Years of drought along the Colorado River have created a harsh reality for the booming Las Vegas Valley: The metropolitan area will not be able to grow in the decades ahead without new sources of potable water.

The Southern Nevada Water Authority wants to meet that demand by tapping groundwater hundreds of miles north of Las Vegas and moving it to the state's economic, political and population hub through a pipeline that will cost at least $2 billion.

Not everyone likes the idea. Many White Pine County residents fear the water authority's steel straw could suck the Spring Valley dry. So they've enlisted the Western Environmental Law Center and other environmentalists to spike the pipeline proposal.

Hearings that began Monday in Carson City will determine whether the plan goes forward. Over the next week or so, State Engineer Tracy Taylor, chief of the Nevada Division of Water Resources, will hear testimony from elected officials, water managers, ranchers and said environmentalists about the possible consequences of pumping -- or not pumping -- enough water to supply as many as 425,000 homes in Southern Nevada.

Of primary importance to all sides in the debate is adequate monitoring. Can the Southern Nevada Water Authority be trusted to watch groundwater levels once water starts flowing south? If groundwater supplies don't recharge as quickly as first believed, could the flow be slowed regardless of how thirsty the Las Vegas Valley might be? Can the environment possibly be guaranteed protections from a project designed to nurture population growth?

Pipeline opponents have answered "no way" to all those questions. And they've had a powerful ally in their corner: Uncle Sam.

Because the authority's groundwater applications and proposed pipeline route cross a nearly uninterrupted swath of federal land, no part of the plan could go forward without the blessing of the U.S. government. The Interior Department expressed many concerns about the project.

But on Monday, the Interior surprised the greens by endorsing the integrity of the water authority. The National Park Service, the U.S. Fish and Wildlife Service, the Bureau of Land Management and the Bureau of Indian Affairs signed onto an agreement with the authority that drops all federal protests to the pipeline project, effectively certifying the authority's ability to draw groundwater without harming the environment.

Did the greens, who've gladly accepted scores of assists from federal authorities in stymieing highway construction, off-road access and residential development, rush to stand behind the Interior and declare their confidence in a local-federal groundwater monitoring partnership?

"There is nothing enforceable about these agreements," said Simeon Herskovits, the Western Environmental Law Center's southwest office director. "These are agreements we essentially see as sellouts for political purposes."

As opposed to the various government actions that benefit causes defended by Mr. Herskovits? Those aren't "sellouts for political purposes"?

In fact, Mr. Herskovits and many extreme environmentalists wouldn't support any open, public process that allows the transfer of groundwater from White Pine County to Southern Nevada. If Mr. Taylor authorizes the extraction of any water from the Spring Valley, the Western Environmental Law Center and other organizations will immediately file a federal lawsuit to block the pipeline project. A couple of sympathetic justices on the 9th U.S. Circuit Court of Appeals in San Francisco could stall the project for years, if not dissolve it outright.

Mr. Herskovits and his organization have been granted two full days next week to present their anti-growth views to Mr. Taylor.

Anyone who believes their testimony about the pipeline might contain a sliver of objectivity and open-mindedness is all wet.