Federal: Regulations applicable to geothermal resource leasing include USFS’s Technical Guide to Managing Ground Water Resources (Groundwater Technical Guide) at the federal level.
Local: The Long Valley Hydrologic Advisory Committee (LVHAC) at the local level.
The impact on groundwater should be negligible during all phases of the project, and no net deficit in aquifer volume or lowering of the groundwater table level is expected. For the geothermal resources, the proposed action should not result in the depletion or alteration of geothermal outflow to surface water. The impact on geothermal resources should also be negligible. However, some fluctuations in pressure, water level decline, reduction of steam production, and slight temperature changes have been observed in the other power plants in the past.
Cumulative Effects
The power plants already established could contribute to a cumulative impact, but it is predicted to be negligible, as temperatures and pressures seem to recover some time after the installation of a new power plant.
Mitigation
None mentioned.
Residual Impacts
None mentioned.
One major problem is that the analysis of direct and indirect impacts is based on data provided by the proponent. Even if the results have been subjected to independent technical review by a third-party organization, there could be a bias in the data. Further, the report and the review are both confidential "because of the proprietary nature of the model" (EIA Report p.490).
Another critique is that all of the groundwater resources are supposedly protected by a physical barrier, which influences all impact analysis of this resource. However, the report lacks an analysis of the barrier’s reliability. Additionally, there is no alternative plan in case of breach or loss of this unnamed physical barrier.
The cumulative effects were thoroughly discussed for this section. The plan for additional monitoring during the construction as well as the reinjection of geothermal fluids during the operation of the power plant are some appropriate project design measures that were strong additions to the proposed action.