Lomita Responds to Benzene Detection – Temporarily Transitions to Imported Water

City Begins Investigating Source of Benzene Intrusion

During a recent annual water quality test, results showed detection of benzene, a chemical widely used in many industries, at the City’s single groundwater production well, Well No. 5. Immediately following a confirmation of test results, the City took Well 5 offline and transitioned to imported water. The City is now temporarily relying on water from Metropolitan Water District (MWD), the City’s approved alternate source, to supply all households until the source of the contamination can be identified and the issue has been resolved.

The City continues to adhere to all water quality guidelines in its response to confirming detection of benzene and has partnered with State regulators to investigate and mitigate the source. Benzene is a known carcinogen that, in high levels over a long period of exposure, can increase cancer risk. The City does not believe water users are at risk at this time, but–as a measure of precaution–has transitioned to the backup imported water source while it conducts its investigations.

In California, the maximum contaminant level (MCL) for benzene in public drinking water supply is 1 part per billion (ppb) or 0.001 milligrams per liter. On May 9th, the City received a result for a single annual water quality test sample collected on April 30 that showed benzene detection over the MCL at 3.2 ppb in the water supply at Well No. 5 at the Cypress Water Production Facility (CWPF). Lomita Water operators conducted additional confirmation sampling at Well No. 5 and sampling throughout the City’s distribution system to verify the results. Benzene was detected at 3.6 ppb and 3.7 ppb at Well No.5, and from Not Detected (ND) to 1.4 ppb in the distribution system.

The City’s only domestic production well, Well No. 5, was immediately taken offline after the City’s receipt of laboratory confirmation results. The City has temporarily switched to securing all water from MWD and enlisted the assistance of State regulators to identify the source of the benzene contamination. The State has been assisting the City in identifying the source of contamination, further testing, and evaluation of mitigation measures and treatment options and to bring Well No. 5 back into operations with treatment to mitigate the present situation.

“The public’s safety is our top priority, which is why we moved immediately to remove Well No. 5 from our water supply once the benzene results were confirmed. The City’s commitment to open, transparent and high-quality water service is unwavering and we will continue to strictly follow water quality protocols to protect the public’s health. The transition is an operational shift to ensure the safety of our residents and we will continue to exceed State requirements by being transparent with our findings and operational decisions. We want our Lomita community to know the steps we are taking to ensure their water supply is safe and protected. We appreciate the assistance of our partners at the State level and we are working with them to: (1) identify and hold responsible the source of the contamination, and (2) return Well No. 5 to its routine operation.” – Lomita City Manager Ryan Smoot

Benzene is a chemical that is a colorless or light yellow liquid at room temperature. It has a sweet odor and is highly flammable. The Department of Health and Human Services (DHHS) has determined that long-term exposure to high levels of benzene causes cancer in humans. Per the Centers for Disease Control and Prevention (CDC), “long-term exposure” is continued exposure of a year or more. The seriousness of poisoning caused by benzene depends on the amount, route, and length of time of exposure, as well as the age and pre-existing medical condition of the exposed person.

The City is working closely with the State Water Resources Control Board, Division of Drinking Water, the Los Angeles Regional Water Quality Control Board, and other agencies to identify the potential source of benzene contamination through extensive testing. This testing may include identification and investigation of potential sources both inside and outside the City, extensive sampling, boring and monitoring of likely sources in the area, and ongoing monitoring of soil and water levels. It may take some time to identify the source, but with the help of the State’s regulatory agencies, the City will continue to take appropriate action to protect its residents. Throughout the identification and mitigation processes, the City will share progress through LomitaWater.com and other City communication channels.

If you have questions about this notice, please contact the City’s Public Works Director, Carla Dillon at (310) 325-7110 x124, or reach us directly through the City’s dedicated water quality website, www.LomitaWater.com. If you have any other concerns about your water quality, please send us a detailed report.

Timeline of City’s Response

  • April 2018 – Last year’s test confirmed benzene levels at only 0.54 ppb
  • April 30, 2019 – First sample collected showing benzene above MCL at 3.2 ppb
  • May 9, 2019 – First confirmation test
  • May 10-22, 2019 – Additional confirmation samples taken at Well No. 5 and throughout distribution system, and analyzed
  • May 15, 2019 – Confirmation of benzene intrusion from samples
  • May 15, 2019 – Switched to MWD water supply
  • May 29, 2019 – Notification of temporary water supply switch through LomitaWater.com
  • June 10, 2019 – Expect to publish next Water Quality Report
  • Late June/early July – Expect to send next Water Bill to ratepayers
  • July 2019 – Next Consumer Confidence Report (CCR) goes out, which will include data from 2018


Frequently Asked Questions about benzene, the April 30 test results and follow-up confirmation testing, what the City is doing to investigate the benzene intrusion, and future plans to ensure a clean water supply:

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Additional Resources

Laboratory Reports for Benzene

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