Wetland Mitigation

Wetland mitigation refers to the process of compensating for the loss or degradation of wetland habitats due to land use change. It involves creating, restoring, enhancing, or preserving wetlands in order to offset the negative impacts of development projects or other human activities on these valuable ecosystems. Wetlands provide numerous ecological benefits, such as flood control, water purification, habitat for wildlife, and carbon sequestration, making their preservation and restoration crucial for maintaining environmental balance.

In Oregon, wetland mitigation has a significant history as the state recognizes the importance of wetlands and their role in supporting a healthy environment. The first comprehensive wetland mitigation program in Oregon was established in the early 1980s. This program aimed to mitigate the loss of wetlands through a process that involved the replacement of wetland functions and values in a manner that would ensure no net loss of wetland acreage or function.

The state of Oregon adopted a mitigation hierarchy approach, prioritizing avoidance and minimization of wetland impacts before considering compensation measures. Developers were encouraged to avoid impacting wetlands whenever possible. If avoidance was not feasible, they were required to minimize impacts through design modifications or alternative project layouts.

When wetland impacts were unavoidable, compensatory mitigation measures were implemented. These measures could include wetland restoration, creation, enhancement, or preservation activities. The goal was to achieve functional equivalency, meaning that the created or restored wetland would provide similar ecological functions and values as the impacted wetland.

Over the years, Oregon has refined its wetland mitigation policies and practices, aiming to improve the effectiveness and success of mitigation projects. The state's regulatory framework emphasizes the use of mitigation banks, which are large-scale, pre-approved sites where wetlands are restored, created, or enhanced to compensate for wetland losses across multiple projects. Mitigation banks streamline the mitigation process by providing a centralized location for mitigation activities, reducing the burden on individual project developers.

Oregon's commitment to wetland mitigation has resulted in the restoration and creation of thousands of acres of wetlands, ensuring the long-term conservation and enhancement of these valuable ecosystems. The state continues to refine its approach to wetland mitigation to ensure sustainable development while preserving the ecological integrity of wetland habitats.

TWC’s Willamette Valley wetland prioritization has been used as the foundation for a variety of federal, state and local agency and NGO conservation and wildlife plans. Our partnership between the Mud Slough Wetland Mitigation Bank has become the model for successful long-term stewardship of wetland banks in Oregon. TWC holds easements on four additional wetland prairie banks in the Willamette Valley. Involvement in these wetland banks is restoring one of the most threatened wetland types in Oregon.

Bounded on the west by the Coast Range and on the east by the Cascade Mountains, this eco-region encompasses 3,397,106 acres (in the Willamette Valley and adjacent foothills). The Valley is a long, level alluvial plain with scattered groups of low basalt hills. The Willamette Valley once was covered by extensive wetlands. Since the 1850’s, approximately 98% of wet prairies and 67% of emergent marsh habitats have been lost. Most, if not all, remaining wetlands have been degraded to some degree by altered water regimes, pollution, and non-native plants and animals.