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The sustainability of irrigated agriculture in the Lower Colorado River region




Davey, James V., author
U.S. Committee on Irrigation and Drainage, publisher

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There are some 160,000 acres of irrigated agriculture in the region of the Lower Colorado River from below Imperial Dam to the Mexican border. Included in this region are seven irrigation districts, 6 in Arizona and 1 in California, and these districts presently operate on a run-of-the-river basis, diverting waters from the Colorado River and returning flows to the river through agricultural drains and groundwater flows. Demand for water is increasing in the region due to urbanization, particularly the rapidly growing City of Yuma but also the cities of San Luis, Somerton and Wellton, Arizona. Mexico also diverts large volumes of surface water and increasingly relies on groundwater pumping to meet it water needs. The region presently has areas of groundwater excess, where drainage wells and open drains are needed to relieve high groundwater tables, and areas of declining groundwater tables, especially near the border areas with Mexico and potentially along the lower Gila River. Treaty requirements negotiated with Mexico regulate salinity of return flows to the river, resulting in much water being bypassed to the Santa Clara slough in Mexico and potentially being desalted on a large scale basis by the Yuma Desalting Plant in the future. Sustainability of irrigated agriculture over the long term for this region will depend on many factors, including (1) the overuse of groundwater supplies, especially along the lower Gila River and along the Mexican border area; (2) the reduction in surface water supplies due to water conservation; (3) reduction in groundwater recharge as flood events on the Colorado and Gila Rivers become even more infrequent with continued construction of upstream flood control storage; and (4) general impacts on agriculture and water rights from conversion of agricultural lands to urban uses.


Presented at Irrigation district sustainability - strategies to meet the challenges: USCID irrigation district specialty conference held on June 3-6, 2009 in Reno, Nevada.

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