In his presentation at the 2024 National Stream Conference, Bob Siegfried from RES discusses stream mitigation performance standards, emphasizing a shift from traditional engineering success metrics toward ecological success. He highlights that traditional standards often focus on stability and minimal change, which can limit ecological processes essential for stream health, such as natural channel adjustments and vegetative succession. Siegfried argues for performance standards rooted in ecological metrics, which support resilience and biodiversity by allowing streams to change dynamically over time.
Siegfried references the 2008 Mitigation Rule, which underscores ecological performance over-engineering criteria. He critiques current engineering-based standards like bank height ratio (BHR) and cross-section geometry, which may inaccurately gauge ecological function. Instead, he advocates for data-rich ecological standards that incorporate biotic and abiotic factors, using metrics such as floodplain connectivity, bank erosion aligned with natural levels, and habitat assessments. Siegfried also emphasizes the limited role of as-built documentation, suggesting it should not be a basis for assessing ecological performance but rather serve to confirm construction adherence to design.
In closing, Siegfried proposes using baseline data (e.g., pre- and post-restoration habitat and biological assessments) to transparently evaluate ecological improvements, fostering a holistic and adaptive approach to stream restoration.
