Rural areas wetter than expected

Tuesday, July 10, 2001 | 10:06 a.m.

A new study by the U.S. Geological Survey shows that more ground water may be available in 16 valleys of eastern Nevada than previously thought.

The new methods of measuring ground water -- using satellite technology -- shows promise for more accurately estimating how much water is available underground in the nation's driest state, a federal hydrologist said.

But officials warned it is too soon to tell whether the federal study would allow Southern Nevada water officials to draw more from underground resources to supply the Las Vegas Valley.

The study found an extra 30,000 acre-feet in the 16 valleys studied, USGS hydrologist Gary Russell of the Nevada district office said. The latest USGS estimates are taken from data collected more than 60 years ago.

"We feel it is fairly significant," Russell said today.

However, the state has 232 ground water basins, Russell and other scientists said, and some of them could show considerably less ground water available. The USGS wants to measure all of the basins, but the Nevada Legislature did not supply the money in 1999 and this year.

The new study estimates total annual recharge from rain and snow in the 16 valleys at 855,000 acre-feet, roughly twice the quantity of ground water estimated in the late 1940s through the 1960s. An acre-foot of water can supply a family of four for a year.

The rate of evaporation each year is about 790,000 acre-feet, again twice the quantities estimated earlier. But even with the greater evaporation, the valleys showed about 30,000 more acre-feet of water than the previous studies.

Satellites, which became available in the 1990s, collected information on native desert plants with deep roots, which obtain most of their moisture from ground water. The USGS also developed equations for estimating ground-water evaporation through the plants.

In addition, the USGS did new measurements on water levels in wells.

The USGS study was done in cooperation with the Las Vegas Valley Water District and the Nevada Division of Water Resources.

The water district asked the state engineer in 1989 to secure unallocated water rights in rural valleys near the Nevada-Utah border to supply Southern Nevada's explosive growth. It does not have such requests for any of the valleys studied in the newest report.

A hearing is expected on some of the claims later this year.

Ground water is the main source supplying rural communities in 232 valleys throughout Nevada, unlike Southern Nevada, which draws most of its supply from Lake Mead.

When the water district applied for rural ground water in counties as far away as White Pine, in northeastern Nevada, residents of those areas said they would fight to keep their resources for future development.