Gregorys Creek Mitigation Site

SWCA provided construction observation services for the restoration and enhancement of approximately 34,500 linear feet of Gregorys Creek and 13 of its tributaries. Decades of manipulation and watershed impacts have caused Gregorys Creek to become severely incised with vertical banks in excess of 10 feet. A heavy sediment load and lack of appropriate dimensions created indistinct channel features with no bed diversity and little habitat. Base level shifts in Gregorys Creek subsequently created similar conditions in the adjacent tributaries, where land management practices and buffer infringement also exacerbated the channel impacts.

Enhancement activities for Gregorys Creek (DA=10mi2) include grading and revegetating banks, as well as installing bed structures to protect banks, increase habitat and food supplies, and induce local scour for channel bed diversity. The tributaries (DA=.02-.5mi2) are being improved via Priority 1 and 2 restoration or enhancement, including significant improvement to in-channel structure and habitat. Structures vary to accommodate widely varying conditions and constraints.

Project constraints include the following: minimizing impacts to existing wetlands and hardwood buffers; working in narrow, steep valleys with limited access; steep valleys and channel transitions; completing work directly adjacent to property lines and state highway right-of-way; and managing excess spoil materials in a Federal Emergency Management Agency flood zone.