A seemingly benign Consent Agenda item inspired passionate remarks at the April 16 Mammoth Lakes Town Council meeting. The item in question: approval of a letter in support of the Mammoth Community Water District’s (MCWD) concerns regarding the potential impact of the proposed Casa Diablo IV Geothermal project to the Town groundwater supply.
Last September, MCWD presented its case against the proposed Ormat, NV Casa Diablo IV Geothermal Development project. The project would include the construction of a new 40-megawatt geothermal power plant, up to 16 new production and injection wells, multiple pipelines, and an electric transmission line.
Particularly troubling to MCWD is that water use at the proposed plant would increase from the current 19,000 acre-feet to about 29,000 acre feet per year. This water would be extracted from production wells located in the Basalt Canyon area, many in close proximity to MCWD groundwater supply wells.
MCWD currently extracts about 2,000 acre-feet of groundwater per year from the coldwater aquifer above the geothermal aquifer, according to Mark Wildermuth of Wildermuth Environmental Inc., a specialized water resources consulting firm. This is enough to supply more than 70 percent of daily water use in Mammoth.
As Wildermuth explained in September, MCWD extracts cold groundwater from fractured rock known as an aquifer using wells that range from 400-700 feet deep. Beneath the coldwater aquifer is an area of warm water, and beneath that an area of hot, geothermal water.
The Casa Diablo IV geothermal wells, which would range between 1,500-2,000 feet deep, would tap into this geothermal aquifer. Because the condition of the rock between the two aquifers is not well understood, it is possible that extracting geothermal water below the coldwater could have a detrimental effect on coldwater supply, Wildermuth explained.
Ormat’s extraction of geothermal water from below the coldwater aquifer could reduce pressure created by the hotter water, allowing cold water to migrate down through the fractured, permeable rock into the geothermal zone.
Sufficient pressure in the geothermal zone, which may be released when Ormat begins drilling, could also push the geothermal water upward, deteriorating the cold groundwater quality beyond MCWD’s ability to mitigate.
At Wednesday’s Town Council meeting, MCWD Manager Pat Hayes reminded Council that the two District wells closest to the proposed geothermal wells, one at Sam’s Wood Site and one at the Water District headquarters, are already heating up, perhaps as a result of current Geothermal Plant operations.
This could be evidence of connectivity between coldwater and geothermal zones.
Last year, MCWD requested that the U.S. Forest Service (USFS) and Bureau of Land Management (BLM), project leads for the National Environmental Policy Act (NEPA) documents, require stress tests and a mitigation plan, should a stress test determine that the Casa Diablo IV wells are having a negative effect on Mammoth’s groundwater supply.
Hayes said the reservoir model created by Ormat’s scientists showed no connectivity between the coldwater and geothermal zones. Both the USFS and BLM approved the NEPA documents in only seven days, without requiring any testing or mitigation plan, he said.
“After two years of environmental review, what remains true is that these documents remain inadequate,” Hayes said Wednesday night.
“Alternative energy is something that’s very good for this community, and for the country, and we want that,” added MCWD Board member Tom Cage. “But I’ve never seen anything go through the Forest Service that quickly.”
“It’s a fast-tracked project,” Hayes said.
To date, he added, Ormat has not agreed to MCWD’s request for two monitoring wells to perform stress tests. As for a mitigation plan, “That plan has yet to be articulated,” Hayes said. “The proponent has not come back to the table for the last, approximately, 90 days.”
The proponent must come back to the table, however, should the project have a chance for approval through CEQA. Hayes said that Great Basin Unified Air Pollution Control Board (GBUAPCD) Air Control Officer Ted Schade, the lead for the project’s CEQA, agrees that the CEQA documents must include a testing and mitigation plan.
“Mr. Schade is the one remaining linchpin keeping this project from going forward,” Hayes said.
Dave Harvey then rose to address Council. “In 20 years, I’ve never seen an Environmental Review that everyone’s happy with. Not going to happen,” he said. But Harvey noted that Ormat had been treated with an unusual level of disrespect at a prior Planning Commission meeting. “[Ormat] has invested well over $100 million and creates tremendous economic benefit,” he said. “…They don’t deserve to be called ‘crafty.’”
“It was a terrible display, the other day at the Planning Commission, when I listened to the company being denounced because they’re foreign,” Harvey added. Ormat Industries was established in Yavne, Israel, according to the company website.
Planning Commission Chair Mickey Brown agreed. “Ormat was referred to as plunderers; bullies,” she said. “Let’s just talk about the facts and eliminate the name-calling, and we’ll get a lot further in this discussion.”
Although Harvey argued that Council should not approve the letter of support for MCWD’s concerns regarding Casa Diablo IV, Council voted unanimously in favor of the letter. Council did delete “foreign-based company” from the letter’s language.
“I’m not willing to risk the Town’s drinking water supply based upon neither solid nor straight answers [from Ormat],” concluded Council member John Eastman. “Drinking water is arguably the single most important resource we have, and I’m not willing to jeopardize it.”