Document Type

Thesis - Open Access

Award Date

2026

Degree Name

Master of Science (MS)

Department / School

Geography and Geospatial Sciences

First Advisor

Kimberly K. Johnson Maier

Abstract

The American Southwest faces a freshwater supply crisis, as a decades-long drought has reduced reservoir storage and annual streamflow along the Colorado River Basin (Richter et al., 2024; Williams, Cook, and Smerdon, 2022). As of February 2026, the federal government has assumed control of determining how river water allotments will be reduced in accordance with dwindling supply. Arizona, a Southwestern state that relies heavily on the Colorado River, faces the challenge of balancing its freshwater demand with this shortage. Drought conditions in the state have reduced other major river systems, as well as groundwater stores, due to decades of overuse. As there are no unused sources of fresh surface water within the region, the Arizona Water Infrastructure Finance Authority has even looked to produce freshwater through desalination technology to turn seawater from the Gulf of California into freshwater. The purpose of this thesis is to calculate the price of desalinated water needed to fully irrigate the alfalfa grown in Arizona from 2013 to 2023. To do so, the United States Department of Agriculture’s National Agricultural Statistics Service Cropland Data Layer and the OpenET Ensemble Monthly Evapotranspiration v2.1 datasets were used within Google Earth Engine to find the evapotranspiration (ET), or water lost to evaporation and transpiration, for the areas where alfalfa was cultivated. From there, using two price estimates for desalinated water costs, it was calculated that the average amount of water lost as ET would have cost between $3,127,921,569 to $5,473,862,744. The total economic impact of agriculture in the state has been estimated at about $30 billion, meaning that, at such a price, alfalfa production would likely be uneconomic. These results underscore the need to account for the true price of freshwater in a state where it is projected to become increasingly scarce, so that the water may be used more efficiently.

Library of Congress Subject Headings

Saline water conversion -- Arizona -- Costs. 
Alfalfa -- Irrigation -- Economic aspects -- Arizona.
Irrigation water -- Arizona. 
Water-supply, Agricultural -- Arizona.

Publisher

South Dakota State University

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Rights Statement

In Copyright