Isolated wetlands

We regulate waters of the state, including isolated wetlands, regardless of federal jurisdiction.

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.

Even though isolated wetlands are not always protected under federal law, they often perform many of the same important environmental functions as other wetlands. These wetlands recharge streams and aquifers, store flood waters, filter pollutants from water, and provide habitat for a host of plants and animals.

These wetlands continue to be protected under state and local laws and rules.

Court decisions excluded many isolated wetlands from federal jurisdiction

A 2001 U.S. 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 U.S. 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 with no link to interstate commerce are not federally regulated

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.  

Recent developments

More recently, in a February 28, 2017 Executive Order, the Trump Administration directed the EPA to review the 2015 Clean Water Rule, which was intended to clarify protection under the Clean Water Act for streams and wetlands. As part of this effort, the EPA will be reviewing the definition of navigable waters.

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

Applicants and consultants must coordinate all projects potentially affecting isolated wetlands with the Corps of Engineers and receive a written jurisdictional determination. Consultants can provide information to the agencies, but the final determination must be made by the Corps. See the Seattle Corps' Regulatory County Contacts.

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

The Washington 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.

We continue 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.

Impacting an isolated wetland

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 our Federal Permit Coordinator: 

Washington Department of Ecology
Attention Federal Permit Coordinator
PO BOX 47600
Olympia WA 98504-7600

Phone: 360-407-6068

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