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MONITORING THE ACCOTINK CREEK STREAM RESTORATION
Citation:
SELVAKUMAR, A., T. OCONNOR, AND S. D. STRUCK. MONITORING THE ACCOTINK CREEK STREAM RESTORATION. Presented at STREAM RESTORATION WORKSHOP, FAIRFAX, VA, September 19, 2007.
Description:
Since the inception of the Clean Water Act (CWA) in 1972, the United States has made great efforts in restoring and preserving the physical, chemical, and biological integrity of the Nation’s waters. However, nearly half of the nation’s assessed surface water resources remain incapable of supporting basic aquatic values or maintaining water quality adequate for recreational swimming or drinking water supply. In the 2002 National Assessment Database, stormwater runoff was identified as one of the causes of water quality impairment. Natural streams follow a predictable meandering pattern, which dissipates energy and minimizes scouring of the streambed and banks. Increased stream flows impact the natural stream channel morphology, which affects the physical, chemical, and biological integrity of the stream. The purpose of this on-going project is to provide information to Municipal Separate Storm Sewer System (MS4s) operators and states on the performance of selected best management practices (BMPs), specifically, stream restoration techniques, on improving biological and in-stream water quality within an urban watershed. Accotink Creek in Fairfax City, Virginia was selected as the study location. Accotink Creek and its tributaries are important natural sources that provide recreational and aesthetic values that enhance the quality of life in the Fairfax City. The headwaters of Accotink Creek originate within the City of Fairfax and flow southeast through Fairfax County to its confluence with the Potomac River, which flows into the Chesapeake Bay. The Accotink Creek headwater watershed has uncontrolled urban runoff that has resulted in erosive forces causing channel deepening, widening, and bank and bed sediment transport downstream. This project involves monitoring before and after restoration of 1,800 linear feet of degraded stream channel in the North Fork of Accotink Creek from Lee Highway to Old Lee Highway in the City of Fairfax, Virginia. Restoration, which was completed in June 2006 included installation of native plant materials along the stream and bioengineering structures to stabilize the stream channel and bank. These actions were intended to restore the stream channel to a stable condition and reduce stream bank erosion thereby reducing sediment loads in the stream. In-stream samples were collected and analyzed for physical, chemical, and biological (macroinvertebrates) parameters to document the changes in stream quality as a result of the restoration. The goals of the project are to: investigate the effectiveness of stream restoration techniques and in the future other potential watershed enhancements, on increasing available biological habitat and improving in-stream water quality in the impaired stream; and demonstrate the utility of continuous water-quality monitoring as an innovative, cost-effective tool for detecting water-quality improvements following BMP implementation activities. The results of the monitoring are summarized in this presentation.