Las Vegas Needs Luck With Water Supply

Dating back to prehistoric times, this desert oasis has been known for its abundance of water. Thus the name Las Vegas, Spanish for The Meadows.

That was before anyone had heard of perchlorate or plutonium, or envisioned tens of millions of visitors annually, or 1.3 million residents.

Some are now beginning to worry that the very commodity that drew settlers here could become the city’s Achilles’ heel.

Pat Mulroy, head of the Southern Nevada Water Authority, believes she has developed options to provide enough water “to get us through 2030” as the city remains the fastest-growing in America.

But now there’s new concern over perchlorate, a chemical known only to scientific souls until May 1988, when a plant producing ammonium perchlorate exploded, rocking the Las Vegas valley. Two people were killed and 300 injured.

Decades of producing the rocket fuel oxidizer a dozen miles from Lake Mead may have left a legacy that could harm area water supplies.

As if that weren’t enough, scientists now say plutonium has been found in a water well nearly a mile from a major underground nuclear weapons test conducted 29 years ago. Scientists say the plutonium is moving in the water tables much faster than they had expected.

The test, code-named Benham, was conducted in December 1968 and had an explosive yield of 1.15 megatons of TNT, one of the largest tests ever conducted in the United States, said Energy Department spokeswoman Nancy Harkess.

Traces of plutonium were recently found in a water well drilled by the DOE to monitor such tests. Plutonium, a key ingredient in nuclear weapons, is toxic.

Environmentalists say the movement of plutonium from the Benham test is proof the deadly element can move through the water tables, albeit slowly.

“They’ve theorized for a long time that plutonium could move like this, but they have never seen it before,” Harkess said. “This is the first time this has been observed. To see it move almost a mile, even over a 29-year period, was a little bit of a surprise, even though it’s very low level.”

Movement could be a bad omen.

The government conducted 928 nuclear tests at the Nevada Test Site, 65 miles from Las Vegas. A total of 100 tests were conducted aboveground, 828 underground, between 1951 and a test moratorium in 1992. Some were as close as 70 miles from Las Vegas, others, such as Benham, as far away as 125 miles.

Could this plutonium reach Las Vegas’ water supply?

“You’re asking me to look in a crystal ball,” Harkess said. “You’re talking about thousands of years.”

Mulroy says no.

“The plutonium doesn’t concern me because the flow pattern is not toward Las Vegas,” Mulroy said. “The flow of that ground water is toward Death Valley,” south and west of the test site across the California border. Las Vegas is southeast of the site.

“The flow time to Death Valley is 20,000 years,” Mulroy said.

Richard Nielsen, executive director of the Nevada branch of the environmental group Citizen Alert, isn’t so sure.

“The fact there is plutonium in the ground water [at the test site] is not surprising,” he said. “The news is that it’s moving. I think it’s a big threat. The fact that all that has been discovered leads me to believe it’s just the tip of the iceberg and we’re going to find contamination to be a lot more widespread, at some point going off the site and getting into some large aquifer.”

Perchlorate is an equally vexing problem. For decades the rocket fuel ingredient has been produced near Henderson, Nev., on the outskirts of Las Vegas.

Kerr-McGee Corp. continues production there while American Pacific Corp. moved production to Cedar City, Utah, after the 1988 explosion of its Pepcon plant.

State officials agree with Mulroy that perchlorate does not pose a problem for Las Vegas’ water supply, although there is concern about whether it might someday.

The perchlorate level in Las Vegas water is now 11 parts per billion. That’s the equivalent of one drop of perchlorate in 55,000 gallons of water, Mulroy said.

But it’s a far different story at the Kerr-McGee plant, where ground- water samples taken from monitoring wells turned up levels as high as 3.7 million parts per billion.

In August, water samples collected from the Las Vegas Wash, which feeds into Lake Mead, reached levels as high as 1,680 parts per billion.

California, the only state to set a health standard for perchlorate, has a limit of 18 parts per billion for drinking water.

“Our challenge is keeping the perchlorate out of Lake Mead,” Mulroy said. Perchlorate reaching the lake is diluted by the huge body of water, she added.

“We’re talking about some fairly large environmental mitigation efforts,” Allen Biaggi of the Nevada Division of Environmental Protection said of perchlorate cleanup efforts. He said Kerr-McGee and American Pacific had been “very cooperative” in identifying the problem and would share in removal costs. He would not speculate on how much they might be. “Perchlorate is such a new compound, no one has devised a system to remove it from water,” Biaggi said.

Perchlorate is known to affect the thyroid gland in high doses, but there is “no indication it is a significant health hazard in the levels found in the Las Vegas water,” Biaggi said.

Las Vegas’ abundance of water dates back to prehistoric times, said Frank Wright, a curator at the Nevada State Museum and Historical Society. That abundance drew trappers and explorers in the 1800s, Mormon settlers in 1855 and the railroad in 1905, when it needed a major watering point between Salt Lake City and Los Angeles.

Fears of Las Vegas maxing out its water supply shortly after the turn of the century, when the population is expected to crowd 2 million, have been eased somewhat by conservation measures. Mulroy believes the valley has enough water to get it through 2030, while the search continues for additional sources.

That’s based on possibly banking some water in Arizona aqueducts until Nevada begins using its full Colorado River allocation of 300,000 acre-feet annually by the year 2007. The banking deal is still being negotiated.

Meanwhile, Mulroy is banking on a best-case scenario to cope with chemical concerns that were not an issue even months ago.