Benzene occurs infrequently in California public supply wells and comes predominantly from naturally occurring petroleum deposits deep in the ground, according to a study by the U.S. Geological Survey. Spills associated with underground fuel storage and above ground distribution systems have long been considered the main source of benzene in groundwater. This unique study finds that contamination most often occurs in older, brackish, groundwater located near naturally occurring deep underground oil and gas deposits.
As part of a statewide study assessing groundwater quality, scientists analyzed untreated groundwater from wells, not treated tap water. Groundwater used for public supply is typically treated by water providers to ensure compliance with water quality standards. “This study illustrates the value of letting scientific facts speak for themselves when dealing with critical issues such as the frequency and potential sources of groundwater contamination,” said USGS Director Marcia McNutt. READ MORE »