• Projects
  • Trinity River Restoration Potential


Northwest Fisheries Science Center (NWFSC) Fish Ecology FE - Watershed


Trinity River Restoration
Trinity River Restoration Potential
The goal of the Trinity River project is to identify the potential positive effects of large-scale restoration actions in a 63 kilometer reach of the Trinity River below Lewiston Dam, in the hope of guiding on the ground restoration actions. River restoration plans often propose numerous rehabilitation actions to address key habitat impairments for salmonids. However, restoration plans rarely propose alternative sets of actions or attempt to quantify the potential benefits to targeted biota. In this paper, we use geomorphic and biological analyses to estimate restoration potential for each of 37 reaches in a 64-km section of Trinity River, California, from the North Fork Trinity River to Lewiston Dam (the focus of habitat rehabilitation efforts under the Trinity River Restoration Program). We first predicted the channel pattern that might develop based in each reach on slope-discharge criteria, and then used these potential patterns along with floodplain width to estimate the maximum sinuosity that restoration actions could likely achieve, as well as a maximum side-channel length that might be created in each reach. For each scenario, we then used existing stream habitat and juvenile salmonid data from previous studies in the Trinity River and other watersheds to determine current and restored carrying capacity. Potential increases in Chinook and steelhead carrying capacity range from 39% for a relatively realistic estimate of increasing habitat quality (more low velocity areas with cover) to 67% for a more optimistic scenario that increases both sinuosity and habitat quality. Only the most optimistic scenario that increases habitat quality, increases sinuosity, and constructs tens of kilometers of side channels more than doubles potential juvenile salmonid production (140% increase). These quantitative predictions provide a frame of reference for evaluating alternative restoration options, and for setting measureable restoration goals.

Research Themes

Habitats to support sustainable fisheries and recovered populations
Healthy oceans, coastal waters, and riverine habitats provide the foundation for aquatic resources used by a diversity of species and society. Protecting marine, estuarine and freshwater ecosystems that support these species relies on science to link habitat condition/processes and the biological effects of restoration actions. The NWFSC provides the habitat science behind many management actions taken by NOAA Fisheries and other natural resource agencies to protect and recover aquatic ecosystems and living marine resources. The NWFSC also maintains a longstanding focus on toxic chemical contaminants, as a foundation for regional and national research on pollution threats to fisheries and protected resources.

Research Foci

Develop effective and efficient habitat restoration and conservation techniques
Maintaining and re-establishing viability and sustainability of living marine resources requires conservation and rehabilitation or restoration of habitats upon which species depend. Common habitat restoration approaches and tech-niques often presume that habitats are static features of the environment, and that creation of stable habitats is a desirable restoration strategy. However, riverine, nearshore, and marine habitats are created and sustained by dynamic landscape, climatic, and oceanographic processes and biota are adapted to changing habitats that are within the range of natural variability. Hence, current restoration strategies often have limited success, in part because they fail to recognize larger scale processes that drive habitat change, and in part because they fail to recognize intrinsic habitat potential of individual restoration sites. The main goals of this research focus are to: improve understanding of how large-scale processes create diverse and dynamic habitats that support marine and anadromous species, better understand how human activities alter habitat-forming processes and habitats, develop new restoration techniques that are compatible with sustainable habitat-forming processes, and understand the variety of actions needed to adequately conserve intact critical habitats. In addition, NWFSC’s research will improve understanding of how new and existing habitat restoration and protection techniques affect fish and habitat at multiple scales (i.e., reach, watershed, Evolutionarily Significant Unit).


Chinook salmon
species of interest
landscape ecology
study of the effect of patterns on processes and vice versa
habitat restoration
Oncorhynchus mykiss


Estimated steelhead and Chinook salmon smolt production potential from the Trinity River, North Fork to Lewiston Dam


Species Oncorhynchus mykiss
rainbow trout, steelhead trout, syeelhead trout
Species Oncorhynchus tshawytscha
Chinook salmon, king salmon, spring salmon


George Pess
Hiroo Imaki
Timothy Beechie
Principal Investigator