Lake Mead’s decline points to scary water future in West

CALIFORNIA (thehill): The Hoover Dam is seeing record-low water levels, a significant and scary development with major implications for water and climate in the entire American Southwest.

Amid drought conditions, Lake Mead’s level last week reached an all-time low of 1,071.56 feet above sea level, leaving it just 37 percent full.

The body of water’s level has been declining since 2000, and has fallen about 140 feet in the last two decades. It comes amid a drought in the Southwest that is the worst in two decades, according to a New York Times analysis.

Long-standing water issues in the West are heightening the challenges posed by more recent effects of climate change.

The Colorado River, which feeds the reservoir, is severely over-allocated, with the demand for its water exceeding the actual flow of the river, according to Kathryn Sorensen, a member of the Board of Advisors at the Kyl Center for Water Policy at Morrison Institute. Scientists have projected the river’s flow may diminish by up to 25 percent in the future, she noted.

Seven states are located in the river’s basin and affected by the Colorado River Compact: Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming. Experts say the overarching problem with water management in the Southwest, and these states in particular, is that existing systems are based on a climate that, because of warming, no longer exists.

The compact was ratified in 1922, and policymakers, including the late Sen. John McCain (R-Az.), have repeatedly called for it to be updated to reflect current circumstances.

“Politicians in the 1920s ignored science and promised more water to the cities and farms of the west than the river can deliver. So we’d be in trouble even without climate change. But warming temperatures are making the problem worse, by increasing evaporation so less water can make it downstream to users,” John Fleck, director of the University of New Mexico’s Water Resources Program, told The Hill.

Moreover, snowpack in the West has begun melting significantly earlier than it did at the time the water agreements were made, according to Noah Diffenbaugh, the Kimmelman Family Senior Fellow at the Stanford Woods Institute for the Environment.

 “We’re about to begin negotiating a new set of Colorado River water management rules, and we need to base the discussions on a realistic assessment of how deeply climate change is going to cut into the river’s flow,” Fleck told The Hill. “There’s a danger of repeating the mistake of a century ago and ignoring the inconvenient science. But only if we take the science seriously can we plan for the difficult future.”

In December 2020, representatives of the seven states wrote to then-Interior Secretary David Bernhardt that they were “initiating preliminary conversations” on another round of talks.

Under the arrangement between the states, river water is managed under the doctrine of prior appropriation, Sorensen said. This means water saved by one member of the compact is made available to the member with the next-senior water right under the agreement to maximize use. The end result, she said, is that there is eventually either no water remaining or no demand for it.

“This means the only viable long-term solution is that we must collectively use significantly less water from the Colorado River.  Cities cannot solve this problem alone because something like 75-80 percent of Colorado River water is used for agriculture. Everyone must contribute,” she told The Hill. “That’s easier said than done because of course everyone thinks their own water use is justified and that no one else’s is.”

Some stakeholders in the river basin have taken steps to forestall or push back against shortages, she said, such as through a strategy called system conservation, in which one user leaves any water they save in Lake Mead, and those who are next in line for the water under the agreement agree to place their right to the saved water in forbearance.

“However, relative to the scale of the problem of over-allocation and climate change, use of this tool has been very small and limited,” Sorensen said. “We need to ramp it up by orders of magnitude.”

“Mother Nature is in charge.  The basin has experienced more than twenty years of drought and we continue to drain an over-allocated river system,” she added. “I don’t think anything short of a miracle can forestall a shortage declaration in August.”

In the meantime, Diffenbaugh said, stakeholders and policymakers are exploring a number of potential long-term solutions to the drought conditions caused by climate change. These include processes to make water from other sources suitable for use, such as desalination of salt water or treatment of wastewater.

Another potential solution, he said, is artificial groundwater recharge, or directing excess surface water and wastewater back into aquifers. This approach “would require some additional infrastructure but it wouldn’t require a new infrastructure system,” he said.

However, the situation also illustrates the need for a larger overhaul of water infrastructure in the Southwest, Sorensen said. “It’s really important that water providers put the infrastructure in place that makes sure that they can move alternative supplies where they need to go when Colorado River supplies run short,” she said.

These options could range from large transmission mains to local wells but “our first obligation” should be to put such backup plans in place, she said.

At a time when extreme heat threatens to knock out Texas’ self-contained power grid, both the heat and the water levels have major implications for energy in the West as well. Last month, the operator of California’s own grid issued an assessment warning that the extreme temperatures would likely affect hydroelectric power generation in the state, citing lower snow water content than the previous year.

The lower Lake Mead levels will almost certainly affect power in the West as well due to the “tremendous amount” of power production out of the Hoover Dam, according to Felicia Marcus, the William C. Landreth Visiting Fellow at Stanford University’s Water in the West Program.

On the West Coast, she added, residents have already gotten a preview of these issues. “We found that certainly in terms of the timing in California during our drought where a variety of hydroelectric facilities just didn’t have the water flow to generate as much energy.”