Drought and a shrinking Lake Powell are forcing federal and state water managers to consider significant cuts to the releases at the dam in order to save the reservoir and power production, to the possible detriment of flows in the Colorado River and water reserves at Lake Mead, which provides most of the municipal water in Las Vegas.

Southern Nevada Water Authority General Manager Pat Mulroy told the Las Vegas Review-Journal on Thursday that the plan was floated by representatives from the upper Colorado River Basin states of Colorado, Utah, New Mexico and Wyoming.

Two more years of less than 50 percent runoff, and Powell's a dead pool, she said. That's how close we are.

Mulroy did not return calls from The Salt Lake Tribune.

On Friday, officials from the federal Bureau of Reclamation and the Upper Colorado River Commission called Mulroy's statement "premature."

But Don Ostler, executive director of the Upper Colorado River Commission, would not specifically refute Mulroy's numbers. He said no specific number - either for increasing or decreasing dam flows - will be officially proposed until this winter's snowpack is known.

Still, Ostler did suggest significant changes will come if the drought persists.

The business as usual approach is not going to work, Ostler said Friday. We have asked that there be a midyear review of the annual operating plan by the Bureau of Reclamation that covers releases at Lake Powell and other reservoirs. We don't know enough about what winter is going to bring us.

The upper states, which operate under a compact signed in 1948, plan to review the water situation in April. Ostler said that if the Intermountain area experiences an average water year, no changes would be needed. Should the drought continue, the states would modify the way Glen Canyon Dam is operated to mitigate the effects of the drought.

Ostler said that the sooner water managers can mitigate the drought, the better water levels, power production and the flow of drinking water can be managed.

Bureau of Reclamation spokesman Barry Wirth said Lake Powell was at a 3,575-foot level Thursday. If it drops 85 more feet, it will be impossible to generate power.

He said that while Mulroy had been briefed on the situation, there was no current proposal in the operating plan to make any reduction in current releases.

The Upper Basin states have a compact dating back to 1948 with a mechanism to deal with times like today and issues like they are facing, said Wirth. They are working in context of the current compact.

By contrast, Lower Colorado Basin states Arizona, Nevada and California have no such pact. The U.S. Interior secretary is the final arbiter on disputes in those states.

Water levels in Lake Mead - the next reservoir below Lake Powell - are critical to southern Nevada and especially Las Vegas. Lake Mead provides 90 percent of the water the Las Vegas Valley consumes.

The low water at Lake Powell continues to affect boaters. The only cement ramp in operation is at remote Hall's Crossing. Boat launching at Bullfrog, Wahweap and Stateline ramps is allowed, but only at boat owners' risk because of largely muddy conditions. A temporary mat installed at Bullfrog has helped.

Because Lake Powell is so low, many rock formations that haven't been exposed since the reservoir filled in the 1960s are now surfacing, creating interest from a generation of outdoor enthusiasts who have never seen so much of Glen Canyon's geology out of the water.

Lake Powell's shrinking water level also is affecting the management of the ecosystem downstream from the Glen Canyon Dam. Earlier this week, the Salt Lake City-based Glen Canyon Institute criticized a recent decision by the Grand Canyon Adaptive Management Work Group to delay until 2006 an artificial flood in the Grand Canyon below Lake Powell.

The institute, which favors draining Lake Powell, said the work group is ignoring scientists' recommendations to conduct the flood. Instead, they said the group favors maintaining low power rates that come from hydroelectric power generated by turbines at the dam. Institute leaders said endangered species and sediment resources in the Colorado River that flows through the Grand Canyon are on the decline.

Wirth said the reason for the delay is that the last artificial flood in 1996 took sediment from the upper part of the canyon and moved it downstream, which only shifts the problem.

Our conclusion was that we ought to watch for sediment that comes into the system, primarily from the Paria River, he said. When we get a volume of sediment from monsoon storms, then you take action to build new beaches.

Wirth said the Grand Canyon work group had not ruled out an artificial flood in 2005.

wharton@sltrib.com

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The Associated Press contributed to this report.

Thursday meeting

* The Southwest Center for Environmental Research, a consortium of five U.S. universities and several Mexican research institutes, is hosting a conference Thursday at the University of Utah on issues affecting the Colorado River, including water supply and management, the Colorado River Compact, pollution, vegetation and wildlife management, Native American water rights and university research relating to the river. Registration is $25, or $5 for seniors and students. Information, online registration, an agenda and directions are available at http://www.utah.edu/uees/water/water_home.html, or by calling 801-581-6348.