Wetland mapping and field verification
The City of Portland has been conducting the Wetland Inventory Project (WIP) for several years to update the citywide mapping of wetlands. Starting in 2018 and 2019, City staff used aerial photography, soil maps, previous wetland inventories, and other information to identify probable locations of wetlands. Written notices were mailed to the owners of all properties on which wetlands were identified in either 2020 or 2021 to offer free wetland field verifications to confirm or correct the wetland mapping. City staff received many requests for field verifications and have since completed more than 1,000 wetland field verifications on public and private properties.
The initial phase of the WIP is complete, but the City of Portland is continuing to offer free wetland determinations by request on sites where wetland mapping has not been field verified. Wetland determinations are typically conducted during the wet part of the growing season, between February and June. But in some circumstances, they may need to take place outside of this time period.
Wetland determinations usually take less than 30 minutes. Small test holes (1 foot wide by 1.5 feet deep) may be dug, but the holes will be refilled after testing. Staff will not enter sites that have not requested wetland determinations or granted permission to access. If you would like to request a wetland determination on your site, please contact Ezone staff for more information.
What is a wetland?
Wetlands are areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas. Wetlands are critical natural infrastructure that minimize flood risk, manage stormwater and provide important wildlife habitat. Additional explanation can be found on this Oregon Department of State Lands fact sheet.
How will the wetland data be used?
The City of Portland is currently undertaking a project that will update the mapping of Ezones in the Columbia Corridor and other areas of the city that have industrial zoning. This project is called the Columbia Corridor and Industrial Lands Environmental Overlay Zone Project and it is being carried out in coordination with the citywide Economic Opportunities Analysis (EOA). Recommendations for updates to the ezones will be made as part of the process of drafting the EOA.
Ezones are applied to important natural resources, such as rivers, streams, forest, wildlife habitat, and wetlands. Ezone Project staff offer site visits throughout the year to verify natural resource mapping. There is no immediate deadline to request a site visit, but the wetland field verifications must be done by specialized professionals and cannot be offered at all times.
View the draft Ezone and natural resource mapping on the Map App
To see if there are mapped wetlands on your site:
- Enter your address in the search bar in the upper left-hand corner of the map.
- Turn on the wetland data using the layer manager dropdown menu in the upper right-hand corner of the map.
- To see the wetlands more clearly, you may have to turn off the draft Ezone layer.
If you have any questions about natural resource mapping, or if you would like to request a site visit or a wetland field verification, please call or email project staff.