High-frequency water quality and discharge data for selected stormwater facilities in Baltimore County, MD, USA

This resource is a repository for water quality and discharge data collected at the inlets and outlets of three stormwater facilities in Baltimore County, MD, USA. EXO sondes outfitted with temperature, SC, and turbidity sensors, SUNAs (for measuring nitrate), and Blue Siren depth and velocity sensors were installed in fall/winter 2025-2026. The EXO sondes and Blue Siren sensors collect data at a 5-minute interval; the SUNAs collect data at a 15-minute interval. The sensor data is complemented by ISCO grab sampling of a subset of storms for laboratory analysis of nitrate, chloride, sulfate, fluoride by ion chromatography; and total nitrogen, total phosphorus, and total suspended sediment by EPA standard methods. The purpose of the data collection is to assess TN, TP, and TSS removal efficiency of the facilities before and after Continuous Monitoring and Adaptive Control (CMAC) installation. The three facilities include two extended detention basins retrofitted with gabion sand filters and one vegetated wet pond. Data are being collected for 2 years. This project is supported by Chesapeake Bay Trust.