Isolated Wetlands Information

Some types of wetlands are regulated by state and local governments but not by the federal government. The most common type is isolated wetlands. Isolated wetlands generally have no hydrologic connections to other aquatic resources. Though not always protected under federal law, isolated wetlands often perform many of the same important environmental functions as other wetlands, including recharging streams and aquifers, storing flood waters, filtering pollutants from water, and providing habitat for a host of plants and animals (see Wetlands in Washington State - Volume 1, Chapter 5 [PDF]). These wetlands continue to be protected under state and local laws and rules.

A 2001 Supreme Court decision, known as the "SWANCC decision" (Solid Waste Agency of Northern Cook County v. United States Army Corps of Engineers et al., 531 U.S. 159), excluded many isolated wetlands from federal regulation. The Supreme Court based this decision on a legal interpretation of jurisdiction under the federal Clean Water Act (CWA). The key factor was the language in the Act that relates to navigable waters. Under Section 404 of the CWA, federal protection extends to those wetlands located on or adjacent to navigable waters of the United States or their tributary systems. Wetlands that do not meet this requirement, such as isolated wetlands with no link to interstate commerce, are not regulated as waters of the United States and are therefore not protected under the CWA.

Prior to the SWANCC decision, the presence of migratory birds was considered enough to establish a link to interstate commerce, and thus CWA protection for isolated wetlands. In SWANCC however the Court ruled that the mere presence of migratory birds is not sufficient for asserting CWA jurisdiction over isolated, intrastate, non-navigable water bodies. As a result of this ruling, many isolated wetlands in Washington are no longer protected by federal law.

In general, the Corps considers isolated wetlands to be those of any size that are not adjacent* to or do not have a sufficient hydrologic connection to navigable waters. Corps policy regarding the definition and regulation of isolated wetlands is currently in flux, and future court or administrative decisions may further change how isolated wetlands are regulated by the federal government. (*See 33 CFR 328.3[c] for definition.)

After the SWANCC decision, there was confusion about which wetlands were covered under the CWA. The U.S. Supreme Court provided little clarity in their 2006 “Rapanos decision” (Rapanos v. United States, 547 U.S. 715). Therefore, in 2008, the Corps and the U.S. Environmental Protection Agency (EPA) issued joint guidance describing how they determine which wetlands are covered under the CWA based on the two decisions.  

The Corps of Engineers determines whether a wetland meets the federal requirements for being isolated

Applicants and consultants must coordinate all projects potentially affecting isolated wetlands with the Corps and receive a written jurisdictional determination. Consultants can provide information to the agencies, but the final determination must be made by the Corps. Staff at the Governor's Office for Regulatory Innovation and Assistance can give you contacts for the staff at the Corps that can help you or go the Seattle Corps' webpage for a list of Corps contacts by county.

The Supreme Court’s SWANCC ruling did not change Washington State laws governing wetlands

The state Water Pollution Control Act (Chapter 90.48 RCW) and associated water quality regulations (Chapter 173-201A WAC) make no distinction between isolated and non-isolated wetlands. All waters of the state, including isolated wetlands, are covered by state law. Ecology continues to regulate isolated wetlands and to apply the water quality standards prescribed by state law. Ecology’s process for regulating projects involving isolated wetlands is similar to the process used for federally regulated wetlands. For more information, see Ecology's Focus Sheet, Focus on Regulating Isolated Wetlands.

When proposing to impact an isolated wetland, print and fill out the Isolated Wetlands Information Sheet.  The information provided on the sheet will augment information provided in the Joint Aquatic Resources Permit Application (JARPA) and will expedite review of your project. Submit the information to the Federal Permit Coordinator at Ecology: 

Federal Permit Coordinator
WA Department of Ecology
SEA Program HQ
P.O. Box 47600
Olympia, WA 98504-7600

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