HR: 0800h
AN: H31B-1313    [Abstracts]
TI: Sources and Pathways of Bacterial Contamination in Urban Streams and Ocean Beaches, Santa Barbara, California
AU: * Johnson, R D
EM: rujohns@usgs.gov
AF: U.S. Geological Survey, 5735 Kearny Villa Rd, Ste O, San Diego, CA 92123 United States
AU: Mendez, G O
EM: gomendez@usgs.gov
AF: U.S. Geological Survey, 5735 Kearny Villa Rd, Ste O, San Diego, CA 92123 United States
AU: La, J X
EM: janla@usgs.gov
AF: U.S. Geological Survey, 5735 Kearny Villa Rd, Ste O, San Diego, CA 92123 United States
AU: Izbicki, J A
EM: jaizbick@usgs.gov
AF: U.S. Geological Survey, 5735 Kearny Villa Rd, Ste O, San Diego, CA 92123 United States
AB: Streams and ocean beaches in Santa Barbara, California, occasionally have concentrations of fecal indicator bacteria that exceed public health standards for recreational water, forcing temporary beach closures. Possible sources of fecal bacteria contamination include transient human populations, animal populations, and leaking sewer lines. The purpose of this three-year study is to identify important sources of fecal bacteria affecting the urban streams and beaches and to identify important pathways of transport. Contamination may enter streams and beaches directly by surface runoff, but also may be transmitted short distances through shallow ground water. Our analysis of existing historical data shows that fecal indicator bacteria concentrations are higher in near-shore ocean water following extreme high tides. The possible role of near shore ground water in supplying contaminants to the sea will be investigated by sampling water from an array of shallow wells installed for this study between an older city sewer line and the ocean. The ground water flux to the ocean will be inferred from water levels in these wells, and further tested by radium isotope values in near shore ocean samples. Two additional well arrays will be installed to test for leakage from residential sewage hookups and measure associated exchanges between ground water, streams, and ocean. Preliminary data collected by this study show fecal indicator bacteria concentrations in urban reaches of Mission Creek and its tributaries, the principle drainage through the city, are higher during low flow periods than during periods of higher flow. Analysis of preliminary data also shows short-term temporal variations in bacterial concentrations during twenty-four hour periods. Human enterovirus has been detected in our sample from one urban-drain tributary to Mission Creek. In order to identify the origins of fecal indicator bacteria water samples from Mission Creek, its tributaries, urban drains, and associated shallow ground water will be analyzed for nutrients, dissolved organic carbon (including optical properties to characterize the composition of the organic carbon), fecal sterols, DNA (using Terminal-Restriction Fragment Length Poylmorphism), and phospholipid fatty acids.
DE: 1830 Groundwater/surface water interaction
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: Fall Meeting 2005