Stream Physical Assessment

Fairfax County Ecologists, from the Watershed Assessment Branch:
LeAnne Astin
Emily Benoit
Eric Collins
Chad Grupe
Chris Mueller
Chris Ruck
Joe Sanchirico
Samantha Duthe Tockman
Jonathan Witt
Danielle Wynne
Shannon Curtis, Branch Chief
Public Works GIS staff:
Chip Galloway
Yeoanny Venetsanos
Rita Noorzad
Enawgaw Jemberu

Since the implementation of the Chesapeake Bay TMDL municipalities learned that stream restoration is the most cost-effective best management practice (BMP) to reduce sediment, nitrogen, and phosphorus export. Prior to 2020, many of the identified stream restoration projects in Fairfax County’s watershed improvement plans (WIPs) were already in design, implemented, or determined to be infeasible. A new way to identify additional areas for stream restoration was needed to supplement the WIPs, to help meet the required reductions for the Bay TMDL. The stream physical assessment (SPA) program was developed to meet these needs.

The primary goal of SPA is to identify areas of stability or in need of physical alterations/improvements (i.e. unstable/eroded areas) in support of the County’s Capital Improvement Project (CIP) process. Staff reviewed, created, and tested habitat and stability metrics, defined assessment scope, and utilized mobile collection technology to capture data. The program is designed to ensure that field assessment results can be visualized on GIS maps, and the data utilized by existing stormwater management implementation processes. Additionally, SPA field staff can identify at risk or degraded stormwater and wastewater infrastructure allowing for maintenance and repair of previously unknown infrastructure problems. This is the first program in Fairfax County’s DPWES to use mobile collection technology tied to Survey123, and the results are provided as GIS layers to internal agencies and other stakeholders for their use.