LOS ANGELES — A toxic plume of chromium has spread to multiple groundwater wells near the California desert town made famous by the movie "Erin Brockovich."
In a letter sent Monday to Pacific Gas & Electric, which had discharged the chromium decades ago, water regulators said wells near Hinkley are showing increased concentrations of the cancer-causing substance despite efforts to contain it.
More storms loom, tornadoes possible in many parts
An area stretching from the lower Great Lakes to the Tennessee Valley was expected to be hit by severe thunderstorms on Wednesday, forecasters warned.
- Chaos and courage in wrecked elementary schools
- Search for Oklahoma tornado survivors set to end
- 'She was always happy': Families grieve tornado victims
- Ex-IRS official doubts explanation on Tea Party scandal
- More storms loom, tornadoes possible in many parts
The board on Monday also ordered the utility to conduct more tests after discovering more polluted wells.
"In parts of the chromium plume, concentrations of total chromium exceed the current drinking water standard ... thereby rendering areas of the groundwater unusable," the regulators added.
A company spokesman said PG&E is complying with the directive.
PG&E tried to stop the spread after the contamination was exposed during a 1996 case in which the utility settled with Hinkley residents for $333 million.
Only on NBCNews.com
- From belief to betrayal: How America fell for Armstrong
- US to Syria neighbors: Be ready to act on WMDs
- China: One-child policy is here to stay
- New 'Practice Range' shooter game says it’s from NRA
- 'Gifted' priest indicted in crystal meth case
- China's state media admits to air pollution crisis
- French to send 1,000 more troops to Mali
In 2008, PG&E agreed to pay $20 million to settle the last in a series of lawsuits over the wells.
The agreement involved claims that 104 people were exposed to water that contained chromium 6, a possible carcinogen.
The lawsuits claimed PG&E contamination sickened hundreds of people in Kings, Riverside and San Bernardino counties from the 1950s through the mid-1980s.
In 2006, PG&E agreed to pay $295 million to settle other lawsuits involving about 1,100 people.
Erin Brockovich, then a law firm assistant, rallied Hinkley's 600 residents to sue PG&E. That battle was the basis for the 2000 movie staring Julia Roberts.
The Associated Press contributed to this report..