YUCCA FLAT - A sea of ancient water tainted by the Cold War is creeping deep under the volcanic peaks, dry lake beds and pinyon pine forests covering a vast tract of Nevada.
Over 41 years, the federal government detonated 921 nuclear warheads underground at the Nevada Test Site, 75 miles northeast of Las Vegas. Each explosion deposited a toxic load of radioactivity into the ground and in some cases directly into aquifers.
When testing ended in 1992, the U.S. Energy Department estimated that more than 300 million curies of radiation had been left behind, making the site one of the most radioactively contaminated places in the nation.
During the era of weapons testing, Nevada embraced its role almost like a patriotic duty. There seemed to be no better use for an empty desert. But today, as Nevada faces a water crisis and a population boom, state officials are taking a new measure of the damage.
They successfully pressured federal officials for a fresh environmental assessment of the 1,375-square-mile test site, a step toward a potential demand for monetary compensation, replacement of the lost water or a massive cleanup.
"It is one of the largest resource losses in the country," said Thomas S. Buqo, a Nevada hydrogeologist. "Nobody thought to say, `You are destroying a natural resource.'"
In a study for Nye County, where the nuclear test site lies, Buqo estimated that the underground tests polluted 1.6 trillion gallons of water. That is as much water as Nevada is allowed to withdraw from the Colorado River in 16 years - enough to fill a lake 300 miles long, a mile wide and 25 feet deep.
At today's prices, that water would be worth as much as $48 billion if it had not been fouled, Buqo said.
Although the contaminated water is migrating southwest from the high ground of the test site, the Energy Department has no cleanup plans, saying it would be impossible to remove the radioactivity. Instead, its emphasis is on monitoring.
Federal scientists say the tainted water is moving so slowly - 3 inches to 18 feet a year - that it will not reach the nearest community, Beatty, about 22 miles away, for at least 6,000 years.
Still, Nevada officials reject the idea that a massive part of their state will be a permanent environmental sacrifice zone.
Access to more water could stoke an economic boom in the area, local officials say. More than a dozen companies want to build solar electric generation plants, but the county cannot allow the projects to go forward without more water, said Gary Hollis, a Nye County commissioner.
The problem extends beyond the contamination zone. If too much clean water is pumped out of the ground from adjacent areas, it could accelerate the movement of tainted water. When Nye County applied for permits in recent years to pump clean water near the west