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Measuring Urban Stream Restoration Success in Flatlick Branch: Processes, Goals, Monitoring, and Regulations May Confound “Ecological Lift”

Chris Ruck
Fairfax County, VA
Watershed Assessment Branch
Fairfax, VA

Authors:
Chris Ruck, Fairfax County Watershed Assessment Branch
Aaron Porter, USGS Virginia & West Virginia Water Science Center
Neely Law, Fairfax County Office of Environmental and Energy Coordination

Urban stream restorations in Fairfax County, VA are typically driven by nitrogen, phosphorus and sediment load reductions required by the Chesapeake Bay TMDL. Most experts agree applying urban stream protocols will reduce sediment and nutrient delivery to the Bay. However, what represents the “recovery” or “ecological lift” of local stream functions is still debated. Highly complex inter-relationships regarding stream function, urbanization, and ecosystem responses to restoration (expressed as goals-based trade-offs) may be limiting factors for stream corridor recovery. Further, it takes concerted effort, time, and funding for both pre- and post-construction monitoring to identify noticeable changes in higher-level stream functions. We examine biological, chemical, and geomorphic data from County-implemented stream restoration projects designed for Chesapeake Bay TMDL crediting. Using a long-term dataset we illustrate how stream prioritization, design, and implementation processes to meet the Bay goals may be at odds with higher-level functional lift (Eg. geomorphology improved while physiochemistry declined and biology is a complicated story). Despite more holistic approaches to stream corridor restoration, the data suggest defining more realistic goals is needed coupled with monitoring efforts to effectively understand and restore urbans streams.