Protection of well water major valley concern

Friday, May 16, 1997 | 11:59 a.m.

While Lake Mead supplies most Las Vegas Valley drinking water, many homes and industries rely on groundwater, a hidden treasure in the desert that well owners want to protect.

If the Legislature approves Assembly Bill 436, in its first hearing today before the Assembly Committee for Government Affairs, Southern Nevada water officials will spend the next two years planning how to protect well water from contamination and overuse.

Las Vegas residents will hear about groundwater through an education program designed to reach elected officials as well as ordinary citizens.

For Bill Starkey, Sheep Mountain Homeowners Association member and the chairman of a 20-member groundwater committee that met for more than a year before producing the proposed legislation, the panel's guiding statement says it all:

"The primary aquifer that provides potable water in the Las Vegas Valley is a valuable, finite resource that needs to be protected from both overdrafting and potential sources of contamination."

Most people don't realize that groundwater was the major source of drinking water for Indian tribes, early pioneers and those who founded Las Vegas, said Kim Zikmund, a hydrologist with the Southern Nevada Water Authority.

But between 1945 and today more than 7,000 wells in the valley supplying homes, hotels and businesses managed to draw more water than rain and snow falling in the Spring Mountains west of Las Vegas could replenish.

A well watched by the U.S. Geological Survey near Floyd Lamb State Park plummeted in the past 50 years, the record shows.

The valley's wells used 72,000 acre feet of water out of the ground last year, according to Kay Brothers, director of SNWA's resources department. An acre foot of water supplies a family of five with enough water for a year.

But the mountain rains and snows replaced roughly 35,000 acre feet, she said.

The water authority has placed 120,000 acre feet of Lake Mead water underground during winter months since 1987, Brothers said, in an effort to deliver drinking water to the valley during the demands of the hot summer months.

Officials have watched levels rise up to four feet with the recharge, but it's not enough to stop subsidence where the valley floor has dropped up to 100 feet in some places, she said.

It costs $210 per acre foot to bank the water underground in the valley, and the water, if it isn't used, won't stay there, Brothers said. "Water moves to the lowest point, and the west side of the valley isn't the lowest," she said. All the valley's water eventually runs into the Las Vegas Wash.

Another threat to well water comes from contamination, either infiltrated from the surface or leaked accidentally from underground septic systems and buried tanks.

Gasoline and motor oil, pesticides and septic tanks can seep or leach through the ground, reaching the water there.

SNWA will inventory Southern Nevada wells, working and abandoned, if the legislation passes, Brothers said.