Comparative Assessment of Water Quality at The Rainwater-Harvesting Basin and Neighborhood-Wash Scales

One of the anticipated benefits of green infrastructure is the capture in curb-cut basins of stormwater runoff that has accumulated urban contaminants like motor oil as it runs over asphalt and pavement. The desert-tolerant vegetation and soils within these residential rainwater-harvesting basins are expected to improve water quality by capturing these contaminants that would have otherwise flowed into local washes, and recharged into the groundwater. This project reports on a preliminary comparative study of stormwater runoff quality in two Tucson washes (High School Wash and Bronx Wash) that receive runoff from neighborhoods containing rainwater-harvesting basins. One goal of this research is to determine if a correlation exists between water quality in residential curb-cut basins and associated neighborhood washes. A secondary goal is to determine if there is a statistically significant relation between water quality and maintenance (or lack thereof) of curb-cut basins; previous research shows a strong correlation between basin maintenance and basin hydraulic conductivity. Finally, this project aims to design a water-sampling device and protocol that accounts for variability in basins’ soil composition, successfully filters debris and soil, and collects a sufficient sample size for water quality analysis.