The U.S. Environmental Protection Agency (EPA) and the U.S. Army Corp of Engineers (Army Corp) just released the final rule providing guidance on which waters are considered “Navigable Waters of the United States” and thus subject to Clean Water Act (CWA) jurisdiction. “We’re finalizing a clean water rule to protect the streams and wetlands that one in three Americans rely on for clean water and we’re doing that without any new permitting requirements and maintaining all previous exemptions and exclusions,” said EPA Administrator Gina McCarthy during a call with reporters announcing the release of the final rule.

The EPA and the Army Corp first proposed this rule, known as the Waters of the United States (WOTUS), in the spring of 2014. Since the rule’s promulgation, the agencies involved have held more than 400 meetings with outside groups and reviewed over one million public comments. The rule is issued under the 1972 Clean Water Act, which granted broad authority to the federal government to regulate pollution in major bodies of water as well as streams that drain into those larger bodies of water.

The EPA contends that the new rule is necessary after two Supreme Court rulings called into question the breadth of the EPA’s regulatory authority, especially for streams and wetlands that do not flow directly into larger bodies of water. According to Gina McCarthy, the new rule protects only waters that have been historically covered under the CWA without adding “any new requirements.”

The rule seeks to clarify the term “navigable waters” for purposes of establishing the breadth of jurisdiction granted under the CWA. Section 502(7) of the statute defines navigable waters as “waters of the United States, including territorial seas,” and the term “navigable waters” is used throughout the CWA, including Section 402 of the NPDES program, the Section 404 permit program, the oil spill prevention and response program, the water quality standards and TMDL program and the state water quality certification process.

The US Supreme Court has issued three decisions interpreting the meaning of the term “waters of the United States” for purposes of federal regulatory jurisdiction. In United States v. Riverside Bayview Homes, 474 US 121 (1985), a unanimous Court found that the EPA and the Army Corp had broad authority to protect aquatic ecosystems, and found that wetlands that are adjacent to navigable waters should be included in the definition of “waters of the United States.” In Solid Waste Agency of Northern Cook County v. US Army Corps of Engineers, 531 U.S. 159 (2001), a divided Court introduced the concept of “significant nexus” in deciding that use of isolated, nonnavigable intrastate ponds by migrating birds was not a sufficient basis for the exercise of federal regulatory authority under the CWA. The Court continued its effort to further refine the definition of navigable waters in its 2006 case Rapanos v. United States, 547 US 715 (2006), by first finding that the term “waters of the United States” does encompass some waters that are not “navigable” in the traditional sense. The Court reintroduced the concept of “significant nexus” and without contradicting previous holdings ruled that wetlands can possess the significant nexus the Court requires if the wetlands “either alone or in combination with similarly situated land in the region, significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as ‘navigable.’” 547 US at 780.

In response to these court decisions upholding the basic tenets of the CWA while introducing factors to consider in evaluating jurisdictional scope, agency decisions to regulate certain bodies of water under the CWA depended on a case-specific analysis that created more ambiguity and slowed down the impacts of the regulatory program. The new rule announced by the EPA attempts to provide clear and consistent guidance by defining which categories of waters are subject to jurisdiction, while maintaining existing exclusions for other categories of waters. Among the waters subject to jurisdiction by definition are traditional navigable waters, interstate waters, territorial seas and impoundments of jurisdictional waters. The new rule includes by definition both adjacent lands and tributaries as navigable waters of the United States.

The rule defines adjacent waters as those waters “that currently available science demonstrates possess the requisite connection to downstream waters and function as a system to protect the chemical, physical or biological integrity of those waters.” Similarly, the rule covers only tributaries that provide chemical, physical or biological functions to downstream waters. Any body of water not included in the definition of jurisdiction by rule must go through a case-specific significant nexus analysis to determine whether such waters are “waters of the United States.” The rule also limits EPA regulatory oversight to any body of water within 1500 feet of another body of water already covered by the rule unless the bodies have a surface water connection. The EPA believes that the rule expands the scope of the CWA by only about 3%.

Despite EPA’s pronouncements that the new rule merely clarifies existing practice and conforms the CWA to the jurisdictional limits announced by the Supreme Court, numerous opponents continue to object to the WOTUS rulemaking. Among the strongest critics are farmers, homebuilders, pesticide manufacturers and golf course operators, among other corporate interests. The stated concern is that the new rule will allow the EPA to increase regulatory control over private property. The rule is being challenged both in court and by legislation introduced in the House of Representatives designed to thwart the EPA’s rulemaking authority on this issue. Opponents not only allege that the EPA has gone beyond its jurisdiction in establishing this rule, but further allege that the EPA engaged with rule proponents to actively support the rule, raising questions about the legitimacy of the rule adoption process.

The rule is set to go into effect 60 days after its publication in the Federal Register. Litigation is likely even before the rule goes into effect and then certainly as the case specific analyses ensue.