Wednesday, Aug. 13, 1997 | 9:12 a.m.
Tests show that drinking water in Las Vegas contains a small amount of the rocket fuel booster known as perchlorate.
Montgomery Watson Laboratories of Pasadena, Calif., reported the finding this week to the Southern Nevada Water Authority, which had sent samples.
The origin of the perchlorate contamination is unknown, although from World War II through the late 1980s the fuel oxidizer was manufactured by two companies near Henderson and continues to be manufactured by one company there.
Lake Mead and treated drinking water samples both contained 11 parts per billion of the chemical, which is also found in fireworks and explosives.
There is no national standard for safe levels of perchlorate, but drinking water in San Bernardino County in Southern California has registered from between 5 and 216 parts per billion, with no known ill effects. There is no state "standard" in California, but a guideline has been developed that triggers concern at 18 ppb.
Medical literature indicates health effects, which include thyroid and bone marrow problems, would not occur at levels below 2,800 ppb.
California has problem
Concern over the chemical surfaced when some Northern California water wells showed perchlorate levels as high as 8,000 ppb, high enough to force water authorities to close wells used as drinking water sources.
Scientists pulled the local samples of drinking water from Saddle Island in Lake Mead, which is near both the intake pipe for Las Vegas' drinking water and the Alfred Merritt Smith Water Treatment Facility.
"There's no danger at the levels we're talking about," said David Rexing, SNWA treatment plant laboratory manager. "There are a lot of unanswered questions."
It will take many more samples before anyone can know the source, Rexing said.
Montgomery Watson also found perchlorate in two Las Vegas Valley wells recharged during the winter with Colorado River water. Levels of 5.6 ppb and 13 ppb were recorded at the wells, whose specific locations were not released. Montgomery Watson is one of four laboratories in the country able to detect perchlorate.
Artificial recharge wells inject the treated river water into the groundwater basin and produce a mixture of groundwater and treated river water to meet peak summer demands.
Eight other wells from the area did not detect perchlorate. Of the 10 total wells tested, five pump groundwater only and five have been used for artificial recharge. Only recharge wells indicated perchlorate.
Two in-valley pumping stations, Broadbent and Fayle, that carry treated surface water, registered at 7.6 ppb and 9.6 ppb.
The Nevada State Division of Environmental Protection will take the lead on tracking the source of the perchlorate.
"We're taking this very seriously, but it will be a difficult task," said Allen Biaggi, deputy administrator of NEDP.
The Los Angeles Metropolitan Water District first tested Lake Mead near Hoover Dam, finding 8 ppb of perchlorate. It also discovered the same level at its drinking water intake pipe in Los Angeles.
That prompted the Southern Nevada Water Authority to conduct tests of its own.
Treatment expensive
Perchlorate cannot be removed from municipal drinking water, even in treatment plants as sophisticated as those in Southern Nevada. The only way to remove it is through reverse osmosis or ion exchange, both advanced treatments considered non-conventional and very expensive for municipal water systems.
The Los Angeles district also tested water upstream of Lake Mead, but found no detectable levels, prompting speculation from water engineers that the perchlorate could originate from the manufacturing sites in Henderson.
American Pacific Corp., which suffered a major explosion and fire in 1988 at its manufacturing site near Henderson, moved its operation to Cedar City, Utah, where another explosion rocked the plant last month.
Kerr McGee Corp. is the only plant remaining near Henderson that manufactures perchlorate. It stores the chemical at Apex.
American Pacific President and Chief Executive Officer John Gibson denied that practices at either plant caused water contamination. Terrence Clow, 46, who worked at the American Pacific plant from 1971 to 1973, however, said workers routinely dumped contaminated water into the desert east of the plant.
Rexing agreed that it was too early to place the blame for contamination on any site. "We have very few samples to work with," he said.
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