Stream Habitat Restoration Guidelines (April 2012 Draft)

Few endeavors in resource and environmental management in the Pacific Northwest are more compelling than rapidly expanding efforts to restore the region's streams and rivers. The region's history and strongly held values are inseparably intertwined with our streams and rivers. In coastal and inland settings, historic and current settlement and development patterns have centered on streams for transportation, residential, municipal, agricultural, and industrial water supply, power generation, and crop irrigation. Pacific Northwest streams and rivers, and their floodplains provide; food, construction aggregates, and recreational opportunities. Their floodplains provide relatively flat, fertile agricultural land and their forested riparian zones historically supplied timber. However, competing uses of stream corridors in modern society, combined with large-scale alteration of watersheds, have directly and indirectly impacted the abundance, quality, and stability of stream and riparian habitats. Streams, with their associated floodplain and riparian ecosystems compose the sole habitat, or critical habitat elements for a majority of the region's native fish and wildlife. Approximately 85% of Washington's terrestrial vertebrate wildlife species depend on riparian habitats for all or critical portions of their life histories. This rich floral and faunal biodiversity is the basis for much of the state's cultural heritage, economy, and famous quality of life.

After more than a century of adverse impacts from a multitude of economic activities following Euro-American settlement, recognition of the need to restore streams has spread throughout the Puget Sound region, coastal watersheds draining directly to the Pacific Ocean, and the entire Columbia River watershed. Much of this awareness and activity is driven by the serious decline of the region's once robust anadromous runs of wild salmon, cutthroat, bull trout, smelt, and sturgeon. The accelerating interest in stream restoration also stems from a desire to restore wild populations of native resident salmonid fish species, including redband, cutthroat and bull trout, and other aquatic and riparian species, many of which have been listed as threatened or endangered under the federal Endangered Species Act and the Washington Wildlife Code.

Securing supplies of clean, cool water for a host of human and wildlife needs also depends on healthy stream systems in functionally intact watersheds. A majority of the state's major rivers and hundreds of tributary streams fail to attain federal and state water quality standards for a host of pollutants including heavy metals and toxic compounds and nutrients, and for temperature, turbidity, dissolved oxygen and biological oxygen demand parameters. Great progress has been achieved in reducing industrial and municipal point sources of water pollution, yet a large challenge remains to achieve and maintain reductions of urban, rural and wildland sources of non-point water pollution. The purpose of the Stream Habitat Restoration Guidelines (SHRG) is to promote process based natural stream restoration, rehabilitating aquatic and riparian ecosystems. These guidelines advance a watershed scale assessment of the stream system, establishing goals, objectives and design for restoring optimum sustainable native biodiversity, using principles of landscape ecology and integrated aquatic ecosystem restoration.

While a number of specific watershed assessment, characterization, project design and construction approaches are presented in this volume, these guidelines do not offer a "cookbook" approach that provides every step and equation along the way. Rather, the intent is to provide Chapter 1. Stream Habitat Restoration Guidelines 1-2 readers with a comprehensive list of factors and criteria to consider, which are essential to make informed decisions when planning and designing stream restoration and rehabilitation work. Readers are strongly cautioned not to pluck and apply individual techniques from these guidelines without first conducting the necessary watershed and reach based assessments and analysis. The techniques presented in these guidelines are not meant to limit the designer. Other innovative stream restoration techniques may exist and are sure to be developed and included in future editions of this document.

Topics addressed in the SHRG include site, reach, and watershed assessment, problem identification, general approaches to restoring stream and riparian habitat, factors to consider in identifying and selecting an approach, approaches to solving common restoration objectives, and stream and riparian habitat restoration techniques. Watershed processes and conditions that shape stream channels, stream ecology, geomorphology, hydrology, hydraulics, planting considerations and erosion control, and construction considerations are also presented in the main text and appendices.