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Author: Chris Swann
Last Updated: 01-05-2019 19:53
Hill, Colin R., Pieper, Michela J., Medina, William and Mark S. Richmond.. 2019. Monitoring Stream Restoration in Howard County, Maryland to Determine Effectiveness in Reducing Pollutant Loads. Watershed Science Bulletin. Center for Watershed Protection, Ellicott City, MD. 15 pages.
Monitoring, stream restoration, pollutant
Under the 2010 Chesapeake and Atlantic Coastal Bays Trust Fund program, the Howard County Department of Public Works initiated a monitoring program at the Brampton Hills stream restoration project site located in Ellicott City, Maryland to evaluate the effectiveness of stream restoration in reducing loading of primary pollutants nitrogen, phosphorus, and sediment. Monitoring efforts included water quality sampling, both baseflow and storm flow, for two years prior to restoration (2010–2011) and for six years post-restoration (2012–2017). We developed a procedure using precipitation data to derive modeled storm flows using the U.S. Environmental Protection Agency’s Storm Water Management Model, calibrated using verified gaged flow data, as well as derived base-flows, to create an annual flow record at five-minute intervals, enabling estimates of annual loading rates for total nitrogen (TN), total phosphorus (TP), and total suspended solids (TSS). We calculated pollutant loads using the U.S. Army Corps of Engineers FLUX32 load estimation software for each sampling parameter and compared pre- and post-restoration loading rates to obtain estimates of load reductions resulting from the project. We then standardized loads by flow volume to allow for more direct comparisons since total annual flows differed considerably from year to year during the period of study. We calculated reduction rates per linear foot of restored stream of 0.20 pounds per foot per year (lbs/ft/yr) for TN, 0.20 lbs/ft/yr for TP and 73.4 lbs/ft/yr for TSS. Overall, the study found that the stream restoration project led to a considerable reduction of nutrients and suspended solids being generated within the study area.