A STREAM RESTORATION'S ENDEAVOR: ABATING EXCESS NUTRIENTS IN SEDIMENT

The Chesapeake Bay's Watershed is directly impacted by surrounding land use and associated management; the steady increase of urban expansion and a lack of regulation concerning fertilizer use is fostering an overabundance of nutrient rich sediments in streams. Excess nutrients in stream sediments are typically attributed to agricultural, residential, and industrial land use. Eutrophication, caused by algae blooms fed from these nutrients, is one of the leading causes of poor water quality in the Chesapeake Bay. In response to the nutrient pollution problem in the Chesapeake Bay, stream restorations have been adopted as a solution. The restorations are meant to aid streams in naturally filtering the sediments, reducing the need for continuous maintenance in stream health. The goal of our study is to determine if these engineered restorations are self-sustaining and abating downstream nutrient accumulation.

While there are multiple types of stream restorations in Lancaster County, the three common types of stream restorations are in-stream bank stabilization with rip-rap, bank stabilization with vegetation, and holistic flood plain restoration. Sediment samples from each site were collected from three key locations: upstream, instream, and downstream relative to the original restoration site. Total nitrogen, total phosphorous, zinc, copper, potassium and magnesium values were analyzed in each sediment sample, and the data collected was used to identify the relative performance of the restorations' ability to filter excess nutrients. Preliminary analyses indicate that the restorations are effective in reducing sediment nutrients when external factors do not influence the stream. Primary external factors are wastewater treatment plants and agricultural runoff inlets adding water to the restoration site, but other factors include surrounding land use and presence of water fowl. Where there are no observable external factors, a general decrease in sediment nutrients is apparent throughout the restoration. Notably, streams that had legacy sediment removed had a greater efficiency in nutrient removal than streams that did not. However, the influence of external factors suggests that watershed management also strongly influences sediment nutrient levels.