Impacts of Stream Hydrologic Characteristics on Ambient Water Quality and Aquatic Health in the Austin, Texas Area

Glick, Roger H.
Gosselink, Leila
Bai, Baolin
Herrington, Chris
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City of Austin Watershed Protection Department

Water quality and aquatic health data collected as part of the City of Austin (COA) Environmental Integrity Index (EII) were compared to stream flow characteristics using forty-four metrics derived from daily average flows collected by the U.S. Geological Survey (USGS) and COA. Water quality data were highly correlated with impervious cover (r = -0.911). Most of the flow metrics were correlated with each other, as was expected, resulting in a redundancy of information and the possibility of cross-correlation when performing additional analyses. A statistical relationship between aquatic life data and three flow metrics, fraction of time the creek is dry, single pass baseflow ratio and the natural log of the 90th percentile flow, was developed based on the correlations and what metrics can be predicted reliably with existing watershed models. The resulting model has an adjusted r2 = 0.702. This model will be used to predict aquatic life potential in Austin-area streams using modeled flows under different development scenarios.