Urgent Alert

Compressor stations

Learn about PG&E environmental restoration at our compressor stations

Our natural gas distribution system includes more than 40,000 miles of distribution pipelines and more than 6,000 miles of transportation pipelines. The pipelines provide service to around 4.2 million customers from Bakersfield to the Oregon border.


Eight gas compressor stations are crucial to our system. These stations receive, store and move natural gas through company pipelines. Nearly 40 percent of our natural gas supply enters the system at our Topock Compressor Station, which is located 15 miles southeast of Needles, California. The next station is located in Hinkley in San Bernardino County.


A map of California

Continue reading to learn about our environmental cleanup activities at the Topock and Hinkley facilities.


Learn why remediation is needed

Topock and Hinkley, the first two compressor stations on our distribution line, began operating in the early 1950s. These facilities prepared the gas for transportation through our pipelines to Northern and Central California. At that time, an additive containing hexavalent chromium was used at both stations to prevent rust in the cooling towers.


The cooling water that contained this additive was disposed of next to the compressor stations. This action was consistent with industry practices of the time. Later, the water was treated to remove the chromium before disposal. We have long since discontinued the use of hexavalent chromium at Topock and Hinkley. Under the direction of state and federal regulatory agencies, and with input from stakeholders, we are working to investigate, clean up and restore the environment at the Topock and Hinkley facilities.


Get details on the Topock and Hinkley facilities

To learn about the Topock Compressor Station, visit Topock Compressor Station.

To learn about the Hinkley Compressor Station, visit Hinkley Compressor Station.

Topock Compressor Station

The Topock Compressor Station is located in eastern San Bernardino County, about halfway between Needles, California and Lake Havasu City, Arizona. The Station has played an important role in supplying natural gas to PG&E’s service areas since 1951.

The Station and others like it safely pressurize natural gas, moving it through hundreds of miles of pipeline on its way to homes, businesses, and other customers in California. During compression, the temperature of natural gas increases and needs to be cooled before being pushed to the next compressor station.

Prior to 1985, PG&E followed industry standards in adding chromium compounds to water used during the cooling process to prevent corrosion of equipment. For a portion of that time, wastewater containing hexavalent chromium was discharged into an adjacent ravine known as Bat Cave Wash. Those historical activities contaminated groundwater and soil at and near the Station.

PG&E employees investigating grounds at the Topock Compressor Station

Since 1996, PG&E has investigated and initiated cleanup activities in close coordination with several agencies, Native American tribes, and stakeholder organizations. Early on, interim measures were used to ensure that no hexavalent chromium would reach the Colorado River until a final groundwater cleanup plan could be selected, designed, and implemented. Long-term monitoring data show that hexavalent chromium has not reached or been detected in Colorado River water.


In 2011, the agencies selected in-situ treatment with freshwater flushing as the final groundwater remedy. PG&E uses this in-situ or “in place” method to safely remove hexavalent chromium while dozens of monitoring wells help track progress. Construction of the remedy began in 2018 after a detailed engineering design process. The in-situ treatment zone and other initial components became operational in December 2021. Construction of remaining components is ongoing, with the next phase of work expected to be completed in 2024.


Meanwhile, PG&E continues its efforts to investigate and remediate contaminants in soil at and near the Station that may have been affected by historical operations. To date, hundreds of soil samples have been tested to define where cleanup is needed and how best to do it. Guided by a federal directive, a non-time-critical removal action began in 2022 to remove soil from several identified areas. In parallel, the state-led soil investigation and decision-making process is ongoing.


Alongside all of its environmental cleanup activities, PG&E takes seriously its role in protecting sensitive biological and cultural resources in the project area. Our efforts range from surveys and monitoring of bats, birds, reptiles, mammals, and desert plants to detailed tracking of important cultural resources that must be honored and protected during our work. 

PG&E supports local community events and programs with regional tribes, municipalities, public service organizations, and local school districts. Recent examples include cleanup days to help remove trash and debris from a nearby national wildlife refuge, tree plantings to provide shade for elementary school children, helpful grants to fund programs for schools and organizations, and being supportive and present during tribal gatherings to learn more about their culture and community programs.

Follow our groundwater cleanup effort

Nothing is more important to PG&E than the safety of its customers and communities. This commitment to safety includes taking responsibility for and addressing any potential environmental impacts from our historical operations.


We’re working under the direction of the Lahontan Regional Water Quality Control Board (Water Board) to clean up chromium-6 found in groundwater resulting from historical operations at the Hinkley Compressor Station. We’re committed to protecting public health and safety at the plant. The Hinkley Compressor Station. is located in San Bernardino County, five miles west of Barstow, California.


Hinkley Compressor Station

Station History

Hinkley Compressor Station and others like it are needed to safely pressurize natural gas, moving it through hundreds of miles of pipeline on its way to homes, businesses and other gas customers.


The temperature of natural gas increases during compression, and the gas must be moved to cooling towers. To prevent corrosion of cooling tower equipment, chromium compounds were added to the water used in the cooling towers and other equipment.


Consistent with industry standards at the time, cooling tower wastewater containing hexavalent chromium was discharged into the adjacent area through 1964.  Thereafter, chromium containing wastewater was managed in a manner to prevent discharge into the environment.  


Investigation and cleanup efforts at Hinkley include cleaning up the environment, restoring water quality and working closely with the community. We’ve taken action to stop the migration of affected groundwater, and we’re operating numerous treatment systems to clean up the groundwater. Our robust network of more than 800 monitoring wells tracks the effectiveness of the cleanup.


Understanding drinking water standards for hexavalent chromium

PG&E has monitored the levels of chromium in over 400 local domestic wells in the Hinkley valley. Levels of chromium 6 in domestic wells in use by Hinkley residents and sampled by PG&E are well below the California drinking water standard for total chromium of 50 ppb and the proposed chromium 6 drinking water standard of 10 ppb.


Establishing Independent Technical Expertise

We recognize that it’s in the best interest of all community stakeholders to understand the complex technical issues involved in the groundwater cleanup efforts in Hinkley. For this reason, we provided funding for the community to hire an independent technical expert. The community interviewed and hired an Independent Review Panel Manager in early 2012. This expert continues to assist the community with reviewing and understanding  ongoing remediation work.


To learn more about our cleanup efforts or if you are interested in attending a community meeting:

  • Meetings are open to the public.
  • Meetings are held the fourth Thursday of every quarter from 6 p.m. to 7:30 p.m.

Meeting agendas are available at the independent review panel manager's office at 36236 Serra Road, Hinkley, CA 92347. Agendas are available online. Visit Hinkley Groundwater Remediation Program.

Learn about the cleanup underway

In 2015, a new cleanup order for chromium 6 received unanimous approval from the Lahontan Water Board. Building on the environmental review and approved Environmental Impact Report (EIR) completed in 2013, the Lahontan Water Board, Hinkley residents and PG&E spent more than a year working towards a consensus-based order for the cleanup. The new order consolidated and simplified numerous past orders and  streamlined our processes while making them more understandable and transparent to the community and other key stakeholders. 

With the order in place and remedy construction complete, PG&E remains committed to implementing a thorough and sustainable cleanup plan for Hinkley. Utilizing the remedial technologies we have built over the last decade, our long-term remedy continues to treat the highest concentrations of chromium 6 in the near-term, while sustainably treating and managing lower concentrations for the next several decades. There’s a lot of work to do, we are committed to doing what's right for the Hinkley community, and we will be here until we finish the job. 


Updated Background Study

As part of PG&E’s commitment to applying the best science and knowledge to our programs in Hinkley and at the Lahontan Water Board’s request, PG&E provided funding for an Updated Background Study for chromium 6 in area groundwater led by Dr. John Izbicki of The United States Geological Survey (USGS).


The findings of the study, published in April 2023, support our approach to remediation treating the highest concentrations of chromium 6 in the near-term, while sustainably treating and managing lower concentrations for the next several decades. The USGS study provides further clarity on the difference between naturally occurring chromium 6 in the Hinkley Valley and Chromium 6 present as a result of PG&E’s historic operations.

The USGS study also concluded that chromium present in the northern Hinkley Valley and Water Valleys, previously referred to as the northern disputed plumes, is naturally occurring and not associated with the PG&E release. PG&E is committed to working with the community and Water Board to best utilize this new information as we continue to improve and adapt our remedial approach.

Actively Engaging the Community

We continue our commitment to the community through local hiring, sustainable practices and community partnerships.

Local community support includes:

  • Health fairs
  • Community clean up events
  • Charitable contributions to nearby communities and schools

Hinkley 4H Club members participate in a Hinkley Community Clean-up event.

More on compressor stations

Contact us

If you have additional questions, call our environmental remediation hotline at 1-866-247-0581 or email remediation@pge.com.

Get more details

The full Topock Project website provides more details about the cleanup, including photos, schedules, public factsheets, and documents.