Arizona Water Use

Science Center Objects

The Arizona Water Use program collects and estimates annual water withdrawals for the categories of irrigation, municipal, mining, thermoelectric-power, and drainage uses. The data for these categories are compiled for the Arizona Department of Water Resources groundwater basins outside of Active Management Areas. 

Because of the predominantly semiarid to arid climate in Arizona, economic development in the State is largely influenced by access to adequate water supplies. Water demand is met by pumping groundwater from aquifers or by conveying surface water through a system of reservoirs and canals. Anthropogenic water use is a significant component of the hydrologic cycle in Arizona, and accurate spatial and temporal water-use data are useful for management of this valuable resource. Water-withdrawal data provide important information on how water demand affects the State’s water resources. Information on water withdrawals can also help planners and managers assess the effectiveness of water-management policies, regulations, and conservation activities. 

Approach

Agricultural lands in Arizona

Map showing agricultural lands in Arizona

The semiarid to arid climate in Arizona necessitates the need for groundwater and (or) surface water for irrigation of nearly all agricultural fields in the state. When metered groundwater or surface-water withdrawal data are not available for a particular basin, total irrigation withdrawal is typically estimated based on crop acreage, consumptive water requirement rates for crops, and irrigation system efficiency. Irrigated acreage will be delineated using the aerial photography and then field verified. Consumptive water requirement rates for crops are determined by using a modified Blaney-Criddle method. Irrigation efficiency is then estimated, based upon an estimate of conveyance losses during transport and the type of irrigation system used to apply water. Considering all these factors, an accurate water-use estimate can be determined on a field-by-field basis where metered data is unavailable.

Municipal-withdrawal data represent water withdrawn by public and private water suppliers and self-supplied domestic users. Data for municipal withdrawals by public water suppliers are obtained from the water suppliers themselves. Private water suppliers report water withdrawal data to the Arizona Corporation Commission, which is the primary provider of delivery data for private water suppliers in Arizona. Self-supplied domestic water withdrawals are rarely measured or reported. Consequently, these data are estimated from the self-supplied domestic population and the per-capita water use. Water withdrawal data for mining, thermoelectric power, industrial, livestock, and aquaculture are obtained directly from water users. Drainage groundwater withdrawals are for irrigation drainage and the 242 well fields. Drainage data for agricultural lands in the Lower Gila and Yuma Basins are published in the USGS annual water resources data report for Arizona. Data for the 242 well fields are obtained from the Bureau of Reclamation.

Relevance and Benefits

This water-use data provides planners and water-resource managers with information that can be used to properly manage water resources. Published water-use data reports serve as one of the few sources of information about groundwater and surface-water withdrawals in Arizona.