South Fork Ten Mile River Habitat Enhancement Project, Phase 2

South Fork Ten Mile River Habitat Enhancement Project, Phase 2

This Project is the third phase of implementation of The Nature Conservancy’s larger reach-wide habitat enhancement program in the lower 1.7 miles of the South Fork Ten Mile River with a goal of increasing survival and populations of coho salmon. This phase includes the following habitat enhancements immediately downstream of the Phase 1 improvements: 1) A long, deep alcove and shallow pond will be constructed to connect to the existing seasonal pond and valley wall wetland complex along the left valley edge; 2) The dry, rarely flooded 1965 gravel deposit on the left bank will be excavated out to create a 1.6-acre, tidal-bore flooded wetland. The wetland surface get flooded daily during high tides and during nearly every storm event; 3) A small alcove set into a wide, tree-covered gravel bench will be constructed to provide complex, low-velocity, off-channel winter habitat in the upper project reach; and 4) Four accelerated recruitment-type large wood structures will be constructed to increase channel bedform and habitat complexity in the long glide reach. A mix of downed alder, willow slash, and whole redwood trees will be used to form the structures. The Project also includes implementation of adaptive management measures at two locations in the Phase 1 project area, including: 1) The inlet at the off-channel, seasonally flooded wetland will be excavated to inundate at baseflow conditions to make the constructed side channel accessible to salmonids through a full range of future winter conditions. The inlet will be deepened about 3 feet. The excavated floodplain material will be trucked to the quarry located along the mainstem Ten Mile River. Monitoring indicates the habitat feature is limited to accessibility during high flows only. The inlet adjustment will provide additional accessible habitat for salmonids; and 2) Alcove Pilot Channels. Monitoring indicates pilot channels are needed in the constructed alcove to create a network of channels through alcove to make the upper alcove more accessible to salmonids.

Fort Bragg

Mendocino

Northern California

Mendocino