In situ sensors for monitoring BMP performance and in-stream pollutant loading

Abstract

For this research, a sensor network was used to evaluate pollutant loads and concentrations in the targeted portions of streams and to evaluate the performance of pond/wetland stormwater best management practices (BMPs). The study sites were chosen to examine whether BMPs achieve their intended purpose of improving surface water quality. This data was also collected with intent of examining whether a sensor network could provide more a more efficient and comprehensive means of monitoring surface waters and BMP systems. Violations of water quality standards for turbidity, dissolved oxygen, and chloride (chronic) were periodically observed at both sampling locations. Measured concentrations of pollutants we converted to loading rates to determine flow profile influences on water quality. Dissolved oxygen and chloride violations were generally observed during periods of low flow, while those for turbidity were generally independent of flow. Water quality downstream of BMPs was often (but not always) better than upstream water quality, suggesting that BMPs controlling stormwater inflow are not contributing to the degradation of downstream water quality. Analysis of water quality before and during rain events indicates that chloride and suspended solids are controlled in the pond/wetland systems studied. Evidence for phosphorus removal was also obtained.