SNWA's lawyers contend King's decision is nuanced, requiring the rights to be phased in over 16 years with careful monitoring. Staged development would allow withdrawals to be adjusted if it becomes apparent the pumping causes impermissible impacts.
"The state engineer saw the benefit of making this unused water available for use, but balanced that benefit with a measured, careful approach to allowing water development," the water authority wrote in its brief. "GBWN and other protestants make emotionally charged arguments against the groundwater project, but they cannot back them up with evidence."
Other petitions seeking to invalidate SNWA's water rights include Utah's Juab and Millard counties, various tribal interests, and The Church of Jesus Christ of Latter-day Saints, which operates the 4,000-acre Cleveland Ranch in the northern part of Spring Valley. The cattle operation, which supplies beef to the church's Welfare Service Department, is concerned groundwater pumping could deplete its springs.
The struggle began 24 years ago when water agencies serving Nevada's fast-growing Clark County applied for rights to appropriate water from under 26 rural basins, including Snake Valley on the Utah state line, and the four Nevada valleys at issue in this week's court battle Spring, Delmar, Cave and Dry Lake.
Las Vegas water honchos say they need to pump distant groundwater because Nevada does not get a fair share of the Colorado River's prodigious flow, forcing the desert metropolis to look for untapped sources to the north and underground.
The Bureau of Land Management last year granted rights of way to construct a $15 billion, 285-mile pipeline connecting these basins with Las Vegas. While the Snake Valley is not technically at issue in the case, Utah interests are tracking it because Snake and Spring valleys are connected hydrologically.
In March 2012, after hearing from 84 witness in a six-week hearing, King overruled the objections of rural residents and conservationists. He awarded the water authority rights to 84,000 acre-feet, mostly from Spring Valley about 21,000 acre-feet less than Vegas wanted.
Critics of the water project believe King's monitoring requirements lack sufficient teeth to actually protect the valleys. After Las Vegas builds an 8-foot-diameter pipeline, there will be enormous economic pressures to fill it with water.
"It's one of those 'If you build it, they will come' things. Once you get a population dependent on a water source, how are you going to withdraw that from them?" asked Steve Erickson, a Salt Lake City conservationist on the Great Basin Water Network's board. Spring Valley groundwater flows to the northeast, while Cave, Dry Lake and Delmar groundwater flows south toward the over-allocated Colorado River.
"It's ancient water, so this is a temporary fix," he said. "Over the longer time, it is not going to supply the water."