At the March meeting of Metropolitan’s One Water and Stewardship Committee, staff updated the committee on the Reclamation’s release of the final SEIS for the interim Colorado River operating guidelines and the Lower Colorado River Basin’s alternative for post-2026 operations.
Reclamation releases final Supplemental Environmental Impact Statement for Colorado River operations up to 2026
On March 5, the Bureau of Reclamation released a final Supplemental Environmental Impact Statement (SEIS) to update the current interim operating guidelines through the end of 2026, when they expire. Engineer Laura Lamdin provided an update on the document and the preferred alternative.
In the summer of 2022, Lake Powell, Lake Mead, and Lake Oroville were all at their lowest level ever, and new short-term rules for the Colorado River were needed. Reclamation gave the states time to come up with a consensus alternative. The three lower basin states submitted a proposal, which was selected as the preferred alternative in the Final SEIS, released last week.
The lower basin proposal was built off an October 2022 letter from the Colorado River Board of California, which called for 400,000 acre-feet of conservation for four years for a total of 1.6 million acre-feet. With Arizona and Nevada joining in, the lower basin offered 3 million acre-feet of system conservation over the four years.
The alternative assumed that at least 1.5 million acre-feet would be conserved by the end of 2024, and the numbers show that in 2023, the Lower Basin states conserved 1.1 MAF. California’s obligation under the proposal was to conserve 400,000 acre-feet per year, and in 2023, California conserved 700,000 acre-feet, well above the target. The alternative assumed that Metropolitan would add 216,000 acre-feet to ICS supplies at Lake Mead; the preliminary numbers show 450,000 acre-feet was added to the ICS.
“So the lower basin, California, and Metropolitan are all meeting and exceeding the expectations in the preferred alternative and the lower basin proposal,” said Ms. Lamdin.
However, she pointed out that the work is not yet done. “While the lower basin proposal was selected as the preferred alternative, it will not actually be adopted until a record of decision is issued later this year. Additionally, we have three more years of implementation to go, so we will need to continue implementing the existing system conservation projects and pursue new ones. And sometime in the next month or two, I plan to be back before you with some of those new projects.”
Lower Basin States submit proposal for post-2026 Colorado River reservoir operation guidelines and strategies
With the interim guidelines set to expire in 2026, attention now turns to the post-2026 guidelines, which will include provisions for lower basin water use, coordinated operations of Lake Powell and Lake Mead, and provide for storage and delivery of conserved water.
On March 6, the Lower Basin States jointly submitted a proposed alternative to Reclamation; the Upper Basin States have submitted their own alternative. Shanti Rosset, Colorado River Program Manager, updated the committee on the lower basin’s proposal and the difference between the two proposals.
Ms. Rosset said the seven basin states have made efforts to collaborate, meeting frequently since the Interior Department initiated the process to develop the post-2026 operational guidelines in June of last year, but they could not reach a consensus. Last week, even though both the upper basin and lower basin states submitted their own alternatives, the basin states have reiterated their commitment to work together.
“There are significant differences between the two,” said Ms. Rosset. “This means that reaching a consensus will be challenging, but it is in the state’s interest to do so. Agreement reduces risks of litigation resulting uncertainty and improves the likelihood that Reclamation will select the state’s alternative as the preferred alternative.”
The lower basin alternative is designed to address the impacts of drought and climate change by addressing evaporative and system losses in the lower basin, known as the structural deficit. The lower basin alternative shifts away from reliance on forecasts and elevations in Lake Powell and Lake Mead to determine reservoir releases and lower basin shortages; instead, sustainable management must focus on the contents available in the system as a whole. The total system contents include Flaming Gorge, Blue Mesa, Navajo, and Lake Powell in the upper basin and Mojave, Havasu, and Lake Mead in the lower basin.
The lower basin alternative proposes a new framework for determining annual water use reductions based on total system contents. The upper basin would not take a reduction until system contents fall below 38% or lower. The lower basin alternative also would alter the schedule and amount of releases from Lake Powell to Lake Mead.
“This approach commits to the simple principle that when less water is available in the system, less water should be taken from the system,” said Ms. Rosset. “It resolves the structural deficit between Lee’s Ferry and the US-Mexico border. It reduces the risk of the system declining to critical levels. It shares water use reductions broadly. It improves predictability for water users and includes the upper basin and water use reductions under most critical system conditions.”
The lower basin alternative includes the assumption that Mexico is participating in the program, which has not yet been determined and will be a separate process. However, to provide sufficient information for analysis of a full range of impacts within the US, changes and flows associated with Mexico’s potential participation needed to be analyzed.
The lower basin alternative proposes a new program to allow the storage of water for future delivery or to meet reduction requirements of between 5 and 10 MAF. Allowing agencies to store water provides flexibility in managing reductions and allows water conserved in wet years to be available to meet dry-year reductions.
When total system contents reach 58% full, then the Lower Basin and Mexico share the 1.5 MAF Static Reduction in the volumes shown in the table. “Arizona’s share of the static reduction represents 27% of that state’s apportionment,” said Ms. Rosset. “California’s share is 10% of the state’s apportionment, and Nevada and Mexico both share 16.7%. This approach shares reductions broadly while honoring the spirit of California’s senior rights.”
As for the differences between the upper basin and lower basin proposals, Ms. Rosset said the upper division states’ alternative emphasizes refilling storage on Lake Powell. “The upper division states alternative assumes water use reductions only in the lower basin,” she said. “It doesn’t include any provisions on the storage or delivery of stored water, and it is silent on Mexico both on the upper basins half of the Mexico treaty obligation and Mexico’s participation in the reductions and surpluses. We anticipate that other alternatives may be submitted by Tribes, NGOs, and other stakeholders as well.”
Ms. Rosset closed by noting that Reclamation plans to have a draft EIS in December. The states will work towards consensus and to further refine alternatives.
Discussion
During the discussion period, Director Russell Lefevre asked how the upper basin reservoirs could be part of the plan if the upper basin itself is not involved.
Ms. Rosset replied that the Bureau of Reclamation’s scoping report explicitly said it would consider a shift to system contents. “So they have provided in the document that they’re permitted to include that potentially and the federal action. And it was the view collectively of the lower basin that shifting to include the upper basin initial units for the Colorado River storage project and treating the system more holistically made sense.”
Director Lefevre asked what the most significant point of contention between the upper and lower basins is.
“The upper basin is very focused on refilling storage at Lake Powell,” said Ms. Rosset. “That is the primary goal stated in the alternative they submitted. Secondarily, they’re also very focused on lower basin uses. And from the perspective of the lower basin, the silence on the Mexico treaty obligation, which is 1.5 million acre-feet under normal conditions, stands out. And it is something that will have to be included in the operations of the reservoirs. And they don’t make any provisions for it.”
Ms. Rosset acknowledged that at this stage, the alternatives don’t include all the details of what would be in a final Record of Decision. “However, there have been public statements about the view that the upper basin share of the Mexico treaty obligation isn’t triggered unless there are very particular circumstances. They say those circumstances may not exist because tributary use in Arizona isn’t accounted for. So this silence speaks volumes in that it’s signaling this unwillingness to accept that they have an obligation, which is very clear in the compact, for half of the Mexico treaty obligation.”
