Pacific Gas Litigation
The case alleged contamination of drinking water with hexavalent chromium, also known as chromium (VI), in the southern California town of Hinkley. At the center of the case is a facility called the Hinkley Compressor Station, part of a natural gas pipeline connecting to the San Francisco Bay Area and constructed in 1952. The case was settled in 1996 for $333 million, the largest settlement ever paid in a direct action lawsuit in U.S. history.

Brockovich's work was and remains controversial. Chromium (VI) is known to be toxic and carcinogenic, and the 0.58 ppm in the groundwater in Hinkley exceeded the Maximum Contaminant Level of 0.1 ppm currently set by the Environmental Protection Agency. However, while it has long been known that chromium (VI) is carcinogenic when ingested via inhalation, drinking water laced with chromium (VI) is widely believed to be less toxic; some experts argue that the exposures at Hinkley were too low to cause health effects, while others respond that there were too many gaps in the data on chromium to dismiss the Hinkley residents' case.

When Harvard's School of Public Health gave Brockovich an award in 2005, scientists were divided on the merits of her work. National Institutes of Health researchers announced May 16, 2007 there is strong evidence that hexavalent chromium causes cancer in laboratory animals when it is consumed in drinking water. The two-year study conducted by the National Toxicology Program (NTP) shows that animals given hexavalent chromium developed malignant tumors. The report warns that extrapolation of these results to other species, including characterization of hazards and risks to humans, requires analyses beyond the intent of the report.

Working with Thousand Oaks, California-based lawyer Edward L. Masry, Brockovich went on to participate in other anti-pollution lawsuits. One accuses Whitman Corporation of chromium contamination in Willits, California. Another lawsuit, which lists 1,200 plaintiffs, alleges contamination near PG&E's Kettleman Hills Compressor Station in Kings County, California, along the same pipeline as the Hinkley site.

After experiencing problems with mold contamination in her own home in the Conejo Valley, Brockovich became a prominent activist and educator in this area as well. Today, Brockovich is a noted speaker in demand all over the U.S.

Popular culture
Her story is the topic of a feature film, Erin Brockovich, starring Julia Roberts in the title role. The film was nominated for several Academy Awards, including Best Actress in a Leading Role, Best Actor in a Supporting Role, Best Director, Best Picture, and Best Writing in a Screenplay Written Directly for the Screen. Roberts won the Academy Award for Best Actress for her portrayal of Erin Brockovich. Erin Brockovich herself portrayed a cameo role as a waitress named Julia.

After the success of the film about her, Brockovich was the target of a blackmail attempt by her old boyfriend, George (played by Aaron Eckhart in the film), one of her ex-husbands, and an attorney who threatened to smear her reputation as a parent. She called the police, who later arrested the three for extortion after conducting a sting operation.

In The Simpsons episode "Sweets and Sour Marge", Homer twists Brockovich's name and makes a few puns referring to Marge: "Erin Choco-Snitch", "Blue-hairin Brocko-witch" and Marge's favorite: "Carin' A-lot-ovich". Brockovich is also appearing in The Simpsons Movie, playing herself.