Water

PG&E is committed to using water responsibly in our operations and at our facilities—and to helping our customers do the same.

Our approach

Water is essential to operating our infrastructure—including our vast network of hydroelectric generating stations—just as it is essential to our customers in their daily lives. PG&E is promoting sustainable water use in a number of ways:

• Strategically managing our power generation facilities
• Reducing water consumption at PG&E offices and service centers
• Providing outreach and guidance to customers on how to reduce water usage

PG&E also reports our water data and strategies to the CDP. 

Power generation

At our Diablo Canyon Power Plant, we use saltwater from the Pacific Ocean for once-through cooling, with a maximum discharge of 2.5 billion gallons per day, set by the facility’s Clean Water Act permit. PG&E closely monitors the marine environment at the plant by conducting regular studies and sampling, also required under the plant’s Clean Water Act permit.

PG&E relies fully on air cooling at two of our three natural gas power plants: Humboldt Bay Generating Station and Colusa Generating Station. At Gateway Generating Station, we use air cooling the majority of the time and use a small water cooling tower on hot days to assist in cooling for operations and power generation.

Additionally, PG&E owns and operates one of the nation’s largest investor-owned hydroelectric systems. Our hydroelectric power plants are largely non-consumptive, meaning that after water passes through turbines to produce electricity, it is returned to the river. In addition, PG&E’s 1,212 MW Helms Pumped Storage Project uses water for energy storage to help balance daily variations in electric demand.

Water conservation

PG&E’s offices and service centers rely on water for restrooms, kitchens, mechanical system cooling, vehicle washing, and landscape irrigation. We work to identify, report, and repair leaks quickly; manage our irrigation systems; install low-flow plumbing fixtures; and replace landscaping with drought-resistant approaches. 

We also deliver free wood mulch to homes and businesses to help them reduce water needed for plants and trees.

2023 milestones

• Saw an increase in water usage at our facilities, with overall consumption rising 63% relative to the prior year. The increase was largely driven by a combination of more sites and total square footage, numerous construction projects underway across the portfolio, and coworkers returning to offices following a period of remote work.
  
  We remain committed to water conservation at our facilities and continue to deploy a water management technology program at 27 different facilities. The program alerts facility managers about unusual water usage via real-time readings. Detected leaks are immediately repaired, and we investigate other high use cases to encourage conservation.
• Helped customers save water. Altogether, customers who participated in PG&E’s programs reduced water usage by about 47 million gallons in 2023, based on our most common energy-efficiency measures that deliver water savings.

• Hosted the 20th-annual Water Conservation Showcase, which covered the water-energy nexus, landscape design, California’s water future, and other topics with a range of nonprofits, universities, and other institutions.
• Repurposed over 200,000 gallons of water used in hydrostatic testing for beneficial reuse, including toward irrigation, dust suppression, backfill compaction, and reseeding and watering disturbed areas to return them to their pre-project state. 

Measuring progress

1. Net operating capacity on December 31, 2023: Diablo Canyon: 2,240 MW; Humboldt Bay Generating Station: 163 MW; Gateway Generating Station: 580 MW; Colusa Generating Station: 657 MW. 
2. The California Water Board adopted a policy in 2010 that generally requires power plants with once-through cooling to install cooling towers or other significant measures to reduce marine impacts by at least 85%. Diablo Canyon must comply with this policy by November 2024 for Unit 1 and August 2025 for Unit 2. In January 2018, the CPUC approved a joint proposal to retire Diablo Canyon at the end of its current Nuclear Regulatory Commission licenses, November 2024 and August 2025. Until plant retirement, Diablo Canyon will pay an annual interim mitigation fee as required by the California Water Board policy. Following passage of SB 846, Diablo Canyon is concurrently pursuing a relicensing extension in addition to decommissioning efforts; this legislation allows for a once-through cooling exemption for the plant.
3. Freshwater sources consist of well water for backup and emergency purposes.
4. Water withdrawal data is significantly lower in 2022 due to an issue with the flowmeter from the water supplier. This issue has been resolved.
5. The represents data from office facilities and service centers for the 12 months from October to September. In 2023, 150 sites reported water data.
6. PG&E monitors water usage at permitted public water systems owned and operated by PG&E. These systems are metered in accordance with state regulations. About three-fourths of the total water withdrawal/usage by permitted systems in 2023 was comprised of remediation and process water used at the Hinkley Compressor Station.
7. These figures include once-through cooling discharge (equivalent to withdrawal amounts) plus estimated reverse osmosis system brine/backwash discharge.
8. Colusa Generating Station uses a zero-liquid discharge system. A septic system is used to manage sanitary waste.
9. In 2023, approximately 15% of the water used in hydrostatic testing was recycled or reused for irrigation, dust control, or project restoration.