Water Conservation and Management

Water is an integral resource for the utility industry and is used in many ways. Increased demand and limited water resources have led PG&E and other utilities to identify and implement water use reduction strategies.

PG&E is taking steps to conserve and protect water in our facilities and operations. In 2011, we made progress toward our five-year water use-reduction goal of 20 percent for our offices and service yards, compared to a 2009 baseline. PG&E also uses air rather than water to cool all but one of its thermal power plants and has incentives to help customers conserve water—which not only lowers their bills and helps the environment, but reduces energy consumption.

Taking a Sustainable Approach

At PG&E, we are working to use water in a more sustainable manner in our facilities and operations. Taking a sustainable approach allows us to ensure we meet our future business needs, while also addressing near-term opportunities for efficiency and cost savings.

PG&E’s water conservation and management efforts span a range of areas:

In 2011, PG&E voluntarily responded to the Carbon Disclosure Project’s (CDP) annual information request on water. This request was made on behalf of more than 350 investors around the world representing $43 trillion in assets. The CDP once again recognized PG&E for demonstrating best practice among major companies worldwide.

  • Reducing water consumption at PG&E offices and service yards
  • Using air for cooling (versus once-through “wet” cooling) at repowered and new generation facilities
  • Developing plans to manage the potential future impacts of climate change on our hydroelectric system
  • Considering freshwater usage when evaluating potential third-party suppliers of electricity
  • Working with non-electricity generation suppliers to reduce their water use
  • Helping customers reduce their water use
  • Using best management practices in maintenance and construction projects to protect water quality.

Water Use Statistics

PG&E has no power plants that use freshwater for once-through cooling; however, we have one power plant with a once-through cooling system that uses saltwater. PG&E does use freshwater to support the internal operations of our plants, but this, by comparison, represents a much smaller volume of water. As discussed more fully below, PG&E’s largest use of freshwater is the generation of hydroelectricity; this is not considered a consumptive use of water because the water runs through the turbines and returns to the river or stream.

We will continue to expand the scope of water use included in our water footprint. For example, as we expand the metering and tracking of our facility water use, we will include this usage in our summary of water use statistics.

Water Use Statistics
2009 2010 2011
Water Withdrawal (Saltwater and Freshwater) (thousand gallons)
Once-Through Cooling (Saltwater)
Diablo Canyon Power Plant1 802,067,000 856,154,000 863,753,000
Humboldt Bay Power Plant2 24,365,000 18,145,000 N/A
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant 134,440 138,093 145,546
Freshwater3 14,640 17,650 13,410
Seawater Reverse Osmosis Product Water 119,800 120,443 132,136
Humboldt Bay Power Plant 7,195 5,808 N/A
Humboldt Bay Generating Station1,2 N/A 39 281
Gateway Generating Station1,4 17,615 16,769 20,339
Colusa Generating Station1,5 N/A 2,063 2,810
California State University, East Bay Fuel Cell1,6 N/A N/A 699
San Francisco State University Fuel Cell1,6 N/A N/A 419
Corporate Real Estate Facilities (Freshwater)
Offices and Service Yards7 154,100 129,200 121,400
Public Water System Usage (Freshwater)
Designated Facilities8 N/A N/A 55,324
Wastewater Discharged (Saltwater and Freshwater) (thousand gallons)
Once-Through Cooling (Saltwater)9
Diablo Canyon Power Plant 802,067,000 856,154,000 863,753,000
Humboldt Bay Power Plant 24,365,000 18,145,000 N/A
Domestic and Process Water (Freshwater)
Diablo Canyon Power Plant
Permitted Discharge 124,385 123,498 134,345
Humboldt Bay Power Plant 15,685 11,793 N/A
Sanitary Sewer 3,595 3,108 N/A
Permitted Discharge 12,090 8,685 N/A
Humboldt Bay Generating Station
Sanitary Sewer N/A 39 137
Gateway Generating Station
Sanitary Sewer 7,552 7,452 10,115
Colusa Generating Station10 N/A N/A N/A

1 Net operating capacity on December 31, 2011: Diablo Canyon: 2,240 MW; Gateway Generating Station: 530 MW; Colusa Generating Station: 530 MW; Humboldt Bay Generating Station: 163 MW; CSU-East Bay Fuel Cell: 1.4 MW; San Francisco State Fuel Cell: 1.6 MW.

2 The Humboldt Bay Power Plant (Humboldt Bay) facilities, two operating fossil fuel-fired plants and two mobile turbines, were retired at the end of September 2010. The Humboldt Bay Generating Station, which does not use once-through cooling, became operational in September 2010.

3 Freshwater sources were well water and creek water through June 2008 and are now solely well water for back-up and emergency purposes.

4 The Gateway Generating Station, which does not use once-through cooling, became operational in January 2009.

5 The Colusa Generating Station, which does not use once-through cooling, became operational in December 2010.

6 The Utility owns and operates three fuel cell sites in the Bay Area that became operational in September 2011 and have a combined capacity of 3 MW.

7 This figure represents the water supplied to 125 of the 194 offices and service yards managed by the Utility’s Corporate Real Estate Department for the 12-month period from October to September. These facilities represent the scope of operations covered by PG&E’s water reduction target in 2011. Water usage reported for 2009 and 2010 has been adjusted to reflect an increase in the number of sites measured from 78 sites in the 2009 report and 91 sites in the 2010 report. We expect to report water consumption from additional facilities in subsequent sustainability reports, consistent with our plan to encompass more facilities in our water reduction target.

8 These facilities operate public water systems which are metered in accordance with the California Code of Regulation, Title 22, Division 4, Chapter 16, Article 3, Section 64561 (a) and (b).

9 These are estimated figures as PG&E only measures water withdrawal associated with once-through cooling.

10 Colusa Generating Station uses a zero liquid discharge system. A septic system is used to manage sanitary waste.

Use of Saltwater for Once-Through Cooling

PG&E owns and operates one power plant that uses saltwater for once-through cooling to condense steam to water in the electricity generating process. Diablo Canyon is a 2,240 MW nuclear power plant with a maximum discharge limit of 2.5 billion gallons per day. The water discharge limit is set by the facility’s Clean Water Act permit.

PG&E closely monitors the marine environment at its Diablo Canyon Power Plant by conducting regular studies and sampling required under the plant’s Clean Water Act permit. The marine studies at Diablo Canyon, ongoing since the mid-1970s, represent one of the largest databases of intertidal marine data in the United States.

The Clean Water Act requires that cooling water intake structures at electric power plants, such as Diablo Canyon, reflect the best technology available to minimize adverse environmental impacts. In April 2011, the U.S. EPA published draft regulations that propose specific reductions for impingement (which occurs when larger organisms are caught on water filter screens) and provide case-by case site specific assessment to establish compliance requirements for entrainment (which occurs when organisms are drawn through the cooling water system). In June 2012, U.S. EPA requested comments on proposed revisions to the draft regulation that would provide additional flexibility for impingement compliance. The final regulations are expected in 2013.

Additionally, the California State Water Resource Control Board (State Board) adopted a policy, effective in 2010, regulating the use of once-through cooling at existing power plants and establishing a compliance schedule to phase out once-through cooling at most facilities. The policy acknowledges the unique contributions of nuclear plants to both baseload power and meeting the state’s greenhouse gas reduction goals, and allows for alternative compliance requirements for these facilities after a review of compliance costs and factors such as engineering and permitting constraints, as well as any adverse environmental impacts of a cooling tower installation. If the State Board allows a nuclear plant to comply through alternative requirements, the policy requires that the impacts of the plant be mitigated through projects that increase marine life near the facility.

For new generation projects, PG&E supports efforts to transition away from once-through cooling and is using alternative technologies that rely on air for cooling at its repowered and new facilities. For example, we are using new advanced reciprocating engine technology at the repowered 163 MW Humboldt Bay Generating Station. Because this plant is cooled with air radiators using a closed loop liquid coolant, it requires minimal water use.

PG&E is using another dry cooling technology, an air-cooled condenser, at the Gateway and Colusa Generating Stations. The Gateway Generating Station is a state-of-the-art 530 MW combined-cycle natural gas power plant with 50 MW peaking capacity that uses approximately 97 percent less water and discharges 98 percent less wastewater than a traditional “wet” cooled plant. The similarly designed 530 MW Colusa Generating Station with 127 MW peaking capacity also uses dry cooling—a zero liquid discharge system that recycles wastewater.

In addition, PG&E owns and operates fuel cell sites in the San Francisco Bay Area that became operational in September 2011 and have a combined capacity of 3 MW: 1.4 MW at California State University, East Bay and 1.6 MW at San Francisco State University. All require freshwater for the electrochemical energy generation process.

Freshwater Consumptive Uses

PG&E consumes some freshwater for the internal operations at the four power plants we own and operate. These operations are largely closed-loop systems that minimize the amount of water consumed. The systems draw from on-site groundwater, irrigation canal water and/or municipal water. Additionally, the Diablo Canyon Power Plant uses freshwater generated through seawater reverse osmosis. The freshwater is used to generate steam, cool auxiliary equipment, support fire water systems and supply drinking water at the power plants, among other uses. To ensure operational efficiency and maintain plant chemistry, we closely monitor these internal systems to ensure they are watertight, thus reducing consumptive use.

PG&E also purchases a significant portion of its delivered electricity from third-party suppliers. Some of this purchased electricity may come from conventional power generation facilities that use freshwater for once-through or other wet cooling technologies.

We also consume freshwater in our office buildings for kitchens and bathrooms, landscape irrigation and cooling towers associated with heating, ventilation and air conditioning systems. Our gas and electric transmission and distribution facilities consume freshwater as well for operation, maintenance and construction activities. These include washing electric circuit insulators, cleaning vehicles, controlling dust and conducting pipeline and other operations. Water is also used as part of ongoing environmental remediation.

In 2011, PG&E used a significant amount of water to perform hydrostatic testing on more than 160 miles of its gas transmission pipelines to verify the safety and reliability of its natural gas transmission system. PG&E plans to test hundreds of additional miles over the next several years.

Hydrostatic pressure testing involves filling a section of pipe with water, pressurizing it to a much higher level than the pipe operates with natural gas, then monitoring the pipe for at least eight hours. Any pipe sections that do not pass are repaired and retested. Following a completed test, the water is sampled and analyzed to verify that applicable discharge limits are met. Water is then discharged either under permit from a Regional Water Quality Control Board or the local sanitary sewer agency.

In 2011, PG&E also began tracking groundwater use at fifteen of its facilities in compliance with California's requirements for permitted public water systems.

Freshwater Non-Consumptive Uses

PG&E’s hydroelectric power plants are largely non-consumptive. After water passes through turbines to produce electricity, it is returned to the river.

Of PG&E’s 68 hydroelectric power houses, 24 are classified as “run-of-the-river.” This refers to hydroelectric plants that operate on water as it is available from the natural flow of a stream without the need for storing the water. The other units draw water from reservoirs. Some experts characterize the evaporation that naturally occurs from reservoirs as water consumption. PG&E will continue to monitor such reporting developments as we further quantify our water conservation and management efforts. Evaporation represents a small percentage of the total water that flows in the watersheds where PG&E operates hydroelectric facilities.

PG&E also uses water for energy storage to help balance daily variations in electric demand at the Helms Pumped Storage Project, a site more than 1,000 feet inside a solid granite mountain. With a total output of 1,212 MW, the facility alternately draws water from an upper reservoir to produce electricity when demand is high, and pumps it back when demand is low for reuse during the next high-demand period.

Water Conservation in Our Facilities

PG&E set a five-year goal to reduce water usage in offices and service yards by 20 percent by the end of 2014, with 2009 as the baseline year.

In 2011, we reduced water use by 6.0 percent—or 7.8 million gallons—at 125 offices and service yards, exceeding our 5.7 percent target. To achieve these reductions, we reduced landscape water use through enhanced maintenance and the installation of “smart” irrigation controllers at seven additional sites to govern the use of sprinkler systems.

We also replaced landscaping at our Sacramento and Redding service centers with a design that includes native drought-resistant plants and materials that require no irrigation. In our headquarter complex we installed automatic faucets and low-flow valves on plumbing fixtures. In 2012, our goal is to achieve an additional 2 percent reduction at an expanded set of 135 sites.

Helping Customers Reduce Water Use

By encouraging energy efficiency, PG&E also enables our customers to reduce their water use. As a demonstration of potential water savings from our energy efficiency programs, PG&E analyzed six of the more common water-saving technologies incentivized as part of our 2011 energy efficiency portfolio and found that they equated to approximately 850 million gallons of water savings per year, which is equivalent to the annual water consumption of approximately 5,000 California households. We estimate that these technologies will also save customers nearly 1 million kWh and 2 million therms of energy in the first year after installation.

Ninety-two percent of these water savings resulted from programs for residential customers in 2011, both where we directly installed the water-saving devices and where we provided rebates to lower the cost of the devices. Through PG&E’s Energy Savings Assistance Program, we installed hundreds of thousands of low-flow showerheads and faucet aerators at no cost to low-income homeowners and renters; we also made other improvements such as caulking and lighting upgrades. In addition, PG&E issued more than $6.5 million in residential rebates for dishwashers and clothes washers. The rebates for clothes washers were issued through a collaborative program with 30 local water agencies, where customers received a combined rebate from PG&E and their local water agency.

The remaining eight percent of water savings resulted from commercial and industrial customers. We helped save these customers water by installing or providing rebates for low-flow showerheads, faucet aerators, dishwashers, clothes washers, ozone laundry equipment and ice machines. The laundry equipment uses ozone as a cleaning agent in lieu of hot water, while the ice machines use air instead of water to keep the ice cool.

Photo: Joseph Dannels

Since 2004, PG&E has hosted an annual Water Conservation Showcase in San Francisco.

Since 2004, PG&E has hosted an annual Water Conservation Showcase in San Francisco that brings together experts and innovative products and services to explore new policies, strategies and technologies to conserve water. At the event, industry experts cover a wide range of topics related to building and landscape water savings for both residential and commercial building projects.

The event is held in collaboration with the U.S. Green Building Council’s Northern California Chapter and the East Bay Municipal Utility District. The attendees—which include architects, engineers, building owners and operators, manufacturers and government employees—see new technologies firsthand through a range of exhibits.

PG&E’s Pacific Energy Center also provides workshops and classes during the year on various topics related to water conservation and energy efficiency. This includes a new course added in 2011 on how to provide a water audit for small to medium sized commercial facilities.

Managing Storm Water Run-Off and Protecting Species

In California, storm water run-off can pose an environmental threat, with precipitation transporting pollutants into nearby lakes, rivers, wetlands and coastal waters. Some of these sites are also home to sensitive plants and animals.

PG&E has developed a comprehensive program to comply with state permitting requirements for storm water management associated with construction projects. The stringent requirements call for PG&E to implement storm water pollution prevention plans and best management practices commensurate with a project’s risk level to minimize potential impacts to water quality.

These best management practices protect water quality, as well as plants and animals. They include using reusable fencing to prevent sediment from entering streams and waterways and deploying active treatment systems that remove sediments and other pollutants from collected storm water at construction sites.

We also use portable vehicle wash stations to prevent the spread of plant diseases and invasive weeds and install biological exclusion fences to prevent sensitive species, such as the California red-legged frog and the California tiger salamander, from entering construction sites. We select and implement best management practices on a site-specific basis.

PG&E has developed a program to protect water quality at construction project sites that do not trigger state permitting requirements.

PG&E is also focused on best practices for managing storm water at its power plants. For example, at our Humboldt Bay Generating Station, storm water is managed through a process that takes advantage of plants and microbes to filter and clean the storm water, thereby protecting water quality.

Learn more about how we are minimizing our impacts to natural resources.