PG&E Corporate Responsibility and Sustainability Report 2020

Plan of Reorganization Commitments


Water remains a precious resource in California, and PG&E is committed to using it as responsibly as possible in our operations and at our facilities. We work to help our customers do the same, particularly in the Central Valley.

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 percent 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, particularly those in the agricultural community, on how to reduce water usage.

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

Power Generation

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 percent. Diablo Canyon must comply with this policy by December 31, 2024. In January 2018, the California Public Utilities Commission 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 its 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. Our water-saving solutions for residential customers include supporting markets for high-efficiency clothes washers and direct installation of low-flow shower heads and faucet aerators. We also offer incentives to agricultural customers who convert from sprinkler systems to water-efficient drip irrigation, as well as programs for energy-efficient pumping systems and more.

2019 Milestones

PG&E’s efforts to conserve water and protect the watersheds where we operate in 2019 included:

  • Continued to offer rebates and incentives on water and energy-saving appliances and equipment. Altogether, customers who participated in PG&E’s programs reduced water usage by about 166 million gallons in 2019, based on an analysis of our most common energy-efficiency measures that deliver water savings.
  • Hosted the 16th-annual Water Conservation Showcase. A variety of topics were discussed at the event, including the water efficient home of the future, the water-energy nexus, rainwater harvesting, and the essentials of community-wide fire protection. A range of institutions lent their expertise including the San Francisco Public Utilities Commission, Contra Costa Water District and the California Native Plant Society.
  • Repurposed water for beneficial reuse. PG&E repurposed more than 11 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.

Measuring Progress

Water Use Statistics
2017 2018 2019
Water Withdrawal (Saltwater and Freshwater) (thousand gallons)
Process and Facilities Water (Saltwater)
Diablo Canyon Power Plant Footnote 1a 834,495,352 855,098,304 756,054,502
Once-Through Cooling 834,166,000 854,778,000 755,762,000
Reverse Osmosis 329,352 320,304 292,502
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant Footnote 2 5,627 13,310 17,110
Humboldt Bay Generating Station Footnote 1b 197 233 252
Gateway Generating Station Footnote 1c 18,621 14,425 17,416
Colusa Generating Station Footnote 1d 21,774 18,577 22,114
Facilities (Freshwater)
Offices and Service Yards Footnote 3 123,419 121,447 124,244
Permitted Water Systems Footnote 4 85,016 122,718 129,594
Hydrostatic Testing (Freshwater)
Water for Testing 41,420 4,757 15,983
Water Discharged (Saltwater and Freshwater) (thousand gallons)
Water Discharge (Saltwater) Footnote 5
Diablo Canyon Power Plant 834,360,617 854,967,271 755,934,842
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant (Permitted Discharge) 128,274 136,561 126,110
Humboldt Bay Generating Station (Sanitary Sewer) 134 87 99
Gateway Generating Station (Sanitary Sewer) 11,609 8,089 8,319
Colusa Generating Station Footnote 6 341 0 0
Hydrostatic Testing (Freshwater)
Water from Testing Footnote 7 14,664 3,021 11,712
  • 1. Net operating capacity on December 31, 2019: 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. This figure represents all sites where water was consumed, and data was available for the 12-month period from October to September. The 2018 figure was updated with actual versus estimated usage.3
  • 4. 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.4
  • 5. These figures include once-through cooling discharge (equivalent to withdrawal amounts) plus estimated reverse osmosis system brine/backwash discharge.5
  • 6. Colusa Generating Station uses a zero-liquid discharge system. A septic system is used to manage sanitary waste.6
  • 7. In 2019, nearly three-fourths of the water used in hydrostatic testing was recycled or reused for irrigation, dust control or project restoration.7