Club 20: More water storage in Powell seen as way to maintain river pact
The magic number for managers of the upper basin of the Colorado River has long been thought to be 7.5 million, the average number of acre feet of water they must send down the river to the lower basin.
Turns out a better number is 3,490.
That’s the minimum elevation of Lake Powell that can drive the turbines in Glen Canyon Dam, generating electricity through the Southwest and bringing in money for a multitude of projects.
More important, Eric Kuhn, general manager of the Colorado River Water Conservation District, told the spring meeting of Club 20 on Saturday, it appears to be a number that protects the upper basin from running the risk of violating the terms of the 1922 compact that governs the river.
Under the compact, the upper basin states are to deliver 75 million acre feet of water to the populous lower basin every 10 years, what is frequently termed a 10-year rolling average of 7.5 million acre feet.
Modeling of river flows suggests that if Lake Powell’s level drops below the magic elevation of 3,490 feet above sea level, “the chances of a compact violation go up exponentially,” Kuhn said.
That has implications for drought years that suggest it would be better to store more water in Powell than to hold it in upstream storage, such as in Flaming Gorge, Blue Mesa and Navajo reservoirs, Kuhn said.
Not only would the additional water in Lake Powell serve as a better hedge against a compact violation, it also would make more financial sense because an acre foot of water in Lake Powell generates as much as 10 times more electricity than it would in the higher elevation reservoirs simply because of the additional pressure in Lake Powell, Kuhn said.
Federal officials monitoring the level of Lake Powell this month summoned Colorado officials to Washington, D.C., to explain how they planned to deal with the low elevation of Lake Powell, though there was no immediate danger of levels falling so low that Glen Canyon couldn’t generate electricity.
Managing the upper level reservoirs to avoid problems with electricity generation is one of several measures water managers are considering as they prepare for drought and the demands of increasing populations, Kuhn said.
The lower basin states, in the meantime, have to learn to live on a water diet, Kuhn said.
“We deliver 8.25 million acre feet (to the lower basin) and they’re using 10 million acre feet,” Kuhn said, “They’re using way more water than they’re entitled to and they have got to fix that.”