LAS VEGAS — After nearly two decades of busily converting desert into sprawling metropolis in the fastest growing region in the nation, southern Nevada finds itself beset by a four-year drought and straining against limits in the water it can pump from nearby Lake Mead.

Las Vegas is turning to neighboring counties to the north to quench a thirst the nation's largest man-made reservoir can't sustain. Plans include drilling wells and building a $1 billion pipeline to tap rivers and groundwater from neighboring rural counties.

The Southern Nevada Water Authority says there is enough water out there to let the Las Vegas area population nearly double in the next decade — to more than 3 million — without drawing more from the Colorado River that supplies Lake Mead.

Some at the head of the proposed pipeline worry their high desert valleys and ranches will dry up if precious underground water is pumped to Las Vegas. They say the obvious solution is being ignored.

"You have growth in an area that doesn't have water and the decisions aren't how to control growth, it's how to get water," said Paul Johnson, chairman of the White Pine County Commission in Ely, 250 miles north of the Las Vegas Strip.

Farrel Lytle, who lives in Eagle Valley — an enclave of about 30 homes, a trailer park and a bar near Pioche, is worried his community will go the way of California's Owens River Valley.

"That country dried up. It lost its water to a big city," Lytle said.

Johnson also sees parallels in the early 1900s Los Angeles water project that drained a valley north of Los Angeles and turned Owens Lake, east of the Sierra, into a dust bowl. The 1974 film "Chinatown" was loosely based on the episode.

"All of these preceding disasters are examples that people use when they talk about transferring water," Johnson said.

The Southern Nevada Water Authority last year settled a 1989 water rights claim it staked across vast stretches of Lincoln County, and is negotiating with White Pine County, the next county to the north.

White Pine's five-member commission suspended talks last month to address community opposition to water sharing.

"The community is very divided on how to deal with this," Johnson said. He acknowledged that 8,800 people living in a rural county the area of Massachusetts may be no match for business and political interests in Clark County — which includes Las Vegas and 1.6 million of the state's 2.3 million residents.

"We're trying to save our water," said Gary Lane, a truck stop owner, cattle rancher and alfalfa farmer outside the White Pine community of Lund, 210 miles from Las Vegas. "We're looking at our pumps and our springs running dry if the water is pumped out."

No one really knows how much water exists beneath the desert. State Engineer Hugh Ricci estimates there are millions of acre-feet.

"The question is, where can you get it and how much can you get?" Ricci said.

Water officials say they'll need to drill test wells to determine whether the supply is finite ancient water trapped underground or is replenished by springs and scarce surface precipitation.

Nevada in 2003 led the nation in population increase for a 17th year, according to the state demographer. About 80 percent of new residents moved to Las Vegas or nearby.

The Lake Mead reservoir behind Hoover Dam is at its lowest level in 35 years, at 1,140 feet above sea level or 65 feet below its high water mark. It is still more than half full, with about 5 trillion gallons of water.

A growth study delivered to the Southern Nevada Water Authority on Feb. 26 did not refer directly to water. But it came the same day the authority received a report on plans to reach far to the north to meet future demands.

One project calls for tapping groundwater in northern Clark County by 2007. Another would draw water from the Virgin and Muddy rivers before they empty into one end of Lake Mead. The third would extend the pipeline north to Lincoln and White Pine counties.

The growth study, by Las Vegas-based Hobbs Ong & Associates, was commissioned to determine whether growth control would work as a means of drought management and to provide an answer to other states relying on the Colorado River who wonder why southern Nevada won't stop growing.

It said the economies of southern Nevada and the rest of the state depend on continued growth, as well as on gambling, tourism and mining. Turn it off and the entire state would suffer, it concluded.

The report made a case for growth that the construction industry in southern Nevada wanted to make, said Daniel Patterson, a desert ecologist with the Center for Biological Diversity in Tucson, Ariz.

"It was, 'Maximum water for maximum development,' and, 'We need Congress to do it,"' he said.

Patterson noted that Sen. Harry Reid, D-Nev., plans to introduce legislation in Congress to free acreage for development around Lincoln County's four largest towns — Caliente, Pioche, Alamo and Panaca — and set aside other land as protected wilderness.

The proposal would include a spider-web of hundreds of miles of mile-wide utility easements that could serve as a route for the water pipeline.

"There doesn't seem to be an acknowledgment of the reality that Las Vegas is in the driest desert in the United States," Patterson said. "If you're going to have a sustainable city there into the future, Las Vegas has got to get very serious about reducing waste."

Water authority general manager Patricia Mulroy insisted that conservation is a top priority for her agency, which delivers water to most of Clark County and the 35 million tourists who visit each year.

Although the water board last month relaxed drought restrictions on car washing, outdoor misting systems and decorative fountains, Mulroy said aggressive conservation measures remain in place.

"We're paying for people to take turf out," she said. "Everything that reaches the sewer system is treated and returned to the Colorado River, or it goes to a regional system for parks and golf courses and turf applications."

The state is allowed 300,000 acre-feet of river water a year under a deal in which water is shared by seven Colorado River states and Mexico.

The Las Vegas area draws 85 percent of its water — 297,000 acre-feet in 2003 — from Lake Mead, Ricci said. The remaining 15 percent comes from underground wells. An acre-foot can supply a family for a year.

Ricci said that in 1995 his predecessor as state water engineer approved letting the water authority draw up to 190,000 acre-feet per year from the Virgin River.

Meanwhile, the Reid bill would underpin a deal last year between the water authority and Lincoln County and its business partner, Vidler Water Co., to split 200,000 acre-feet of groundwater reserves in Lincoln County.

Some critics have accused Las Vegas water officials of duping Lincoln County, with fewer than 4,000 residents, into giving up its water rights.

"I've described it as a rape," said Lytle, a retired Boeing scientist who traces his family back to the first Mormon settlers in the Pioche region. "All we see ... is fountains in front of casinos down there, while some old grizzled cowboy up here is trying to get a drink for his cattle at a trickling creek."

Lincoln County Commissioner Tim Perkins, who chairs the Lincoln County Water District, said a pipeline could help develop property in his county.

"A lot of residents feel like Las Vegas is coming up and stealing their water. In reality, it all belongs to the state," he said.

Ricci, who decides what water goes where in Nevada, said his determination will be made on how the water can best serve the public interest.

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