Navigating the Many Definitions of “Waters of the United States”

By Keelyn Gallagher, Charles Yates, and Megan Jenkins

More than a third of Montana homes are in areas of moderate to high wildfire risk.^{1 Kimiko Barrett, “Montana Wildfire Risk Is Widespread and Growing,” Headwaters Economics, October 26, 2020, https://headwaterseconomics.org/natural-hazards/montana-wildfire-risk-widespread/.} That risk is especially pronounced for rural homeowners like Navy veteran and former firefighter Joe Robertson. He lived in the woods of Montana, where wildfires have become increasingly common and severe. If a wildfire would have threatened Joe’s property, the only available water source would have been a small, nameless streamlet that flowed nearby—equivalent to the capacity of a few garden hoses.

In 2013 and 2014, Joe dug some small ponds around the streamlet so fire engines could fill up to defend his and his neighbor’s homes in case of fire. What Joe didn’t realize was that these actions to protect his home from wildfire would trigger a powerful federal agency to aggressively pursue him for legal penalties.

According to the Environmental Protection Agency (EPA), the nameless channel adjacent to Joe’s property constituted “navigable water” or “waters of the United States” (WOTUS) subject to federal regulation under the Clean Water Act (CWA). The agency claimed that Joe needed permission from the United States Army Corps of Engineers (Corps) to dig these ponds. At age 77, the federal government sentenced Joe Robertson to prison for 18 months and fined him $130,000—a conviction upheld by the Ninth Circuit Court of Appeals.

Joe appealed the decision to the United States Supreme Court, contesting the confusing and unclear definition of “navigable waters.” On April 15, 2019, the Court granted his petition, vacated the Ninth Circuit’s ruling, and overturned the fine.^{2 “Robertson v. United States,” Pacific Legal Foundation, accessed April 22, 2024, https://pacificlegal.org/case/united-states-v-robertson/.} Sadly, Joe passed away in March 2019 before he could receive justice.

Congress passed the CWA to regulate pollution in the nation’s navigable waterways. But over time, its application has expanded to cover many types of water on private property across the United States.

This research in brief examines how the federal government’s definition and regulation of WOTUS has changed over the past several decades, creating regulatory uncertainty for property owners. To add to the problem, the burden of identifying whether regulated waters exist on a property falls on its owners—not on the government. Instead of punishing private landowners for their failure to follow opaque laws, the federal government must follow the clear standards set by recent Supreme Court rulings for which waters are federally regulated and which are not.

Federal oversight of American waterways began in earnest in 1899 with the Rivers and Harbors Act. This act granted the Corps regulatory power over any navigable water and prevented the construction of any structure in any navigable waterway without the Corps’ authorization. It also made it unlawful to “excavate or fill, or in any manner to alter or modify” any navigable water of the United States.^{3 33 U.S.C. 403.}

The Water Pollution Control Act of 1948 followed, becoming the first major federal law to address water pollution. In 1972, it was amended to create the CWA.^{4 “History of the Clean Water Act,” US Environmental Protection Agency, last updated June 12, 2024, https://www.epa.gov/laws-regulations/history-clean-water-act.}

The CWA was created to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.^{5 33 U.S.C. 1251.} Congress granted the EPA (created in 1970), along with the Corps, the authority to enforce the Act through the prevention, reduction, and elimination of pollution of the “navigable waters” defined as “waters of the United States.” In this piece, we use these two terms interchangeably. The EPA, however, has the final say and can veto almost any Corps action. Since 1972, government and industry have spent over $1 trillion to reduce water pollution.^{6 David A. Keiser and Joseph S. Shapiro, “Consequences of the Clean Water Act and the Demand for Water Quality,” Quarterly Journal of Economics 134, no. 1 (2019): 349¬¬–96, https://doi.org/10.1093/qje/qjy019.} For over 50 years, these agencies have steadily expanded their claimed authority over private property, interpreting “navigable waters” in the broadest terms possible, as figure 1 shows.

A series of rulemakings that started in 1977 and later became known as the
“1986 Regulations” extended the scope of the agencies’ claimed authority to regulate “navigable waters” to the outer limits of Congress’s power to regulate interstate commerce.^{7 Rapanos v. United States, 547 U.S. at 724 (citing 42 Fed. Reg. 37,122, 37,144 n.2 (July 19, 1977)).} Federal authority was asserted not just over interstate waters, but also intrastate waters that are connected in some way to interstate or foreign commerce, as well as all tributaries of such waters and all “wetlands” that are “adjacent” to any regulated water.^{8 33 C.F.R. § 323.2(a)(2)–(5), (d) (1978).} This definition encompassed ditches that occasionally filled with water and many other ephemeral channels through which water occasionally flowed.

In 1985, the Supreme Court ruled in United States v. Riverside Bayview Homes that wetlands may qualify as WOTUS due to their proximity to navigable waters.^{9 United States v. Riverside Bayview Homes, Inc., 474 U.S. 121 (1985).} In 1986, the so-called Migratory Bird Rule extended the agencies’ power even further to isolated bodies of water that are occasionally used by birds when they migrate.^{10 51 Fed. Reg. 41,217 (November 13, 1986).}

For the next 20 years, the EPA and the Corps continued to enforce this expansion of the power originally intended by the CWA. Only once during that period did the Supreme Court limit the agencies’ power. In its 2001 ruling in Solid Waste Agency of Northern Cook County v. USACOE, the Court ruled that the EPA and the Corps do not have authority over isolated waters under the Migratory Bird Rule.^{11 531 U.S. 159 (2001).}

The issue of the continued expansion of the EPA and the Corps’ regulatory authority came to a head again in 2006 when the Supreme Court decided Rapanos v. United States.^{12 547 U.S. 715 (2006).} Michigan landowner John Rapanos had come under fire in 1989 after the Corps decided it had jurisdiction over his land by claiming that 80-year-old drainage ditches were “navigable waters.”^{13 Rapanos v. United States,” Pacific Legal Foundation, accessed August 16, 2024, https://pacificlegal.org/case/scotus-rapanos/.} After being threatened with jail time and thousands of dollars in fines, Rapanos appealed his case to the Supreme Court.

In Rapanos, five justices held the agencies’ 1986 Regulations invalid for attempting to assert authority over all tributaries of traditionally navigable waters and adjacent wetlands. However, no single opinion garnered a majority.

The plurality opinion, authored by Justice Antonin Scalia, restricted the definition of “waters of the United States” to encompass only “relatively permanent” bodies of water, excluding “occasional,” “intermittent,” or “ephemeral” flows, and required wetlands to have a “continuous surface connection” that makes it difficult to determine where the water ends and the wetland begins.^{14 Rapanos v. United States, 547 U.S. 715, 739 (2006) (Scalia, J., plurality).} The concurring opinion, presented by Justice Anthony Kennedy, proposed a broader “significant nexus” standard, allowing for federal regulation of wetlands if they “significantly” impact the integrity of more traditionally navigable waters.^{15 Rapanos v. United States, 547 U.S. 715, 776 (2006) (Kennedy, J., concurring).} These two opinions set the stage for the next 20 years of WOTUS uncertainty.

Shortly after Rapanos, the EPA and the Corps issued guidance on establishing jurisdiction.^{16 US Environmental Protection Agency and US Army Corps of Engineers, Clean Water Act Jurisdiction Following the U.S. Supreme Court’s Decision in Rapanos v. United States and Carabell v. United States, December 2008.} This “post-Rapanos guidance” combined aspects of both Justice Scalia’s Rapanos plurality and Justice Kennedy’s concurrence, creating additional confusion.

Michael and Chantel Sackett were early victims of this new regime. They had purchased a lot in Idaho and were preparing to build a home. In 2007, the EPA informed the couple that their preliminary earth-moving activities to prepare their lot for building had breached the CWA’s prohibition on discharging pollutants into navigable waters. The EPA then issued a compliance order threatening fines exceeding $40,000 per day if the couple didn’t follow its Restoration Work Plan.

In fact, the Sacketts’ property was separated from any water by a 30-foot road. But the EPA asserted that it was regulated because it was connected under the surface to an unnamed tributary that flowed into a non-navigable stream, ultimately leading to Priest Lake, a navigable body of water.^{17 David D. Boyer, Eddy R. Beltran, and Suparna Jain, “U.S. Supreme Court Issues Ruling in Sackett v. Environmental Protection Agency,” Atkinson, Andelson, Loya, Ruud & Romo, June 20, 2023, https://www.aalrr.com/newsroom-alerts-3980.}

While the Sacketts worked their way through the court system (including a trip to the Supreme Court in 2012 that proved they had the right to sue the EPA), the post-Rapanos guidance and its version of the significant nexus test reigned supreme.^{18 Sackett v. EPA, 566 U.S. 120 (2012).} However, in 2015, the Obama administration finalized the so-called Clean Water Rule, an expansive definition of “navigable waters” covering an estimated 60% of the nation’s waterways.^{19 “Changes to the Clean Water Act,” Transect Team, April 21, 2023, https://www.transect.com/blog/changes-to-the-clean-water-act.}

The EPA claimed the new rule would add clarity by using the significant nexus test.^{20 Laura Gatz and Kate R. Bowers, “Redefining Waters of the United States (WOTUS): Recent Developments” (report no. R46927, Congressional Research Service, Washington, DC, July 8, 2022), https://crsreports.congress.gov/product/pdf/R/R46927.} However, this definition was blocked by courts in 27 states within months of its adoption.^{21 In re EPA & Dep’t of Defense Final Rule, 803 F.3d 804 (6th Cir. 2015), vacated on other grounds; In re U.S. Dep’t of Defense, 713 Fed. Appx. 489 (6th Cir. 2018); North Dakota v. U.S. EPA, 127 F. Supp. 3d 1047 (D.N.D. 2015).} A patchwork approach emerged: the Clean Water Rule governed in some states, and the 1986 Regulations and post-Rapanos guidance governed in others, adding to regulatory uncertainty. This patchwork regime governed until December 2019, when the Trump administration repealed the 2015 rule and recodified the 1986 Regulations.^{22 Office of the New York State Attorney General, “AG James Leads Coalition in Suing over Trump’s Repeal of Clean Water Rule,” New York State Attorney General, July 21, 2019, https://ag.ny.gov/press-release/2019/ag-james-leads-coalition-suing-over-trumps-repeal-clean-water-rule.}

In 2020, the Trump administration published the Navigable Waters Protection Rule defining WOTUS based primarily on Scalia’s relatively permanent test.^{23 “EPA and Army Deliver on President Trump’s Promise to Issue the Navigable Waters Protection Rule – A New Definition of WOTUS,” US Environmental Protection Agency, January 23, 2020, https://www.epa.gov/newsreleases/epa-and-army-deliver-president-trumps-promise-issue-navigable-waters-protection-rule-0.}

The new rule returned to states and tribes the right to manage their resources. It also directly stated what WOTUS does not include: “objects that only contain water in direct response to rainfall; groundwater; many ditches, including most farm and roadside ditches; prior converted cropland; farm and stock watering ponds; and waste treatment systems.”^{24 US Environmental Protection Agency, “EPA and Army Deliver on President Trump’s Promise to Issue the Navigable Waters Protection Rule,” January 23, 2020, https://www.epa.gov/newsreleases/epa-and-army-deliver-president-trumps-promise-issue-navigable-waters-protection-rule-0.} This rule narrowed the definition of WOTUS and reduced the resources subject to the EPA and the Corps’ authority. But this rule still allowed jurisdiction beyond navigable waters, including wetlands that have no surface connection and intermittent tributaries.

The Trump administration’s rule was implemented nationwide,^{25 Due to a stay entered against the rule by the US District Court for the District of Colorado, the rule did not take effect in Colorado until March 2021. Colorado v. U.S. Env’t Prot. Agency, 445 F. Supp. 3d 1295, 1300 (D. Colo. 2020), rev’d and vacated, 989 F.3d 874 (10th Cir. 2021).} but a federal judge in the District of Arizona vacated it in August 2021.^{26 “U.S. Judge Vacates Trump Water Rule on Environmental Grounds,” Reuters, August 30, 2021.} This decision returned the entire country to the 1986 Regulations.

In January 2023, the Biden administration enacted yet another definition of navigable waters. It permitted the regulation of waters based on (1) a “relatively permanent standard” test inspired by Justice Scalia’s Rapanos plurality and (2) a test inspired by Justice Kennedy’s “significant nexus” test.^{27 Michael Smith, Kathryn Tipple, Ryan Waterman, Katherine Duncan, and Paige Samblanet, “Here We WOTUS Again,” Brownstein Hyatt Farber Schreck, February 2, 2023, https://www.bhfs.com/insights/alerts-articles/2023/here-we-wotus-againt.} The test brought under federal control any feature that might affect the “chemical, physical, or biological integrity” of navigable waters. The agencies were to make determinations under the tests with reference to a broad and open-ended list of factors.^{28 Noah Mack, “EPA’s ‘Waters’ Rule Fluid, as Courts Block Enforcement in 26 States,” Cronkite News, April 17, 2023, https://cronkitenews.azpbs.org/2023/04/17/epas-waters-rule-fluid-as-courts-block-enforcement-in-26-states/.} However, the Biden rule was blocked by courts in 27 states, so it did not take effect in large portions of the country.^{29 These states are Alabama, Alaska, Arkansas, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Louisiana, Mississippi, Missouri, Montana, Nebraska, New Hampshire, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, and Wyoming.}

In September 2022, the Sacketts returned to the Supreme Court to argue the illegality of the significant nexus test and challenge the regulation of their property 15 years earlier. On May 25, 2023, all nine justices ruled that the significant nexus test is illegal. In a majority opinion written by Justice Samuel Alito, the Court criticized numerous aspects of the agencies’ historical approach to navigable waters and adopted the Rapanos plurality’s approach to federal jurisdiction. The Court’s opinion stated that the CWA only protects “those relatively permanent, standing or continuously flowing bodies of water.”^{30 Sackett v. EPA, 598 U.S. at 678 (2023) (quoting Rapanos, 547 U.S. at 742).} For a wetland to be protected by the CWA, it must (a) have a continuous surface connection to a covered waterway and (b) be “as a practical matter indistinguishable” from the covered waterway.^{31 Sackett v. EPA, 598 U.S. at 684 (2023).}

With Sackett on the books, the EPA and the Corps amended their 2023 rule, purportedly to adhere to Sackett. They issued a “conforming” rule that removes references to the significant nexus test but otherwise leaves the remainder of the rule intact. Since then, the EPA has resumed activities under a truncated version of the pre-2015 approach that it claims adheres to Sackett.

Source: Created with data from https://permits.ops.usace.

After each rule change, court cases have let judges block the changes for their respective districts. Different federal standards emerged from state to state. Currently, 23 states use the 2023 rule, and 27 states use the pre-2015 regime compliant with Sackett.

Through all these changes, the burden of navigating the EPA and Corps’ regulations has crushed landowners, who are required to identify potential WOTUS on their property. Not getting the agencies’ approval before starting renovation or development work can result in substantial fines and even imprisonment, as in Joe Robertson’s case.

To initiate any work requiring a permit, property owners must generally first secure an Approved Jurisdictional Determination (AJD) to definitively identify which waters are subject to the CWA. Obtaining an AJD often means hiring expensive consultants.

As Judge Jane Kelly of the United States Court of Appeals for the Eight Circuit pointed out, “This is a unique aspect of the CWA; most laws do not require the hiring of expert consultants to determine if they even apply to you or your property.”^{32 Hawkes Co., Inc. v. U.S. Army Corps of Engineers, 782 F.3d 994, 1003 (8th Cir. 2015) (Kelly, J., concurring).}

The permitting process can take up to 10 years to complete.^{33 Texas Water Conservation Association, “Clean Water Act Issue Paper,” 2023, https://www.twca.org/resources/Documents/Federal%20Issue%20Papers/Fed%20isssue%20papers%202023/CWA.pdf.} An affirmative AJD may result in additional permitting requirements and project design changes to mitigate water impacts. In Rapanos v. United States, the Court cited academic research that found the average cost to obtain a permit was over $270,000^{34 David Sunding and David Zilberman, “The Economics of Environmental Regulation by Licensing: An Assessment of Recent Changes to the Wetland Permitting Process,” Natural Resources Journal 42, no. 1 (2002): 59–90. https://digitalrepository.unm.edu/nrj/vol42/iss1/5.}—about $470,000 in 2024 when adjusted for inflation.^{35 U.S. Inflation Calculator, adjusted 2002 to 2024 on July 11, 2024, https://www.usinflationcalculator.com/.} This figure does not include any mitigation or design change costs.^{36 Sunding and Zilberman, “Wetland Permitting Process.”}

Additionally, those who applied for a permit during a rule change may have to re-apply to comply with an ever-changing regulatory regime.^{37 “Changes to the Clean Water Act,” Transect Team.} Property owners who don’t get permits for activities near water bodies risk being sued by the EPA, environmental groups, or even private citizens for violating regulations—even where such violations were entirely accidental.^{38 Coral Davenport and Julie Hirschfeld Davis, “Obama Announces New Rule Limiting Water Pollution,” New York Times, May 27, 2015, https://www.nytimes.com/2015/05/28/us/obama-epa-clean-water-pollution.} Fines can reach over $66,000 per day for each violation.^{39 33 C.F.R. § 326.6, https://www.law.cornell.edu/cfr/text/33/326.6.}

Congress is aware of this burden and has tried to limit it. In early 2023, both houses of Congress voted to overturn the 2023 rule under the Congressional Review Act, but President Biden vetoed this action, leaving the rule in place.^{40 Mariana Alfaro, “Biden Vetoes GOP-Led Effort to Undo New Clean Water Rules,” Washington Post, April 6, 2023.} Senator Joe Manchin (D-WV) stated that “[t]he Administration’s WOTUS rule is yet another example of dangerous federal overreach. The proposed changes would inject further regulatory confusion, place unnecessary burdens on small businesses, manufacturers, farmers and local communities.”^{41 Joe Manchin, “Manchin Votes to Repeal Overreaching WOTUS Rule,” press release, March 29, 2023, https://www.manchin.senate.gov/newsroom/press-releases/manchin-votes-to-repeal-overreaching-wotus-rule.}

On January 17, 2024, the Creating Confidence in Clean Water Permitting Act was introduced to limit the burden on property owners and to require agencies to interpret WOTUS in compliance with Sackett v. EPA. The bill passed in the House on March 21 but did not move forward.^{42 H.R. 7023, 118th Cong. § 1 (as passed by the House, 2023).}

Since the passage of the CWA, the definition of WOTUS has had various interpretations through court cases, executive orders, and agency rules.^{43 “Changes to the Clean Water Act.”} With the past three presidents each creating different rulings on what WOTUS entails, it is difficult for property owners to comply because the law is unclear on what is regulated and what is not. What’s more, the burden of determining what constitutes WOTUS and what does not falls on property owners. If they get it wrong, they could be subject to ruinous fines and even jail time.

In 2023, in response to the Biden administration’s expansion of what constitutes WOTUS, Congressman Frank Lucas (R-OK) stated, “America’s farmers, ranchers, and landowners deserve a WOTUS definition that is fair and provides regulatory clarity and certainty to agriculture and businesses.”^{44 Frank Lucas, “Congressman Lucas Applauds Preliminary Injunction Stopping Implementation of Biden Administration WOTUS Rule,” press release, April 12, 2023, https://lucas.house.gov/posts/congressman-lucas-applauds-preliminary-injunction-stopping-implementation-of-biden-administration-wotus-rule.} Later that year, the Supreme Court provided such a definition in Sackett. The Court clarified that the agencies may only regulate relatively permanent and continuously flowing bodies of water and wetlands with a continuous surface connection that are “as a practical matter indistinguishable” from such covered waterways.^{45 “Wetlands,” Fish and Wildlife Service, accessed July 23, 2024, https://www.fws.gov/initiative/protecting-wildlife/wetlands.}

After years of ambiguity, the Supreme Court has finally provided a clear definition of what constitutes WOTUS and what does not. To provide certainty to landowners across the United States, the EPA and the Corps must faithfully interpret the Sackett decision. Doing so will provide clarity for landowners seeking to follow the law, instead of punishing them for their failure to follow an extremely complex and murky set of regulations. Landowners like Joe Robertson deserve clarity and notice of the law.