Threemile Slough Pipeline Crossings Remediation and Decommissioning Project

Pacific Gas and Electric Company is advancing the Threemile Slough Pipeline Crossings Remediation and Decommissioning Project to address environmental and safety concerns associated with aging pipeline infrastructure within Threemile Slough. The project entails four major phases: preparing the project area and mobilizing equipment, remediating the currently active L-131Y and L-131Z pipelines, and removing the full extent of the previously abandoned L-131 East and West pipelines—both on land and underwater. Following these activities, the site will undergo comprehensive restoration and equipment demobilization to ensure ecological recovery and compliance with environmental standards. While the active pipelines will continue operating under existing conditions after remediation, the decommissioning of the obsolete lines aims to eliminate potential risks and reduce long-term environmental liabilities. The project is managed under oversight by the California State Lands Commission, with work planned to occur in and around Rio Vista, California, and all activities aligned with environmental mitigation measures outlined in the Mitigated Negative Declaration. Point of contact for the project includes senior environmental and land planning staff from both PG&E and the State Lands Commission, ensuring coordinated implementation and regulatory compliance.