Birds blamed for bacteria in Las Vegas Wash

Friday, April 12, 2002 | 9:51 a.m.

University of Nevada, Las Vegas scientists have pinpointed the source of a common bacteria in the Las Vegas Wash: bird droppings.

A study discovered 500 organisms in the samples of wash water taken in February and August 2000 -- among them streptococcus bacteria, a harmless form that does not cause strep throat.

Researchers originally suspected that the bacteria was coming from Las Vegas Valley sewage treatment plants and were relieved Thursday when it was announced during a Lake Mead Water Quality Forum meeting that the source was only birds.

However, scientists could not trace the origin of traces of human strep found in the samples. Two possibilities, they said, were homeless people or the 16,000 septic tanks buried throughout the Las Vegas Valley.

There is no danger to public health because the natural flow of the Colorado River into Lake Mead removes potential contaminants, scientists said.

Allen Biaggi, administrator of the Nevada Environmental Protection Division and chairman of the forum, said bacteria seeping from septic tanks is a common problem in Northern Nevada and other areas of the country.

By the time the Southern Nevada Water Authority treats the lake's waters for drinking, the organisms are killed, he said.

Federal, state, local and university scientists have spent four years studying Las Vegas Wash and Lake Mead after the rocket fuel booster perchlorate, pesticides and other chemicals were discovered in the lake, the major drinking water source for the Las Vegas Valley, Arizona and Southern California.

UNLV professors Penny Amy, David James, Tom Piechota and Jacimaria Batista have studied the wash's water for two years to find out the extent of nutrients that feed algae, chemicals and bacteria in runoff and treated sewage.

The three major treatment plants in Clark County, Las Vegas and Henderson contributed virtually no bacteria or phosphorous to the waters, they said.

In one study of phosphorous -- a nutrient that helped create the green algae bloom in Lake Mead last year -- the scientists found that roads, parks and golf courses contributed the highest levels of the chemical, almost two-thirds of the amount in the wash.

Phosphorous is carried on dust particles from roads and fertilizers into gutters and gullies that feed the wash.

This year the conditions in the wash and the lake should not produce an algae bloom, the scientists said.