The once-through cooling policy approved by the State Water Resources Control Board became effective on October 1, 2010. This policy calls for the retirement or modification of 16 power plants within the ISO balancing authority that are critical for system and local reliability and to ensure sufficient availability of ancillary services to support renewable resource integration. Compliance dates for most of these plants range from 2015 to 2020. The state's two nuclear facilities have until 2022 and 2024 to comply.The ISO will study the reliability impacts of the policy implementation as part of its annual transmission planning process and will join with the California Energy Commission, California Public Utilities Commission, California Coastal Commission, State Lands Commission, California Air Resources Board and the State Water Resources Control Board to form the Statewide Advisory Committee on Cooling Water Intake Structures (SACCWIS). The organizations will work together to implement the new policy in a manner that does not threaten the reliability of the state's power supply. For more details, please refer to the Policy on the Use of Coastal and Estuarine Waters for Power Plant Cooling located at: http://www.waterboards.ca.gov/water_issues/programs/npdes/docs/cwa316/policy100110.pdf.