MTBE in Southern California water

Methyl tertiary butyl ether (MTBE) is a common fuel oxygenate used in motor vehicle fuels to control emissions and boost octane. It is more water-soluble than other fuel constituents and does not adsorb well to substrates such as soil. It can contaminate groundwater supplies through leaking underground fuel storage tanks and pipelines, and through spills, urban storm runoff, and precipitation. It can also contaminate open water reservoirs through exhaust from motorized watercraft. The Metropolitan Water District of Southern California surveyed six reservoirs that supply drinking water in Southern California. Recreation on these reservoirs ranged from none at all to high activity with personal watercraft. It was found that motorized watercraft can contribute a significant amount of MTBE to the water supply.