Abstract: Session C 8:55 am (Back to Session C)
TMDL Reduction Credit for Stream Restoration – Case Studies and Comparison of Several Methods
Bryan Dick, PE, PH
Freese and Nichols, Inc.
Author: Bryan Dick, PE, PH and Emily Darr, EI, CFM, ENVSP
As a reduction in TMDL’s for receiving waters has become a focus for both local and regional concerns, the question arises as to what credit to allocate for various types of implemented projects. Stream restoration has been one of the most cost-effective types of projects for reducing TMDL’s in the Chesapeake Bay contributing watersheds and it may prove to be the same for North Carolina, as we continue to deal with causes of impairments of our watersheds. Much can be learned from the extensive efforts that have been focused on answering these questions for the Chesapeake Bay watershed, specifically by evaluating the protocols that are outlined in the white paper, Recommendations of the Expert Panel to Define Removal Rates for Individual Stream Restoration Projects, which has been adopted by multiple agencies and regulators in the region. I will present the comparison of predicted TMDL reductions using three methods: the direct measurement/analysis of site specific erosion rates; an off-site regional erosion curve; and finally, the default credit rate developed for stream restoration projects by the Chesapeake Bay TMDL Expert Panel. One constructed site with post-project assessment and three other analyzed sites are presented, along with field observations to inform agencies and practitioners of the methods and how they compare and differ from each other.