Agriculture provides extraodinary benefits for humans and consumes the vast majority of the Colorado River’s water. Diversions from the River for agriculture total about 78% of the River’s entire flow, almost 4 trillion gallons. Water is pumped in tunnels through the Continental Divide in Colorado to the vast irrigated plains of northern Colorado where it grows alfalfa and corn, much of which is used to feed cattle. Conversely, many times more water is pumped to the desert landscapes of southern California where it is used to grow vegetable crops that are shipped to grocery stores and restaurants across the United States.
Using this water for agriculture creates vast amounts of food, but also creates many ecological and public health problems. The rivers water is used and reused so many times, that by the time it reaches the U.S./Mexico border, it contains high levels of salt, selenium, and other minerals that have leached out from the soils of agricultural lands across the basin. At the very southern tip of the basin, farmers have installed miles of underground drains to help leach away harmful minerals. Because of this water pollution, and because of the increasing demand for water, farmers throughout the Southwest are being encouraged to practice water conservation and efficiency, which could ultimately be the biggest source of new water available for cities.