What a difference a month makes.
The forecast for how much water will flow this year into Lake Powell, a bellwether reservoir on the Colorado River, was already meager. Now, after a dry April, it’s even more miserly.
That does not bode well for a basin mired in contentious debate about which of the seven states should cut their water use and by how much.
“It provides even more urgency to what was already an urgent situation,” said Anne Castle, former U.S. commissioner and chair of the Upper Colorado River Commission.
On April 1, the traditional end of the snow accumulation period in the American West, the forecast for spring and summer runoff into Lake Powell, on the Arizona-Utah border, was 67 percent of the 30-year average. Not great, but not unusual for the boom-and-bust river.
A month later, the runoff forecast has dropped considerably. In the most probable scenario, it’s now just 55 percent of average. That equals a decrease of 800,000 acre-feet, or roughly two-fifths of the Colorado River water used by Arizona in 2023. If the forecast holds – the average error in the May estimate is 15 percent – it would be one of the lowest runoff totals in the last 35 years.
The runoff decline represents a lot of water, especially in a basin as precariously situated as the Colorado, which is drying due to a warming climate. Lake Mead and Lake Powell, the basin’s two big reservoirs, are each just 33 percent full. Another low runoff year will not help and could signal more severe water-use cutbacks in the coming years.
Cody Moser, a hydrologist with the Colorado River Basin Forecast Center, the federal agency that produces the runoff forecasts, said the runoff decline had several causes. Earlier runoff models overestimated snow high in the mountains. The weather was atypically dry in April. Precipitation in the watershed above Lake Powell was just 60 percent of normal last month.
Soils, which take the first gulp of moisture, are also abnormally parched. Those conditions – dry air and dry soils – decrease the “runoff efficiency,” Moser said. The snowpack was nearly average in late March. But much less of that water is reaching rivers and reservoirs.
Hydrological conditions are starting to mirror the frightful years between 2020 and 2022, when meagre runoff sent the reservoirs into a deep plunge to record lows. That sparked panic among federal water managers in the summer of 2022. Camille Touton, then the commissioner of the Bureau of Reclamation, ordered the basin states to cut water consumption by 2 million to 4 million acre-feet, a gargantuan number.
Luck and money intervened to relieve the pressure. A wet winter in 2023 temporarily pulled the basin out of its tailspin, while up to $4 billion in federal funding for water conservation eased the path to using less.
The basin’s politics today are perhaps even more fraught. The states are in a stalemate as they negotiate new management rules to replace an operating plan that expires at the end of 2026. A centerpiece of that debate is how to share the burden of cutting water use so that demands align with the river’s waning supply.
“We have to provide for seriously dry conditions because all of our efforts so far have not slowed the declines in the reservoirs that we’re seeing again this year,” Castle said.
John Fleck, a writer in residence at the Utton Center at the University of New Mexico’s School of Law and a close observer of the basin, said a key difference between today and the 2022 crisis is a lack of breakthrough leadership, even as the potential for interstate litigation grows.
“The inability of the basin state negotiators to get beyond their disagreements and try to see what a solution space that serves the basin as a whole might look like is just in really poor shape,” Fleck said. “We’re not seeing that kind of visionary governance leadership out of this community. The network of governance is really frail right now.”
The end of this month is the deadline for the basin states to come to a consensus agreement to put forward to the Bureau of Reclamation as that agency analyzes options for a new management regime on the river. The draft analysis is expected this fall.