Review of storm water toxicity from California urbanized watersheds

Storm water runoff from urban areas are typically a complex mixture of contaminants from a variety of anthropogenic and natural sources. Aquatic toxicity testing can be a useful measure to predict the effect of storm water runoff in receiving water bodies. Over 250 storm water samples were collected from both storm drains and receiving waterways at five different regions over a large geographic area ranging from San Diego to Sacramento. All samples were collected in a similar fashion using automated sampling devices to capture flow-weighted composites of storms which occurred between 1989 and 1995. Chronic toxicity screening tests were conducted on these samples using three freshwater species including Ceriodaphnia dubia, Selenastrum capricomutum, and Pimephales promelas. Ceriodaphnia dubia was utilized for all samples tested while Pimephales promelas and Selenastrum capricomutum were also tested for some samples. Phase 1 Toxicity Identification Evaluations (TIEs) were conducted on approximately 25 of these storm water samples which showed early acute toxicity. Most of the toxicity was associated with the C{sub 18} removable chemicals (non-polar organic compounds). Metal toxicity was generally associated with stations or areas receiving industrial runoff. High levels of metal constituents were confirmed by analytical measurements. Toxicity was shown to decrease over storagemore » time for some samples using Ceriodaphnia which may have implications for testing. Patterns of toxicity could be observed between distant geographic regions both within and between storm seasons.« less