Final EIS advances adaptive Colorado River framework, but uncertainty remains
Conditions on the Colorado River continue to deteriorate. Last month, Lake Mead dropped to its lowest level since it was first filled, and last week Lake Powell reached a record low of its own. Both reservoirs are still falling. Against this backdrop, the Bureau of Reclamation recently released the final environmental impact statement for Colorado River operations from 2027 through 2036. At Metropolitan’s August One Water and Adaptation Committee meeting, Shanti Rosset, Colorado River Policy Manager, briefed committee members on the final EIS for post-2026 operations, outlining what it decides, what it means for Metropolitan’s water supply, and what questions remain unresolved.
AN ADAPTIVE FRAMEWORK
On July 31, the Bureau of Reclamation released the final environmental impact statement for post-2026 operations. The FEIS identifies the 10-year framework as the preferred alternative and organizes it into three nested layers:
- The outer layer is the 10-year framework for 2027 through 2036. It sets the principles and sideboards that will not change year to year, including protections for Glen Canyon Dam infrastructure and the minimum and maximum annual releases from Lake Powell.
- The middle layer consists of two-year operating guidelines, beginning with 2027-28. These guidelines make the decisions that move water, including Lake Powell releases, how Lower Basin shortages are shared, and ICS deliveries. They would be negotiated and adopted every two years within the 10-year framework.
- The innermost layer is the annual operating plan, which applies the Lake Powell and Lake Mead operating guidelines each year.
The key point is that the outer layer is durable, while the middle layer—the guidelines that determine deliveries—is renegotiated every two years. Ms. Rosset said this outcome is a departure from the seven basin states’ 2023 goal of developing a single, durable operating plan for the next 20 or 30 years, based on consensus among all states.
“Reclamation’s preferred alternative is an adaptive framework, reopened on a two-year cycle through 2036, with the door left open for a longer-term consensus agreement to be folded in if the states reach one,” she said. “Near-continuous negotiation is now the operating reality on the river, and it’s what our team is preparing for.”
PLANNING FOR THE COMING YEAR
The 10-year framework establishes the outer limits for how Reclamation can operate the system. Lake Powell releases may range from 5 million to 12 million acre-feet; Lower Basin shortages may reach up to 3 million acre-feet; and the system may store up to 3 million acre-feet of conserved water in Lake Powell and 8 million acre-feet in Lake Mead. Ms. Rosset emphasized that these figures define the range of possible federal action, not what will necessarily happen in 2027.
The Lower Basin states have tentatively agreed to 1.25 million acre-feet of reductions, including 440,000 acre-feet from California, pending Board approval of the Lower Basin implementation agreements.
Because Lake Mead and Lake Powell are both at record lows, the states will enter the new framework with very low initial conditions. For water year 2027, Ms. Rosset estimated that the Lake Powell release will likely be in the 6 million to 7 million acre-foot range, with the final determination made in the spring based on the runoff forecast. Lake Mead is also expected to decline further in 2027, even with 1.25 million acre-feet of Lower Basin reductions and additional voluntary conservation.
She cautioned that the numbers remain preliminary. “All of these figures are subject to the spring forecast, to the August 24-month study, and to the guidelines that aren’t yet final,” said Ms. Rosset. “So please hold them as current best estimates, but not as numbers that have been settled.”
ACCESS TO ICS SUPPLIES
The new guidelines would change access to intentionally created surplus (ICS) supplies. Under the current rules, no ICS can be withdrawn if Lake Mead is at or below 1,025 feet on January 1. The new guidelines create a conditional delivery window between 1,025 and 1,000 feet, allowing Metropolitan to request ICS delivery after consulting with the Secretary, who may reduce or deny the request. If Lake Mead falls below 1,000 feet, no ICS deliveries may be made.
California may take up to 400,000 acre-feet of ICS in a given year, and the chart below illustrates why that matters. Lake Mead’s observed elevation through July is shown by the solid line. Based on last month’s 24-month study, the projected January 1, 2027, elevation is about 1,037 feet—still above the 1,025-foot threshold—so 2027 ICS deliveries would proceed under normal terms.
If Lake Mead is between 1,025 and 1,000 feet on January 1, 2028, the new rules would provide a process to request ICS delivery where the current guidelines would have prohibited it. Ms. Rosset said the provision was tied to California’s commitment to annual top-priority reductions. “This was negotiated as a contingency for supporting California’s taking 440,000 acre-feet of annual top-priority reductions,” noted Ms. Rosset.
WHAT’S COMING NEXT
Ms. Rosset emphasized that Reclamation’s publication of the FEIS finalized the environmental analysis, but it did not constitute a final decision. The record of decision, or ROD, and the accompanying 2027-28 operating guidelines have not yet been signed.
The ROD and 2027-28 guidelines are expected later this week or next week and are needed to set Lake Powell operations for the water year that begins October 1. The current guidelines and related agreements expire for Lake Powell on September 30, so new rules must be in place by October 1.
Reclamation is also expected to release the August 24-month study this week. That study will carry into the new guidelines and help set the 2027 annual operating plan. It will include 1.25 million acre-feet of Lower Basin reductions and the recently finalized system conservation implementation agreements executed in the Lower Basin.
Ms. Rosset noted that the FEIS still leaves several issues unresolved. There is no seven-state consensus, and the FEIS deliberately avoids interpreting the Colorado River Compact amid competing Upper and Lower Basin views. Three implementing agreements also remain unfinished: the Lower Basin agreement covering 1.25 million acre-feet of reductions and additional voluntary conservation; the Upper Initial Unit agreement between the United States and the Upper Division states; and the successor to Treaty Minute 323, which is being negotiated through a separate binational process.
IN SUMMARY
Ms. Rosset then closed with three takeaways. “First, the framework is adaptive, not fixed; it institutionalizes near-continuous negotiation with guidelines that would be reissued about every two years through 2036. Second, our near-term deliveries are constrained on volume, but this is the point I’d like to underline: the new rules make our ICS more deliverable at low elevations, not less. Third, the decisions that affect us most—the record of decision, the 2027-28 guidelines, and the three agreements that may be incorporated into the guidelines—are still being finalized.”
UNCERTAINTY PERSISTS
Vice Chair Nancy Sutley asked what could differ in the ROD, given that the FEIS is complete and a preferred alternative has been identified.
“I don’t know what is in the ROD,” said Ms. Rosset. “We are very nervous about what’s not in the ROD or in the ROD. They have not shared a draft with the basin states, so it creates a lot of uncertainty. We’ll have to wait until the public release to know what is and isn’t in the ROD.”
“Where’s the room for difference from what they identified as a preferred alternative in the FEIS?” asked Vice Chair Sutley.
“The concerns that we have are with the particulars of how they write up various parts of the operations,” said Ms. Rosset. “For example, we haven’t seen the successor to Treaty Minute 323, and we’re being assured that yes, Mexico has agreed in principle to share reductions in parity with the domestic reductions. But until we actually see how it’s written, there’s a lot of uncertainty about what that actually means, and so there are a lot of operational pieces. There are also many ways they interpreted—or didn’t interpret—the Law of the River. That’s very concerning to us, not just Metropolitan, but throughout the basin … with the ROD, there’s a lot of mystery.”
“Yeah, it just seems like the more it deviates from the FEIS, the more room for mischief,” said Vice Chair Sutley.
