Mono County Court rules on MCWD Casa Diablo IV suit

This week Mono County Superior Court announced that it had reached a decision regarding the Mammoth Community Water District (MCWD) lawsuit against Great Basin Unified Air Pollution Control District (Great Basin) over Great Basin’s approval of the Ormat Casa Diablo IV project.

MCWD claimed Great Basin had violated the California Environmental Quality Act (CEQA) in approving the project, which MCWD feared could negatively impact Mammoth’s groundwater supply.

MCWD asserted that the project as proposed by Ormat did not have the necessary monitoring and mitigation measures to ensure there would be no effect from geothermal extraction on Mammoth’s groundwater.

But the Court held that the record of evidence, including expert opinions and scientific studies, established “substantial evidence that there is no connectivity between the deep geothermal reservoir and MCWD’s groundwater aquifer,” according to a Great Basin press release this week.

As part of Great Basin’s approval of the Casa Diablo IV project, federal and state agencies must approve a groundwater monitoring plan, and Ormat must implement that plan before drilling any new geothermal wells.

Ormat has obtained assistance from the California Energy Commission for three new monitoring wells and agreed on the location of those wells with MCWD. The Bureau of Land Management (BLM) is currently in the process of permitting the wells.

The wells are intended to monitor the middle ground between MCWD’s approximately 20 monitoring wells, and Ormat’s existing monitoring wells.

According to BLM Bishop Field Office Supervisory Natural Resource Specialist Dale Johnson at the July 1 Town Council meeting, one of the new monitoring wells will be located north of Shady Rest Park on an existing well pad, while the other two wells will be located across the Park to the south. Those two wells will include one shallow coldwater well about 600 feet deep, and one deep well about 2,000 feet deep to monitor the geothermal resource.

Johnson said that because the BLM was also concerned about the potential effect of Casa Diablo IV’s geothermal extraction on Mammoth’s groundwater supply, it made its approval of the project’s environmental review contingent on “a cooperative groundwater monitoring program.”

The shallow wells are scheduled for drilling later this month, while the deep well is scheduled for drilling sometime in the fall of 2016. The north site well will take about eight days to complete, while the south site well will take about 12 days. Johnson acknowledged that this meant impacts to users of Shady Rest Park.

Council member John Wentworth wondered whether maintenance of the wells would create disturbance on trails, particularly over snow vehicle and cross country skiing trails during the winter.

Mammoth District Ranger Jon Regelbrugge said “It could have some effect to the road and trails system for long term access … roads might need to be plowed in the winter, or we might use a snowmobile. We might need to potentially re-route a road or trail, or widen it.”

MCWD General Manager Pat Hayes also noted that there may be another well going in on U.S. Forest Service land behind Mammoth Hospital, which would be a paired cold and warmwater geothermal well. Hayes said funding for the well would be split 80-20 between the Water District and Ormat.

“While the Water District is disappointed by the court decision yesterday, we remain focused on groundwater,” Hayes said. “… We’ve worked diligently, and progress is being made, and I think you’re seeing the evidence of that.”