Water District objects to geothermal expansion


 Mammoth Community Water District completed its environmental assessment of the proposed expansion of Casa Diablo Geothermal Plant on Feb. 25, according to Irene Yamashita of the Mammoth Community Water District.

While the project’s environmental documents conclude there will be no significant impacts to the Water District, the district remains skeptical.

“The draft document,” Yamashita said, “does not provide sufficient information to support these conclusions.”

The Water District had filed an extension to the comment period in order to find specialists qualified to assess the proposal’s impacts. They since hired two hydro-geology specialists to review the proposals.

Yamashita said the district remains concerned about how this might affect its ability to meet local water demand, due to possible adverse effects to groundwater and surface water resources.

Pumping or reinjection of geothermal fluids for the project could impact the district’s groundwater supplies by decreasing aquifer recharge or by altering the water quality in the aquifers, Yamashita said.

In addition, she said, increased pumping for the proposed project may decrease flows in Mammoth Creek, already subject to state-mandated minimum stream flow requirements.