by Jeniffer Solis, Nevada Current
The most cost-effective and quickest way to conserve the Colorado River’s shrinking water supply amid persistent drought and rapid population growth is changing how states handle the largest use of water on the river: agriculture.
Agriculture uses about 80% of the river’s water, but the good news is that paying farmers not to use water allotted to them has proved to be remarkably cost-effective.
That’s according to a comprehensive study examining 462 federally funded Colorado River conservation and supply projects using available spending data from the U.S. Bureau of Reclamation.
The study, published in the Journal of the American Water Resources Association last week, was conducted by UC Riverside’s School of Public Policy in partnership with the Utah Rivers Council.
The water projects examined – ranging from large-scale infrastructure such as reservoirs and wastewater treatment plants to agricultural water use – totaled about $1 billion in federal funding between 2004 and 2024.
“How much water is actually being saved for every dollar we are spending?” asks Mehdi Nemati, an assistant professor of public policy, co-author of the study. “If we want to be more efficient or gain more water saved per dollar spent, then answering this question matters.”
“The big message is not all water savings are equal. Some projects saved water at a fraction of the cost of others,” he continued.
Agricultural conservation programs conserved water for as low as $69.89 per acre-foot. On average, agricultural conservation programs cost about $417 per acre-foot, while local supply projects —such as reservoirs, wells, and wastewater treatment facilities—cost more than $2,400 per acre-foot on average. (An acre-foot is the amount of water needed to cover one acre of land to a depth of one foot, or about 325,851 gallons.)
“Spending money to conserve water within the agriculture sector seems to be one of the most cost-effective ways. There’s also a lot of room to improve and save more water in this sector,” Nemati said. “About 80% of the water goes to agriculture. If you’re using a big share and it’s more cost-effective, then that’s going to need to be the target.”
Historically, farmers have been reluctant to lower their water use out of fear the government might take their water permanently. But the study found that agricultural conservation programs, particularly those that provided financial incentives to promote behavioral changes among farmers, were successful at delivering water savings at a relatively low cost.
The most common type of agricultural conservation program was paying farmers who rely on the Colorado River to reduce their water use on crops during certain non-critical periods, saving an average of 747 acre-feet per year at a cost of about $140 per acre-foot.
Paying farmers to temporarily leave their fields empty – particularly for water-intensive crops like alfalfa – produced an average annual water saving of 17,500 acre-feet per year at an average cost of about $193 per acre-foot, according to the study.
“Grass, alfalfa, corn pasture, these are all water intensive crops. That’s where we get our most savings per dollar, and there is huge room for savings. I would say these are low hanging fruit,” Nemati said.
Other programs studied paid farmers to replace flood irrigation with precision methods such as drip or sprinkler systems, which demonstrated substantial efficiency improvements while maintaining agricultural productivity.
The U.S. Bureau of Reclamation spent about 30% of water conservation funding between 2004 and 2024 on agricultural projects.
Agricultural conservation projects had an average lifespan of about three years, meaning once those short-term projects end water savings are expected to gradually decline.
Water-intensive crops are where the savings are
Much of the funding used to pay farmers to conserve Colorado River water was provided by the Biden-era Inflation Reduction Act, which helped double agricultural water conservation from 1.5 million acre-feet of water to over 3 million acre-feet of water, according to the study.
Water recycling and treatment facilities also proved to be a cost-effective way to conserve substantial amounts of water in the long-term, despite higher initial construction costs. Water recycling and treatment facilities had an average lifetime cost of $385 per acre-feet with an average annual water savings of about 18,600 acre-feet.
Despite the large potential for water savings through water reuse projects, only about 7% of the bureau’s water conservation funding was spent on reuse projects. California got the lion’s share of that funding, about 80%. Upper Basin states received only 4% of reuse funding, while Tribal areas received no funding.
There’s a lot of room for improvement in water recycling across states that rely on the Colorado River. One recent study found that Upper Basin states – Colorado, Utah, Wyoming and New Mexico – recycled less than 5% of their water, as compared to Lower Basin states – California, Arizona and Nevada– which recycled more than 30% of their water.
The study also revealed a major disparity in federal funding for water conservation projects between the Upper Basin and Lower Basin states.
Between 2004 and 2024, Upper Basin states only received about 6% of overall water conservation spending by the U.S. Bureau of Reclamation, while about 75% was directed to the Lower Basin, and about 19% was designated for Tribal areas, some of which extend across both regions.
Nevada received nearly $6 million for 28 water conservation projects for an average annual savings of roughly 1,500 acre-feet at a cost of about $3,800 per acre-foot.
It’s a stark contrast to Upper Basin states like Colorado, which received about $610,000 in federal funding for 47 water conservation projects for an average annual savings of about 2,100 acre-feet at a cost of about $285 per acre-foot.
It’s an example of how federal dollars could be more efficiently used to conserve water across the Colorado River Basin by rethinking funding priorities.
“In some areas in Nevada there has been tremendous investment in the urban side and efficiency gains in the urban side. But if you’re looking at the lowest dollar per acre feet, water-intensive crops are the areas we want to target,” Nemati said.
“There are areas in the Upper Basin that could save water for a fraction of money being used in Nevada or southern California,” he said.
Nevada Current is part of States Newsroom, a nonprofit news network supported by grants and a coalition of donors as a 501c(3) public charity. Nevada Current maintains editorial independence. Contact Editor Hugh Jackson for questions: info@nevadacurrent.com.
