(Editor’s note: This analysis is appearing this week in both ADWR’s Arizona Water News and CAP’s Know Your Water News.)

At this time last year, conditions in the Colorado River Basin were dire. We knew we were heading into the first Tier 2a shortage for 2023. But we also knew that more needed to be done to stabilize the critical levels of the Basin’s two main reservoirs – Lake Powell (held back by Glen Canyon Dam) and Lake Mead (held back by Hoover Dam). Lake Powell was set to release the lowest volume since filling and Mead was anticipated to head into a Tier 3 shortage or greater in 2024. The Bureau of Reclamation (Reclamation) was considering additional protection measures as part of a Supplemental Environmental Impact Statement (SEIS) that would modify Powell and Mead operations.

So, what happened this year – and where are we headed for 2024 and beyond?

2023: Mother Nature and the Lower Basin States step up

The Basin experienced excellent snowpack last winter and above average runoff in 2023.  That helped forestall an immediate crisis, but more actions were necessary.  In April, Reclamation released the Draft SEIS, with action alternatives that were unacceptable to the Lower Basin States. In May, Arizona, California and Nevada announced a consensus proposal to conserve historic volumes of Colorado River water in Lake Mead. With this proposal in hand, Reclamation withdrew its Draft SEIS and in October released the revised Draft SEIS with the Lower Basin States’ consensus proposal designated as an Action Alternative. We anticipate a final decision in spring 2024.

Historic conservation in Arizona

Arizona has already made significant progress toward the Lower Basin States proposal, conserving those historic volumes of water in Lake Mead. In 2023, we’ve conserved nearly 950,000 acre-feet, including our mandatory 592,000 Tier 2a shortage reduction, plus an additional voluntary contribution of more than 356,000 acre-feet. A big thank you to our 2023 conservation champions.

2024: A return to Tier 1 shortage

The combination of favorable basin-wide hydrology and conservation efforts across the Lower Basin have improved the reservoir contents to the point that in August, Reclamation announced a Tier 1 shortage reduction for 2024 and not the Tier 3 or greater reduction that was anticipated earlier in the year.  This still requires a heavy lift from Arizona with a 512,000 acre-foot reduction, just 80,000 acre-feet less than the Tier 2a shortage reduction we’ve taken this year. This represents about 30% of CAP’s normal supply; about 18% of Arizona’s Colorado River supply; and just under 8% of Arizona’s total water use.

Looking toward the future

The 2007 Shortage-Sharing Guidelines and the Drought Contingency Plans expire in 2026. The good hydrology and additional voluntary conservation in the Lower Colorado River Basin have resulted in a relatively stable Colorado River Basin system in the short-term, giving the Basin states and Mexico a bit of breathing room to negotiate the next set of guidelines that will go into effect post-2026.

In June of this year, Reclamation formally announced its intent to prepare an Environmental Impact Statement (EIS) for post-2026 operations and solicited public comments on the scope of specific operational guidelines, strategies and related issues. In October, Reclamation released its post-2026 Scoping Report, which summarized the more than 24,000 comments received and identified its anticipated purpose, need and proposed federal action.

Arizona has been working with the lower basin states to come up with concepts that would lead to a sustainable River system. The Lower Basin’s stated primary objectives are to:

• Improve the sustainability of the Colorado River over a broad, but plausible range of future conditions
• Increase the predictability of reductions
• Address the structural deficit by sharing reductions among the Lower Basin states and Mexico
• Share the risks and benefits of the system equitably within and between the basins

At the Arizona Reconsultation Committee meeting on November 2023, a new system contents approach was presented, basing shortage reductions on the volume of water available within Lake Mead, Lake Powell and the other major reservoirs in the system (Blue Mesa, Flaming Gorge, Havasu, Mohave and Navajo).

Unlike the current approach, which is based on the elevations of only Lake Powell and Lake Mead, the new dynamic approach is based on water available in all major reservoirs in the Colorado River system. This approach helps provide a clearer picture of the health of the system, as well as achieve supply demand balance by triggering reductions based on the health of the system. To provide as much certainty as possible to water users, and with the understanding that drier futures are likely, the intent is to keep the reservoir contents in a range that ensures a less variable reduction volume. Of course, the primary goal is to avoid crashing the system with this approach.

We anticipate that other alternatives will be put forward and that Reclamation will issue a draft EIS in late 2024 with a comment period to follow.

This summary should catch you up as we look forward to the new year. Please stay tuned to the River Updates section of Know Your Water News for updates in 2024 and beyond!