Agricultural water use

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Figure 1. Irrigated agricultural lands within the U.S. potentially receiving Colorado River water, both inside and outside of the physical basin, are shown in yellow. Some of these irrigated lands may receive non-tributary groundwater, or water from tributaries not administratively treated as Colorado River water, such as from the Gila River. Irrigated lands in Mexico, totaling about 0.5 million acres, are not shown. Irrigated acreage is mapped from the 2011 National Land Cover Database. (Source: Moving Forward Phase 1 Report, 2015.)

Agricultural water use accounts for about 75% of the beneficial uses of the Colorado River and about 60% of all consumptive uses and losses. Water from the Colorado River is used to irrigate approximately 5.5 million acres of agricultural lands: 3.2 million acres within the Basin and 2.2 million acres outside of the Basin (Figure 1), fueling a multi-billion-dollar agricultural industry. These irrigated lands account for 15% of all farmland acreage nationwide, and produce 90% of winter vegetables in the United States. While a diversity of agricultural products are grown with Colorado River water, irrigated livestock-feed crops (alfalfa, hay, silage, pasture) account for the majority of the water used for agriculture.

Approximately 1.5 million acres were irrigated with Colorado River water in the Upper Basin states in 2016-2018. Almost half of the irrigated acres in the Upper Basin are located in Colorado; Wyoming and Utah each accounted for approximately 20% of irrigated acres; New Mexico and Arizona both have small quantities of acres irrigated with Colorado River water. The Lower Basin states and Mexico together irrigate just under 4 million acres of agricultural lands. About half of this acreage is located outside of the Colorado River Basin. Most of the irrigated acreage that uses Colorado River water is overseen by irrigation districts. Irrigation districts act as diversion and ditch managers and oversee ditch maintenance; farmers pay dues to irrigation districts for water deliveries.

Managing agricultural water use is complicated by the difficulty of accurately quantifying the actual consumptive use by crops, from the field scale to basin scale. In the past decade, new methodologies that combine satellite imagery with in-situ measurements and physical modeling have come to the forefront (see Evapotranspiration (ET)). In September 2022, Reclamation and the Upper Colorado River Commission (UCRC) adopted a satellite-based method, eeMETRIC, as the standard for measuring evapotranspiration (ET) and agricultural consumptive water use in the Upper Basin.

As basin stakeholders discuss the need for further reductions in basinwide water use in the face of critically low reservoir levels, increased attention has fallen on the water use in the agricultural sector. Short-term reductions in water use are being pursued through payouts to Lower Basin agricultural producers to fallow fields, as well as voluntary reductions; longer-term strategies for water conservation include measures such as shifting planted acreage to lower-water-use crops; installing more efficient irrigation technology; and reducing conveyance losses (e.g., better monitoring of diversions, lining ditches). The challenge will be to invest limited funds in ways that both reduce overall water use and maintain economic viability of the agricultural sector.

Data and tools

Reclamation reporting of consumptive uses and losses

The Reclamation Consumptive Uses and Losses Reports (since 2006, covering only the Upper Basin) contain estimates of aggregate agricultural use within the Upper Basin, based on mapped irrigated acreage and the calculated consumption by crop and location. These estimates may change significantly in the future due to the new method adopted in 2022 by the UCRC and Reclamation. The Reclamation Water Accounting Reports (covering only the Lower Basin) breaks down consumptive use by point of diversion, which identifies the individual water usage of a number of agricultural users and irrigation districts, but not all agricultural users.

Additional resources

Water to Supply the Land: Irrigated Agriculture in the Colorado River Basin

The intent of this 2013 report by the Pacific Institute is to improve understanding of crop acreages and water use in the basin. It also describes a set of scenarios in which some irrigation water could be conserved and used for other purposes without reducing the amount of land in production. Note that the report only covers agricultural uses occurring within the basin's boundaries, not those outside the basin that also use Colorado River water.

Lists and directories of major irrigation districts

Major irrigation districts and water users are tabulated by Reclamation for both the Upper and Lower basins: