A 2007 deal creating guidelines governing how Lake Powell and Lake Mead are operated in coordination isn’t scheduled to expire until 2026. But water officials in Colorado River Basin states are already beginning to talk about the renegotiations that will be undertaken to decide what succeeds the 2007 criteria.
“I think the guidelines have been a big success,” John Entsminger, general manager of the Southern Nevada Water Authority, said Wednesday during the 10th annual Upper Colorado River Basin Water Forum. The forum is put on by Colorado Mesa University’s Ruth Powell Hutchins Water Center and this year is taking place online due to the pandemic.
The 2007 criteria dictate how much water must be released each year from Powell into Mead, in an effort to equalize water levels in the two reservoirs. The criteria are important to Colorado and other states in the Upper Colorado River Basin because those states rely on Powell water storage for meeting long-term delivery obligations to downstream states based on a 1922 interstate compact.
Amy Haas, executive director of the Upper Colorado River Commission, which represents Upper Basin states, said she thinks the 2007 guidelines have reduced the “safe yield” of water for the Upper Basin. Even with low inflows into Powell, the guidelines resulted in releases of 9 million acre-feet a year of water from Powell every year from 2015-19, compared to the 8.3 million acre-feet negotiated average minimum objective, she said.
Entsminger called that a simplistic analysis that cherry-picks data. He says his entity’s modeling indicates that under the 2007 criteria there is more water in Powell and less in Mead than otherwise would have been the case.
Tom Buschatzke, director of the Arizona Department of Water Resources, said that with the guidelines in places, Powell water levels largely have remained around 50% of capacity “through some horrendously dry years” and only three or four years of above-average inflows.
The criteria encourage water conservation and provide rules for determining water shortages and reducing water use by Arizona and Nevada.
Entsminger said the 2007 agreement increased cooperation and communication among states in the river basin, provided certainty by operating the two reservoirs together, and headed off litigation only two years after states were close to going to the Supreme Court over river water issues.
The criteria were implemented after long-term drought gripped the Southwest starting just after the beginning of the new millennium. Despite some wetter years, that drought continues to this day. Haas said the level of Powell has fallen 20 feet in elevation over the past year, and diminished flows only accelerate the risk of curtailment of water uses by Upper Colorado Basin states if they can’t meet downstream compact obligations.
Those states are evaluating the possibility of demand management measures to temporarily curtail agricultural, municipal and other use during droughts. The goal is to bolster Powell levels with water that could be reserved for compact delivery obligations. But Haas said it’s important to assess the risk of curtailment of Upper Basin uses occurring as well. Such a curtailment has never happened.
Haas said she has heard demand management described as an insurance policy against curtailment.
“I don’t think it would be prudent to take out insurance without also assessing the risk,” she said.
Steve Wolff, administrator of the Wyoming Interstate Streams Division, also thinks it’s important to consider the possibility of curtailment occurring. For him and others in Wyoming, the concern is what curtailment would mean in that state.
“The possibility (of curtailment) is there. We don’t know how it will be implemented if it ever had to be,” he said.
The CMU forum continues today starting at 9 a.m. Registration is still possible online. For more information, visit www.coloradomesa.edu/water-center/forum/index.html.