Low-Cost Restoration Techniques for Rapidly Increasing Wood Cover in Coastal Coho Salmon Streams

Abstract

Like many rivers and streams in forests of the Pacific Northwest, California north coast rivers and streams have been depleted of downed wood through timber harvest and direct wood removal. Due to the important role of wood in creating and maintaining salmonid habitat, wood augmentation has become a common element of stream restoration. Restoration efforts in North America often focus on building anchored, engineered wood structures at the site scale; however, these projects can fail to meet restoration goals at the watershed scale, do not closely mimic natural wood loading processes or dynamics, and can be expensive to implement. For critically imperiled populations of Coho Salmon Oncorhynchus kisutch in California, there is a strong impetus to achieve as much habitat restoration as possible in priority watersheds in the shortest time and with limited resources, so cost-efficient techniques are necessary. In this multi-site project, we investigated unanchored techniques for wood loading to evaluate cost and contribution to salmonid habitat in Mendocino County, California. Over a period of 6 years, 72.4 km of stream were treated with 1,973 pieces of strategically placed wood. We found that unanchored wood loading techniques were much less costly than commonly used anchored techniques, reliably improved habitat, and retained wood at high rates (mean = 92%) in small- to moderate-sized streams, at least over the short term (<6 years). The average cost of design and construction for the unanchored projects was US$259 per log, equivalent to 22% of the cost associated with the anchored wood augmentation methods examined here. Our results suggest that this unanchored wood loading approach has the potential to increase the pace and scale at which wood augmentation projects are implemented in the Pacific Northwest and beyond.

Received January 22, 2014; accepted June 25, 2014

ACKNOWLEDGMENTS

We thank Hawthorne Timber Company, The Conservation Fund, Weger Associates, Redwood Forest Foundation, and California State Parks for supporting the implementation of these projects on their properties. We also thank The Nature Conservancy, Trout Unlimited, Campbell Timberland Management, and The Conservation Fund staff members who dedicated countless hours to these projects. Special thanks are extended to Ken Smith and Allison Chambers for their work in building these projects. Work was completed under grants from the national partnership between the National Oceanic and Atmospheric Administration Community-Based Restoration Program and The Nature Conservancy (awards 1051253804 and 1981483953), the California Department of Fish and Wildlife Fisheries Restoration Grant Program (awards P0530420, P0710546, P0810522, P0910519, P1010303, P1010306, P1010309, P1010507, and P1181002), the Felton Family Foundation, and The Nature Conservancy. We are also grateful to Tim Beechie, Lisa Hulette, Peter Kareiva, Stacey Solie, and two anonymous reviewers, who provided thoughtful comments and critiques that improved the manuscript.