Farming in Callao

Thursday, September 28, 2006

Overview of the Las Vegas water exportation scheme

Las Vegas and other cities in southern Nevada are running out of water. Back when the Colorado River was divided in the 1920's sparsely-populated Nevada got a very small share of water. It was no problem when they were just a railroad town but following World War 2 the population began increasing dramatically. In the 1980's through currently it exploded.

Because of the decade-long drought and dangerously low water levels in Lake Mead -- and given the unnaturally high growth rate -- southern Nevada is projecting to be out of water by 2013 - 2016. Not wanting Nevada to take the Colorado River Compact to court looking for more water there, the other six Colorado River states suggested Nevada to look to instate groundwater resources for southern Nevada's needs.

In 1989 the Southern Nevada Water Authority (SNWA) applied for nearly 200,000 acre feet per year of groundwater from rural Nevada basins in Lincoln and White Pine Counties. These applications were on hold for 16 years until the drought caused a reawakening of interest in them.

Two valleys in particular are of concern to rural Nevadans and Utahns. Spring Valley is the key to SNWA's water export plan. They have half of their water rights applications there -- 91,000 acre feet. Spring Valley is completely in Nevada. Snake Valley, straddling the Utah-Nevada border, will involve an interstate transfer of water as well as an interbasin transfer. SNWA has applied for about 51,000 acre feet but says only 25,000 acre feet will be pumped in any year.

Snake Valley is home to the Great Basin National Park (in Nevada) and Fish Springs National Wildlife Refuge (in Utah). Roughly 70% of the Snake Valley aquifer lies in Utah and 90% of the current aquifer usage in Utah. Approximately 60% of the recharge comes from snowpack in the mountains on the Nevada side of the border.

Because of local agricultural pumping and the drought (the same one that has southern Nevada looking for new sources) springs in Snake Valley have dried up. Local use, however, is only a small fraction of what SNWA wants to pump so local ranchers and conservationists expect the water table to drop significantly if SNWA plans are executed, resulting in even more springs drying and the destruction of habitats for sensitive species such as the least chub, Columbia Spotted Frog, and Bonneville Cutthroat Trout.

The Utah Geological Survey reported in early 2005 that SNWA pumping likely would lower water tables in Garrison, Utah more than 100 feet resulting in key springs drying and reversal of normal groundwater flows. In 2006 the United States Geological Survey (USGS) studied Great Basin National Park and identified several streams and springs at risk if pumping begins.

SNWA claims to be able to pump from two aquifer systems. One is the relatively shallow, alluvial aquifer from which the local farmers irrigate. The other is a much deeper, carbonate aquifer which was originally filled as ice age glaciers melted and Lake Bonneville desiccated. These valleys are not very well understood and have not been tested under the stress of such massive pumping as SNWA proposes.

So residents of Spring and Snake Valleys, along with a coalition of environmental, sport, and ranching organizations have opposed the SNWA scheme until better science is available. The USGS currently is working on a study that will better determine amounts of water and flow patterns. But it will not study the effects and impacts of pumping.

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