Proposed Bank

We are in the process of establishing the Wapato Valley Mitigation and Conservation Bank through the Washington State Mitigation Banking Program, which if approved will be an approximately 876-acre combined wetland mitigation and habitat conservation bank. The purpose of the Wapato Valley Mitigation and Conservation Bank is to provide mitigation credits for impacts to aquatic resources authorized under the Clean Water Act, impacts to special-status species including federal ESA-listed or otherwise protected species and habitats and state ESA-listed and protected priority habitat and species, Critical Area Ordinance protected resources, and floodplain impacts. Bank credits would be used to offset future, unavoidable impacts that could result from development projects in the Columbia River floodplain and basin.

More specifically, the proposed Bank would function to:

  • Provide compensatory mitigation for unavoidable impacts to ecosystem services. Mitigated resources include aquatic resources as authorized under the Clean Water Act by the U.S. Army Corps of Engineers (USACE) and the U.S. Environmental Protection Agency (EPA) in 33 Code of Federal Regulations (CFR) Parts 325 and 332 and 40 CFR Part 230 (USACE and EPA 2008), and by the Washington State Department of Ecology (Ecology) as authorized under Washington Administrative Code 173-700 (State of Washington 2009) and Revised Code of Washington (RCW) 90.48.260 (State of Washington 2012).
  • Compensate for unavoidable impacts to aquatic and terrestrial habitats and contribute to the recovery of at-risk species authorized under the federal Endangered Species Act (ESA) by the National Marine Fisheries Service (NMFS) and U.S. Fish and Wildlife Service(USFWS). The proposed Bank will specifically provide conservation credits for ESA-listed salmon and steelhead, and could provide conservation credits for a number of ESA-listed wildlife species, including Columbian white-tailed deer, Oregon spotted frog, streaked horned lark, western pond turtle, and other species.
  • Provide compensatory mitigation for unavoidable impacts to other protected natural environments, including but not limited to: floodplain ecosystem services such as flood storage or Columbia River floodplain habitats; Critical Areas protected by ordinances as regulated by Washington State counties under the Growth Management Act; Priority Habitats and Species identified by the Washington Department of Fish and Wildlife; and Waters of the State regulated by Washington Department of Fish and Wildlife under the Hydraulic Code in Washington Administrative Code 220-660 (State of Washington 2014), and specifically RCW 77.55.241 (State of Washington 2010) which allows off-site mitigation for hydraulic projects.
  • Provide mitigation or conservation for other non-listed fish and wildlife species and their habitats as required by federal, state, and local agencies who share responsibility for trust resources.

Through the Washington State Mitigation Banking Program, the proposed Wapato Valley Mitigation and Conservation Bank is co-chaired by the USACE and Ecology, with Interagency Review Team participation by interested agencies anticipated to include NMFS, USFWS, EPA, WDFW, Clark County, the Cowlitz Indian Tribe, and other stakeholders identified, and invited to participate, by the co-chairs. The Bank proposal will also be reviewed and approved by NMFS and USFWS as a Conservation Bank.

Learn about the Wapato Valley Mitigation and Conservation Bank and access the full prospectus document below

The proposed Wapato Valley Mitigation and Conservation Bank is located in northwest Clark County, in southwest Washington State (Proposed Bank Location Map), and is located in the Columbia River watershed within the freshwater tidally influenced portion of the lower floodplain at the confluence of the Lewis River at River Mile (RM) 87. We are approximately two-thirds the distance between the mouth of the Columbia River as it enters the Pacific Ocean (RM 0) and Bonneville Dam (RM 146), which is the most downstream of 14 mainstem dams on the Columbia River. According to the Washington State Department of Ecology’s Water Resource Inventory Area (WRIA) classification system, we are located in WRIA 27, the Lewis River watershed.

Proposed Bank Location

Regional Land Use

Property Overview

Our proposed Bank is situated west of U.S. Interstate 5, east of the Columbia River, north of the town of Ridgefield and south of the town of Woodland, in portions of Sections 1, 2, 11, and Donation Land Claim (DLC) 37 , and Section 12 in Township 4 North, Range 1 West (Clark County 2015, AINW 2013) (Property Overview Map). The proposed Bank is bordered by the BNSF Railway to the east, the Lewis River to the north, the Columbia River to the west, and Gee Creek and the Ridgefield National Wildlife Refuge to the south.

Next Section: Goals
  • Wapato

The goals of the Wapato Valley Mitigation and Conservation Bank are compatible with local land use goals, regional estuary management plans, regional recovery plans for salmon and other fish and wildlife species including the subbasin and watershed management plans, and adjoining lands’ comprehensive conservation plans. The location of the proposed Bank is ideal in both location and scale to address notable local and regional goals for ecosystem restoration and conservation.

The overarching goal of the proposed Bank design is to restore site-scale watershed processes with a focus on dynamic floodplain habitat-forming and maintaining processes that support a broad range of ecological functions. Specific goals include:

  • restoring natural landform and hydrology by removing site-scale stressors and land use constraints;
  • using restoration methods that have a proven track-record for achieving objectives, provide a high certainty of success, and require minimal maintenance;
  • restoring an evolving landscape comprised of a continuum of diverse aquatic and terrestrial habitats that form a mosaic of different seral stages that supports biodiversity of native fauna and flora; and
  • increasing wetland functions and area by re-establishing freshwater tidal and wetland hydrology within the porposed Bank property that will also benefit imperiled ESA-listed species.
Next Section: Objectives

The objectives provided below help to define the strategies and actions necessary to achieve our stated goals. These objectives will be refined and quantified during the design process so that they are measurable and can be linked to a monitoring plan and success criteria that will be developed for the proposed Bank. Each mitigated resource may have different metrics used to measure area or function restored, and will be developed in concert with the Interagency Review Team. General objectives are described below.


  • Restore tidal hydrology and reconnect surface water flood storage to impounded areas north of and including Lancaster Lake by removing levee fill and water control structures.
  • Improve surface water connections, increase tidal exchange, and reduce areas of fish stranding in Lewis River side-channel habitats by excavating fill from and regrading in relic side-channel habitat.
  • Increase the range of hydrologic connectivity with Gee Creek over a wider range of flows and tidal cycles by removing levee fill and water control structures from three locations in the southwest portion of the proposed Bank location.
  • Rehabilitate degraded off-channel wetland habitat impacted by the same three levees mentioned above (in the southwest portion of the Site) through excavation and levee fill removal, and regrading a distributary channel network for positive drainage.

Floodplain connectivity

  • Improve live floodplain storage (direct surface water connection) capacity by removing 4 levees that are barriers to inundation.
  • Increase the opportunity for overbank flooding and floodplain habitat inundation through barrier removal as noted above.

Water quality

  • Improve water quality through increased area and frequency of tidal exchange by removing barriers to normative tidal hydrology (as detailed above).
  • Reduce thermal gain in currently impounded areas by restoring tidal exchange.
  • Increase connectivity of areas with cool water inputs in off-channel and side-channel habitats to provide thermal refuge habitat for native fish and wildlife.
  • Reduce suspended sediment impacts from presence of non-native warm water fish species by reducing habitat conditions that support carp and other invasive species.
  • Increase capacity of the proposed Bank for nutrient uptake and nutrient cycling.


  • Increase native cover across all plant communities on the entire Bank.
  • Encourage native emergent wetland marsh communities through excavation to preferred elevations and restored hydrology in lowest-lying elevations.
  • Reduce non-native cover through design of preferential elevations for native species, using mechanical and chemical control as appropriate.
  • Enhance upland Washington Department of Fish and Wildlife Oak Woodland Priority Habitat by removing competing tree and understory species.


  • Restore normative sediment transport processes and floodplain sediment storage across the Bank property by removing barriers to tidal hydrology, floodplain flooding, and connectivity.
  • Reduce channel constriction, off-channel habitat isolation, and fish stranding through excavation of accumulated sediments and placed fill.
  • Reduce suspended sediment load and export into Gee Creek by eliminating preferred habitat of non-native species that chronically perturb the substrate.

Aquatic habitat values (species dependent, to be determined)

  • Increase habitat quantity and diversity—improve opportunity to access juvenile rearing habitats.
  • Improve habitat quality and complexity—improve the capacity of the habitat to support more native species and more individuals.

Terrestrial habitat values (species dependent, to be determined)

  • Increase habitat quantity and diversity—improve opportunity to access habitats, enhance habitat linkages, and increase native vegetation cover.
  • Improve habitat quality and complexity—improve the capacity of the habitat to support more native species and more individuals.

Biological response (species dependent, to be determined)

  • Decrease habitat conditions preferred by non-native species.
  • Increase fitness and survival rates for native species.
  • Improve food web dynamics.

As noted above, during the Bank development process in collaboration with the Interagency Review Team, these broad-scale objectives will be utilized to develop more resource- and implementation-phase specific objectives that will evolve into the Performance Standards for incorporation into the Monitoring Plan and Mitigation Banking Instrument.

Next Section: Conceptual Design

Our conceptual restoration design is anchored in a watershed approach based on historical ecology and process-based restoration whereby historical and modern reference conditions are utilized to re-create an approximation of pre-development ecosystem processes to the extent possible. Given current landscape-scale land use patterns and river management programs, this is only possible to a certain degree. Restoration to pre-development conditions are not feasible in light of past and present actions (both off- and on-site) that are anticipated to continue impacting the Site to some extent. The focus of the conceptual restoration design is to remove on-site constraints to ecosystem and habitat-forming processes to allow for a self-sustaining landscape to the extent practicable. The conceptual design highlights the human-made infrastructure that was established over the course of over 150 years of surrounding development, river training and management, and land use conversion to a managed agricultural setting.

The design takes into account off-site land use and aquatic resource management activities which are outside the scope of the proposed Bank. A couple of examples are current Columbia River management practices including USACE maintenance of the federal navigation channel, and U.S. Army Corps of Engineers (USACE)/Bonneville Power Administration (Columbia River system) and PacifiCorp (Lewis River system) hydropower operations and seasonal fluctuations of surface water elevations and flow for flood control, hydropower generation, and fish habitat. In the Columbia River, the USACE uses both flow augmentation in spring and summer and spill releases over dam spillways, which are intended to improve juvenile migration through the Columbia River system. Working at the confluence of two hydropower-modified river systems adds both complexity and predictability to the design process. It allows restoration designers to work within the established flow release schedules for these systems, to use the continuous river stage data collected from nearby gages to help set design criteria, and to utilize flood and flow predictions to anticipate wetted conditions and to validate the site-specific hydrology model in real time during the design process.

Within the constraints of off-site hydrological influences, the proposed conceptual design will utilize proven restoration techniques focused on restoring self-sustaining processes, thus reducing the need for intense maintenance. The conceptual design is focused on restoring dynamic habitat-forming processes, which will include the installation of certain habitat features that will provide structure and function in the short-term while longer term, more process-based habitat functions evolve. The design initiates succession on the landscape and will result in a mix or mosaic of terrestrial and aquatic habitats in a range of successional stages including seral, early, mid-, late and climax successional stages. A process-based approach will be more successful than forcing static conditions on a site that is already dynamic and complex, and will become increasingly effective when land use management and infrastructure constraints are removed.

Conceptual Design Maps

Construction Actions and Phases

Construction Actions and Phases

Proposed Wetland Conditions

Proposed Wetlands

Proposed Fish Habitat

Proposed Fish Habitat

Proposed Wildlife Habitat

Proposed Wildlife Habitat