10-year plan to improve water quality proposed

Wednesday, Aug. 18, 1999 | 11:27 a.m.

It's time Lake Mead got the kind of respect that Lake Tahoe does, State Sen. Jon Porter says, and he's working to develop a 10-year plan to improve the water quality in the nation's largest man-made reservoir -- an effort that would also improve the quality of the drinking water in the Las Vegas Valley.

A summit at Lake Tahoe lead by President Clinton and Vice President Al Gore in 1998 triggered a 10-year plan to save the deteriorating quality of Tahoe's sky-blue waters.

"I think it's time to elevate Lake Mead as our national treasure," Porter, R-Boulder City, said. Lake Mead provides drinking water to 25 million people in Nevada, Arizona and California as well as offering recreation to more than 10 million visitors a year.

Teaming up with Sen. Harry Reid, D-Nev., Porter said he is committed to a plan that lays out who is responsible for solving the problems in Lake Mead and what needs to be done.

While Porter credited the work of the state and local water officials serving on the Lake Mead Water Quality Forum and the Las Vegas Wash Coordination Committee, he said a coordinated approach is necessary to solve concerns.

"In Lake Tahoe people live around the lake so the awareness is there daily," Porter said. "At Lake Mead visitors come and go, but it's not like we're living there and noticing problems every day."

One of the big concerns about the water of Lake Mead is the quality of the runoff flowing into it daily from the valley through the Las Vegas Wash. A a plume of pollution has developed in the wash where it meets the lake consisting of insecticides, chemicals, bacteria and other pollutants.

The plume itself does not threaten the quality of Las Vegas Valley drinking water because the water drawn from Lake Mead into treatment plants is six miles downstream from the runoff and 150 feet beneath the surface. The plume usually flows 30 feet below the surface and has been tracked as far as Hoover Dam, a distance of roughly 12 miles.

However, when the Colorado River runs low or a flood such as one on July 8 sweeps animal and human feces from the valley's surface, bacteria that scientists are finding in the plume thrive and could threaten swimmers, scuba divers, boaters and eventually the drinking water supply.

Scientists are acting like detectives, studying water in the Las Vegas Wash where it enters Lake Mead in an effort to understand where bacteria come from and how they grow.

The mystery was discovered by Bureau of Reclamation researcher James LaBounty and other experts who started tracking the plume nine years ago. "It is literally a river running within the lake," LaBounty said.

The U.S. Geological Survey has studied water quality in Lake Mead as part of a nationwide effort. The survey's study revealed pesticides, insecticides and traces of other chemicals. Then perchlorate, a rocket fuel oxidizer, was detected in the lake's water in 1998.

Bacteria and perchlorate are of particular concern for those who swim, boat or bathe in the lake and for certain times of the year for Southern Nevada Water Authority officials who deliver drinking water, LaBounty said.

The bacteria puzzle scientists, who want to know how they manage to survive in the wash's water. While the chemicals in the water may take years to affect fish, birds, plants and animals, bacteria can cause immediate illness, even death.

Southern Nevada suffered a cryptosporidium outbreak in 1994 that killed 43 residents. The worst crypto outbreak in the U.S. came in 1993 when 100 residents of Milwaukee died and another 4,000 became ill from the organism.

The Centers for Disease Control and Prevention in Atlanta investigated the Southern Nevada outbreak of cryptosporidium and concluded it spread through drinking water and sickened 132 residents in addition to the deaths.

Although no active crypto cells were discovered in the Las Vegas drinking water supply, the CDC concluded the illness spread through one of the world's most modern treatment systems. The hardy, one-celled organism is not killed by chlorine, the major disinfectant used to protect drinking water.

The Southern Nevada Water Authority is spending millions to protect the water supply, adding ozone treatment to the plants by 2002 to destroy organisms such as cryptosporidium and giardia.

Yet for people who come in contact with the waters of Las Vegas Bay while at play, scientists are still searching for answers because bacteria enter the wash from surface runoff, which is not treated.

UNLV scientists began to investigate the bacteria problem on a $40,000 shoestring grant from the university and the Nevada Division of Environmental Protection last year. They discovered streptococcus in water and sediment samples.

The theory of where the streptococcus came from includes a wide range of sources, including the discharges from sewage treatment plants upstream of the wash and bay, surface runoff containing animal feces or wildlife droppings and the homeless population living along tributaries to the wash.

Strep may come from people, pets or any warm-blooded creature living in the valley. Scientists look for a total of fecal coliforms, containing bacteria and streptococcus.

UNLV engineering associate professor David James teamed up with microbiologist Penny Amy to identify the source of the strep.

Streptococcus indicates other bacteria may be growing in the water. "Strep is everywhere," Amy said on a recent trip to the Las Vegas Wash to sample water, plants and sediments. People carry strep around inside their bodies, protected by their immune system. If an individual's defenses break down, she said, it creates a perfect host for a serious infection to thrive.

The research to explain why strep survives in the wash and Las Vegas Bay waters is exactly what the university does best, Amy said.

"Everybody is testing the water," she said, referring to the federal, state and local scientists monitoring the wash and lake to protect the drinking water, "but this is applied science to answer the question why it happens."

While tests of water flowing from treated sewage appears to contain low numbers of bacteria, why they continue to grow in the wash waters is the ultimate question to answer, Amy said.

The strep may simmer in the sediments, until a flood or a surge flows through the Colorado River, stirring the bacteria to life in the warm wash waters.

Or it may regrow from discharges into the warm waters of the wash and bay. Since the water in the wash is salty and its temperature is similar to a mammal's intestine, that may encourage it to live. "Any time they have nutrients, they will grow," Amy said.

In order to discover the answer to this mystery, graduate microbiology student Angela Rosenblatt, who also works at Henderson's water treatment plant, will try to regrow strep under controlled conditions inside the laboratory over the next year. Amy is her academic adviser.