How do you estimate sediment and nutrient load reduction benefits associated with stream restoration and keep your sanity, self-respect and professional integrity? This was a question posed to a Panel of Experts brought together by the Chesapeake Bay Program (CBP) and jointly facilitated by the Center for Watershed Protection and Chesapeake Stormwater Network. The CBP uses an expert panel process to review and update the sediment and nutrient removal performance of Best Management Practices to provide “planning level” estimates in meeting load reduction targets established by the sediment and nutrient TMDLs for the Bay.
The Stream Restoration Panel of Experts was comprised of practitioners, scientists, and state, local and federal government representatives (not to mention a few curmudgeons) spanning the entire Chesapeake Bay region. They faced a daunting task given widely divergent and highly charged views on the science and state-of-the-art practices of stream restoration (e.g., Rosgen, legacy sediment removal…).
The Panel recognized that streams are ecosystems and that while their recommendations focus on reducing sediment and nutrient loadings, stream restoration projects have to consider and assure improvements to all of the stream functions. Likewise, the Panel agreed that stream restoration has to be integrated into a comprehensive watershed restoration framework.
The first part of the expert panel process involved a comprehensive review of the literature. While there was a paucity of studies that provided actual sediment and reduction rate estimates for specific practices, there were numerous studies that showed typical stream erosion rates were an order of magnitude or greater than existing estimates used for crediting stream restoration practices by the CBP. The Expert Panel used the literature to develop three protocols to estimate sediment and nutrient reduction benefits. The first uses estimates of stream erosion rates either through monitoring or modeling methods, such as Rosgen’s BANCS method (Rosgen 2010), and applying a conservative 50% reduction efficiency. The second estimates nitrogen removal during base flow conditions resulting from projects that include instream design features to promote denitrification and the third estimates the sediment and nutrient reduction that occurs when stream flows are connected to a floodplain wetland.
The Panel recommended a stringent reporting and verification process to assure that the projects will perform as designed. The Panel also recommended improvements to the Chesapeake Bay Watershed Model to address how sediment transport is modeled from the edge-of-field to the Chesapeake Bay. The main objectives of the expert panel process stated in the opening sentence were accomplished and most Panel members seem happy and still talk to themselves and each other.
Bill Stack
As the Deputy Director of Programs, Bill’s responsibilities include program and resource development, supervision, and marketing. With over 35 years of experience in the field, Bill is the senior resident expert on staff. Before coming to the Center, Bill worked in Baltimore City and also served as a past Center Board Member. Bill has a B.S. in Biology from St. Mary’s College of MD and a M.S. in Biology from Towson University. Bill lives in Carroll County, MD with his wife.
