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Identifying Wetlands and Waters

Large trees surrounded by green grass and purple flowers.Wetlands and streams, rivers, lakes, and other waters in Oregon are protected by the state’s removal-fill laws because they provide important benefits to the environment and communities. Most work that adds or removes materials in wetlands or waters requires a removal-fill permit, even on private land. For this reason, it’s important to accurately identify whether there is a wetland or water on a site before starting work.

While waters are often easy to observe, wetlands can be difficult to identify because they range in appearance and can include tidal marshes along the coast, seasonal prairie wetlands in the valleys, and fens and bogs along the coast and in the mountains. Some wetlands are seasonal and may be completely dry by the summer, while others have been altered by past activities, like farming, and may be difficult to observe at all.
The following steps will help guide you through the process of identifying whether wetland or water is located in a planned project location.

Steps to Identify Wetlands or Waters on a Property

  1. Look around. You may be able to observe wetlands or waters on your property. If you cannot see a wetland, look for their indicators. Indicators can include natural drainage channels, ground that is soggy at certain times of the year, seeps on or near the base of slopes, depressions where water pools, or plants that typically are found in wetlands.

  2. Consult maps and inventories. Maps and inventories available through DSL can help identify whether there are known waters, wetlands, or places with soil characteristic of wetlands on a site.

  3. Consider contacting DSL to request a preliminary determination of wetlands or waters. As capacity allows, the we wetland ecologist for your county can help determine if wetlands may be present on your property. DSL may recommend hiring a qualified wetland consultant to conduct a full site investigation.  

  4. Work with a wetland consultant to delineate boundaries. If DSL determines wetlands or waters may be present, a consultant will help you delineate the boundaries of these resources. A delineation report prepared by your consultant should then be submitted to DSL for review and approval. 

  5. Apply for a removal-fill permit. If wetlands or waters have been identified in an area you want to work in, contact DSL to determine if a removal-fill permit will be needed. A wetland consultant can also help determine if a permit will be needed.

Yellow and white wildflowers in bloom wih blue sky in the backgroundDetermining if Wetlands or Waters may be Present

As capacity allows, DSL staff are available at no cost to help determine if a wetland or waters may be present on a given site. To ask for a determination, submit a request form to The wetland ecologist who assists you will use existing maps, aerial photographs, and other information to determine whether a wetland may be present. A determination can usually be made without an onsite visit. 
If DSL has already made a wetland determination for your property in the past, you may be able to request an extension. Contact the wetland ecologist  for your county to see if you are eligible.
DSL staff are only available to help determine if a wetland or waters may be present on a property. If they are detected, you will need to work with a wetland consultant to delineate the boundaries of the site.

Delineating the Boundaries of Wetlands or Waters

If wetlands or waters have been detected on a site, the next step is to work with a professional consultant to identify the boundaries of the protected resource. Delineating boundaries helps determine where a project could potentially impact a resource.

When wetlands or waters are present, a delineation report needs to be submitted. The report combines site mapping with other information, like site history and characteristics. Delineation reports are prepared by environmental consultants who assess the site and submit the report to DSL for review and approval. Approved report findings are typically valid for five years unless new information necessitates revision. The DSL approval letter will describe the criteria under which a removal-fill permit will be required for projects within the wetlands and waters.

Submitting Delineation Reports

Delineation reports may be submitted to DSL in two ways: 

Hiring a Consultant

Consultants assess the boundaries of wetlands or waters on a site, submit delineation reports to DSL, and can help guide clients through the removal-fill permitting process.
While DSL cannot recommend a specific consultant, we recommend reviewing a list of wetland consultants that is maintained by the Society of Wetland Scientists Pacific Northwest Chapter. DSL also maintains a summary of consultants that have submitted delineation reports to the Department in recent years.
It’s normal to interview several consultants to determine who could be a fit. DSL recommends contracting someone who meets the following standards:
  • Has an educational background in science or ecology, with wetland-specific training, including wetland delineations.
  • Has a good working relationship with DSL and proven track record
  • Certification as a Professional Wetland Scientist or Wetland Professional in Training by the Society of Wetland Scientists’ Professional Certification Program is a plus. 
It may be helpful to ask a consultant about the following:
  • Their knowledge of local, state, and federal permit requirements and processes, as well as development standards and options.
  • Experience assisting applicants with the removal-fill permitting process.
  • An estimate of how much it will cost to complete an approved delineation report and/or a complete removal-fill permit application.

Applying for a Removal-Fill Permit

If a wetland or waters have been determined to be present and their boundaries have been delineated, the next step is to submit this information to DSL for review and approval. Work with the consultant or builder to see if the project can be designed to avoid or minimize construction within wetlands and waters. If impacts must occur then work with the consultant to submit a removal-fill permit application. DSL will review proposed projects and work with applicants to determine if the project can move forward.