I n 2006, the Supreme Court decided Rapanos v. United States, the most recent and well-known of three Supreme Court decisions wrestling with the question of which wetlands are covered by the wetlands permitting program in the Clean Water Act (CWA). The Sixth Circuit Decisions

Rapano s in the Sixth Circuit involved the Corps' assertion of 404 jurisdiction over a wetland adjacent to a tributary (man-made ditch) that ultimately flowed, miles later, into a traditional navigable water. The problem is that no single rationale in these three opinions commands the support of a majority of the Justices. No circuit decision has opted for the plurality test alone. The Corps and EPA had previously issued other guidance, attempting to clarify the Court's rulings on the jurisdictional issues discussed here. Under this test, the existence of a continuous surface connection, as demanded by the plurality, but not Kennedy or the dissenters, is required to establish adjacency. However, in May 2015, EPA and the Corps jointly announced a rule to revise regulations that define "waters of the United States," that is, waters protected under the CWA. According to the agencies, the new rule—which they now refer to as the Clean Water Rule—revises the existing administrative definition of "waters of the United States" in regulations consistent with legal rulings—especially the recent Supreme Court cases—and science concerning the interconnectedness of tributaries, wetlands, and other waters to downstream waters and effects of these connections on the chemical, physical, and biological integrity of downstream waters. The rule was controversial even before it was proposed in March 2014, and controversies have persisted since the final rule was issued, including among Members of Congress. Policy Implications

As with the legal questions, the policy questions associated with the Supreme Court cases—what should be the outer limit of CWA regulatory jurisdiction and what are the consequences of restricting that jurisdiction—also have challenged regulators, landowners and developers, and policymakers since passage of the act in 1972. The answer to this question is important, because it may determine the extent of federal CWA regulatory authority not only for the Section 404 program, but also for purposes of implementing other CWA programs. While regulators and the regulated community debate the legal dimensions of federal jurisdiction, scientists contend that there are no discrete, scientifically supportable boundaries or criteria along the continuum of waters/wetlands to separate them into meaningful ecological or hydrological compartments. Wetland scientists believe that all such waters/wetlands are critical for protecting the integrity of waters, habitat, and wildlife downstream. SWANCC, Rapanos , and the subsequent lower court decisions also highlight the role of states in protecting waters not addressed by federal law. But if a larger portion of wetlands are no longer federally jurisdictional, they say, it can be argued that the Section 404 program no longer provides a baseline for consistent, minimum standards to regulate wetlands. None of these court rulings prevents states from protecting non-jurisdictional waters through legislative or administrative action, but few states have done so. It defined "waters of the United States" by a rewritten version of the regulatory definition in use by EPA and the Corps:
The term "waters of the United States" means all waters subject to the ebb and flow of the tide, the territorial seas, and all interstate and intrastate waters including lakes, rivers, streams (including intermittent streams), mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes, and natural ponds, all tributaries of any of the above waters, and all impoundments of the foregoing. In the 114 th Congress, bills to narrow the statutory definition of waters that are subject to CWA jurisdiction have been introduced, as has legislation to bar EPA and the Corps from issuing a revised "waters of the United States" rule or to require the agencies to re-start the rulemaking process for such a regulation. (For details, see CRS Report R43943, EPA and the Army Corps' "Waters of the United States" Rule: Congressional Response and Options , by [author name scrubbed].)
In 1985 and 2001, the Supreme Court grappled with issues as to the geographic scope of the wetlands permitting program in the federal Clean Water Act (CWA). In 2006, the Supreme Court rendered a third decision, Rapanos v. United States, on appeal from two Sixth Circuit rulings. The Sixth Circuit rulings offered the Court a chance to clarify the reach of CWA jurisdiction over wetlands adjacent only to nonnavigable tributaries of traditional navigable waters—including tributaries such as drainage ditches and canals that may flow intermittently. (Jurisdiction over wetlands adjacent to traditional navigable waters was established in the 1985 decision.)
The legal and policy questions associated with Rapanos—regarding the outer geographic limit of CWA jurisdiction and the consequences of restricting that scope—have challenged regulators, landowners and developers, and policymakers for 40 years. The answer may determine the reach of CWA regulatory authority for all CWA programs, since the CWA uses but one jurisdiction-defining phrase ("navigable waters") throughout the statute. The Court's decision provided little clarification, however, splitting 4-1-4. The four-Justice plurality decision, by Justice Scalia, said that the CWA covers only wetlands connected to relatively permanent bodies of water (streams, rivers, lakes) by a continuous surface connection. Justice Kennedy, writing alone, demanded a substantial nexus between the wetland and a traditional navigable water, using an ambiguous ecological test. Justice Stevens, for the four dissenters, would have upheld the existing broad reach of Corps of Engineers/EPA regulations.
Because no rationale commanded the support of a majority of the Justices, lower courts are extracting different rules of decision from Rapanos for resolving future cases. Corps/EPA guidance issued in 2008 says that a wetland generally is jurisdictional if it satisfies either the plurality or Kennedy tests. In 2011, the agencies proposed revised guidance intended to clarify whether waters are protected by the CWA, but this proposal was controversial and was not finalized. The ambiguity of the Rapanos decision and questions about the agencies' guidance increased pressure on EPA and the Corps to initiate a rulemaking to promulgate new regulations, which they did with regulatory revisions to define "waters of the United States" that are subject to CWA jurisdiction, issued in May 2015. (For discussion of this rule, seeCRS Report R43455, EPA and the Army Corps' Rule to Define "Waters of the United States"). The rule has been very controversial, including among Members of Congress. (For discussion, see CRS Report R43943, EPA and the Army Corps' "Waters of the United States" Rule: Congressional Response and Options, by [author name scrubbed] ). Challenges to the rule, called the Clean Water Rule, have been brought in a number of federal courts, and the rule has been stayed for the duration of litigation.
While regulators and the regulated community debate the legal dimensions of federal jurisdiction under the CWA, scientists contend that there are no discrete, scientifically supportable boundaries or criteria along the continuum of wetlands to separate them into meaningful ecological or hydrological compartments. Wetland scientists believe that all such waters are critical for protecting the integrity of waters, habitat, and wildlife downstream. Changes in the limits of federal jurisdiction highlight the role of states in protecting waters not addressed by federal law. From the states' perspective, federal programs provide a baseline for consistent, minimum standards to regulate wetlands and other waters. Most states are either reluctant or unable to take independent steps to protect non-jurisdictional waters through legislative or administrative action.