Reference Evapotranspiration Estimates for Arizona

Irrigated agriculture is the largest single user of available water in Arizona. Present estimates show water use at about 85 percent of available water with the major portion coming from groundwater reserves. The state has been facing an estimated overdraft of two million acre-feet per year from groundwater aquifers. As a result, the 1980 Groundwater Management Code is forcing the agricultural sector to manage and use the available water more efficiently.