The new study in the Journal of the American Water Resources Association estimates about 380,000 acre-feet of water a year is lost when it soaks into the lake's sandstone banks each year. That’s more than the state of Nevada is entitled to take from the river under a 1922 interstate compact.
The Glen Canyon Institute paid for the study, and it says the findings back up its proposal to lower the level of Lake Powell and fill Lake Mead, which loses much less water to seepage. The Institute’s Michael Kellett says that could be done easily without major changes in the law.
“We don’t think we need to deal with looking at changing the Colorado Compact or any of those things at the moment," Kellett tells KUER. "It may be necessary in the future. That’s a much bigger issue. But we’re saying the ‘Fill Mead First’ approach could be done within the current law of the river.”
Barbara Hjelle with the Washington County Water Conservancy District says the seepage issue at Lake Powell has been studied for years and factored into the management of the reservoir. And she says Utah has a lot to lose in the ‘Fill Mead First’ plan.
“Utah’s water is Upper Basin water and Lake Mead is a regulating reservoir for Lower Basin water," Hjelle said in an interview with KUER. "So once the water has passed through Lake Powell and on downriver, it is lost to Utah.”
The level of Lake Powell is currently at about 3600 feet, a hundred feet below its peak level from the 1980’s. The Bureau of Reclamation expects the level of Lake Mead to drop close to the level of the water intakes for Las Vegas within a couple of years.
The lake loses about 560,000 acre-feet to evaporation each year.