As negotiators for the seven Colorado River Basin states rapidly approach Reclamation’s November deadline for providing a framework for a seven-state agreement for the Post-2026 Operating Guidelines for Lakes Powell and Mead, a larger threat looms. Reclamation’s recently released September 24-Month study minimum probable projection is consistent with our mass balance analysis of storage in the next year, solidifying the likelihood of critical conditions if the coming winter is dry. Reclamation’s latest analysis predicts that storage at Lake Powell would fall below the 3500-ft elevation as early August 2026 and might continue to be below this critical elevation until March 2028. As we noted in our recent white paper, Reclamation has committed to protecting Lake Powell from going below 3500 ft.

This projection of future conditions in the event of persistent dry conditions poses a conundrum—Reclamation could reduce releases from Powell to protect the 3500-ft reservoir elevation, but in doing so, low releases would most likely trigger the dreaded 1922 Colorado River Compact tripwire–the amount of water delivered from Lake Powell to Lake Mead during a 10-year period that is less than the threshold. The Lower Division states are likely to litigate if the 10-yr average wire is tripped. Under one prevailing interpretation of the Compact, Upper Basin states must not cause the 10-yr flow at Lee Ferry to be depleted to less than 82.5 MAF to deliver water to the Lower Basin and Mexico. As explained in a new white paper, there is a very real chance that the 10-yr running average will be 82.78 MAF, just a hair above the tripwire, one year from now. In alternate scenarios, the 10-yr running average would hit the tripwire in 2027 or 2028. If Reclamation exercises its authority to reduce Lake Powell deliveries to as low as 6 MAF, the tripwire is triggered even earlier. In the face of this imminent possibility, Basin States and the Federal Government must commit to an enforceable agreement to reduce their total consumptive Colorado River uses with an equitable sharing of the burden sufficient to justify a waiver of claims under the Compact for the duration of the agreement. The alternative is a deeply uncertain future for the Basin.

Read the full white paper.