The Central Coast Regional Water Quality Control Board has released two draft permits for public comment. The permits are necessary to extend operations at Diablo Canyon Nuclear Power Plant, as directed by Senate Bill 846 (2022). The comment period closes on Dec. 8th.
Operated by Pacific Gas & Electric Company, The plant, near Avila Beach, is California’s last operable nuclear power plant. The draft permits, which require approval by the Central Coast Water Board to become final, contain critical regulatory requirements for PG&E to continue operations following the state mandate to extend the plant’s operational timeline.
The drafts include stricter effluent limits and monitoring requirements to strengthen environmental protection and ensure compliance with the latest state and federal water quality standards. As part of the permit renewal process, regional board staff comprehensively evaluated PG&E’s compliance with the plant’s current discharge requirements and incorporated new regulatory provisions. Among these are requirements to bring the plant in line with the state’s 2010 Once-Through Cooling Policy, which aims to reduce the harmful effects cooling water intakes used at coastal power plants can have on marine life.
To continue operations, PG&E must obtain an updated National Pollutant Discharge Elimination System (NPDES) permit, which regulates how the plant discharges once-through cooling water, desalination brine and treated wastewater into the ocean. In addition, PG&E is required to secure a Clean Water Act Section 401 water quality certification from the regional board before the federal Nuclear Regulatory Commission can finalize its licenses for the plant’s two reactors.
On Nov. 12th, the regional board will hold a workshop to answer questions and solicit public comments and it expects to consider the draft permits in early 2026.
More information on the permitting process and access to related documents can be found on the regional board’s program page at: waterboards.ca.gov/central coast.
