Washington Habitat Connectivity Action Plan (2025)

Terrestrial habitat connectivity is critical to maintaining Washington’s biodiversity, ecosystem resilience, and climate adaptation potential. As landscapes become increasingly fragmented due to transportation infrastructure, urban expansion, and other land-use changes, wildlife populations face growing barriers to movement, increasing risks of genetic isolation, habitat loss, population extirpation, and wildlife-vehicle collisions.

The Washington Habitat Connectivity Action Plan (WAHCAP) builds upon Washington’s leadership in connectivity science, synthesizing decades of research to establish clear priorities for on-the-ground projects that will protect and reconnect Washington’s landscapes for wildlife. This Action Plan identifies both transportation and terrestrial landscape-connectivity priorities, ensuring that Washington’s approach to connectivity conservation is comprehensive and focused on implementation.

Washington’s Connectivity Vision – A Network of Connected Landscapes

Habitat connectivity is the degree to which wildlife can move across the landscape as needed to find food and shelter, migrate seasonally, establish new territories, and maintain healthy populations through genetic exchange. Connectivity also supports broader ecological functions such as seed dispersal and pollination and sustains species important to cultural traditions like hunting and gathering.

As climate change continues to shift habitats and environmental conditions, maintaining connected landscapes becomes even more important to allow species to adapt and persist. However, habitat connectivity in Washington is increasingly threatened by population growth, expansion of transportation and energy infrastructure, increased recreation in historically remote areas, and expanding development. Maintaining connected networks of lands and waters at statewide, regional, and local scales is essential to retaining resilient and healthy wildlife populations. Protected areas managed to support biodiversity and ecosystem functions are the cornerstones of this connected network but are insufficient alone. Rural and working lands, protected critical areas, and backyard habitats all play a key role in supporting this connected network across the state in ways that can benefit both people and wildlife.

The WAHCAP offers a framework for prioritizing critical terrestrial connectivity areas and strategic locations for road barrier mitigation to protect and enhance wildlife movement across Washington's diverse ecosystems. The WAHCAP identifies important elements of connected terrestrial landscapes including large and relatively intact habitat core areas, regions where working lands provide diffuse landscape permeability for wildlife, habitat corridors or pathways that facilitate movement among core areas, and fracture zones created by major highways and other development that restrict or impede wildlife movement in crucial locations throughout the state.

The WAHCAP framework includes four primary prioritization criteria and associated data to support decision-making:

1. Landscape Connectivity Values

WAHCAP identified or developed indicators for 10 key connectivity values in Washington including ecosystem connectivity, network importance, landscape permeability, hot spots of species of greatest conservation need, focal species functional connectivity, climate connectivity, and consistency with pre-existing landscape conservation priorities.

We synthesized these 10 metrics into a layer mapping and quantifying connectivity values across the state. This layer was further used to identify broad-scale priority connectivity areas, transportation priority locations where barrier mitigation would most improve statewide ecological connectivity, and locations with a high density of multiple connectivity functions and values.

2. Network importance at a statewide scale

We used the underlying Landscape Connectivity Values data and maps to identify 13 terrestrial Connected Landscapes of Statewide Significance (CLOSS) (Figure 1). These connected landscapes visualize big-picture terrestrial connectivity goals for the state, providing a statewide blueprint to ensure connected pathways are maintained for wildlife among each of the major ecological regions of the state. The CLOSS are broad pathways, not precise routes, and are intended to help users identify barriers and linkages critical to supporting a statewide connectivity network. These broad pathways connect the Olympic Peninsula, Willapa Hills, Cascade Mountains, Northern Rockies, Blue Mountains, and shrubsteppe on the Columbia Plateau.

In addition to the CLOSS, the WAHCAP also identifies Connected Landscapes of Regional Significance (CLORS) and includes regional profiles for five major connectivity regions in Washington state: the Cascade Mountains, Southwest Washington and the Olympic Peninsula, the Columbia Plateau and Blue Mountains, Northeast Washington, and Northwest Washington. Each regional profile describes the connectivity characteristics of each region and includes maps and descriptions of statewide and regional priorities identified within each region, regional connectivity threats and conservation strategies, and lists of additional resources.

Image

Figure 1. Connected Landscapes of Statewide Significance (CLOSS)

3. Statewide transportation priorities

A primary goal of this plan was to identify priority locations statewide for connectivity conservation actions. We used the Landscape Connectivity Values layer as the primary input to evaluate the ecological barrier status of every road mile in the state highway system and multiple data sets including, but not limited to, wildlife-vehicle collisions and carcass removals to evaluate safety status. Our analysis ranked the ecological and safety status of every road mile in the state highway system, called the Full Highway System Rankings. From these rankings, we identified a Long List and a more selective Short List of transportation Priority Zones for road barrier mitigation to facilitate safe passage for wildlife and reduce wildlife-vehicle collisions. These transportation priorities and the adjacent connected landscapes leading up to and away from these barriers are priority locations for connectivity conservation in Washington.

4. Protection status and management intent

Protected areas that are actively managed to sustain ecological functions and values form the backbone of a sustainable habitat connectivity network. Land protection and management status have significant implications on the types and feasibility of conservation actions that can be done at a given location.

Public ownership and current management for ecological functions and values alone do not equal permanent or fully effective ecological protection. The connectivity value of public lands depends on their underlying management mandates, land use allowances, operational frameworks, and ongoing political support. Maintaining and improving public lands management to support a connected network of ecologically resilient lands is essential to maintaining habitat connectivity in Washington.

5. Habitat conversion threat

Our final prioritization criterion focused on quantifying habitat conversion pressure, or how vulnerable connectivity functions are to loss. Habitat loss, fragmentation, and conversion can occur on public or private lands and stem from a variety of sources. We were not able to conduct a full and systematic threats assessment for connectivity statewide for the WAHCAP but highlight here that habitat conversion threat is a key factor to consider when prioritizing conservation locations. During our WAHCAP webinar and workshop discussions, the following prominent threats to habitat connectivity in Washington were repeatedly identified as being of high concern:

• Transportation barriers
• Residential and commercial development
• Wind and solar energy development
• Recreation

We performed a detailed analysis of transportation barriers and identified priority locations for road barrier mitigation (Appendix D). We identified or developed data layers that showed conversion pressure from residential and commercial development and locations identified as suitable for solar development (Appendix G). We identified a need to develop data on the impacts of recreational trail and campground use. State and tribal leaders recently convened the State and Tribal Recreation Impacts Initiative (PDF) (STRII) to better characterize the severity and distribution of recreation impacts to inform recreation management decisions.

This list of threats is not comprehensive. Habitat conversion and loss of connectivity functions and values can stem from clearcut logging practices, conversion of native vegetation to agriculture, climate change, wildfire, and shoreline erosion, and more. The four threats identified here were called out by participants in our advisory groups and were the focus of this initial WAHCAP. We included spatial data on these threats where it was available or feasible to do so as an illustration of how mapped threats can be overlaid onto maps of connectivity values to identify priority locations in immediate need of conservation action and recommend further development of threats spatial data as an implementation action for groups looking to support connectivity conservation in Washington.

Figure 2 summarizes WAHCAP’s landscape and transportation spatial priority data products.

Image

Figure 2. WAHCAP spatial products
We combined ten spatial input data layers (left) to produce the Landscape Connectivity Values map which reflects the significance of the Existing Protected Areas map. The Landscape Connectivity Values map informed the identification of the Landscape Connectivity Hot Spots, the Connected Landscapes of Statewide and Regional Significance, and the Full Highway System Rankings Ecological Value Score. On the right, transportation analysis products included Ecological Value and Wildlife-related Safety scores for all highway segments and the resulting Priority Zones in the Long and Short Lists. Together, these products will guide decisions about where connectivity conservation and mitigation efforts can have the greatest impact for habitat connectivity and wildlife-vehicle safety.

From Statewide Vision to Regional Action

While the statewide CLOSS network provides a big-picture road map, successful connectivity conservation also demands finer-grained, regional analyses. Each region of Washington has unique geography, ecosystems, land use patterns, and species needs that a statewide model can only approximate. Recognizing this, we identified Connected Landscapes of Regional Significance (CLORS) that support and feed into the CLOSS network, and the WAHCAP report includes Regional Connectivity Profiles that refine statewide priorities by providing additional information about specific landscape conditions, threats, and opportunities within each region. The regional profiles highlight areas where local connectivity conservation actions can strengthen the statewide network by enhancing permeability across fragmented areas, mitigating barriers, or restoring and reinforcing linkages.

Integrating Local Habitats and Knowledge

By design, the statewide connectivity modeling did not capture every area of local ecological importance. The CLOSS map highlights the most significant linkages for statewide landscape-scale connectivity, but many smaller habitat areas (e.g., urban riparian areas, parks, or isolated forest patches) did not appear as statewide priorities even though they are critical to supporting wildlife and ecosystem functions at the local scale. Due to time and data constraints, WAHCAP was unable to incorporate a complete set of fine-scale local data in this statewide analysis. We encourage local conservation practitioners and land managers to use the WAHCAP as a starting point and use additional data to delineate priority locations for connectivity at the local level. Regional and community-level data (e.g., county open space plans, land trust conservation maps, tribal knowledge and priorities) can identify additional connectivity areas that are not adequately represented in the statewide analysis. When possible, local conservation practitioners should aim to connect local habitat connectivity priorities to the larger Connected Landscapes of Statewide or Regional Significance.

Implementation Pathways

Successful implementation of the WAHCAP depends on integrating habitat connectivity into existing and new planning, funding, and management frameworks across Washington. WAHCAP provides spatial data, strategies, and guidance to support implementation through four key pathways.

• It is crucial for local jurisdictions to incorporate habitat connectivity into land-use planning under the Growth Management Act—through comprehensive planning, zoning codes, critical areas regulations, and countywide planning policies—to protect and restore corridors within and across local jurisdictions.
• State and local governments should offer voluntary conservation incentives to owners of working lands to sustain and restore connectivity.
• WDFW and the Washington State Department of Transportation (WSDOT) should continue to expand the integration of habitat connectivity into transportation design, planning, and infrastructure to reduce wildlife-vehicle collisions and restore landscape permeability.
• Public agencies throughout the state should manage public lands—including recreation planning, forest road decommissioning, and land management plan updates—to protect, enhance, and restore connectivity.

Across all implementation pathways, cross-jurisdictional collaboration, using both voluntary and regulatory tools, and using WAHCAP data as a foundation is essential to supporting a resilient, connected landscape for Washington’s wildlife and communities.

Critical Roles of Riparian Corridors

Across all spatial scales—statewide, regional, and local—riparian corridors emerge as crucial conservation features, particularly in fragmented or human-dominated landscapes. Stream and river corridors often retain continuous strips of vegetation and undeveloped floodplain, making them natural pathways for wildlife movement through otherwise fragmented habitat. In urban or agricultural areas, for example, a riparian corridor may be the only intact habitat strip remaining. Riparian corridors also function as climate corridors, allowing species to move up in elevation in response to warming temperatures. Protecting and restoring riparian areas supports both aquatic ecosystems and terrestrial wildlife movement. Examples like Crab Creek on the Columbia Plateau and the Chehalis River in western Washington illustrate how riparian networks can help reconnect fragmented habitats. Sustaining terrestrial connectivity at all scales depends on prioritizing riparian corridors in planning and restoration efforts.

The WAHCAP did not create data or models to prioritize riparian corridors because of concurrent development of the Riparian Data Engine (RDE), an online decision-support tool to help users identify and prioritize riparian areas for restoration. Although not designed explicitly to support habitat connectivity, it compiles and summarizes data on riparian vegetation condition, water quality, fish presence, and fish passage barriers. In addition, WDFW is finalizing a Statewide Fish Passage Barrier Assessment to prioritize barrier removal and improve aquatic connectivity. Combined with the WAHCAP, these resources provide a wealth of information to understand riparian condition and identify restoration priorities to support aquatic and terrestrial connectivity.

Toward a Connected Future

The WAHCAP presents a vision of landscape connectivity for Washington. The 13 Connected Landscapes of Statewide Significance provide the big-picture connectivity goal for Washington, while regional profiles refine and fill in the network. This multi-scale approach is intended to empower conservation partners, land managers, and planners to align their work towards a common goal: a Washington where wildlife and ecological processes can move freely across connected habitats, and where a safer statewide highway system reduces risks to both wildlife and people. By connecting local landscapes to statewide corridors, prioritizing critical linkages like riparian corridors, and protecting and restoring areas where connectivity is most at risk, we can build a more resilient and safer Washington.