Study finds water in Las Vegas Wash contains pesticides

Art Nadler

Monday, Dec. 14, 1998 | 11:05 a.m.

A newly released U.S. Geological Survey study found that water entering the Las Vegas Wash and downstream ground sediment contained trace amounts of pesticides.

Unfortunately, no one, including the Environmental Protection Agency, seems to know the precise effect of the chemicals on humans, an EPA official said.

The study was conducted at 14 sites in the Las Vegas Valley in 1997. Concentrations of 25 synthetic organic compounds, including pesticides, were discovered in water flowing into the Las Vegas Wash. Another 51 compounds were detected in the sediment.

The Las Vegas Wash drains into Lake Mead. Drinking water is drawn from the lake six miles from the wash drainage.

The pesticides have been attributed to the Las Vegas Valley's urban growth. Four insecticides and four herbicides were detected in samples collected from the Las Vegas Wash. Traces of the pesticide DDT were found in sediments near the mouth of the Las Vegas Wash in the Las Vegas Bay.

The Las Vegas Valley encompasses an area of about 1,640 square miles.

Kenneth Covay, a hydrologist with the geological survey and co-author of the study, said the pesticides were more than likely coming from runoff from golf courses and residential home lawns. He said he didn't think the pesticide amounts posed any danger to the general population.

"It's something we should keep an eye on and see if the concentrations vary," Covay said. "Most urban areas would have pesticides and related compounds" in their water sources.

Allen Biaggi, administrator of the Nevada Division of the Environmental Protection Agency, agrees that urban growth is creating a problem with water resources throughout the nation.

While environmentalists can take action against a "point source" of pollution, Biaggi said, such as a drainage pipe leading from a factory, it's difficult to act on pollution that has no apparent single source.

The geological survey said that more than 600 million pounds of pesticides are used each year in urban and agricultural areas. Rapid population growth and changes in land and water use, the study said, are to blame for the contamination of water resources by pesticides.

The only thing that can be done at this time, Biaggi said, is to educate people about using too many pesticides on their lawns and to properly dispose of pollutants -- such as old motor vehicle oil, antifreeze, Freon, etc.

"If it (pesticide concentrations) gets bigger, they could have an impact on fish," Biaggi said. "They should not be there, but at the same time, it's not unusual around urban areas. There are no standards now that constitute a problem in sediment levels."

Concentrations of the synthetic organic compounds were greater in the Las Vegas Wash and Bay. Calville Bay, an up-reservoir site, was less contaminated.

The 14 sampling sites tested that enter the Las Vegas Wash included:

* The Las Vegas Wash below the Flamingo Wash near Las Vegas.

* City of Las Vegas sewage treatment plant.

* Clark County sewage treatment plant.

* City of Henderson sewage treatment plant.

* Las Vegas Wash above Three Kids Wash below Henderson.

* Las Vegas Wash at Owens Avenue.

* Las Vegas Creek above Las Vegas Wash.

* Flamingo Wash at Swenson Street.

* Tropicana Wash at Swenson Street.

* Duck Creek at Patrick Lane.

* Upper Flamingo Wash detention basin.

* Angel Park detention basin.

* North Las Vegas detention basin.

* Kyle Canyon detention basin.

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