Mitigation Management

Mitigation Management

We manage over 900 acres of wetland and upland mitigation and enhancement sites. These managed natural areas provide compensation for temporary and unavoidable, permanent impacts to wetlands and other natural resources from our development or operational activities. Their benefits include: 

  • Increasing habitat value by enhancing or creating nesting, foraging and resting habitat;
  • Improving connectivity between wildlife areas;
  • Improving or restoring wetland hydrological functions;
  • Reducing and controlling the spread of invasive weeds;
  • Improving air and water quality; and
  • Providing valuable “greenspace” in a highly urbanized area.

We initiated the Mitigation Management Program in 1997 to respond to mitigation requirements and mandates from regulatory agencies. The program continuously evolves to incorporate the latest science and technology. We report annually on sites under compliance and conduct reporting every two years for stewardship on all sites. 

Mitigation Management Program Report
The Mitigation Management Program report provides an update on the previous two year's activities for all Port mitigation sites and other natural areas. For each site, this report provides permits and agreements, background, mitigation plan, success criteria, permit requirements, activity update, site performance, action plan and a map of the site..

    Mitigation Status Report (pdf - 10 MB) 
    Contact us with questions about the Port's Mitigation Program

Mitigation Management

Vegetation Management Plan 
The Vegetation Management Plan provides information about invasive species control methods used by the Port on our mitigation sites and natural areas. This document includes background and purpose, invasive plant species profiles, methods and equipment, site maps and Best Management Practices including maintenance timing to avoid and protect wildlife. 

    Vegetation Management Plan - 2023 (pdf)

Long-term Management Plans
To further demonstrate the Port's commitment to long-term management, Long-term Management Plans (LTMP's) are being developed for most sites, especially those with a high potential for transferal to a land trust or some other land management entity. The plans summarize our knowledge about the site to provide a new steward with a valuable tool for management and to ensure the site’s value and function over time.

   Vanport Wetlands: LTMP 2018
   Government Island: Management Plan 2021
   Randall: LTMP 2016
   Rivergate Enhancement Sites: LTMP 2022
   TRIP Phase I: Vol. I LTMP 2022
   Buffalo Site: LTMP 2024



Mitigation Sites
If new development is proposed where wetlands or other regulated natural resources are impacted, federal, state and local laws and regulations require that project alternatives be evaluated to 1) avoid the impact; 2) minimize the impact; and 3) mitigate or compensate for the impact to these natural resources. Mitigation is usually in the form of restoration, establishment (creation), enhancement, or preservation of the habitats and functions lost through the proposed development activities.

Permitting and compliance responsibilities for all mitigation sites are primarily enforced by the US Army Corps of Engineers, Oregon Department of State Lands and Oregon Department of Environmental Quality, with associated federal, state and local agencies having influence and comment on permit compliance. Mitigation may also be required through the City of Portland’s land use process as a condition of project approval or Clean Water Services in Washington County.
In 2011, the Port and the City of Portland signed an Inter-Governmental Agreement (IGA) for natural resources related to the Airport Futures Project, a collaborative effort to create an integrated long-range development plan for PDX. The IGA requires that the Port mitigate for 300 acres of upland grassland resources in lieu of having four PDX properties (totaling approximately 268 acres) zoned as environmental overlays.

Grassland mitigation began on Government Island in 2011 and will be phased in six 50 acre allotments through 2035. The IGA states that the first 50 acres of mitigation must occur in advance of any development on one or more of the four PDX properties identified in the IGA. Future grassland mitigation on the island, above the initial 50 acres, would be triggered when development on the four properties is proposed to exceed 25 acres.

In addition, the Port agreed to undertake the conversion of the 6.2 acre Portland International Center Wetland Enhancement Site from a mixed wetland and upland area to an area with native shrub cover. The site was planted in 2014 and seeded in 2017. Plantings included 14 different species of native shrubs and wildflowers.