Much of the water that California receives from the Colorado River flows to the Imperial Valley, where canals spread out across fields of hay, wheat and vegetables of all sorts, from carrots to broccoli.

Because the Imperial Irrigation District holds the single largest entitlement to water from the river, its participation would be vital in any agreement for California to share in water cutbacks to avert a looming shortage in Lake Mead, the nation’s largest reservoir. But major hurdles remain for the district to support a potential deal, and the reasons begin with the shrinking Salton Sea.