Ocean Standards - CWA §316(b) Regulation
- Official Policy Documentation
- Public Meetings
- Interim Mitigation Measures
- Other Relevant Documents
- Power Plants That Are Affected
- General Energy Company Correspondence
- Questions or Comments
- Once Through Cooling Fact Sheet
Cooling Water Intake Structures
On May 4, 2010, the State Water Resources Control Board (State Water Board) adopted a Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling (Once-Through Cooling or OTC Policy). The OTC Policy became effective on October 1, 2010, and the last amendment became effective on November 30, 2020.
The OTC Policy establishes technology-based standards to implement federal Clean Water Act section 316(b) and reduce the harmful effects associated with cooling water intake structures for power generating facilities on marine and estuarine life. The OTC Policy applied to 19 existing power plants (including two nuclear plants) with the combined ability to withdraw almost 16 billion gallons of water per day from the state’s coastal and estuarine waters using a single-pass system, also known as once-through cooling (OTC). Closed-cycle wet cooling has been selected as Best Technology Available (BTA). Permittees must either reduce intake flow and velocity (Track 1) or reduce impacts to aquatic life comparably by other means (Track 2).
Ten plants have ceased their once-through cooling operations. Eight of the remaining plants have informed the State Water Board that they are planning to comply by retiring their existing OTC plants’ equipment. In some cases, plants will repower their locations with modern non-water-cooled systems. Dynegy’s Moss Landing Power Plant is the only OTC plant that is complying with the OTC Policy through Track 2.
Once-Through Cooling Policy – Current Version – Effective December 23, 2021
» Go to the Official Policy Documentation
- On August 15, 2023, the State Water Board adopted the Amendment to the Water Quality Control Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling to Revise the Compliance Schedules for the Alamitos, Huntington Beach, Ormond Beach, and Scattergood Generating Stations and Diablo Canyon Nuclear Power Plant.
- Revised Public Notice of Document Availability, Opportunity for Public Comment, and Public Listening Sessions on Potential Revisions to the Once-Through Cooling Policy’s Interim Mitigation Calculation
- Modificado Aviso de disponibilidad de documentos, oportunidad de comentarios públicos y audiencias públicas sobre las posibles revisiones del cálculo de los pagos provisionales de mitigación de la Política de Enfriamiento de Paso Único
- The draft Resolution and Staff Report for the Interim Mitigation Payment Calculation is now available for public comment until noon, October 30, 2023. Please refer to the notice above for additional information on the public comment procedure. Documents are available under Revisions to the Interim Mitigation Payments Calculation of the Interim Mitigation Measures webpage.
Public Listening Sessions on Potential Revisions to the Once-Through Cooling Policy’s Interim Mitigation Calculation
The State Water Board host two virtual public listening sessions with the Ocean Protection Council and the State Coastal Conservancy to receive input regarding potential revisions to the current calculation to determine interim mitigation payments by coastal power plants required by the Once-Through Cooling Policy as follows:
Monday, October 2, 2023, at 5:00 pm to 7:00 pm
Thursday, October 5, 2023, at 2:00 pm to 4:00 pm
For additional information on the public listening sessions, please refer to the revised notice.
- Electric Grid Reliability Impacts from Once-Through Cooling in California (Jones & Stokes Associates, April 2008)
- California's Coastal Power Plants: Alternative Cooling System Analysis (TetraTech, February 2008)
- Assessment of Once-Through Cooling System Impacts to California Coastal Fish and Fisheries (Electric Power Research Institute, December 2007)
- Issues Analysis of Retrofitting Once-Through Cooled Plants with Closed Cycle Cooling (Electric Power Research Institute, October 2007)
- 1975 Policy on the Use of Inland Waters for Powerplant Cooling - Includes Resolution 75-58
- Federal Water Pollution Control Act: Title 33, Chapter 26, Sec. 316 (b)
Two committees were convened by the Executive Director of the State Water Board, as required by the OTC Policy. The committees are subject to the Bagley-Keene Open Meeting Act.
Statewide Advisory Committee on Cooling Water Intake Structures (SACCWIS)
SACCWIS was established to advise the State Water Board on the implementation of the OTC Policy to ensure that implementation plans and schedules established by the OTC Policy are realistic and will not cause disruption to the State’s electrical power supply. SACCWIS includes representatives from the California Energy Commission, California Public Utilities Commission, California Coastal Commission, California State Lands Commission, California Air Resources Board, California Independent System Operator, and the State Water Board.
Review Committee for Nuclear Fueled Power Plants
This Review Committee was established to oversee special studies, which investigated ability, alternatives, and cost, for the two nuclear-fueled power plants to meet OTC Policy requirements. The special studies were conducted by an independent third party with engineering experience with nuclear power plants, selected by the Executive Director of the State Water Board, and paid for by the two nuclear-fueled power plants subject to the OTC Policy. The Review Committee included representatives from the SACCWIS agencies, the nuclear power companies, the environmental community, and staffs of the State Water Board and appropriate Regional Water Boards. The Review Committee last convened in 2013 to provide and present a final report describing the results of the special studies to the State Water Board.
The OTC Policy is implemented through National Pollutant Discharge Elimination System (NPDES) permits. The applicable Regional Water Boards are responsible for implementing the OTC Policy requirements in NPDES permits for existing coastal and estuarine power plants. The Water Boards determine requirements to implement best technology available for cooling water intake structures to be included in the permits. State Water Board staff provides technical support to the Regional Water Boards to ensure a high level of statewide consistency in implementing the OTC Policy.
»» For more information on each power plant required to comply with the OTC Policy, visit the Power Plants That Are Affected page.
- Permitting Issues - Renan Jauregui at (916) 341-5505 or by email at Renan.Jauregui@waterboards.ca.gov
- Policy Issues - Katherine Walsh at (916) 445-2317 or by email at Katherine.Walsh@waterboards.ca.gov