In May 2010, Wetland Studies and Solutions, Inc. (WSSI) and Fairfax County completed the restoration of a small tributary to Big Rocky Run just downstream of Braddock Road in Fairfax County. Prior to the restoration, Fairfax County staff noted that based on visual observations, the stream did not support any fish populations. However, a post-restoration fish survey was recently conducted by the County in November 2011, which identified 15 species of fish in the restored stream reach, including a locally rare species!

Big Rocky Run (post-restoration)

WSSI's plan involved the restoration of approximately 250 linear feet of this stream. The design included raising the streambed to reconnect the previously incised stream to the floodplain, generally maintaining the existing alignment, reshaping the channel cross section to reduce shear stresses on the bed and banks, importing a reinforced bed material to support the design shear stresses, installing rock and wood structures to provide grade control and help redirect flow away from potential high stress points on the banks, and planting a diverse mix of native vegetation in the stream corridor and floodplain areas.

Following the completion of construction, the site has been stable with successful first year growth of native vegetation. In addition, the one year old restored stream showed no signs of degradation following Hurricane Irene and Tropical Storm Lee, a storm event in excess of 200 years!

As mentioned, the fish survey of the restored reach noted a total of 15 species of fish. One of the species, Pimephales promelas (fathead minnow), is a locally rare species. (Click here to view the sampling data) Based on multiple visual inspections during years prior to the restoration, the tributary is not believed to have supported any fish populations. While the stream is too small to have a calculated Index of Biological Integrity (IBI), the recent fish survey results are impressive in both the variety and quantity of species now observed in this very small reach. Thus, the restoration efforts for this stream have not only been successful in providing a stable, naturally functioning stream, but have also been successful in restoring fish populations to this small ecosystem.

If you have questions concerning the restoration of Big Rocky Run or would like to discuss how stream restoration may be beneficial to your site, please contact Mike Marsala or Scott Petrey.