SANTA MONICA, Calif. - Miriam Cardenas was puzzled when she first saw the strange reading in the water-quality report she got back from the laboratory. As chief water chemist for the city of Santa Monica, it was her job to see that the tap water in this sun-drenched beach community is safe to drink.
The annual test Cardenas had run for potentially harmful contaminants in the city's water came back in the fall of 1995 with the usual negative results --- except for finding traces of a new chemical, methyl tertiary butyl ether, or MTBE. Cardenas had never heard of it.
"What is this?" she recalled wondering. "Why is it there?" She quickly found out what most of the rest of the country has since learned as well. MTBE is a gasoline additive that has proven incredibly adept at contaminating groundwater, and is maddeningly difficult to get out once it's there.
As residents living near Fallston in Maryland wrestle with the recent discovery of an MTBE plume contaminating the wells of 84 homes around an Exxon service station there, they can consider what happened in Santa Monica.
This upscale, slightly offbeat city just west of Los Angeles - where homeless men lounge next to parked Mercedes-Benz autos - was one of the first communities in the country to discover the gasoline byproduct in its water supply, and one of the worst hit.
Eight years ago, after MTBE began showing up in one municipal well after another, city officials shut down seven of them, eliminating roughly half of the community's water supply.
To this day, those wells remain dormant, as Santa Monica has been forced to import replacement water from Northern California and from the Colorado River, hundreds of miles away.
The cost, about $3 million a year, is borne by a group of oil companies that had gas stations around the city's well field. Until those companies were forced to step forward, though, Santa Monica had to increase its water rates by 25 percent.
Now, after eight years of litigation and negotiations, the city has reached an out-of-court settlement with the oil companies to pay $100 million in damages and to clean up the MTBE-tainted aquifer.
Once studies under way determine the best approach, the companies have agreed to underwrite construction of a treatment plant - which officials project could cost $50 million to $100 million to build, plus millions more annually to operate.
It may be another five years, at the earliest, city officials predict, before they can begin pumping water again from the city's largest well field.
"It just boggles the mind how much money this has cost and will cost," says Craig Perkins, Santa Monica's director of environment and public works. "The irony, I guess, is that the cheapest thing for the oil companies would be just to pay for our replacement water in perpetuity, but that's not acceptable to us, or, fortunately, to the regulatory authorities."
MTBE was supposed to help clean up the environment, not contaminate it.
Made from wood alcohol and a byproduct of petroleum refining, MTBE had been added to gasoline on a limited basis since the late 1970s to enhance octane and reduce engine knock.
Beginning in the 1980s, though, it began to be put in gas to combat harmful air pollutants like carbon monoxide and ozone, the chief ingredient in summertime smog. Its use really took off, though, after 1990, when Congress ordered the sale of clean-burning "reformulated gas" in the 10 metropolitan areas with the worst smog levels. Los Angeles was at the top of the list, and Baltimore wasn't far behind.
But the same chemical properties that made MTBE useful as an "oxygenate" in cleaner-burning fuel also made it prone to contaminate groundwater. It dissolves easily, much more so than the other ingredients of gasoline.
With many service stations' underground fuel tanks corroding and springing leaks by the early 1980s, it didn't take long for the chemical to start showing up in people's wells - in Rockaway, N.J., and locally, in Jacksonville in rural Baltimore County.
Despite such warnings, no one was looking for MTBE when Santa Monica officials learned they had it in their wells. There were no federal or state guidelines then on how much was safe in drinking water, and precious little information on its health effects.
When the additive showed up in the city's Charnock well field, recalls Cardenas, she initially thought it was a lab error.
Even after follow-up samples confirmed the finding early in 1996, city officials at first figured they could keep the contaminant at minimal levels by mixing the water from the one tainted well with clean water from the other four.
But, within a few weeks, MTBE levels soared in the first well to 610 parts per billion, prompting officials to shut it down - only to watch with alarm as the contaminant began popping up in the remaining wells in its Charnock well field.