Accotink Creek Stream Stability Assessment and Prioritization within the City of Fairfax
As the City of Fairfax (the City) progresses through the 3rd Phase of the Chesapeake Bay TMDL, there is an increased need for project implementation to meet its Pollutant of Concern (POC) reduction requirements. The headwaters of Accotink Creek and its combined major tributaries are located within the City and offer significant TMDL project opportunities. The City has collaborated with Kimley-Horn on the 2023 Accotink Creek Stream Stability Assessment and Prioritization Plan to efficiently catalog and prioritize these project opportunities that will assist in meeting their POC reduction goals.
Phase 1 of this project involved utilizing a GIS-based data collection methodology that leveraged ESRI’s Survey123 in conjunction with ArcGIS Online geodatabases to simultaneously collect multiple types of data, such as stream reach geometry, stream health characteristics, and stream restoration potential. The results of this rapid stream assessment ultimately yielded 6 high priority potential candidates for stream restoration within the City as well as qualitative and quantitative data on why these projects are needed and how they could meet multiple City objectives.
Phase 2 of this project includes public outreach and further evaluation of the 6 high priority stream reaches identified in Phase 1. Individual Bank Assessments of Non-point source Consequences of Sediment (BANCs) will be part of Phase 2 and will further aid the City by quantifying project POC reductions to ensure that the 3rd Phase of the City’s Chesapeake Bay TMDL goals are met in the most cost and time-effective way possible.
The data collection methodology used for this project was the first of its kind for stream assessment within the City and yielded supplemental benefits beyond the typical objectives of capturing the extent of stream bank erosion for potential stream restoration candidates. Not only has this project’s data collection methodology created a framework for future routine stream assessments, but it has also proven to seamlessly integrate into the City’s existing stormwater and wastewater GIS-based schema. The synergy of data collected during this project with other City GIS data has assisted City staff in identifying vulnerable and deficient infrastructure within stream corridors and has identified potential future stormwater outfall channel and tributary restorations that will further assist the City’s progress toward meeting its TMDL reduction targets.