Delivering Pollution Reductions, Ecological Uplift and Axillary Benefits through Stream Restoration
Stream restoration is a significant component of VDOT’s compliance with the Chesapeake Bay TMDL. VDOT has restored over 35,000 lf of stream across 13 separate stream restorations. These projects have delivered roughly 13,000 pounds of TP, 32,000 pounds of TN and 10,000 tons of TSS reductions per year. In terms of phosphorous and sediment, stream restoration projects make up approximately 1/3 of VDOT’s achieved pollutant reductions (and approximately 15% of VDOT’s nitrogen reductions).
In addition to the impressive pollution load reductions achieved, these projects have led to significant ecological improvements. Proctors Creek Restoration, in Chesterfield Virginia, has demonstrated full ecological uplift within 2 years of restoration. Prior to restoration only 4 species of fish were present, but a total of 12 species were present after restoration. Both fish and benthic data now show full uplift to match the upstream forested reference reach.
The Pike Branch stream restoration project in Fairfax County is a case study in the many axillary benefits generated while meeting the TMDL goals of the project. Pike Branch is a 4,300 linear foot perennial stream in a densely developed residential neighborhood which lacks stormwater management. Prior to restoration the stream was deeply incised with banks up to 10 feet tall. There were 22 failing stormwater outfalls, exposed sanitary sewers, and debris dumping. The auxiliary benefit of the Pike Branch stream restoration includes elimination of annual stabilization of two roads, stabilization of 22 stormwater outfalls and lining of 9 failing culverts, and protection of two exposed sanitary sewers. These efforts provide long-term cost savings to public agencies.
Going into the Pike Branch Restoration VDOT knew that aquatic ecological uplift would be limited due to a fish blockage downstream as well as water quality issues in the watershed. To jumpstart the ecological recovery ~6,500 trees and shrubs were planted and over 200 pounds of native seed created native grasslands and pollinator habitats. Wetlands which were absent prior to restoration were created in the floodplain and support amphibians. There is an on-going extensive invasive species control program. Pike Branch has met the goal of reducing sediment inputs while also creating wildlife habitats not otherwise found in this typical urban watershed.