Water’s Right
New data supports MCWD on geothermal
The Mammoth Community Water District (MCWD) has been shouting for a decade that the geothermal development operated by Ormat Technologies, NV, could have impacts on local water supplies and that more data is needed to determine whether or not there is an intermingling between the cold and geothermal water layers, but no one listened.
The United States Geological Survey (USGS) gave a presentation to the Mono County Board of Supervisors Tuesday, July 19 on new data that has been collected in the last 16 months. The data supports MCWD concerns. One Ormat well, 14-25, has tell-tale water chemistry associated with geothermal fluids, according to data collected by the USGS, and the water coming out of the well is between 220-225F, compared to the temperature of MCWD production wells with water temperatures of 75-125F.
The previous model of the groundwater system suggested the geothermal water was confined by a solid barrier of rock that prevented the hot fluid from leaking into the cold water above, said Pat Hayes, General Manager of the MCWD, in an interview this week. That barrier is made of Bishop Tuff, the cracked red rock full of holes a result of volcanic activity. That model doesn’t explain the fumeroles found throughout the area south of Shady Rest park, where Ormat already has wells and is proposing to drill up to 16 more wells for the Casa Diablo IV project.
