Concentrations of methyl-tert-butyl ether (MTBE) in inputs and receiving waters of southern California

The occurrence and concentration of the fuel additive methyl-tert-butyl eth er (MTBE) were measured in dry weather runoff, municipal wastewater and ind ustrial effluents, and coastal receiving waters in southern California. Com bined, refineries and sewage treatment plants release approximately 214 kg day(-1) of MTBE into the marine environment, with Santa Monica Bay receivin g most (98%) of this discharge. Dry weather urban runoff was analysed for s amples collected from 25 streams and rivers, and accounted for less than 0. 5% of the mass of MTBE discharged to coastal waters. Receiving water sample s were collected from 23 stations in Santa Monica Bay, Los Angeles Harbour and Mission Bay or San Diego Bay. MTBE was detected at low concentrations n ear effluent discharges, however there was no evidence of bay-wide MTBE con tamination related to these outfalls. Marinas and areas used intensively fo r recreational boating had the highest average MTBE concentration (8.8 mug l(-1)). Surface water contamination was most widespread in San Diego Bay an d Mission Bay, areas with no refinery or sewage treatment plant inputs. (C) 2001 Elsevier Science Ltd. All rights reserved.