Two years ago, the Colorado River Lower Basin states united to conserve an extra 3 million acre-feet of water by 2026, aiming to stabilize Lake Powell and Lake Mead while crafting the post-2026 guidelines for managing the river. With last year’s near-normal snowpack and conservation efforts ahead of schedule, success seemed within reach. However, over the last few months, this year has become anything but normal, and the system is looking to be anything but stabilized.
At Metropolitan’s Imported Water Subcommittee, Laura Lamdin, Senior Engineer and interim team manager for the Colorado River, briefed subcommittee members on the challenging situation.
Rapidly deteriorating hydrologic conditions on the Colorado River
At a kickoff meeting for USBR’s annual operating plan process for 2026 operations, as well as the June 24-month study for Colorado river conditions, the news was that the forecasted inflow to Lake Powell had dropped 2.6 million acre-feet between the January and June forecasts. That is more than Arizona and Nevada used last year and represents 40 feet at Lake Powell, almost an entire operating tier in Lake Powell. So what happened?
There is a stark difference between the hydrology in California and the Upper Colorado River watershed. In California, nearly all precipitation occurs in the first half of the water year, primarily during the winter, as shown on the left. It builds as snowpack, and then it melts off; by that time, no more precipitation is expected for the remainder of the water year.
On the Colorado River, on the other hand, as shown on the right, the blue bars indicate precipitation throughout the year. Only a little over half of the water year precipitation happens in the first half of the water year.
That difference has implications for that runoff efficiency relationship.
What happens is that spring precipitation ends up playing a bigger factor in runoff efficiency than it does in California. Increased instances of dry and hot springs are part of the explanation for the significant reduction in runoff efficiency in the Colorado River Basin.
2020 to 2022 was a three-year critical dry period, and the system pulled about 10 million acre-feet from storage to meet demands. The blue line represents the combined contents of Mead and Powell, as well as the decline in storage. 2023 was a wetter year, and there was some recovery. The Lower Basin came together and developed a plan to conserve an additional 3 million acre-feet, which effectively stabilized the levels of both reservoirs.
The snowpack peaked at 93% of average at the end of March. A storm came through in early April, resulting in a second peak in the first week of April, which was a good sign.
However, it was not enough because it was a hot and dry spring. Precipitation in the spring has been between 60 and 70% of average; temperatures have been about a degree Fahrenheit more than normal.
“When I say normal, in this case, I’m referring to the average between 1991 and 2020, and so to the degree that that 30-year period is warmer and drier than average, this spring has been even warmer and drier than that. You can see that impact in the runoff: In April, it was projected to be 67% May, 55%, and by June, down to 45%.”
This will impact system storage. The graph shows Lake Powell’s elevation. The solid blue line represents historical numbers, while the dashed blue line indicates forecasted conditions under the most probable or average conditions. The dark orange line is the minimum probable, or 10th percentile dry conditions.
Ms. Lamdin noted that the difference between average and dry conditions is quite significant; some might see that as concerning, but it’s actually pretty normal. The inflow into Lake Powell is a result of natural hydrology, which is highly variable, so she said that’s what’s really driving the two apart.
She pointed out that what is more concerning is that even under average dry conditions, Lake Powell isn’t seeing its annual boost. “Normally, this is the runoff season. This is when Lake Powell levels rise, and then you draw from storage throughout the year. However, even under dry conditions, Lake Powell is not expected to rise this year, and if conditions remain dry, it’s expected to decline in 2026. By the end of 2026, the forecast is showing Lake Powell around 3490 and then declining even further to 3474 by the end spring of 2027.“
“3474 is lower than Powell’s been since its initial filling,“ she continued. “It is lower than it was in 2022 when USBR took emergency action to protect Glen Canyon Dam infrastructure. It’s lower than 3,500, which is the target elevation that Reclamation would like to keep Lake Powell above, and it’s below 3,490, which is the minimum power pool. That means that when the lake level declines below that threshold, power production at Glen Canyon Dam would cease. And all of that would be happening if conditions remain dry right when we would be looking to be operating under a new set of guidelines.”
Similar circumstances exist for Lake Mead. Under both average and dry conditions, Lake Mead is projected to decline over the next couple of years. The difference between average and dry conditions is much smaller because what is released from Lake Powell into Lake Mead is governed by a rule curve, which has significantly less variability than natural hydrology.
“The real concerning part is if dry condition conditions continue, that Lake Mead would go down to elevation 1030 by early 2027,“ said Ms. Lamdin. “Elevation 1030 is below a new critical elevation at Lake Mead of 1035. 1035 is when USBR has concerns that cavitation may occur in the normal hydro turbines. They have normal turbines and low-head turbines; the low-head ones would be fine, but they have concerns about cavitation in the regular turbines. Below an elevation of 1035, they plan to cease operating those turbines. That represents about 40% of the power capacity at Hoover, so if it does get to those low levels, there would be a significant impact to our power resources.“
In addition, if 2026 is dry, Reclamation could take actions, such as releasing water from upstream reservoirs to boost levels at Lake Powell. They could also reduce releases from 7.48 million acre-feet to 7 million acre-feet, but less water released from Lake Powell would drive Lake Mead even lower. Reclamation has the authority to reduce releases from Lake Powell to as low as 6 million acre-feet.
If 2026 turns out to be dry, significant reductions would be needed – more than the 1.5 MAF that the Lower Basin has proposed. “So it is a possibility that we could see expectations of cuts in the lower basin above 1.5 million acre-feet, right off the bat, in 2027, which makes the discussions that we need to have throughout the basin over the next year just that much more complicated.“
Negotiations for post-2026 operating guidelines are ongoing
Bill Hasencamp, Manager of Colorado River Resources for Metropolitan, then updated the subcommittee on the ongoing negotiations on the post-2026 guidelines.
The Colorado River Board held a meeting last week with all the California agencies that depend on the Colorado River, including the Palo Verde Irrigation District, Imperial Irrigation District, Coachella Valley Water District, Bard Water District, the Quechan Tribe, Metropolitan and San Diego County Water Authority. The purpose of the meeting was to initiate a discussion on how shortages would be allocated, although the initial plan assumed a shortage of 440,000.
“However, we might need more than that right off the bat,“ said Mr. Hasencamp. “That’s something that the states are coming to grips with, the possibility that we may have to do a lot more in 18 months than we have been planning on.”
The goal is to have a framework agreement by the end of the year regarding how shortages would be shared, which would be ready by the time Reclamation’s draft EIS is released, expected to be around mid-December, coinciding with the Colorado River Users Association’s annual conference.
At the meeting, the Colorado River Board went over three types of options for the group to discuss:
- One was a strict law of the river, where, like the QSA, Metropolitan takes all the shortage and then implements additional ag programs to share the pain, as well as Metropolitan itself making significant cuts.
- Another approach is to divide the shortage equally between agricultural and urban areas, leaving Metropolitan and San Diego to decide how to allocate their portion while agricultural agencies determine the distribution of theirs.
- The third option would be based on recent water use history, along with conservation credits. Each agency would have a share.
“No agency liked any of those proposals,“ said Mr. Hasencamp. “Not a surprise because they weren’t meant to be proposals. They are meant to get the discussion and dialog going.“
Mr. Hasencamp noted that this would be a voluntary agreement, not a strict shortage provision. He also said they are in negotiations with the Upper Basin that would set aside the Upper Basin’s delivery obligation under the Compact and negotiate some other release arrangement. They are also negotiating with Arizona, where they would set aside Arizona’s junior priority and negotiate an agreement outside of that. Likewise, in California, Metropolitan is the junior priority; however, they are setting that aside and working out an arrangement where every entity would have some commitment to Lake Mead.
Mr. Hasencamp concluded by noting that agencies will be meeting regularly over the next several months. Once firm proposals are received, they will be shared with the subcommittee for input and feedback.
Director Karl Seckel noted the recent media reports of a plan based on the new hydrology. Is there any reality to that?
“It has been discussed in public meetings that Scott Cameron said that the alternatives report that came out earlier this year is no longer in effect, although some of the alternatives will continue,“ Mr. Hasencamp said. “But they do want to develop a new alternative, and one of the alternatives that they are pursuing is a natural inflow-based alternative, which says, if the basin is drier, then both basins share the risks equally in some percentage, proportionally or equally, or however it’s done. But there’s a risk that both basins face if it’s drier, and if it’s not as dry, then both basins benefit.”
The Compact is pretty hard on the Upper Basin facing the risks of climate change,“ he said. “This shifts the risks of climate change to both basins in a way that gets each basin out of each other’s business. We still have a long way to go to reach agreement on what that release would be, and those discussions will continue, but the draft EIS will, what we’re told, have a range of different releases, so at least the alternative with the range will be included and a final agreement could be crafted from that. Generally, what they said is the EIS will come out with alternatives that probably people don’t like, but there’ll be recipes to build an agreed alternative that people do like.“
“We did learn things in the QSA,“ Mr. Hasencamp said. “A hard transfer with a fixed volume probably isn’t the best way. The PVID program turned out really well because we could ramp it up and down as needed, depending on whether we needed water or not. So I envision that this California agreement will have some flexibility that, maybe in a year when there are wet conditions in Northern California, and we have extra State Water Project water, maybe we cover the lion’s share of California’s contributions in those conditions. Then, in dry years, when we need every drop we can, the ag agencies step up, and they cover more. So we’re going to need to be creative and flexible. Having just a hard number for each agency is probably not the best path forward, based on our experience.”
