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CWA 316(b) Thermal Discharges-Cooling Water Intake Structures

Ocean Standards - CWA §316(b) Regulation


The State Water Resources Control Board (State Water Board) implements the Federal Clean Water Act §316(b) regulations on cooling water intake structures. Control and/or mitigation of entrainment and impingement of marine life related to power generating facility intake structures is paramount.

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Proposed Amendment to the Water Quality Control Policy on the use of Coastal and Estuarine Water for Power Plant Cooling – Encina Power Station (Proposed Amendment).

To begin the public comment period, the State Water Board is releasing the Draft Staff Report and Proposed Amendment for extending the Encina Power Station compliance date from December 31, 2017 to December 31, 2018. This Policy is often referred to as the Once-Through Cooling Water Policy. Documents are available for public comment starting May 23, 2017, for 45 days. Written comments must be received no later than 12:00 PM noon on Friday, July 7, 2017, and must be addressed to:

Jeanine Townsend, Clerk to the Board
State Water Resources Control Board
1001 I Street, 24th Floor
Sacramento, CA 95814

Comment letters may be submitted electronically in pdf text format (if less than 15 megabytes in total size), to the Clerk to the Board via e-mail at commentletters.@waterboards.ca.gov. If the file is greater than 15 megabytes in total size, then the comment letter may be submitted by fax at (916) 341-5620.  Please indicate in the subject line: "Comment Letter – Once-Through Cooling Policy Amendment"

Couriers delivering hard copies of comment letters must check in with lobby security personnel, who can contact Ms. Townsend at (916) 341-5600.

The State Water Board will consider adoption of the proposed amendments following a hearing that will be held on August 15, 2017.

Public Meetings

Pubic Adoption Hearing and Opportunity to Comment August 15, 2017

The State Water Board will hold a public hearing to receive public comment on a proposed amendment to the Water Quality Control Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling (Policy). The State Water Board is proposing to amend the Policy to extend the final compliance date for Encina Power Station from December 31, 2017 to December 31, 2018 to maintain grid reliability. The State Water Board will consider adoption of the proposed amendments following the hearing that will be held at:

Tuesday August 15, 2017 - 9:00 a.m.
Joe Serna Jr. Cal/EPA Headquarters Building
Coastal Hearing Room
1001 I Street, Second Floor
Sacramento, CA 95814

Documents for the Proposed Amendment are linked below. Written comment deadline is July 7, 2017 at noon.

The Once-Through Cooling Water Policy

On May 4, 2010 the State Water Board adopted a Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling (Policy). The administrative record for the Policy was approved by the Office of Administrative Law (OAL) on September 27, 2010. The Policy became effective on October 1, 2010 when the California Environmental Quality Act Notice of Decision was submitted to the Secretary of Resources.

The 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 on marine and estuarine life. The Policy applies to the 19 existing power plants (including two nuclear plants) that currently have the ability to withdraw over 15 billion gallons 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).

The Policy is implemented through an adaptive management strategy by which the standards can be achieved without disrupting the critical needs of the State’s electrical generation and transmission system. A Statewide Advisory Committee on Cooling Water Intake Structures (SACCWIS) has been established to review implementation plans and schedules and provide recommendations to the State Water Board at least annually. The State Water Board will consider SACCWIS’s recommendations and make modifications to the Policy, as appropriate. The permittees’ NPDES permits will be reissued or modified to conform with the Policy.

Determinations Approving Interim Mitigation Measures

State Water Board-Contracted Expert Review Panel II on Intake Impacts and Mitigation

The State Water Board contracted with the Moss Landing Marine Laboratory to establish an expert panel to address issues associated with minimizing and mitigating intake impacts from power plants and desalination facilities. The panel members were Dr. Michael Foster, Dr. Greg Cailliet, Dr. Jim Callaway, Dr. Pete Raimondi, and Mr. John Steinbeck. The panel met on August 8, 2011 and on November 15, 2011.  A public meeting was held March 1, 2012 at the Moss Landing Marine where panel members presented their recommendations and took questions and comments from the public on the panel’s Draft Report.  Updates were given on the other two studies.  The panel members deliberated and made changes to their report, which was finalized on March 14, 2012.

  • Expert Review Panel II on Intake Impacts and Mitigation

Other Relevant Documents


The two committees listed below, were convened by the Executive Directory of the State Water board, as required by the 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 this Policy to ensure that implementation plans and schedules established by the 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
The Review Committee was established to oversee the special studies, which will investigate ability, alternatives, and cost for two nuclear-fueled power plants to meet the Policy requirements.  The special studies will be 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 Policy.  The Review Committee includes representatives from the SACCWIS agencies, the nuclear power companies, the environmental community, and staffs of the State Water Board and appropriate Regional Water Boards.

Permitting of Affected Power Plants

The Policy is implemented through National Pollutant Discharge Elimination System (NPDES) permits for coastal and estuarine power plants. The applicable Regional Water Boards are responsible for implementing the 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 Policy..  »»   Get more information …

Questions or Comments

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