PG&E Corporate Responsibility and Sustainability Report 2021

COVID-19 Response


Water remains a precious resource in California, and PG&E is committed to using it responsibly in our operations and at our facilities—and we work to help 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. At the same time, about 20% of California’s electricity usage goes toward moving, treating, disposing of, heating and consuming water. This connection, also known as the “water-energy nexus,” places PG&E in a unique position to help our state and our customers.

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 yards, and
  • Providing outreach and guidance to customers on how to reduce water usage.

PG&E also reports our water data and strategies to the CDP, an international not-for-profit organization that requests information on behalf of institutional investors.

Power Generation

A river flowing between mountain peaks At the 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.

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.

PG&E relies on air for cooling at our three natural gas power plants: Humboldt Bay Generating Station, Gateway Generating Station and Colusa Generating Station.

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 remain focused on identifying, reporting and repairing leaks quickly; managing our irrigation systems; installing low-flow plumbing fixtures; and replacing landscaping with drought-resistant approaches.

PG&E also offers customers a wide range of options to help them reduce their water use, such as direct installation of low-flow shower heads and faucet aerators. We also deliver free wood mulch to homes and businesses to help them reduce the amount of water needed by plants and trees.

2020 Milestones

PG&E’s efforts to conserve water and protect the watersheds where we operate in 2020 included:

  • Continued to support customers’ efforts to save water. Altogether, customers who participated in PG&E’s programs reduced water usage by about 108 million gallons in 2020, based on an analysis of our most common energy-efficiency measures that deliver water savings.
  • Hosted the 17th-annual Water Conservation Showcase. A variety of topics were discussed at the virtual event, including emerging water technologies and building a career in the water industry. A range of institutions lent their expertise including the San Francisco Public Utilities Commission, California Department of Water Resources and the California Water Efficiency Partnership.
  • Repurposed water for beneficial reuse. PG&E repurposed nearly 1.9 million gallons of water used in hydrostatic testing for beneficial reuse, including toward irrigation, dust suppression, backfill compaction and project restoration—reseeding and watering all disturbed areas to return them to their pre-project state.
  • Reduced water use at our facilities. We added 36 new irrigation controllers to nearly 20 large facilities across our service area to take advantage of new technology and optimize water usage.

Measuring Progress

Water Use Statistics
2018 2019 2020
Water Withdrawal (Saltwater and Freshwater) (thousand gallons)
Process and Facilities Water (Saltwater)
Diablo Canyon Power Plant Footnote 1a 855,098,304 756,054,502 834,911,227
Once-Through Cooling 854,778,000 755,762,000 834,539,000
Reverse Osmosis 320,304 292,502 372,227
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant Footnote 2 13,310 17,110 16,200
Humboldt Bay Generating Station Footnote 1b 233 252 217
Gateway Generating Station Footnote 1c 14,425 17,416 16,251
Colusa Generating Station Footnote 1d 18,577 22,114 22,733
Facilities (Freshwater)
Offices and Service Yards 121,447 124,244 120,388
Permitted Water Systems Footnote 3 122,718 129,594 133,748
Hydrostatic Testing (Freshwater)
Water for Testing 4,757 15,983 2,520
Water Discharged (Saltwater and Freshwater) (thousand gallons)
Water Discharge (Saltwater) Footnote 4
Diablo Canyon Power Plant 854,967,271 755,934,842 834,758,952
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant (Permitted Discharge) 136,561 126,110 150,726
Humboldt Bay Generating Station (Sanitary Sewer) 87 99 98
Gateway Generating Station (Sanitary Sewer) 8,089 8,319 10,836
Colusa Generating Station Footnote 5 0 0 0
Hydrostatic Testing (Freshwater)
Water from Testing Footnote 6 3,021 11,712 1,891
  • 1. Net operating capacity on December 31, 2020: Diablo Canyon: 2,240 MW; Humboldt Bay Generating Station: 163 MW; Gateway Generating Station: 580 MW; Colusa Generating Station: 657 MW.1a, 1b, 1c, 1d
  • 2. Freshwater sources consist of well water for backup and emergency purposes.2
  • 3. 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.3
  • 4. These figures include once-through cooling discharge (equivalent to withdrawal amounts) plus estimated reverse osmosis system brine/backwash discharge.4
  • 5. Colusa Generating Station uses a zero-liquid discharge system. A septic system is used to manage sanitary waste.5
  • 6. In 2020, three fourths of the water used in hydrostatic testing was recycled or reused for irrigation, dust control or project restoration.6