LAS VEGAS/LOS ANGELES (Reuters) - Desert golf course superintendent Bill Rohret is doing something that 20 years ago would have seemed unthinkable -- ripping up bright, green turf by the acre and replacing it with rocks.

Bill Rohret, golf course superintendent for Angel Park in Las Vegas, Nevada, resets a sign that states the water pond feature is made from recycled water February 10, 2009. REUTERS/David Becker

Back then “they came in with bulldozers and dynamite, and they took the desert and turned it into a green oasis,” Rohret said, surveying a rock-lined fairway within sight of the Las Vegas strip. “Now ... it’s just the reverse.”

The Angel Park Golf Club has torn out 65 acres of off-course grass in the last five years, and 15 more will be removed by 2011, to help conserve local supplies of one of the most precious commodities in the parched American West -- fresh water.

But Rohret’s efforts have their limits. His and many other golf courses still pride themselves on their pristine greens and fairways and sparkling fountains, requiring huge daily expenditures of water.

Aiming to cut per capita use by about a third in the face of withering drought expected to worsen with global warming, water authorities in the United States’ driest major city are paying customers $1.50 per square foot to replace grass lawns with desert landscaping.

Built in the Mojave Desert, Las Vegas leads Western U.S. cities scrambling to slash water consumption, increase recycling and squeeze more from underground aquifers as long-reliable surface water sources dry up.

From handing out fines for leaky sprinklers to charging homeowners high rates for high use, water officials in the U.S. West are chasing down squandered water one gallon at a time.

Nowhere is the sense of crisis more visible than on the outskirts of Las Vegas at Lake Mead, the nation’s largest manmade reservoir, fed by the once-mighty Colorado River. A principal source of water for Nevada and Southern California, the lake has dipped to below half its capacity, leaving an ominous, white “bathtub ring” that grows thicker each year.

“We are in the eye of the storm,” said Pat Mulroy, general manager of the Southern Nevada Water Authority. “As the realities of climate change began to manifest themselves at the beginning of this century, we had to get serious about it.”

For now, policymakers have emphasized the need to curb water use rather than urban growth, though the U.S. recession has put the brakes on commercial and housing development that otherwise would be at odds with the West’s water scarcity.

GETTING TOUGH

Warm, dry weather has long made the American West attractive to visitors, but piped-in water has created artificial oases, luring millions to settle in the region. Las Vegas has ranked as one of the fastest-growing major cities.

But scientists say climate change is shriveling the snow pack in California’s Sierra Nevada, the state’s main source of fresh surface water, and in the Rocky Mountains that feed the Colorado River, whose waters sustain seven states.

Further pressure from farming and urban sprawl is straining underground aquifers, placing a question mark over the future growth of cities from Los Angeles to Tucson, Arizona.

“There is going to have to be a big adjustment in the American Southwest and in California as we come to grips with limits in this century -- not just limited water, but also limited water supply,” said James Powell, author of the book “Dead Pool,” exploring challenges facing planners in the West.

Reactions among local water authorities differ.

In Phoenix, the United States’ fifth-largest city, authorities say sustainable groundwater and ample surface water allocations from the Colorado and Salt rivers meet the city’s needs, even factoring in growth through a moderate drought. The city is also recycling waste water and plans to pump some back into the aquifer as a cushion.

Tucson will require new businesses to start collecting rainwater for irrigation in 2010.

California requires developers of large housing projects to prove they have sufficient water.

In Las Vegas, where rain is so infrequent that some residents can remember the days it fell in a given year, front-yard turf has been banned for new homes.

The Southern Nevada Water Authority also has hired “water cops” to fan out into the suburbs to identify violations of mandatory lawn irrigation schedules and wasteful run-off. Repeat offenders get $80 fines.

Major hotel-casinos such as the MGM Mirage and Harrah’s Entertainment have adopted “green” building codes, including modifications designed to slash water use by 40 percent.

Those measures are starting to pay off, with daily water use down 15 percent per person in the greater Las Vegas area.

BUYING TIME

In a wake-up call to California, water officials there recently announced that prolonged drought was forcing them to cut Sierra-fed supplies pumped to cities and irrigation districts by 85 percent.

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That has led many California cities, topped by Los Angeles, the nation’s second-largest, to plan for rationing, including price-enforced household conservation and tough new lawn watering restrictions.

“The level of severity of this drought is something we haven’t seen since the early 1970s,” Los Angeles Mayor Antonio Villaraigosa said in unveiling his city’s drought plan, which also would put more water cops on the beat.

California Gov. Arnold Schwarzenegger last month called on the state’s urban users to cut water consumption 20 percent or face mandatory conservation measures.

The California drought, now in its third year, is the state’s costliest ever. Complicating matters are sharp restrictions on how much water can be pumped from the Sacramento-San Joaquin Delta in northern California, which furnishes much of the state’s irrigation and drinking supplies, to protect endangered fish species.

Moreover, the severe dry spell is leaving the state more vulnerable to wildfires, which last year consumed some several Los Angeles suburbs. The previous year, fires forced a record 500,000 Southern Californians to flee their homes.

PLANNING FOR THE WORST

Conservation will buy time, experts say. But bolder steps are needed in anticipation of longer droughts and renewed urban expansion once the recession ends.

Cities like Los Angeles and San Diego are revisiting an idea once abandoned in the face of staunch political opposition -- recycling purified sewer water for drinking supplies.

Disparaged by critics as “toilet-to-tap,” such recycling plans have gained new currency from the success of the year-old Groundwater Replenishing System in Orange County near Los Angeles.

That system distills wastewater through advanced treatment and pumps it into the ground to recharge the area’s aquifer, providing drinking supplies for 500,000 people, including residents of Anaheim, home of Disneyland.

Water specialists also see a need to capture more rainfall runoff that otherwise flows out to sea and to change the operation of dams originally built for flood control to maximize their storage capacity.

The situation in Las Vegas has grown so dire that water authorities plan to build a $3 billion pipeline to tap aquifers lying beneath a remote part of Nevada, a project critics call the greatest urban water grab in decades.

Southern Nevada water czar Mulroy says a broader national conversation about water is needed -- but not happening.

“We are talking about investing in public infrastructure, we are looking at building projects, but I get frustrated because we are doing it in complete denial of the climate change conditions that we are facing,” she said.

“We are not looking at where the oceans are rising, where the floods are going to occur, where things are going to go from that normal state to something extraordinary.”