Evaluation of Catchment-Scale Stormwater Runoff Management on First-Flush Water Quality and Storm Discharge Quantity

Abstract

Urbanization and resulting imperviousness has caused increased pollutant loadings into receiving water bodies. One of the main sources of pollutant loads is stormwater runoff. The purpose of this study was to investigate the capabilities of low impact development (LID) best management practices (BMPs) and traditional retention ponds to address pollutant loads in first-flush stormwater runoff. Two studies were completed. First, a paired watershed study, in which one basin included a suite of LID BMPs and the other included traditional curb and gutter stormwater controls, was monitored for hydrologic and water quality data. The second study examined the water quality improvement capabilities of four nearby retention ponds. LID BMPs decreased total runoff volume and peak discharge rates for most sampled events. Water quality data showed differences in all pollutants except for dissolved reactive phosphorous. The retention ponds showed decreased nutrient concentrations compared to data from the national stormwater database. The combination of LID BMPs and retention ponds used in series would likely decrease urban stormwater pollutant loads.