RESTORATION OF FLUVIAL PROCESS AND AQUATIC HABITAT IN THE SANDY RIVER AND TRIBUTARIES TO THE KENNEBEC RIVER, MAINE

Stream restoration efforts in northeastern North America have limited success because many channels remain in a disequilibrium condition after a century of widespread logging in these watersheds. By the mid-1800s sediment deliveries to most streams were greatly increased and many channels were straightened and cleared of trees or large boulders to facilitate log drives. Hydraulic geometries were altered as splash dams, berms, cribbing, and other structures were built. Aquatic habitats were further degraded by channel widening, loss of water depth and velocity variations, and deposition of large bars at artificial constrictions or other areas of energy loss. Today these streams remain in a protracted phase of fluvial adjustment, with the episodic creation of meanders where artificially straightened channels become clogged with wood, sediment, or ice.

Considering these factors, an adapted restoration approach is being used to improve fisheries habitat in the Sandy River and upper Kennebec River basins in Maine. Ecological and hydrogeomorphic studies are conducted to assess aquatic conditions and guide restoration efforts. Relic logging features such as berms and splash dams are removed to enable the stream to reconnect with its floodplain, increase habitat complexity, improve flow in abandoned side channels, and permit more uniform distribution of energy throughout the fluvial system. Rather than constrain the channel in a static position using a traditional Rosgen-based Natural Channel Design methodology, in-stream structures are designed to encourage the stream to naturally create new meanders, bars, or pools and develop a new equilibrium condition on its own.