Las Vegas water agency spots positive test for E. coli bacteria, but supply ‘never compromised’

This year's water quality report from the Las Vegas Valley Water District contains a passing reference to dangerous bacteria in the local drinking supply. But district officials and state regulators insist there is no need to start boiling your tap water as a precaution.

Though the district cannot explain exactly why a water sample taken in August tested positive for E. coli, it found no other trace of the bacteria in any follow-up tests.

Water district spokesman Roger Beuhrer said no one was sickened by the bacteria, which is a leading cause of bloody diarrhea and can be deadly, and the water supply "was never compromised."

Officials from the Nevada Division of Environmental Protection think the suspect sample might have been contaminated because of a crack in the tap from which the water was drawn.

Division spokeswoman Jill Lufrano said the tap was replaced, and three more samples were taken: one from the same spot and one each from locations "upstream" and "downstream." None of the follow-up tests showed any trace of the bacteria.

"It was addressed immediately," Lufrano said. "There was no risk to the public. It didn't even come close."

According to state records, the incident was the first time E. coli has shown up in a district sample in at least five years. That is one time out of roughly 22,800 water samples, Lufrano said.

"In a district of that size, it is not unusual for a sample to come back positive once in a great while for E. coli or another contaminant," she said.

Pat Sampson, water quality and maintenance engineering manager for the district, said such positive results are extremely rare.

"We've got some of the most sophisticated technology in the world out at our treatment facility. It's state of the art," Sampson said.

The district draws more than 380 water samples each month from almost a thousand different locations throughout its distribution system.

The E. coli sample came from a sampling station at a residence near Main Street and Washington Avenue in downtown Las Vegas.

With traces of the bacteria, the lab also found chlorine left over from the water treatment process. "That means the water wasn't compromised," Beuhrer said.

The positive E. coli test is mentioned only once, and with no real explanation, in the district's annual water quality report.

The 12-page report is a summary of tests conducted last year for several contaminants, some federally regulated, some not.

Water delivered by the district continues to meet or exceed all standards set by the federal Safe Drinking Water Act, according to the report.

The results for 2008 varied only slightly those reported the previous year.

About 90 percent of the valley's water comes from Lake Mead. The regulated contaminants most commonly found in local tap water are byproducts of the water treatment process.

"The overall message is that we test for everything that's required and some that are not. We not only do the minimum that's required; we far exceed that," Sampson said.

Federal regulations require water utilities nationwide to report their water quality test results by July 1 of each year.

The water district sent almost 500,000 copies of its annual report. Any district customer who has not received one can call 258-3930 or check out the report online.

Contact reporter Henry Brean at hbrean@reviewjournal.com or 702-383-0350.