Previous Article
Next Article

Your authoritative, multi-channel network for natural resources and environmental information since 1989 – by practioners for practitioners.

Line Spacing+- AFont Size+- Print This Article Back To Homepage

Lower Colorado River Basin Water Agencies Reach Agreement on 500+ Plan as Drought Response Efforts Continue

Related Articles

By Wesley A. Miliband and Kristopher T. Strouse

At the December 15, 2021 Colorado River Water Users Association conference held in Las Vegas, Nevada, water agencies from across Lower Colorado River Basin states came together with the U.S. Bureau of Reclamation to craft a plan for conserving water resources in the Southwest. The result was an agreement between the Bureau of Reclamation (Bureau) and several major water agencies from California, Nevada, and Arizona that proposes voluntary water reductions in order to keep the water level of Lake Mead from continuing its freefall. This agreement comes at a time when urgency to negotiate new rules for managing the waning watershed, which serves more than 40 million people, is at its height, as current guidelines and an overlapping drought plan are set to expire in 2026.

The Setting

The two largest reservoirs in the Colorado River system, Lake Mead and Lake Powell, are well below their halfway point for water elevations. Looking at the two reservoirs together, the Bureau of Reclamation’s Lower Colorado Water Supply Report from December shows that they sit at about 34 and 28 percent of their storage capacities, respectively, so low that the federal government declared the first ever water shortage on the river in the early summer of 2021, triggering cutbacks in Arizona and Nevada. Further stressing the dire nature of the situation, forecasts released at the conference show Lake Mead’s water levels continuing to drop if no further action is taken.

The Plan

Enter the 500+ Plan. In addition to the Bureau of Reclamation, the water agencies taking part in the 500+ Plan include the Southern Nevada Water Authority, Arizona Department of Water Resources, Central Arizona Project, and Southern California’s Metropolitan Water District. Coming in the form of a Memorandum of Understanding signed during the Colorado River Water Users Association’s annual conference, the water agencies involved agreed to work together to keep an additional 500,000 acre-feet of water in Lake Mead over the next two years (through 2023). The additional water saved by the plan, a half-a-million acre-feet, would be enough water to serve about 1.5 million households a year and would add about 16 feet total to the reservoir’s level, which saw record low levels this past summer.

On top of the water savings discussed in the 500+ Plan, the MOU also calls for financial investment from parties involved—$40 million from the Arizona Department of Water Resources, and $20 million each from the Southern Nevada Water Authority, Metropolitan Water District, and the Central Arizona Project, which operates a canal system that delivers Colorado River water in Arizona. The Bureau of Reclamation is also slated to match the funding, for a total of $200 million. This spending is accordingly designed to be used to incentivize farmers, water agencies and tribes to reduce their total water use, freeing up more water for return into the reservoir.

Conclusion and Implications

Agencies throughout the Lower Colorado River Basin have been cooperating for some time now to help curb the effects of the seemingly decades-long drought the basin has experienced. As recently as 2019, for example, the Lower Basin Drought Contingency Plan was crafted and included a provision requiring the three lower-basin states to consult and agree to additional measures to stabilize Lake Mead, at least in the short term. Well the time for consulting came much sooner than anyone had hoped and the 500+ Plan serves as the additional measures contemplated.

The 500+ Plan is also a significant agreement in that it builds on the partnerships of major Colorado River water agencies that began to form while the Drought Contingency Plan was coming together. Now, over the course of the 500+ Plan, and moreover the Drought Contingency Plan and other plans sure to follow, we will be able to witness the efficacy of an interstate drought response fueled by unprecedented emergency. If the desired outcomes of the 500+ Plan can be attained by the 2024 horizon it will surely be a step towards re-establishing stability, even if only a small one, for all who are fueled by the lower Colorado. A link to the 500+ Plan is available online at: