PG&E Corporate Responsibility and Sustainability Report 2018

Northern California Wildfires


Though drought conditions have improved in California, water remains a precious resource, and PG&E treats it as one in our operations and our facilities. We work to help our customers to do so as well, particularly in places such as 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,
  • Coordinating with key agencies to prevent and prepare for wildfires, 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.

Water Use at Diablo Canyon

PG&E does not use freshwater for cooling at any of our power plants. At the Diablo Canyon Power Plant, we use saltwater from the Pacific Ocean for once-through cooling. The 2,240-MW nuclear power plant has 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 on once-through cooling in 2010 that generally requires the installation of cooling towers or other significant measures to reduce the impact on marine life from existing power generation facilities in California by at least 85 percent.

Diablo Canyon must comply with this policy by December 31, 2024, or request approval of alternative compliance requirements allowed for nuclear facilities. Given Pacific Gas and Electric Company’s announcement of a joint proposal to not seek to relicense Diablo Canyon at the end of our existing nuclear licenses and the CPUC’s subsequent decision approving the plant’s retirement, we will pay an annual interim mitigation fee until Diablo Canyon ceases operation, in accordance with the state’s policy.

In addition, PG&E uses an on-site reverse osmosis desalination plant to generate the majority of freshwater that supports the internal operations of the Diablo Canyon facility.

Dry Cooled Conventional Sources

PG&E relies on air for cooling at its three natural gas power plants:

  • Humboldt Bay Generating Station is cooled with air radiators using a closed-loop liquid coolant and requires minimal water use.
  • Gateway Generating Station employs an air-cooled condenser, which uses approximately 97 percent less water and discharges 98 percent less wastewater than a traditional once-through cooled plant.
  • Colusa Generating Station uses dry cooling and a zero-liquid discharge system that recycles wastewater.

PG&E uses some freshwater for internal operations at the plants, but these are largely closed-loop systems that minimize the amount of water consumed.

Hydroelectric Generation

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.

PG&E’s 1,212 MW Helms Pumped Storage Project also uses water for energy storage to help balance daily variations in electric demand. Nestled high in the Sierra Nevada Mountains, the non-consumptive Helms facility dispatches water from an upper reservoir to a lower reservoir to produce electricity when demand is high, pumping it back uphill when demand is low.

Water Conservation in Our Facilities

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.

Helping Customers Reduce Water Use

PG&E 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.

Altogether, customers who participated in PG&E’s programs reduced water usage by about 210 million gallons in 2017, based on an analysis of our most common energy-efficiency measures that deliver water savings.

2017 Milestones

PG&E’s efforts to conserve water and protect the watersheds where we operate in 2017 included:

  • Strategically managing our hydroelectric facilities. Working with state agencies and other stakeholders, we found ways to manage water in our reservoirs so we could generate power during the summer peak demand periods. Conserving water early in the season also helps ensure adequate water supplies for communities, supports recreation and benefits the many species that depend on water.
  • Taking additional steps to prevent and mitigate wildfires. In addition to our routine vegetation management program through which we inspect all of our overhead electric lines, PG&E provided $2 million in funding to local Fire Safe Councils to protect communities from wildfires in at least 21 high fire-risk counties by clearing brush and dead, dying or diseased trees for the current fire season. PG&E also conducted daily aerial smoke patrols over much of our service area—more than 3,350 hours of flight time from mid-June through October.
  • Offering new water management technology. Working with Wexus Technologies, PG&E offered a new cloud-based tool that remotely connects pumps, buildings, SmartMeter devices and water flow meters, giving agricultural customers another option to track, interpret and manage their water and energy use effectively. PG&E continues to offer agricultural energy efficiency programs and incentives.

Measuring Progress

Water Use Statistics
2015 2016 2017
Water Withdrawal (Saltwater and Freshwater) (thousand gallons)
Process and Facilities Water (Saltwater)
Diablo Canyon Power Plant Footnote 1a 861,064,313 867,817,856 834,495,352
Once-Through Cooling 860,732,000 867,498,000 834,166,000
Reverse Osmosis 332,313 319,856 329,352
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant Footnote 2 8,150 13,030 5,627
Humboldt Bay Generating Station Footnote 1b 208 141 197
Gateway Generating Station Footnote 1c 21,320 20,725 18,621
Colusa Generating Station Footnote 1d 25,473 24,938 21,774
Facilities (Freshwater)
Offices and Service Yards Footnote 3 113,874 121,451 123,419
Permitted Water Systems Footnote 4 110,784 87,474 85,016
Hydrostatic Testing (Freshwater) Footnote 5
Water for Testing 5,537 3,175 41,420
Water Discharged (Saltwater and Freshwater) (thousand gallons)
Water Discharge (Saltwater) Footnote 6
Diablo Canyon Power Plant 860,928,367 867,687,006 834,360,617
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant (Permitted Discharge) 140,405 131,217 128,274
Humboldt Bay Generating Station (Sanitary Sewer) 114 104 134
Gateway Generating Station (Sanitary Sewer) 10,153 10,501 11,609
Colusa Generating Station Footnote 7 0 0 341
Hydrostatic Testing (Freshwater)
Water from Testing Footnote 8 2,789 2,885 14,664
  • 1. Net operating capacity on December 31, 2017: 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.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. An increase in diameter and mileage of the pipelines tested last year led to the increase in water used and available to be recycled or reused for irrigation or dust control.5
  • 6. These figures include once-through cooling discharge (equivalent to withdrawal amounts) plus estimated reverse osmosis system brine/backwash discharge.6
  • 7. Colusa Generating Station uses a zero-liquid discharge system. A septic system is used to manage sanitary waste.7
  • 8. Of these totals, a portion of water was reused for other hydrostatic testing prior to being discharged, 35 percent of which was recycled or reused for irrigation or dust control. An increase in diameter and mileage of the pipelines tested last year led to the increase in water used and available to be recycled or reused for irrigation or dust control.8

Looking Ahead

Even though last year’s winter rainfall helped to begin replenishing water supplies, the drought’s impacts on groundwater supplies and tree mortality are still evident. Moreover, last year’s record precipitation following the historic drought signals the importance of planning for extreme weather conditions and their effects, including increased land subsidence and flooding risk as snow melts in the Sierra Nevada.

PG&E will continue to promote water conservation with our customers, in our communities and at our facilities while implementing our Community Wildfire Safety Program to reduce wildfire threats and improve safety. We will also continue to strategically manage our hydroelectric operations and coordinate with business, government and community partners to manage the climate-driven challenge of extreme weather events.