Red Paddle-Blue Paddle: Clean Water Act Ping Pong 
The Clean Water Act (the Act), signed into law in 1972, established federal jurisdiction over "navigable waters," defined in the Act as the "waters of the United States." This serves as the basis for the permitting scheme and other programs set forth in the Act.
The Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers have discretion to define "waters of the United States" in regulations. They have done so through various rulemaking procedures since the Act was passed by Congress. The scope of 'navigable waters' has gone back and forth over time, not unlike a ping pong ball.
Over the past 20 years, key rulings by the U.S. Supreme Court have resulted in uncertainty regarding the scope of federal jurisdiction under the Act. Solid Waste Agency of Northern Cook County v. Army Corps of Engineers in 2001 ("SWANCC") and Rapanos v. United States in 2006 raised difficult questions regarding the scope of federal jurisdiction over wetlands, intermittent streams, and other waters.
In SWANCC, the Court held that the Corps exceeded its statutory authority under the Act by regulating non-navigable, isolated waters based solely on their use as habitat for migratory birds.
In Rapanos, the Court again struck down asserted federal jurisdiction, this time over isolated wetlands. A plurality opinion of four Justices, authored by Justice Scalia, interpreted "waters of the United States" as including "relatively permanent, standing or continuously flowing bodies of water" that are connected to traditional navigable waters, in addition to wetlands that have a continuous surface connection to such waters. Justice Kennedy concurred in the judgment, interpreting "waters of the United States" to include those wetlands that "possess a 'significant nexus' to waters that are or were navigable in fact or that could reasonably be so made."
Chief Justice Roberts penned his own concurring opinion in Rapanos, observing that the Corps' "boundless view" of federal jurisdiction "was inconsistent with the limiting terms Congress had used in the Act." He lamented the agency's aborted rulemaking effort following the Court's SWANCC decision.
Indeed, both the SWANCC and Rapanos decisions were issued during the Administration of George W. Bush. And while they were eventually met with various guidance documents during 2003 and 2008, no new rulemaking resulted during Bush's tenure. An attempted Congressional response to SWANCC and Rapanos, in the form of the "Clean Water Restoration Act," ultimately failed to gain any traction.
It is at this point in the legal and political battle that a game of regulatory ping pong broke out.
Ping. During 2015, the Obama Administration finally responded with the Clean Water Rule, which increased the federal government's asserted jurisdiction over waters, seemingly bucking the trend from the SWANCC and Rapanos decisions. This resulted in a proliferation of litigation, staying the rule in most states, but leaving it in place in a significant number of other states. It also resulted in a decision from the Supreme Court, clarifying that challenges to the jurisdictional rule belong first in the federal district courts, not the courts of appeals.
Pong. The Trump Administration countered with a two-step process: first repealing the 2015 Obama-era Rule and then replacing it with the "Navigable Waters Protection Rule," which became effective on June 22, 2020. The 2020 Rule, which purported to be fashioned around Justice Scalia's plurality ruling in Rapanos, is widely regarding as significantly reducing the number of waters over which jurisdiction can be claimed by the federal government, at least as compared to the 2015 Rule.
Ensuing litigation has resulted in the 2020 Rule being stayed only in Colorado, a decision which was subsequently appealed to the Tenth Circuit Court of Appeals. A nationwide stay was denied by a federal district court in California. Additional challenges have been filed in numerous federal courts across the country.
A wildcard among all of this litigation is Sackett v. EPA, an enforcement case out of Idaho, currently pending in the Ninth Circuit Court of Appeals. While EPA withdrew its compliance order against the Sacketts during 2020, the court has been left to decide whether the agency has jurisdiction over the Sacketts' property as a jurisdictional wetland. This case therefore has the potential to place the jurisdiction question squarely before the U.S. Supreme Court via a petition for writ of certiorari - perhaps before any of the direct challenges to the 2020 Rule that are still pending in the various federal district courts.
It is certainly possible that the Supreme Court will once again attempt to provide some clarity regarding the scope of "navigable waters" and the "waters of the United States" over which the federal government has jurisdiction. After all, it has already been 14 years since Rapanos was infamously decided on a 4-1-4 split vote, without providing a definitive jurisdictional test. And that decision came well before the regulatory ping pong game commenced between the 2015 Obama and 2020 Trump Rules. It may well be time for the Court to weigh in.
In the meantime, the new Administration has already signaled that it may seek to reverse the 2020 Trump Rule. Among the historic flurry of executive orders issued by President Biden on his first day in office was one requiring federal agencies to review regulatory actions taken during the Trump Administration, including those involving water quality. It appears that the next ball may be served up soon in the Clean Water Act jurisdiction game. Ping?
Norman M. Semanko is a shareholder in the Boise office of Parsons Behle & Latimer. His practice includes a variety of natural resource and environmental law matters, with a particular emphasis on water. He retired from playing ping pong some time ago.
 Aficionados of table tennis may question this choice of paddle colors, since the rules have long required that paddles must be black on one side and red on the other side. However, the Rules of Table Tennis have recently been revised to approve the use of additional bright colors - including blue - on the side opposite the black side of paddle, effective October 1, 2021 (following the Tokyo 2020 Olympic and Paralympic Games). The International Table Tennis Federation Handbook, Laws of Table Tennis, Rule 2.4.6 (Forty-eighth Edition 2020), retrieved at https://www.ittf.com.
 33 U.S.C. § 1362(7).
 531 U.S. 159 (2001).
 547 U.S. 715 (2006).
See e.g., S. 787 (111th Congress), introduced on April 2, 2009, retrieved at https://www.congress.gov/bill/111th-congress/senate-bill/787 (“Reaffirms federal jurisdiction over all waters of the United States and overturns the decisions of the United States Supreme Court in Solid Waste Agency of Northern Cook County v. United States Army Corps of Engineers and Rapanos v. United States”).
 80 Fed. Reg. 37053 (June 29, 2015).
 National Association of Manufacturers v. Department of Defense, 583 U.S. ___, 138 S. Ct. 617 (2018).
 84 Fed. Reg. 56626 (October 22, 2019).
 85 Fed. Reg. 22250 (June 22, 2020).
 Order Granting As-Construed Motion for Stay of Agency Action, Case No. 20-cv-1461-WJM-NRN (D. Co. June 19, 2020)
 Appellate Case Nos. 20-1238, 20-1262, 20-1263 (10th Cir.)
 Order Denying Motion for Preliminary Relief, Case No. 20-cv-03005-RS (N.D. Cal. June 19, 2020)
 See, “Who’s suing over Trump’s WOTUS rule?” (E&E News June 24, 2020) (discussing challenges filed by conservative interests, states, environmental groups, and tribes in California, Colorado, New Mexico, Oregon, Washington, Massachusetts, South Carolina, and Arizona).
 Appellate Case No. 19-35469 (9th Cir.)
 86 Fed. Reg. 7037 (January 25, 2021) (Executive Order 13990, “Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis,” signed January 20, 2021).