Chrysotile Asbestos in California Surface Waters: From Upstream Rivers Through Water Treatment

This article describes the input, transport, and removal of chrysotile asbestos fibers delivered to Southern California through the State Water Project. Concentrations of chrysotile fibers in surface waters in California are estimated from a mass-balance model that takes into consideration natural weathering of serpentine rock in the Sierra Nevada and coastal mountains and removal of fibers by coagulation in reservoirs. As predicted, fiber removals of from 90 to 99.8 percent were observed in reservoirs with detention times of from 0.5 to 3 years. Removal of submicron-sized fibers in water treatment plants also ranged from 90 to 99.8 percent, depending on the degree of coagulation prior to filtration.