RUNNING ACROSS A parking lot on a rainy day, you might notice a rainbow at your feet. The iridescent colors swirl across the glistening pavement. Even though it's beautiful, it's the result of an oil spill.

Oil spills occur constantly, but people usually don't pay attention to them. Often, only large drilling or transporting accidents capture the attention of the media and the general public. Yet within the United States, small oil spills are the norm. According to an information sheet published by the National Oceanic and Atmospheric Administration (NOAA), an agency of the U.S. government that deals with many environmental issues, including oil spills, "Most oil spills in U.S. waters involve fewer than 100 gallons. Of the 170,000 U.S. oil spills from 1973 through 1993, over 90% involved fewer than 100 gallons. Less than 1% were spills of 100,000 gallons or more."

These same...