Stream Restoration for Legacy Sediments at Gramies Run, Maryland: Early Lessons from Implementation, Water Quality Monitoring, and Soil Health

While stream restorations are increasingly being adopted to mitigate sediment and nutrient inputs and to meet water quality regulatory targets, less information is available on the drivers behind the design, implementation, effectiveness, and cost of restorations. We address these issues for a $4.2 million stream restoration for legacy sediments implemented for a rural Piedmont stream in Maryland, USA. A total of 1668 m of stream was restored in three phases, which included the partial removal of legacy sediments, the grading of streambanks, floodplain creation, channel reshaping with meanders and pool-riffle forms, the raising of the stream bed, and the planting of riparian vegetation. The sediment, nitrogen, and phosphorus concentrations and fluxes were monitored before- and during the restoration phases. The sites selected for restoration had legacy sediments vulnerable to erosion and were on state-owned land. The restoration design was based on the need to maintain mature riparian trees and preserve existing sensitive wetland habitats. Water quality monitoring indicated that the sediment and nutrient fluxes increased during the restoration phase and were attributed to disturbance associated with construction activities and increased runoff. We also recommend that soil health needs to be included as an integral component to enhance the effectiveness and resilience of stream restorations.