As we look forward to 2026, we wanted to share with you a series of blogs to recap of some of the worst U.S. Supreme Court decisions that will shape our ability to protect our environment for decades to come. (Blog 2/4) 

Where the Water Flows: Sackett v. EPA and the Clean Water Act 

In 2023, the Supreme Court of the United States issued a major decision in Sackett v. EPA, 598 U.S. 651, 143 S. Ct. 1322 (2023), redefining the scope of the Clean Water Act (CWA) and reshaping how federal jurisdiction over wetlands is determined. While not as headline-grabbing as some other recent cases, Sackett has quietly redrawn the map of environmental protection in the United States. 

The case began when Michael and Chantell Sackett purchased a plot of land in Idaho to build a home. Part of their property contained wetlands, which they backfilled during construction. The Environmental Protection Agency (EPA) claimed this action violated the CWA, which prohibits “the discharge of any pollutant” into “navigable waters.” 33 U.S.C. §§ 1311(a), 1362(12)(A). This prohibition applies to “the waters of the United States” (WOTUS) a term that sounds straightforward, but, as Justice Alito asked in his opinion, what exactly does that mean? 

Before Sackett, the EPA interpreted WOTUS broadly. In addition to traditionally navigable waters, it claimed jurisdiction over waters with a “significant nexus” to navigable waters, a standard that allowed regulation of wetlands and other features connected to navigable waters in ways not always obvious to the naked eye. 

The Court rejected this “significant nexus” test as inconsistent with the CWA’s text and as granting the EPA jurisdiction far beyond what Congress intended. In its place, the Court adopted a narrower two-part test: First, the party asserting jurisdiction over an adjacent wetland must prove that the adjacent body of water constitutes a “water of the United States.” Second, the party must show that the wetland has a continuous surface connection with that water, making it difficult to distinguish where the water ends and the wetland begins. This holding significantly restricts the reach of the CWA, limiting jurisdiction to wetlands that are physically and visibly connected on the surface to covered waters. Wetlands that are nearby but separated by barriers such as roads, even if hydrologically connected underground, are now outside the EPA’s regulatory reach. 

The decision has two immediate effects. First, it narrows the federal government’s authority under 33 U.S.C. § 1344(g)(1) and § 1362(7), redefining “waters of the United States” in a way that excludes many wetlands previously covered. Second, it shifts regulatory responsibility for those excluded wetlands to individual states, creating the possibility of a patchwork of protections that vary widely across the country—the very thing the CWA was developed to protect against.  

Unfortunately, Sackett was just the beginning. This November, EPA released its new definition of “waters of the United States” that is even more restrictive than the Supreme Court directed in Sackett.  

According to recent calculations by our friends at NRDC, this rule could remove federal protections from a majority of Pennsylvania’s wetlands. Wetlands not only ensure cleaner water flowing downstream, they also: 

• Reduce flooding  
• Filter harmful pollution  
• Provide essential fish and wildlife habitat 
• Store carbon 

Without streams and wetlands to serve as natural buffers, floodwaters rise faster and hit harder, leaving homeowners, businesses, and taxpayers with massive bills for damage, cleanup, and emergency response. Communities across Pennsylvania–both big and small– will face increased infrastructure and water treatment costs if protections are removed. 

And while Pennsylvania is lucky to have strong state-level water quality protections, we are not immune from the impact of the “Polluted Water Rule.” We must act now and speak up against the gutting of the Clean Water Act! Comments are due January 5, 2026. 

PennFuture’s attorneys are working hard to protect our environment and the rule of law. Support our efforts by donating to our Legal Environmental Advocacy Fund (LEAF) today!