. Continued cooperative efforts among water agencies are needed for the timely implementation of additional identified water resources management programs to ensure the availability of reliable water supplies of high quality for future generations