This Geothermal Permitting Guide was created as a reference tool for geothermal stakeholders interested in developing low temperature direct use and/or power production projects. It addresses the environmental regulatory requirements beginning after acquisition of the land and/or mineral rights. Organized by development activity, it begins with resource exploration and continues to well abandonment and project closure. No one set of standard regulations applies to geothermal projects due to the differences in land and/or mineral rights ownership, location and resource chemistry. Geothermal resources in California occur in disparate environments from mountainous to desert terrains. The resource also differs from being liquid dominated high or low temperature to steam-dominated high temperature. Regional regulators such as counties, regional water quality control boards and air districts develop regulations based on the needs of their jurisdictions. The document contains websites and regulatory citations as statutes and regulations change.