Conferences & Workshops

MORNING SESSION: Overview of floodplain science and restoration approaches

Coffee and Networking

Tracy Bowerman, Science Manager, UCSRB

Floodplain Reunification: The River Restoration Frontier

Janine Castro, Project Leader, U.S. Fish and Wildlife Service (virtual)

Floodplains have long been valued for their ability to dissipate flow energy, store flood water, and provide high flow refuge, but they are increasingly recognized as productive food sources for aquatic organisms. Recent research has concluded that fish grow larger and are more vigorous if they spend part of their life on an inundated floodplain, giving them a survival advantage. PNW stream restoration work has been migrating out of the channel and on to the floodplain because most of our aquatic restoration is funded through salmon recovery dollars, and it is becoming apparent that fish need floodplains.

Tim Beechie, Research Fish Biologist, NOAA Fisheries Northwest Fisheries Science Center

Floodplain disconnection has reduced salmon habitat diversity and abundance throughout the Northwest, and decreased climate-change resilience to increasing peak flow and stream temperature. Process-based floodplain reconnection and restoration aim to reverse those effects by restoring river-floodplain dynamics and habitat-forming processes. Restoration techniques such as beaver dam analogs and stage-0 restoration are increasing the pace and effectiveness of floodplain restoration, and fully restored floodplains are regaining habitat diversity that results from lateral channel migration and hyporheic exchange. Floodplain restoration also increases salmon population resilience to climate change by attenuating peak flows, increasing thermal diversity, and providing flood and temperature refuges.

Morgan Bond, Fisheries Biologist, NOAA Fisheries Northwest Fisheries Science Center

Floodplain habitats can provide direct benefits for several life stages of salmonids, including as refuge from predators, temperature, or high flows, and as a food resource. However, the phenology of the salmon life cycle must match the availability of the habitat in space and time for the value to be realized. We are using satellite imagery-based inundation models and 2-D hydraulic models to estimate the seasonal flows required for floodplain habitat availability. To maximize the potential restoration benefit of floodplain projects, we are combining these estimates with spawning location data and emergence timing so we can generate a clearer picture of where floodplain restoration may work to create better matches between the fish and habitat.

Phil Roni, Principal Scientist, Cramer Fish Sciences Watershed Sciences Lab

The restoration of floodplain habitats is now one of the most common approaches to restoring a variety of ecological and ecosystem services and increase habitat capacity and recovery for Endangered Species Act (ESA) listed salmon and trout. Restoring floodplains or entire valley bottoms for a reach or valley segment to historically anastomosing channels, often called “Stage 0” or valley bottom restoration, has become increasingly common in the Pacific Northwest. To ensure Stage 0 restoration is successful, applied in the right locations, and not the latest costly watershed restoration technique applied inappropriately, some additional guidance is needed. Therefore, using lessons learned from planning and implementation of valley bottom restoration projects designed in the Grande Ronde River Basin in Northeast Oregon, we outline the key steps and decisions needed to plan, design, implement, and evaluate a successful valley bottom restoration project. We first define Stage 0 channels and restoration, detail how it compares to common channel typing systems, and identify natural anastomosing channels in the Grande Ronde Basin to assist with designing Stage 0 restoration projects. We then discuss how to identify potential sites for valley bottom restoration including historic, current, and potential for Stage 0 channels. Next, we discuss key considerations for project design and implementation including hydraulic modeling, habitat suitability modeling, and other tools that also assist in setting objectives and monitoring and evaluation criteria. We close with a discussion of the applicability of information from the Grande Ronde Basin to projects in the Upper Columbia.

Nick Legg, Senior Geomorphologist, Wolf Water Resources

Although widespread and common throughout the region, the problem of reconnecting a stream to its floodplain is still one that requires multiple strategies and approaches. In selecting a restoration approach, we face fundamental questions about whether to bring the stream up, to bring the floodplain down, or (and) to rely on the stream to passively recover. These questions can be informed through careful consideration of watershed processes, their rates, and their influence on system recovery. This presentation will explore these issues and evaluation approaches, with the objective of tying floodplain restoration approach to relevant watershed processes.

Paul Powers, Fisheries Biologist, U.S. Forest Service (virtual)

Steve Fortney, Fluvial Geomorphologist, Gray & Osborne Inc.

Rehabilitating floodplains requires an understanding of the geomorphic context of the reach that is targeted for treatment. The fluxes of water and sediment and their interaction with vegetation and woody material create a wide variety of floodplain forms and patterns. Valley slope and valley bottom width exert control on water and sediment fluxes, therefore they also contribute to the types of floodplain forms and patterns that occur in a given river reach. Depositional processes (e.g., lateral accretion, vertical accretion, log jam-induced accretion, and debris flows), as well as erosional processes (e.g., chute cutoffs, meander cutoffs, and avulsions) are responsible for many of the floodplain types that occur in the Upper Columbia region. Identifying the processes that are responsible for floodplain development and how these processes have changed as a result of human impacts is important for establishing realistic targets for habitat improvement projects in the Upper Columbia region.

Matt Holland, Natural Resources Specialist, Chelan County Natural Resources

Together with other project sponsors and partners, CCNRD has been pursuing a robust array of monitoring activities aimed at tracking the effectiveness of restoration activities on the reach scale in the Middle Entiat. The size and scope of these projects create a unique opportunity to study the effects of restoration through tracking hydrologic, geomorphic, and biologic responses to treatment, and have implications for informing future work. Utilizing data including but not limited to: Green LiDAR, drone imagery, satellite data, survey data, ground/surface water wells, game camera footage, snorkel surveys, and eDNA surveys, we can gain insights into the effects of restoration. These actions and some initial findings are outlined in an ESRI Storymap.

Carlos Polivka, Research Fishery Biologist, US Forest Service Pacific Northwest Research Station

We asked whether post-restoration monitoring results in the Entiat River were concordant at both the individual habitat scale and the stream reach scale, and whether they were temporally consistent with earlier published results from the same system. At the habitat scale, we used Generalized Linear Models to compare fish density in habitat restored through installation of engineered log jams (ELJs) with that in unrestored habitat. We then used habitat isodars, a tool from behavioural ecology, to determine whether restoration had an effect on fish density at the reach scale. Consistent with earlier results, mean density of Chinook Salmon juveniles was greater in ELJ-treated pools than in comparable untreated habitat. Although we combined reaches for statistical analyses, these are habitat scale comparisons. Isodars relating density in ELJ-treated and untreated habitat showed a positive response of both Chinook and Coho Salmon density at the reach scale, whereas Coho Salmon density was not distinguishable at the habitat scale. With respect to habitat capacity and fitness, presence of Coho in ELJ pools affects habitat capacity for immigration into pools by Chinook. Furthermore, individual Chinook remaining in reaches with ELJ-enhanced habitat showed a size advantage over individuals observed outmigrating from the basin. These results suggest the importance of looking at density and survival on activated floodplains where restoration is expected to have further benefits.

Aaron Rosenblum, Project Manager, Cascade Fisheries

Historic and ongoing anthropogenic activities including the construction of the BNSF railway, Highway 2, multiple powerlines, and residential development have negatively impacted the connection of Nason Creek to its floodplain. This has resulted in the loss of riverscape functions and associated habitat values. The Merritt Oxbow Reconnection Restoration Project sought to restore floodplain function at the project scale by reconnecting two wetland oxbows to Nason Creek. Completed in the summer of 2022, the project created a new side channel that provides a perennial hydrologic connection between Nason Creek and the oxbows, resulting in access to 2 acres of floodplain habitat for ESA-listed salmonid species. Lessons learned will highlight the regulatory challenges of working in floodplain wetlands and ESA-species spawning habitat.

Mark Ingman, Resource Specialist II, Cascadia Conservation District

Cascadia CD in partnership with Trout Unlimited and Cascade Fisheries implemented extensive riparian plantings and over two dozen low tech structures in Eagle Creek north of Leavenworth, WA. Primary objectives were to raise groundwater levels to immediately benefit riparian plant establishment and growth, reduce stream incision, reconnect floodplains for off-channel salmonid habitat, create pools, and enhance habitat for beaver recolonization.

Michael DelloRusso, Project Coordinator for the Wenatchee-Entiat Beaver Project, Trout Unlimited

Trout Unlimited’s Wenatchee-Entiat Beaver Project has been using beaver-powered restoration to enhance streams since 2018. Using adaptive management and learning from nature’s greatest wetland builders, beavers, Trout Unlimited has taken a process-based approach to stream restoration. Through building beaver dam analogs (BDAs), Trout Unlimited is reintroducing natural functions to stream systems that were lost due to human use. In the fall of 2021, 25 BDAs were installed over a quarter mile of Rock Island Creek in Douglas County, WA at the behest of landowners who remember the benefits beavers provided there historically. This project is a powerful example of collaboration between many interest groups to achieve the common goal of floodplain restoration.

Refreshments, networking, and tabling

Small group discussions around specific topics of interest related to floodplain restoration.

Return from breakout sessions, summarize comments, discuss shared challenges, solutions, and future actions.

Tracy Bowerman, UCSRB