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Discovery
In August 1995, the City of Santa Monica discovered the gasoline additive MTBE in drinking water supply wells at its Charnock Wellfield, located at 11375 Westminster Avenue, Los Angeles, California. Santa Monica discovered this MTBE through routine analytical testing of well water. EPA has no knowledge of any taste and odor complaints related to the MTBE in the city's wells. The city shut down the affected wells and secured replacement water from the Metropolitan Water District.
In August 1995, the City's Charnock Wellfield had five operating municipal supply wells which provided approximately 45% of the drinking water for the City's 87,000 residents and approximately 200,000 daytime customers. In 1996, levels of MTBE at the City's Charnock Wellfield rose to more than 600 parts per billion (ppb) and, by June 13, 1996, all of the supply wells at the City's Charnock Wellfield were shut down due to persistent and increasing levels of MTBE contamination.
In October 1996, following the shutdown of the City's Charnock Wellfield, the Southern California Water Company ("SCWC"), another water purveyor utilizing the Charnock Sub-Basin, shut down its wellfield in the sub-basin, in order to avoid drawing the contamination toward the SCWC Wellfield. Prior to this shutdown, SCWC had two operating municipal supply groundwater wells that provided a portion of the drinking water for approximately 10,000 residences and businesses in Culver City. Culver City residents are also receiving alternate water supplies.
Since 1996, the City of Santa Monica and Southern California Water Company
have purchased replacement water from the Metropolitan Water District.
A small group of the parties with responsibility for potential pollution
source-sites (Shell and Chevron, joined in 1998 by Exxon) reimbursed the
City and Southern California Water Company for these costs until January
2000. The Agreements under which these parties reimbursed the City and
State for water replacement ended in January 2000. Enforcement orders
from EPA and the Los
Angeles Regional Water Quality Control Board 
now
require a total of 16 parties to provide clean replacement water until
January 2005.
A July 1998 Fact Sheet (PDF) (6pg, 247K, About PDF) provides further background information on MTBE and the early stages of the Project.