EVALUATING THE RESTORATION EFFICACY OF A TEMPERATE URBAN STREAM THROUGH ISOTOPIC ANALYSIS

West Creek like many urban streams in Cuyahoga county (Ohio) frequently receives storm runoff due in part to increased impervious surface from heavily urban development. To reduce the storm runoff, community and local governments have been attempting many restoration measures, e.g., creating artificial wetlands, converting parking lots to parkland, and urging residents to harvest roof-top rainwater. But the efficacy of such restoration efforts has not been adequately monitored and evaluated. Here we report our interim results of δ¹⁸O and δD of rain and stream water samples collected from multiple locations during the summer of 2011. δ¹⁸O and δD of stream waters ranged from -7.4 to -3.7 and from -49.0 to -19.8, with average values of -6.0 and -39.5, respectively. Although variable from site to site and from time to time, the isotopic values of stream waters were significantly lower than those of rainwater samples, averaging δ¹⁸O at -4.3 and δD at -18.0, collected in the same periods. The preliminary results suggest that values of δ¹⁸O and δD may be indicative of the relative contributions of rainwater over groundwater in a stream. A high-resolution sampling protocol is currently under development. We anticipate that the enhanced sampling scheme would facilitate our ability to better delineate the hydrology of this watershed.