A coalition calling itself the Great Basin Water Network, made up of more than 80 groups and individuals, sent Reid a letter Tuesday urging him to seek a delay in finalizing the deal until comprehensive testing is done on groundwater availability, recharge of the aquifer and water use in the region, which straddles the Deep Creek Mountains north from Great Basin National Park to Callao in Juab County.

"We feel very strongly that no agreement should be made until state and U.S. Geological Survey study results have been completed and the Nevada state engineer has ruled on permit requests from [the Southern Nevada Water Authority]," Susan Lynn, executive director of the Great Basin Water Network, said in a statement. "These decisions should be based on sound science, not just pipe dreams."

The Southern Nevada authority, which furnishes municipal water to Las Vegas and Clark County, has proposed drilling a series of groundwater wells in neighboring White Pine and Lincoln counties, then pumping the water south via a 200-mile network of pipelines.

Opponents have argued that such a vast annual removal of groundwater - 25,000 acre-feet out of Snake Valley and another 91,000 acres out of nearby Spring Valley - would deplete water tables, damaging the area's ranching operations and larger ecosystem.

The Great Basin Water Network became alarmed last month when a draft agreement between Utah and Nevada, which would precede the conclusion of the USGS study, was leaked on the Internet. Earlier, the Geological Survey released preliminary test results that showed possible groundwater impacts from the project in and around Great Basin National Park.

The draft agreement calls for Nevada and Utah to sign off on a groundwater-sharing plan by Sept. 5 - before a series of state hearings begins on proposal.

But Reid told The Associated Press on Wednesday that, because the project has been under discussion for years, the sooner an agreement can be negotiated with Utah the better.

However, he added that he had been given "every assurance that this process will be thoughtful and deliberative. While it is important for new water resources to be developed, it is also essential that the natural resources of both states are protected."

Reid's son, Rory, a Clark County commissioner, sits on the board of the Southern Nevada Water Authority.

Utah officials have acknowledged that Reid and the the Water Authority have pressured them to reach an early agreement. But Gov. Jon Huntsman Jr. and Department of Natural Resources Director Michael Styler have assured Snake Valley residents that their interests will be protected.

But those residents have complained that too much of the deal-making has gone on behind closed doors.

"The agreement process should be as transparent as possible," said Trout Creek rancher Ken Hill. "It should take place in the light. Not in a cave."

jbaird@sltrib.com