Monday, May 26, 2008 - 11:45 AM
55

Benthic response to sewage overflows in urban streams

Mateo Scoggins, Mary Gilroy, Andrew Clamann, Heather Perry, Chris Herrington, and Staryn Wagner. Watershed Protection and Development Review Department, City of Austin, 505 Barton Springs Rd., 11th Floor, Austin, TX 78767

In 2005, 121 billion liters of wastewater flowed through 4000 Kilometers of city maintained sanitary sewer lines in the City of Austin, TX. During that same year, there were 224 reportable overflows where raw wastewater reached streams in every watershed in the City of Austin.  Although the effect of raw wastewater on streams has been studied for over a hundred years, spatial and temporal effects from small pulse events to urban stream structure and function have not been documented. Three spill events of varying magnitudes were studied on three intermittent urban streams, assessing biological response using an upstream-downstream approach and through a 2-month recovery period.  Benthic macroinvertebrate community response was dramatic both spatially and temporally, with recovery to background conditions only occurring at one of the study streams after two months of monitoring.  Diel dissolved oxygen ranges (min to max) and the slope of diel oxygen ascent and descent increased significantly at spill affected sites and remained different than upstream conditions at least 4 weeks after the spill occurred.  Results from this study suggest that sewage overflows are a significant stressor in urban streams, causing more severe and longer term degradation than was previously thought.


Web Page: urban stream sewage

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