Since 1950, the AzWSC has estimated water use by county at 5-year intervals, publishing the results in a series of reports since 1981. Water demand is met by pumping groundwater from aquifers or by conveying surface water to users through a system of reservoirs and canals. Because of the importance of water to Arizona’s communities and future economic development, the AzWSC works cooperatively with the Arizona Department of Water Resources to collect data and estimate withdrawals annually. Withdrawals are estimated for five categories of use: irrigation, municipal, mining, drainage, and thermoelectric power.