Opponents of a proposal to draw water from the Utah/Nevada border want to make sure the Department of Interior and four of its regulatory agencies have a strong voice in the process of whether to approve the Southern Nevada Water Authority's plans to pipe the water to Las Vegas.

The fear among watchdogs is that the Snake Valley aquifer on the border will dry up and irreparably damage the environment, wildlife and ranching in the area.

The Center for Biological Diversity, three chapters of the Sierra Club, Utah Moms for Clean Air, Utah Physicians for a Healthy Environment and Western Resource Advocates were among 23 groups from Utah and Nevada that sent a letter Monday to Interior Secretary Dirk Kempthorne.

The groups told Kempthorne in the letter that the Bureau of Land Management, Bureau of Indian Affairs, U.S. Fish and Wildlife Service and National Park Service need to lodge protests regarding the proposal currently being considered by Nevada State Engineer Tracy Taylor.

The Utah Association of Counties is expected this week to send a similar message to Kempthorne in the form of a resolution.

The groups say the Interior Department and its agencies previously gave up their right to protest over the Southern Nevada Water Authority's applications for water in Nevada's Spring, Cave, Delamar and Dry Lake valleys in the central part of the state. The agencies' decision to opt out of protesting those applications included the Water Authority agreeing to certain monitoring and mitigation measures in the event of any negative impacts in the four valleys.

"We believe these actions constituted an abrogation of the responsibility of those agencies to preserve and protect the environmental resources within their jurisdictions and the interests of the tribes and people they serve," Great Basin Water Network coordinator Susan Lynn said in the letter. "We note that suspicions linger that the decision of the (Interior Department) agencies to withdraw their protests may have been made due to political pressures."

Network board member Steve Erickson said it won't be possible to mitigate damages to the Snake Valley region, most of which is in Utah just east of Great Basin National Park.

"Mitigation through payment of damages is not replacing lost water," Erickson said Monday.

Utah Association of Counties' Mark Ward said the Snake Valley is the largest among the aquifers that Nevada's state engineer has had to consider as officials figure out how to supply a thirsty Las Vegas.