Spanning 25 square miles across Vancouver, Washington, the Columbia Slope watershed is a complex web of hillside seeps and streams, open and piped conveyance, infiltration facilities, small ponds, marshes, and wetland areas. The watershed is composed of several riverine floodplain areas supplied by groundwater, surface water runoff, and infiltrated urban stormwater that drains into the Columbia River.
The City developed the Columbia Slope Water Quality Monitoring project to characterize water quality of inputs to the Columbia River and inform stormwater management activities to eliminate or reduce pollution. This project is funded by a grant from the U.S. Environmental Protection Agency (EPA) and will help the City prioritize basins for stormwater treatment and evaluate effectiveness.
In 2021, Herrera began collaborating with the City of Vancouver to conduct water quality monitoring, which includes in situ measurements, flow measurements, and sampling of multiple locations. Herrera is excited to extend this monitoring effort for another 18 months. Using this data, Herrera will provide a data analysis report to inform and support City and state activities designed to improve water quality in the Columbia Slope watershed. Our team will evaluate basins for stormwater treatment retrofitting based on an assessment of pollutants of interest discharged to the Columbia River in each basin.
Herrera will continue to monitor storm and base flow in the Columbia Slope Watershed through 2023.