Click the link to read the report on the UCLA website (Noah Garrison, Lauren Stack, Jessica McKay, and Mark Gold). Here’s the executive summary:

The impacts of climate change and prolonged drought on water scarcity in the Western United States have accelerated since the end of the 20th century. The Colorado River has been strained by a history of excessive withdrawals and long-term drought. Increasingly less water is available across the seven Colorado River Basin states—Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming—for natural ecosystems and the 40 million people that rely, in part or in whole, on its diverted flows to cities and farms. Faced with this challenge, the importance of recycled water at a large scale has never been greater. Water recycling of treated municipal wastewater is a cost-effective source of reliable, sustainable water supply; people shower, flush toilets, and wash clothes and dishes on a regular basis even in times of fluctuating water availability, and these waste flows go to publicly owned treatment works (POTWs) in urban areas.

To assess the current state of water recycling across the Colorado River Basin and its affected states, UCLA Institute of the Environment and Sustainability, in partnership with Natural Resources Defense Council, has investigated water recycling progress and policy development across the seven states in the basin. We analyzed the amount of water entering municipal wastewater treatment plants treating an average of greater than 1 million gallons per day across the 2022 calendar year, the amount these plants reclaim or reuse, and the amount they discharge back into the environment. Our analysis demonstrates that while individual treatment facilities, cities, or even regions may be making substantial progress toward water sustainability, most basin states are falling well short of their potential to reuse wastewater. Overall, the Colorado River Basin states are missing opportunities to ensure a safe, sustainable, climate-resilient supply of water in a hotter, drier future.

While across the Colorado River Basin, an average of 26% of municipal wastewater from POTWs was recycled, there are striking differences between states that are prioritizing reuse and those that are falling behind. Arizona (reusing 52% of treated wastewater) and Nevada (as much as 85%) deserve accolades for their efforts to develop the recycled water supply. California, which produces by far the largest volume of wastewater, only recycled 22% of its treated wastewater in 2022. Of the remaining four states, New Mexico recycles a similarly modest 18%, and Colorado (3.6%), Utah (less than 1%), and Wyoming (3.4%), for a variety of state-specific reasons, have made little to no progress to date on reusing meaningful volumes of treated wastewater. Further and distinct breaks appear to exist between efforts and progress made by states in the lower Colorado River Basin (Arizona, California, and Nevada) and those of the upper basin (Colorado, New Mexico, Utah, and Wyoming). In 2022, the upper basin states as a whole recycled less than 5% of their assessed influent, as compared to more than 30% for the lower basin. (See Figure EX-1 for state-by-state results of our analysis.)

In addition to the lack of progress on wastewater reuse, the overall lack of data on wastewater recycling, including volume, level of treatment, and end use of the recycled water is also glaring. California maintains the most comprehensive database of recycled water, including its end uses, through the California Open Data Portal (see SWRCB, 2022). While we were able to gather data directly from individual wastewater treatment facilities in other states, determining how much water is being recycled was a significant challenge, and determining how much recycled water is ultimately directed to municipal, agricultural, or industrial users was often limited to qualitative description, if information was available at all.

All of the state results have been achieved in the absence of strong federal recycled water policy or any federal regulation. The lack of federal support for or consistency among state programs has hampered efforts and stands as a significant impediment to further growth of recycled water use. Promoting consistent and growing national water reuse will require action at both the federal and state level.

To this end, through our investigation we have developed a set of recommendations for the U.S. Environmental Protection Agency (EPA) and other federal and state partners and stakeholders. Additional detail and guidance for these recommendations is presented in the main report body and conclusions. These recommendations include the following:

Within two years, EPA, working with state partners, water agencies, and nongovernmental organizations, should develop a model state program and ordinance for recycling of municipal wastewater with minimum elements.

• EPA should improve data acquisition and management, including developing guidance for standardized facility-level reporting and state data sharing, to ensure availability of information and comparability of data between states.
• EPA should further develop and disseminate the latest science and technical information on treatment processes and pathogen risk assessment for different sources of water and reuse applications.
• In partnership with the states, EPA should develop wastewater reuse goals and timelines.
• EPA—working with other federal agencies including the Bureau of Reclamation and the Departments of Agriculture, Energy, and Defense—should develop and implement funding strategies beyond those already in existence, including furthering the Pilot Program for Alternative Water Source grants.

In addition, our analysis uncovered that, across the Colorado Basin states, inconsistency between programs and overall lack of state-level oversight or even awareness of wastewater recycling efforts in several states is alarming. Recommended improvements needed at the state level for those states without these programs include:

• Work with local water reclamation or reuse agencies to develop funding strategies to meet targets for 30%, 40%, or 50% goals.
• Work with EPA to establish numeric targets for wastewater reuse for each state, with timelines and interim goals. Figure EX-2 provides a breakdown of the total water supply that would be made available for each state with targeted goals of 30%, 40% or 50% reuse by 2040, a number already exceeded by two of the basin states.
• Improve data acquisition and management, as well as reporting requirements where applicable, for wastewater treatment facilities and wastewater reuse operations.
• Conduct assessments of current state legal and regulatory requirements to identify barriers to wastewater reuse and develop formal state policies for overcoming those barriers.

Overall, substantial action needs to be taken to achieve sustainable water management across the Colorado River Basin. Better use of climate modeling, water pricing that does not encourage waste and unreasonable use, stronger water conservation and efficiency programs and requirements for agricultural and urban users, enhanced stormwater capture, greater and longer-term cutbacks in Colorado River water withdrawals, and, critically, a substantial increase in water reuse all must be embraced as climate resiliency solutions.

As shown in Figure EX-2, if the Colorado Basin states other than Arizona and Nevada were to increase wastewater reuse to even 40% of treated influent it could increase current recycled water availability by nearly 900,000 acre-feet per year (AFY) over current efforts. Reuse of 50% of influent would increase water availability by nearly 1.3 million AFY. This represent a significant percentage of the projected shortfall on the Colorado River, and a rsolution that should be pursued aggressively to ensure sustainable management of the river.