All information on this page is from the Department of Ecology site located at http://www.ecy.wa.gov/programs/sea/ pubs/90031/index.html


What are wetlands?

The most commonly used wetland classification system is “Cowardin,” named for the scientist who developed it. It was officially adopted by the U.S. Fish and Wildlife Service in the 1970s. Cowardin divides wetlands into five major categories based on the type of aquatic environment to which they are connected. (See box for details.) Cowardin further divides wetlands by soil type, vegetation, persistence of wet conditions, and other characteristics. By combining all the different categories and wetland characteristics in Cowardin, scientists can identify hundreds of specific wetland types.

As a wetland owner you do not need to know the exact classification of your wetland to use this guidebook. You might be able to impress your friends by telling them that you own a “littoral non-persistent emergent wetland in the lacustrine system,” but you don’t really need to know all that to be a good wetland steward. You may be more familiar with the common terms “swamp,” “bog,” and “marsh,” which refer to specific kinds of wetlands, each distinguished by its plants, soils, and water chemistry.

The Five Basic Types of Wetlands

  • Marine: sea water wetlands undiluted by freshwater.
  • Estuarine: (ESS-choo-a-reen) wetlands in estuaries — areas where saltwater and freshwater mix.
  • Riverine: (RIV-er-een) freshwater wetlands associated with rivers or streams.
Lacustrine: (la-KUSS-tren) freshwater wetlands associated with lanes.
Palustrine: (pa-LUSS-tren) all other freshwater wetlands (swamps, marshes, bogs, etc.)

Swamps (or forested wetlands) usually occur along river courses. Their vegetation is dominated by trees and shrubs — cedars, spruce, cottonwood, dogwood, spirea, and willows, among others. Swamps have dense under stories — the vegetation growing beneath the trees — and, with their abundance of food and cover, provide diverse wildlife habitat.

Bogs occur in cool, wet areas where the drainage is poor. Bogs often have floating mats of vegetation and very dark colored water. The dominant plants are sedges and mosses, especially sphagnum. As the plant material decays, it forms layers of peat. Many of Washington’s bogs were destroyed when they were mined for their peat. In an era when things change at an astonishing rate, it is comforting and amazing to consider that most of the bogs in our state are 10,000 years old.

Marshes can be either saltwater or freshwater wetlands. Freshwater marshes occur both alone and in association with other bodies of water. Saltwater marshes are located near estuaries and marine water. Marsh vegetation consists primarily of grasses and herbs — plants that have fleshy rather than woody stems.

Do You Have a Wetland?

The first step in determining whether you have a wetland on your property is to consult the available wetlands maps. The National Wetlands Inventory (NWI), compiled by the U.S. Fish and Wildlife Service, covers all of Washington State and identifies wetlands by using aerial photography. Local governments use the NWI as a starting point for their own inventories, and take the additional step of conducting field reviews of wetlands in their areas.

Your local planning department can tell you whether they have NWI or their own wetlands maps, and can help you determine whether your property has an identified wetland. You should recognize, however, that even if the maps do not show a wetland on your property, you may still have one. The maps are limited, often missing small or forested wetlands. And the wetland boundaries, which may change over time with natural cycles, are only approximations.

The next step you can take to determine whether you have a wetland, or to define its boundaries, is to get some professional assistance. Your local planning office may have a wetlands specialist who can help you, or you may want to retain the services of a wetlands consultant. Many environmental consulting firms have staff members who can confirm the presence of a wetland and can conduct a wetland “delineation,” a process of defining the boundaries of a wetland. You may want a delineation for your own information, or to ensure that you keep a proper buffer zone between your wetland and other activities on your property. Chapter Five describes buffers and provides advice on how to select a consultant.

What is wetland delineation?

Wetland delineation establishes the existence (location) and physical limits (size) of a wetland for the purposes of federal, state, and local regulations.

Wetland delineation is also an element of a “jurisdictional determination.” This process identifies which water bodies within a project’s boundaries meet the definition of “waters of the United States.” For more information on this, see the Corps’ Regulatory Guidance Letter 08-02, Jurisdictional Determinations (issued June 26, 2008, PDF 118 kb).

Remember that the Corps of Engineers (Corps), not applicants or their consultants, determines whether or not a wetland is a “water of the United States” and thus regulated under the federal Clean Water Act (CWA). If the Corps determines that a wetland is not subject to the CWA, the wetland may still be a “water of the State” and subject to regulation by Ecology as well as by local jurisdictions. Ecology regulates wetlands determined by the Corps to be non-jurisdictional due to their isolation from navigable waters.

What is mitigation?

Various options are available for mitigation, in addition to the traditional on-site concurrent option, depending on what can work best for the applicant and for the environment. Each option must conform with the appropriate local, state, and federal regulatory requirements and permit processes.

  • Wetland Banking – A mitigation bank is a wetland, stream, or other aquatic resource area that has been restored, established, enhanced, or (in certain circumstances) preserved for the purpose of providing compensation for unavoidable impacts to aquatic resources permitted under Section 404 or a similar state or local wetland regulation. A mitigation bank may be created when a government agency, corporation, nonprofit organization, or other entity undertakes these activates under a formal agreement with a regulatory agency.

In-Lieu Fee (ILF) Mitigation– In this approach to mitigation, a permittee pays a fee to a third party in lieu of conducting project-specific mitigation or buying credits from a mitigation bank. ILF mitigation is used mainly to compensate for minor impacts to wetlands when better approaches to compensation are not available, practicable, or when the use of an ILF is in the best interest of the environment. Compensation for larger impacts is usually provided by project-specific mitigation or a mitigation bank.

An ILF represents the expected costs to a third party of replacing the wetland functions lost or degraded as a result of the permittee’s project. ILFs are typically held in trust until they can be combined with other ILFs to finance a mitigation project. The entity operating the trust is typically a nonprofit organization such as a local land trust, private conservation group, or government agency with demonstrated competence in natural resource management.

Off-site mitigation – Compensatory mitigation that is not located at or near the project that is affecting wetlands. Off-site mitigation is generally only allowed when on-site mitigation is not practicable and environmentally preferable. See guidance on selecting a mitigation site using a watershed approach:

Also see examples of code language in critical areas ordinances related to off-site mitigation (PDF, 51KB).

Advance mitigation – Compensatory mitigation in which the mitigation project is implemented before, and in anticipation of, future known impacts to wetlands. Advance mitigation has been used mostly for large mitigation projects that are constructed in distinct phases where the impacts to wetlands are known. Advance mitigation lets an applicant provide all of the compensation needed for the entire project affecting wetlands at one time.
Although similar to mitigation banking, advance mitigation is different in several ways. Most important, advance mitigation is used only to compensate for a specific project (or projects) with per-identified impacts to wetlands. Several key regulatory agencies are embarking on developing guidance for advance mitigation. This guidance will be available by mid 2011. For more information, please contact Lauren Driscoll.

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