By Mark Waite
Nye County Water Board directors Monday voted to send a letter to the California Energy Commission endorsing the BrightSource Energy project for its frugal use of 140 acre feet of water for a 500-megawatt solar plant at the Hidden Hills Ranch on Tecopa Road.
But at the request of water board member Donna Lamm, they suggested BrightSource purchase two or three acre feet of water rights for each acre foot used on the project and retire them to the state engineer’s office.
Lamm said the water board is missing the boat if they don’t insist on retiring water rights, particularly after recent comments by the state engineer about the over-appropriation of water in the Pahrump Valley. She said the price of water rights is historically low, making it easier for BrightSource Energy to purchase them.
The solar project is planned just across the California state line, but water board members said the mitigation impacts affect Nye County. Officials say concerns abound about federal or out-of-state agencies adjudicating issues over Nye County water availability without including the water board or appropriate agencies on this side of the state line.
“This is one thing we can do to try to get the balance back in the basin somewhat. It’s not huge, but I just don’t think there’s going to be many opportunities like this to bring it back into balance a little and it would be showing good faith with the state engineer,” said Lamm, who is also acting executive director of the Amargosa Conservancy.
Nye County Water Board General Manager Darrell Lacy said by contrast, SolarReserve will use 600 acre feet of water to generate 110 megawatts of power at its Crescent Dunes solar project just outside of Tonopah. BrightSource Energy will mitigate more than 90 percent of its water use by spending millions on dry cooling and other water saving technology, he said.
The water board letter criticizes as draconian a plan by the California Energy Commission to trigger mitigation measures based on a drop of six inches in the water table over the 30-year project.
“Any action based on a six-inch drop cannot be justified from existing water data and models,” the county letter states. By contrast the water level data from Stump Springs shows a two-foot annual seasonal variation and an eight-foot variance over 10 years, mostly from a wet year in 2005. Stump Springs is two and a half miles from the project.
Groundwater modeling by a Nye County consultant predicted the pumping from the solar project would cause a water level decline at Stump Springs of only two inches after pumping 280 acre feet of water per year for three years and a two-inch decline after 27 years for pumping 140 acre feet.
An acre foot of water is the amount of water needed to fill an acre of water one foot deep, or enough to supply two families of five for one year.
The Nye County letter adds additional data is required to characterize groundwater flows across the State Line fault system. The fault indicates geologic separation between Stump Springs and the solar project site, the county said, thus conclusions on impacts at Stump Springs are merely speculative.
The water board letter also criticized the misinterpretation of a U.S. Bureau of Land Management strategy in 2006 for protecting mesquite woodlands by keeping groundwater levels 35 feet or shallower. Mesquite trees aren’t threatened or endangered. The study notes large, dense mesquite woodlands create a unique ecosystem, which serves as a shelter for several species of migratory birds, such as the Phainopepla.
The BLM study was followed up by the designation of the Stump Springs and Ash Meadows Mesquite Areas of Critical Environmental Concern. There is no data to suggest 35 feet is a depth of any special significance that would trigger an adverse impact on the health of mesquites, the county states.
“Mesquite trees themselves are quite plentiful in fragmented stands and watersheds throughout the Pahrump Valley. Aerial photographs over the last 60 years show an increase in mesquite coverage but these are typically small trees, not in dense stands and are predominantly found in washes, sand dunes and escarpments,” the county states.
County officials say water withdrawal for the BrightSource Energy project wouldn’t affect the mesquite trees closest to the site. Mesquite woodlands in the Pahrump area that have been designated an Area of Critical Environmental Concern are primarily in areas of shallow groundwater, like Stump Springs, the county states, where water is at or near the surface and wells are 26 to 27 feet below the surface.
“There’s been a lot of what if’s and speculation that pumpage might have an impact on that site. I think it should be our approach that any mitigation should be based on good science,” Lacy told the water board. “There’s been a lot of discussions about impacts on mesquites that don’t even have any connectivity to the water table.”
The California Energy Commission will hold evidentiary hearings on the BrightSource Energy project beginning at 9 a.m. from March 12 through March 15 at the Death Valley Academy Gymnasium at 127 Old State Highway in Shoshone, Calif.