Monday, March 14, 2005 | 10:39 a.m.
Colorado River states haggling over water rights see value in Southern Nevada's proposal to receive credit for pumping groundwater from rural counties back into Lake Mead.
Under the proposal, the addition of the rural groundwater would allow Southern Nevada to take more water out of the lake than is currently allowed under the Colorado River compact.
The Water Authority has been able to take annually about 300,000 acre-feet from Lake Mead but in fact is able to use much more through leveraging return-flow credits. For every gallon taken from the lake, the Water Authority treats and returns 70 percent of the total, almost everything used indoors.
For every drop returned to the lake, the authority can take that much more out and pump it uphill to the Las Vegas Valley.
That means that while the federal Bureau of Reclamation sets the limit Southern Nevada can use at 300,000 acre-feet, in fact Las Vegas and suburbs use more than 500,000 acre-feet annually. One acre-foot is about 326,000 gallons, or enough for one or two families per year.
While return flow credits are an essential part of the local water plan, groundwater and potential surface water resources cannot, by federal rule, receive similar credits.
A key component of the Southern Nevada Water Authority's plans of augmenting its supply from Lake Mead would be to tap wells in rural Lincoln and White Pine counties and bring water through hundreds of miles of pipelines to Las Vegas.
Pat Mulroy, Water Authority general manager, is trying to change the rule so that the region can take water from rural areas, use it, treat it and send it to Lake Mead, and take out more water from the lake for the rural water it puts in.
Instead of return-flow credits, the Water Authority has dubbed the proposal "augmentation credits" because Lake Mead, which has dropped about 75 feet over the last four years because of drought in the West, would be augmented by the rural water.
Mulroy said the issue is complex, but the potential to receive credit for water from rural groundwater appears more likely to win approval from the other six basin states of the Colorado River than it would be to get credit for water taken from the Virgin and Muddy rivers in northeast Clark County. The Muddy and Virgin rivers already empty into Lake Mead.
The Upper Colorado River Basin states of Colorado, Wyoming, New Mexico and Utah also take most of their annual appropriations from tributaries, so are generally unenthusiastic about granting additional rights to Nevada for the Silver State's use of tributary water.
"There's a huge rift in tributary use between the upper and lower basin," she said. "I understand the complexities around the Virgin River."
But groundwater from wells is a different story. Mulroy said the conservative estimate the Water Authority is using in planning how much could come from wells in rural nevada is about 125,000 acre-feet annually. That number could stretch to 212,000 acre-feet annually with credits for what is put into Lake Mead, she said.
"That shows real potential," Mulroy said.
The Water Authority's more liberal estimate of how much groundwater might come from the rural counties is 180,000 acre-feet. With augmentation credits, that could stretch the usable water available to more than 300,000 acre-feet.
The issue of augmentation credits and how that would affect rural use is still not formally decided by the Water Authority. A citizens' group, the Integrated Water Planning Advisory Committee, is meeting tonight and will talk about augmentation credits and rural water use generally, said Vince Alberta, a water authority spokesman.
He noted that decisions on the final use, reuse and delivery to Lake Mead will be discussed by the committee and the Water Authority board before any decision is made.
Dennis Underwood, vice president of the Metropolitan Water District of Southern California, represents one of the strongest of water agencies that use the Colorado River. He said decades ago, water agencies considered augmenting the Colorado River with water from Washington's Columbia River or other source.
"That's not probably doable anymore," Underwood said, but the idea of diverting used, treated groundwater "as merit."
"You look at it like a return-flow credit," he said. "We definitely would be interested in pursuing it, because it brings more water into the system."
California now takes about 4.4 million acre-feet out of Lake Mead, mostly for agricultural use. Underwood said while bringing more water into the system helps California, it also helps Nevada by diversifying its portfolio of sources.
Extending the relative punch that contributions from the rural groundwater makes sense financially as well, Underwood said, although he, too, made a distinction between groundwater and diversions from the Virgin or Muddy rivers.
Groundwater from well would be "definitely outside the Colorado River basin. That's why it's worthy of consideration."
Bob Johnson, regional director for the federal Bureau of Reclamation, agreed that the proposal has merit and should be considered. The bureau, and ultimately the secretary of interior, would set the rules for such augmentation credits, although historically such issues have largely been negotiated by the states.
"It's a concept that we're willing to consider," Johnson said. "Conceptually, it could work. We would want to do a careful review with the other states."
Virgin River water issues, however, present "a much more complicated legal issue, a much tougher situation," he said.
Kathy Jacobs, an associate professor with the Water Resources Research Center at the University of Arizona, said the proposal "makes sense from a basic math perspective."
More water in the lake means more to take out, potentially, for someone, she noted.
Jacobs, who worked for two decades with the Arizona Department of Water Resources, said that water from tributaries "has all types of (political) baggage," but credits for clean, treated water from other sources would be less problematic.
"They are adding water to Lake Mead that would not otherwise have been there, so it makes sense."
She noted, however, that in the complex legal and political issues affecting the Colorado River and water issues in the West, making sense does not always mean a policy will win the day.
"None of these things is ever simple," Jacobs said.
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