Challenge. Determine impacts of additional groundwater withdrawals required to meet water needs of a large solar plant project in the Dry Harper Lake Basin

Solution. Water requirements for the proposed solar plant meant obtaining a permit for two new groundwater wells. INTERA personnel evaluated existing groundwater use in the basin and determined that the proposed new wells in combination with retiring the irrigation wells on the parcel of land to be used for the parabolic mirror field would actually reduce overall groundwater withdrawal in the basin. Our staff (Dr. Jack Wittman) testified before the California Energy Commission to explain how the addition of the new wells, and retirement of existing irrigation wells, would affect regional groundwater levels. Modeling showed that over decades water levels in the basin rebound from the decades of withdrawal for alfalfa irrigation. Despite the initial concerns of the regulators, testimony demonstrated how the system would recover over the life of the project. Additional scope included aquifer testing, collection of water quality samples, and the refinement of a published United States Geological Survey flow model to evaluate impacts on other water users and the ecosystems. As a result of our contributions, the permit was granted for two local wells as a source for deionized rinse in this arid adjudicated groundwater basin.