People in Wyoming's Green River Basin likely won't see water use reductions this year, but a decision by Interior Secretary Gale Norton Monday could mean curtailment in the future, state officials said.

Norton announced the federal government will not cut releases of Colorado River water this year from drought-depleted Lake Powell, despite the efforts of Wyoming and other so-called "upper-basin" states to hold more water. The Green River in southwest Wyoming is among the largest tributaries in the Colorado River system.

In letters to governors and water officials in the seven Colorado River Basin states, Norton said melting snow is projected to be slightly above average for the rest of the year and more water is stored in reservoirs now than had been projected last year.

"We have concluded that an adjustment to the release amount from Lake Powell during the next five months is not warranted," she said.

The secretary's position will not affect Wyoming residents this year, said Harry LaBonde, deputy state engineer. But it may in the future.

"What it means is for every gallon released out of Lake Powell is a gallon you don't have next year," LaBonde said.

He said the state was disappointed in the secretary's decision, but supported her authority to make the call.

Wyoming and the other upper-basin states - Utah, Colorado and New Mexico - have been pushing for a reduction in water released from Lake Powell, which is now 34 percent full. Lower-basin states of California, Arizona and Nevada received a good bit of moisture this winter, filling Lake Mead - their water source - to 62 percent of capacity, representative argued.

"The concern is if this drought continues that Lake Powell could go empty and then the upper-basin states still have this 7.5 million-acre-feet obligation," LaBonde said. "That's what could potentially lead to upstream curtailment of water use. That's where we're concerned. We would like to see more water held in Lake Powell."

A 1922 "compact" or agreement created allocations among seven states for water in the Colorado River. That agreement requires the water to be split evenly between upper and lower basins, requiring an average of 7.5 million acre feet to be released from Lake Powell every year.

A subsequent agreement with Mexico for water rights requires about an additional 800,000 acre feet to be released from the reservoir.

Lake Powell's capacity is 24 million acre feet, and it currently holds about 7.98 million acre feet. The lake's level is expected to rise by about 45 to 50 feet this year.

LaBonde said current Wyoming water law still applies for people in the Green River Basin. Water use was allotted with "senior" and "junior" rights determined by who used the water first. Many of those rights date back to the 1860s.

"When you have a water-short basin or a period of shortage and someone calls for their senior water, what Wyoming law says is you must curtail the junior water rights first," LaBonde said. That means the junior water rights are shut off until the senior rights are satisfied.

"There have been a lot of folks in the Green River Basin that (have rights from the) early 1900s, and those have not been fully satisfied in the last five years," he said.

Under regulation, people may divert no more than one cubic foot per second of water for every 70 acres of irrigated land.

Proactive plans

This year, the upper and lower Green River has an average snowpack level for this time of year that is 86 percent of average. The lower Green is faring better with 94 percent of average snowpack and 97 percent of average precipitation for this time, according to the Natural Resources Conservation Service.

Last year at this time, though, the upper and lower Green River basins stood at just 51 and 55 percent of snowpack averages, respectively.

Jan Curtis, Wyoming state climatologist, said the future of precipitation in the area is anyone's guess. But he said when the 1922 Colorado River Compact was developed, there was "an abundance of precipitation before and several years after. Ever since then the annual precipitation has been significantly less."

The compact was developed at a time when 13 million acre feet per year was released throughout the system - hence the 7.5 million obligation of upper-basin states.

Curtis said it was not predicted the desert Southwest would develop as it has - a major culprit in the supply-and-demand problem for the West's water.

Curtis also said he asked Gov. Dave Freudenthal last year about the potential water wars, and the governor allocated money to the Water Development Commission to examine the possibility of another reservoir on the Green.

"If they can show we are storing and using water, they think that will show more leverage in keeping that water," Curtis said.

The state is also gathering information in case of litigation down the road, Curtis said. Should lower-basin states get together in future years and clamor for more water, because they have more representatives in Congress it could mean they have more federal clout.

Even with the recent disagreements on the future of water supplies, LaBonde said the compacts are a "valuable tool" that allow states to agree on shared resources like water.

He said it has benefited Wyoming, because the state was settled "relatively later in U.S. history," and previous settlers would have had the rights over Wyoming newcomers.

Mike Besson, director of the Wyoming Water Development Office, said the Green River is important to agriculture, cities and the mining industry in southwest Wyoming.

"Rock Springs is growing … and more people need more water," he said.

Norton said she wants the states to conduct another review next April to see if adjustments should be made to water flowing through the Glen Canyon Dam in Page, Ariz., to Lake Mead.

Lake Powell and Lake Mead are the largest of the more than 40 reservoirs that let the federal government and Western states store Colorado River Basin water in wet years. The 1922 agreement does not specify how the water should be divvied up during dry periods. Last fall, Norton asked the states to find a way to handle water shortages.

Briefing reporters by conference call from Washington, D.C., Tom Weimer, acting assistant Interior secretary for water and science, called Norton's decision "fairly balanced."

"The severity of the drought and length of the drought has forced people to look at everybody's self-interest," he said, adding that lower-basin states lost a bid to get Norton to say she had no authority to change water allocations.

Environmental reporter Whitney Royster can be reached at (307) 734-0260 or at royster@trib.com.