Presentation: Watershed 263 small headwater storm drain catchment hydrology: preliminary water quality results
Belt, K.T., Pouyat, R. V., Stack, W. P., Heisler, G., Groffman, P.M., Ghosh, U., Taylorson, A., and J. Zhou

Two small headwater storm drain catchments in Watershed 263 are being studied with continuous temperature recorders, stage and velocity gauges, automated flow paced samplers. We present preliminary data collected recently at the Baltimore (Bal) and Lanvale (Lan) Street gauging stations that reveal a dynamic thermal system, high bacterial concentrations and large nutrient and metal loads, especially at the Bal site, which has a higher impervious surface cover. Relatively warm dry weather flows (22-24 C) were seen, with great thermal variances suggesting surface and groundwater hydrologic interactions. Runoff induced (August) temperature spikes of 2-5 C (Bal) and <1-4 C (Lan) were common and lasted for long periods (2-6 hrs), followed by extended elevated baseflow levels. Generally Bal had more transient temperature increases, both for storm and dry weather. Transient, non-storm runoff related changes are seen in both watersheds. Bacterial concentrations were high, with storm concentrations of fecal coliform of 900,000 organisms/100 ml and E .coli values of 364,000/148,000 at Bal/Lan. Concentrations in dry weather were lower, with mean levels at Bal/Lan of 1,633/877 org/100 ml. BOD5 concentrations were high (30.5/20.5 mg/l) at the Bal/Lan sites. Cu (36/18 ug/l), Pb (73/28 ug/l), and Zn (143/77 ug/l) concentrations in storm composites (Bal/Lan) were high; Bal site concentrations were 60 to 160 % higher than at Lan. Dissolved metals made up a large part of the total metals (13/20% for Pb, 50/53 % for Cu, and 51/59% for Zn, at Bal/Lan). Nutrient storm concentrations were elevated, with concentrations of nitrate-nitrite N (1.31/1.08 mg/l), TKN (2.55/1.75 mg/l) and total phosphorus (0.67/0.32 mg/l) at the Bal/Lan sites. The Bal site concentrations were 21, 46, and 108 % higher for N03-N, TKN, and TP than at Lan.


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