The California regional board that protects the Central Coast’s water resources recently approved applications for the continued operation of the Diablo Canyon Power Plant in San Luis Obispo County, Calif.
On Feb. 26, the Central Coast Regional Water Quality Control Board voted unanimously to approve Diablo Canyon’s applications for a renewed discharge permit under the National Pollution Discharge Elimination System program and a Federal Clean Water Act Section 401 water quality certification.
The board’s approval of the water quality certification is the last step in California’s process to keep Diablo Canyon open through 2030, per Senate Bill 846.
A federal process to renew Diablo Canyon’s license for 20 years remains on track, California investor-owned utility PG&E reported. The utility owns and operates the nuclear plant.
The approval follows the California Coastal Commission’s approval in December of a Coastal Zone Management Act Consistency Certification and a Coastal Development Permit for Diablo Canyon.
The U.S. Nuclear Regulatory Commission reviewed Diablo Canyon’s license renewal application. The commission found in June 2025 that Diablo Canyon is safe and environmentally sound to operate for another 20 years.
The NRC is expected to issue its decision on Diablo Canyon’s 20-year license renewal application this spring.
The board noted that the applications would allow Diablo Canyon to continue providing clean power during California’s energy transition. Diablo Canyon provides electricity to about 10% of Californians and makes up nearly 20% of California’s clean energy.
In 2016, with state goals to add solar and wind energy and a decline in demand, PG&E agreed with environmental and labor groups to retire Unit 1 in November 2024 and Unit 2 in August 2025.
State regulators approved the agreement in 2018.
But after statewide rotating outages during a heat wave in 2020 and new demand projections in 2022, California lawmakers passed and Gov. Gavin Newsom signed Senate Bill 846, directing Diablo Canyon to run through 2030 for grid reliability and clean energy supply.
In 2023, Diablo Canyon submitted a license renewal application to the NRC to renew its license.
On Aug. 27, 2025, Diablo Canyon’s Unit 2 began extended operations — one day after it was set to shut down. Unit 1 began extended operations in November 2024.
