SALT LAKE CITY — A hydrologic study commissioned by the Utah Legislature seven years ago concludes any significant groundwater development in Snake Valley and adjacent areas is not sustainable and even current pumping is drawing down the aquifer.
The study, released Thursday, compiled data from a monitoring network developed by the Utah Geological Survey that includes wells placed in farm land, ranching areas, springs and at remote sites. A total of 76 wells recorded water levels hourly and six sites featured spring flow gauges.
“The time and resources committed to this study delineates groundwater levels, flow and chemistry in Snake Valley and adjacent basins to a much greater degree than was previously possible,” said Hugh Hurlow, senior scientist for the survey's groundwater and paleontology program. “With pressure to develop groundwater in west-central Utah and east-central Nevada likely to continue, we needed to understand how future development and groundwater use was going to impact Utah residents and natural resources.”
A proposed groundwater development project sought by Southern Nevada Water Authority in eastern Nevada propelled the need for the study for fear that tapping the water on the Nevada side of the valley would impact Utah ranchers and families. There are several ranching communities in the West Desert basin, including Eskdale, Trout Creek and Callao.
In 1989, the water district filed applications for water rights in Snake Valley and four other hydrologic basins in Nevada, seeking to appropriate as much as 185,000 acre-feet of water to Las Vegas and surrounding communities.
Facing a protracted drought and hemmed in by a 90-percent dependency on the Colorado River for its water, the district has turned to other geographic regions of the state and groundwater as a way to meet its water needs in the future.
Simeon Herskovitz, an attorney who has represented multiple groups and individuals suing Nevada over the issue, praised the report's findings and said it should be evidence enough to compel the Southern Nevada Water Authority to back off its groundwater pumping plan.
Over the years, competing studies have led to contradictory conclusions about the amount of water available in the underground reservoirs and the Nevada state engineer has been rebuked by the court rulings asserting more analysis needs to be done before any project goes forward.
Utah, in the interim, has been compiling its own data, with this report laying the most definitive blueprint to date. The study found that current groundwater use in Snake Valley is slowly depleting the basin-fill aquifer and that even present pumping rates will continue to lower groundwater levels and reduce the flows of springs.
More ominously, the study showed that future water development and increased pumping in Nevada or Utah would significantly increase the rate and scope of groundwater level decline.
Additional pumping for local agriculture use, or export from the area would harm springs and shallow groundwater that supports habitat of sensitive species and vegetation used for grazing.
Hurlow said researchers also found that the shallow basin-fill aquifer and deep carbonate rock aquifers are connected, meaning increased pumping could cause a draw down on both, potentially impacting valleys beyond Snake Valley.
“Groundwater pumping would affect environmental conditions and current and future groundwater use in Snake Valley,” Hurlow said. “Taken together, the proposals for groundwater development in the region exceed the groundwater available for development. The current ecosystem would be negatively impacted by all but small levels of additional pumping.”
The district's orignal plan requested more than 50,000 acre-feet of water per year in Snake Valley and over 90,000 acre-feet per year in in Spring Valley, immediately west of Snake Valley in Nevada.
Legal challenges have the project on hold, and a proposed groundwater sharing agreement inked between Nevada and Utah remains in limbo after Utah Gov. Gary Herbert refused to sign it.