In a review of 40 years of habitat restoration projects, a panel of fisheries scientists concluded that projects that remove barriers to salmon and steelhead, augment stream flows and add wood to give streams structure would likely achieve what they set out to do within a short period of time.
However, the scientists said there is “substantial uncertainty” in how long it would take for other habitat improvement projects – restoring forests along streams and restoring connectivity and complexity in flood plains – to achieve their intended outcomes, and they concluded that “the persistence of restored cold-water refuges is variable and highly uncertain.”
The Independent Scientific Review Panel on June 30 released its retrospective review of habitat and restoration projects under the Northwest Power and Conservation Council’s 2014 Columbia Basin Fish and Wildlife Program and 2020 Addendum to assess progress and identify challenges and successes. ISRP representatives presented their findings at a July 16 Council meeting.
“Overall, the ISRP found significant improvements in all the major components and commended the Program’s restoration efforts for evolving and expanding over time in a manner consistent with the science,” a July 8 Council Memorandum says (https://www.nwcouncil.org/fs/19493/2025_07_3.pdf). “However, challenges remain, particularly for understanding watershed scale restoration responses and research, monitoring, and evaluation.”
The review includes evaluations of three interdependent components of habitat protection and restoration: habitat action planning and prioritization, project implementation methods and research, monitoring, and evaluation.
It also takes a look in one chapter at large watershed scale restoration (intensively monitored watershed) responses and recommends, as they have in prior reviews, improvements to the research, monitoring and evaluation component in order to better understand how much restoration is needed to produce biologically meaningful results and under what conditions would those results achieve the greatest benefits.
In another chapter in the review, the ISRP assesses “how projects accommodate and adjust to confounding factors such as climate change and variable ocean conditions.”
And in its final chapter, the review identifies what makes an “exemplary” project.
“The Program’s restoration efforts have evolved and expanded, in a manner consistent with the state of the science, recognizing the importance of high-quality tributary habitat and associated natural processes for recovery and persistence of fish populations in the Columbia River Basin,” the report’s key findings say. “Also consistent with the science, there has been an evolution toward greater complexity and integration of restoration actions, both within individual projects and in multiple coordinated projects across large spatial scales.”
Stan Gregory, emeritus, Oregon State University, told the Council that one of the big shifts in habitat restoration is a change from restoring just structure to restoring processes as well as structure. In addition, he said, the scientists saw an “evolution toward larger and more complex projects,” with multiple coordination.
Still, he continued, few projects meet the full description of process-based restoration, but the proportion designed to restore impaired processes has increased since 2000 to emphasize ecosystem function.
Planning and prioritization
The ISRP report says Council Program efforts the first 10 years focused on passage improvements at dams for salmon and steelhead juveniles and adults, hatchery construction and habitat restoration in some selected sub-basins. In later years, efforts expanded significantly and the emphasis shifted to include river, lake and estuary habitat restoration.
The ISRP said in its Key Findings for Planning and Prioritization that the Program’s restoration efforts “have evolved and expanded, in a manner consistent with the state of the science, recognizing the importance of high-quality tributary habitat and associated natural processes for recovery and persistence of fish populations in the Columbia River Basin. Also consistent with the science, there has been an evolution toward greater complexity and integration of restoration actions, both within individual projects and in multiple coordinated projects across large spatial scales.” The scientists added that increasing and effective use of models, such as habitat and life cycle models, more rigorous analysis of limiting factors, and use of strategic planning, have improved.
Restoration Methods
The scientists reviewed eight methods of restoring habitat, including barrier removal, floodplain reconnection, large wood addition, riparian planting and fencing, estuary habitat restoration, flow augmentation, cold-water habitat restoration, and wildlife habitat restoration.
They found that of the eight methods:
— Removing barriers to restore connectivity and reconnecting side channels and floodplains, including in the estuary, have a strong likelihood of positive benefits for anadromous salmonids.
— Barrier removal, flow augmentation, and some wood additions are likely to achieve their intended outcomes in a short period of time (i.e., 5-10 years).
— There is substantial uncertainty about the time required for restoration of riparian forests, and restoration of connectivity and complexity of floodplains.
— The persistence of restored cold-water refuges is variable and highly uncertain.
Among the response times are 2 to 5 years for removing barriers, 10 or more years for adding large wood to streams, 5 to 10 years for removing dikes and tidegates, 10 or more years for coldwater refuges, about 10 years for reconnecting flood plains and 30 to 50 years for riparian restoration.
Among their recommendations is an emphasis on habitat protection along with restoration and developing a “coordinated study, building on past work, to monitor and evaluate the long term effectiveness of floodplain reconnection, riparian forest and meadow restoration, and creation and restoration of cold-water refuges.”
Research, Monitoring and Evaluation
RM&E have been components of the Council’s Fish and Wildlife Program since 1982, when the Program began. Although the Council has made multiple efforts to tackle deficiencies in RM&E, challenges remain, the ISRP report says. In addition, the report lists other key findings, including:
— The Columbia Basin Tributary RM&E Strategy represents a step forward, providing high level guidance for monitoring, especially at the project and reach level.
— Although implementation and compliance monitoring are expected for every project, rigorous effectiveness monitoring requires substantial time, technical and financial resources, and expertise.
— Effectiveness monitoring should emphasize understanding of how much restoration is needed to produce biologically meaningful effects (i.e., a dose-response) and under what conditions such effects can occur (i.e., geomorphic, hydrologic, and ecological contexts).
Intensively Monitored Watersheds
The ISRP in its report asked; 1) did restoration improve habitat at the watershed scale and increase or stabilize viability of fish populations, and 2) what mechanisms caused these improvements?
A series of these watersheds from California through Washington were established to address these questions across the broadly overlapping distributions of major Pacific salmon and steelhead populations. According to the ISRP:
— To date, IMWs have provided important information at appropriate spatial scales that match management decision scales.
— Although results have not been rigorously analyzed, simple tallies showed positive responses for a range of habitat metrics in nearly all IMWs evaluated to date. Responses for fish metrics were positive in about two-thirds of cases but were equivocal (neither positive nor negative) in the remaining third of cases analyzed.
— Extensive time is needed to conduct successful restoration and to detect change in fish populations across watershed scales amid the background of annual variability.
One of the recommendations, according to the scientists, is “an integrated analysis of habitat restoration results across the network of IMWs to answer broad questions about 1) treatments and responses for salmon, steelhead, and other important fish across the Pacific Northwest and 2) how well the existing IMWs represent the diversity and distribution of landscapes and fish and wildlife resources of the Columbia River Basin.”
Confounding factors
These can affect planning and implementation of restoration projects and can alter their outcome. Those identified by the ISRP are climate change, landscape change, variable ocean conditions, nonnative species, predation, supplementation with hatchery fish, dams, water quality, density-dependence, and logistical complexities.
Exemplary Projects
“Some projects were really good,” said Kurt Fresh, ISRP vice chair and retired from NOAA Fisheries’ NW Science Center. The exemplary projects identified by the ISRP are:
— Columbia Land Trust Estuarine Restoration Project
— Wind River Watershed Project – U.S. Forest Service, Underwood Conservation District, Washington Department of Fish and Wildlife, U.S. Geological Survey
— John Day Watershed Restoration Project – Confederated Tribes of the Warm Springs Indian Reservation
— Umatilla Anadromous Fish Habitat Project – Confederated Tribes of the Umatilla Indian Reservation
— Evaluate the Life History of Native Salmonids in the Malheur River Basin – Burns Paiute Tribe
— Coeur d’Alene Reservations Fisheries Habitat Project
— Scotch Creek Wildlife Area Project – WDFW
— Kootenai River Operational Loss Assessment – Kootenai Tribe and Montana Fish, Wildlife and Parks
— Upper Columbia United Tribe’s Wildlife Monitoring and Evaluation Project
— Shoshone-Bannock Wildlife Mitigation Project – Southern Idaho Wildlife Mitigation Program
“Success of the Program in the future will depend on its ability to accommodate and adapt restoration in the face of a diverse array of challenges, including climate change, variable ocean conditions, non-native species, and ongoing landscape changes,” the report concludes. “Success will also depend on developing and implementing a sound monitoring and evaluation program to address the remaining key management questions and critical uncertainties.”
Congress, in a 1998 House-Senate conference report, called for the ISRP to review fish and wildlife programs reimbursed by the Bonneville Power Administration, such as habitat projects recommended in the Council’s Fish and Wildlife Program. The ISRP was created by the Council in response to a 1996 amendment to the Northwest Power Act.
The full report, “Habitat Retrospective Report: Review and Synthesis of Progress and Challenges in Columbia River Basin Fish and Wildlife Program Habitat Protection and Restoration Projects,” is here: https://www.nwcouncil.org/media/filer_public/0c/34/0c34abd8-9cc2-4e65-ab97-f684f0f3012a/ISRP_2025-2_HabitatRetro30June.pdf
For background, see:
— CBB, July 26, 2024, COUNCIL GETS RUNDOWN ON OVER 130 HABITAT PROJECTS AIMING AT IMPROVING LOT OF STRUGGLING WILLAMETTE RIVER SPRING CHINOOK, WINTER STEELHEAD, HTTPS://COLUMBIABASINBULLETIN.ORG/COUNCIL-GETS-RUNDOWN-ON-OVER-130-HABITAT-PROJECTS-AIMING-AT-IMPROVING-LOT-OF-STRUGGLING-WILLAMETTE-RIVER-SPRING-CHINOOK-WINTER-STEELHEAD/
— CBB, APRIL 18, 2024, REVIEW OF SALMON HABITAT PROJECTS SHOWS PUTTING WOODY DEBRIS IN RIGHT PLACE IN STREAM CAN LEAD TO INCREASED JUVENILE NUMBERS, HTTPS://COLUMBIABASINBULLETIN.ORG/REVIEW-OF-SALMON-HABITAT-PROJECTS-SHOWS-PUTTING-WOODY-DEBRIS-IN-RIGHT-PLACE-IN-STREAM-CAN-LEAD-TO-INCREASED-JUVENILE-NUMBERS/
–CBB, Jan. 5, 2024, NOAA GRANTS $27 MILLION FOR PROJECTS TO HELP RESTORE WILLAMETTE VALLEY IMPERILED SALMON, STEELHEAD https://columbiabasinbulletin.org/noaa-grants-27-million-for-projects-to-help-restore-willamette-valley-imperiled-salmon-steelhead/
— CBB, July 8, 2022, ‘INTENSIVELY MONITORED WATERSHEDS’ REPORT DETAILS HABITAT RESTORATION BENEFITS FOR JUVENILE SALMON, BUT LACK OF INCREASE IN ADULT ABUNDANCE, https://columbiabasinbulletin.org/intensively-monitored-watersheds-report-details-habitat-restoration-benefits-for-juvenile-salmon-but-lack-of-increase-in-adult-abundance/
— CBB, August 14, 2019, NOAA FISHERIES, BPA, COUNCIL WORKING TO CREATE ONE STRATEGY FOR MONITORING, EVALUATING COLUMBIA BASIN HABITAT PROJECTS, https://columbiabasinbulletin.org/noaa-fisheries-bpa-council-working-to-create-one-strategy-for-monitoring-evaluating-columbia-basin-habitat-projects/