U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

Regional blue and green water balances and use by selected crops in the U.S.

Michael White, Marilyn Gambone, Haw Yen, Jeff Arnold, Daren Harmel, Chinnasamy Santhi, Richard Haney
Journal of the American Water Resources Association 2015 v.51 no.6 pp. 1626-1642
freshwater, irrigation water, water utilization, humans, exports, irrigation, soybeans, corn, virtual water, water resources, wheat, rain, water content, Soil and Water Assessment Tool model, surface water, groundwater, Sorghum (Poaceae), prediction, crops, Western United States
The availability of fresh water is a prerequisite for municipal development and agricultural production especially in the arid and semi-arid portions of the western U.S. Agriculture is the leading user of water in the U.S. Agricultural water use can be partitioned into green (derived from rainfall) and blue water (irrigation). Blue water can be further subdivided by source. In this research we develop a hydrologic balance by 8-Digit Hydrologic Unit Code (HUC8) using a combination of Soil and Water Assessment Tool (SWAT) simulations and available human water use estimates. These data are used partition agricultural groundwater usage blue water by sustainability and surface water usage by local source or importation. These predictions coupled with reported agricultural yield data are used to predict the virtual water contained in each ton of corn, wheat, sorghum, and soybeans produced and its source. We estimate that these four crops consume 480 km3 of green water annually and 23 km3 of blue water, 12 km3 of which is from groundwater depletion. Regional trends in blue water use from groundwater depletion highlight heavy usage in the High Plains, and small pockets throughout the Western U.S. This information is presented to inform water resources debate by estimating the cost of agricultural production in terms of water regionally. This research illustrates the variable water content of the crops we consume and export, and the source of that water.