A California judge has ordered five oil companies to clean up sites contaminated with gasoline additive MTBE. The order is part of a lawsuit leveled by Communities for a Better Environment (CBE), an environmental protection group based in the San Francisco area.

The environmental organization claimed Shell, Chevron, Texaco, Equilon Enterprises, Unocal, Arco, Tosco, Exxon and Mobil knew MTBE could leak into ground water but still used the product. CBE added using it violated the state's Unfair Competition Act because it went on to indeed contaminate ground water.

Shell, Chevron, Texaco, Equilon Enterprises and Unocal settled the suit. The others are still in litigation. The settlement affects approximately 700 sites - for now. About 700 others are being contested. It is estimated the cost of cleanup is between $150,000 and $275,000 per site.

Another California environmental group, Bluewater Network, released a report that details the history of MTBE use in the country. It states that the oil industry knew as early as 1993 that MTBE was not responding to cleanup techniques and that several oil industry experts recommended against its use. However, oil companies ignored the warnings and convinced the U.S. Environmental Protection Agency (EPA) that water monitoring was unnecessary.