Federal regulators are nearing final approval of a commercial solar power plant in California's Colorado Desert that has undergone extensive revisions, including new plans to use treated wastewater for cleaning solar panels rather than tap the desert's dwindling aquifer.
The Bureau of Land Management last week issued a final environmental impact statement (EIS) outlining mitigation steps Tessera Solar North America must take to protect wildlife and water resources at its proposed $2.2 billion Imperial Valley solar-thermal power plant near El Centro.
The 709-megawatt plant is to occupy 6,140 acres of BLM land and is the largest solar project to reach the final environmental permitting stage, according to BLM. At full capacity, the Imperial Valley plant could power more than a half-million homes and businesses in Southern California, including portions of the San Diego metro area.
The project is one of nine commercial-scale solar projects in California that the Interior Department has placed on a fast-track permitting schedule. Projects that break ground by the end of 2010 can qualify for lucrative grants under the American Recovery and Reinvestment Act.
Three other fast-tracked solar projects -- BrightSource Energy Inc.'s 392-megawatt Ivanpah Solar Energy Generating Station, Chevron Energy Solutions' 45-megawatt Lucerne Valley Solar Project, and Tessera's 850-megawatt Calico Solar plant, all in San Bernardino County -- are expected to receive final environmental reviews this month.
A record of decision authorizing construction of the Imperial Valley plant is expected by the end of September, said Jim Stobaugh, a BLM national project manager in Nevada who is overseeing the project.
But the proposal has undergone significant design changes since February, when BLM issued its draft EIS for the project.
Most significantly, Tessera Solar has agreed to alter the plant's layout to avoid constructing solar panels in dry streambeds that are significant for groundwater recharge and flood control, Stobaugh said.
The change will reduce Tessera's projected 30,000 dish panels -- called "SunCatchers" -- by about 1,700 and lower the plant's generation capacity by 41 megawatts from the original 750-megawatt blueprint, according to the final EIS.
Officials at Tessera Solar, based in Houston, did not return calls seeking comment on the revised project or BLM's final EIS.
Nevertheless, the modified version of the project is now BLM's "preferred alternative," Stobaugh said. "This is really just the company taking the proposed action and modifying it to avoid some major environmental impacts," he said.
But Tessera Solar's revisions may still place the plant at odds with environmental groups that have credited the company for committing to use treated wastewater in a region where groundwater supplies are scarce.
To meet the plant's estimated 10.6 million gallon demand for water to wash solar panels, Tessera has agreed to build an 11.8-mile pipeline to the nearby city of Seeley and transport treated wastewater to the desert plant site. The company would pay to make major upgrades to the city's wastewater treatment system to ensure the water meets federal standards, including covering training costs for the sewer plant's staff to operate new treatment and disinfection equipment.
The problem: The sewer plant upgrades will not be ready during plant construction and potentially not even during the first year or more of operation, according to the final EIS.
Tessera has proposed an interim solution that would involve purchasing water from a 560-foot-deep private well in nearby Ocotillo, Calif., and transferring the water in 7,000-gallon trucks to the plant about 13 times a day during construction and seven times a day during plant operation, according to the final EIS.
The company has asked BLM and the California Energy Commission for permission to use this alternate water resource for up to three years.
That has raised the concern of some local environmentalists worried about impacts to the Ocotillo-Coyote Wells groundwater basin -- a sole-source aquifer that supplies water to nearby residents.
Edie Harmon, a member of a Sierra Club task force studying the impacts of renewable energy development on California's deserts, said years of U.S. Geological Survey data show the groundwater table is shrinking.
"I wish I could look at the groundwater data and not feel threatened," said Harmon, who spoke as a longtime Ocotillo resident since the Sierra Club has not taken a formal position on the Imperial Valley project. "Even if it's only temporary, I still believe it could have a big impact on the groundwater basin."
A dwindling aquifer
The groundwater-use proposal has also drawn scrutiny from the California Energy Commission, which has advocated placing strict limits on withdrawals to protect against long-term supply problems.
In a "supplemental staff assessment" of the project issued last month, the CEC reported that its analysis "showed that water levels and groundwater storage will decline as a result of the proposed projects' water use" by as much as 6 feet a year.
Though that amount is "fairly small" compared with the overall supplies in the basin, CEC staff noted that water depletion "cannot be mitigated and is therefore considered a significant negative impact to the basin."
The state also raised the possibility that the use of the Dan Boyer Water Co. well in Ocotillo might not be temporary, noting that the Seeley sewer plant upgrades have not even been permitted and that until they are completed, the use of treated wastewater at Imperial Valley "is not a firm, existing supply."
Stobaugh, the BLM project manager, declined to estimate how long the Imperial Valley project would use the groundwater. And the CEC analysis noted, "it is unclear when water would be available" from the Seeley plant.
CEC will require the Imperial Valley plant to use no more than 11 million gallons of groundwater a year "in order to ensure that local residents do not lose their water supply," according to the state assessment. And BLM will require Tessera to install monitors to track the amount of groundwater used and submit regular water-use reports to regulators, according to the final EIS.
As long as the 11 million gallon limit is upheld, the CEC staff concluded, "the expected water level decline from project groundwater consumption is too small to significantly affect existing well yields."
Tessera Solar, which has won praise for siting the Imperial Valley plant on lands that include 1,039 disturbed acres of BLM holdings, has taken some major steps to mitigate impacts to sensitive wildlife species.
The chief concern is the flat-tailed horned lizard, which the Fish and Wildlife Service is considering listing as an endangered or threatened species.
Much of the 6,140 acres of federal land and a 300-acre parcel of private land would be graded to make way for the solar power systems. To mitigate the "permanent loss" of flat-tailed horned lizard habitat, Tessera has agreed to purchase 6,619 acres, conduct surveys and studies to determine suitable sites, and pay for the long-term management of the sites.
The total cost of mitigation could run to $12.2 million, according to the final EIS.
Tessera has also agreed to put up fences and gates to keep out rare peninsular big horn sheep that forage in the area. And the company will place netting over two 2.5-million-gallon evaporation ponds to keep away birds that prey on flat-tailed horned lizards.
Jeff Aardahl, a biologist and the California representative for the Defenders of Wildlife in Sacramento, acknowledged Tessera's work to mitigate biological impacts. But he said the group remains concerned about the cumulative impacts to the flat-tailed horned lizard.
"Certainly, this project doesn't help" ongoing efforts to keep the lizard off the Endangered Species List, Aardahl said.
Instead, he said, environmentalists want BLM to steer developers to already-disturbed areas as they consider solar and wind power applications covering roughly 1 million acres of California desert.
"It seems to me that given enough time, there are places in the Imperial Valley that would be much more suitable for such a large-scale solar plant rather than on mostly undisturbed desert land that supports such a wide range of species," Aardahl said. "We want it moved to a place where it's already disturbed. We think there is enough degraded private land to support a lot of renewable energy development."
Click here to read the final EIS.
Streater writes from Colorado Springs, Colo.