Definitions Of 'Waters Of The United States' Ebb And Flow

The most controversial issue regarding the geographic scope of Clean Water Act jurisdiction has been which wetlands are regulated. However, there is another underappreciated issue related to the "waters of the United States": Are streams and man-made channels regulated if they are only wet some of the time?

A plurality of the U.S. Supreme Court in the 2006 Rapanos v. U.S. case said that they generally are not. Nevertheless, despite the plurality opinion being adopted by a majority of the Supreme Court in the 2023 Sackett v. U.S. Environmental Protection Agency case, the agencies continue to assert jurisdiction over intermittent streams and channels.

This issue matters for many property owners, because wetlands are only part of the waters of the United States if they have a continuous surface connection to regulated waterways, and because many properties are crossed by intermittent streams, ditches and other man- made channels.

The Trump administration is poised to issue a new regulation defining the waters of the United States in the coming months, and the issue of intermittent streams is on their radar as one to address.

This article discusses the discrepancy between Rapanos and agency practice regarding intermittent streams and channels, and the path from here.

Supreme Court Guidance on Intermittent Streams and Channels

For decades, the U.S. Environmental Protection Agency and Army Corps of Engineers asserted Clean Water Act regulatory jurisdiction over all rivers, streams, ditches and man-made channels that contribute water flow to traditional navigable waters, calling them all "tributaries."[1]

This included streams and channels that are often dry but that sometimes carry water flow. Lower federal courts generally accepted the agencies' approach and found Clean Water Act regulatory jurisdiction over streams,[2] storm sewers,[3] ditches,[4] arroyos[5] and other channels that are usually or often dry.

In 2006, the Supreme Court in Rapanos v. U.S. restricted the types of waterways that are included in the waters of the United States.

According to the plurality opinion, which was later adopted by a majority of the court in Sackett:

the CWA's use of "waters" encompasses "only those relatively permanent, standing or continuously flowing bodies of water 'forming geographic[al] features' that are described in ordinary parlance as 'streams, oceans, rivers and lakes.'"[6]

Clearly included are traditional navigable waters, such as oceans, bays, lakes and rivers where boats can navigate. Also clearly included are features that have "standing" water or are "continuously flowing." These perennial features, by definition, always have water present.

The harder question is whether the waters of the United States include streams and channels that sometimes have water and sometimes do not. These features range from some that are wet most of the time to others that are dry most of the time. What did the Supreme Court mean when it included "relatively permanent" waters?

The Rapanos plurality repeatedly stated that the waters of the United States do not include intermittent and ephemeral streams and channels. "Intermittent streams" are those that flow some but not all of the time.[7]

"Ephemeral streams" are those that flow only immediately after rainfall.[8] In at least five different places, the plurality opinion stated that the phrase "waters of the United States" means "continuously present, fixed bodies of water, as opposed to ordinarily dry channels through which water occasionally or intermittently flows....None of these terms encompass transitory puddles or ephemeral flows of water."[9]

Some of the plurality's language was very pointed: for example, "[i]n applying the definition to 'ephemeral streams,' … the Corps has stretched the term 'waters of the United States' beyond parody."[10]

However, the plurality opinion had a footnote that said that "we do not necessarily exclude streams, rivers, or lakes that might dry up in extraordinary circumstances, such as drought. We also do not necessarily exclude seasonal rivers, which contain continuous flow during some months of the year but not flow during dry months — such as the 290-day continuously flowing stream."[11]

There also is a second footnote that indicates that man-made ditches and channels are different than natural streams, and that they are only regulated if they are permanently wet.[12]

Agency Response to Rapanos

In response to Rapanos, the EPA and Corps in the George W. Bush administration issued a guidance memorandum in 2008 that instructed agency staff how to comply with the decision.

The guidance stated that "'relatively permanent' waters do not include ephemeral tributaries, which flow only in response to precipitation."[13] The guidance also stated that "'relatively permanent' waters do not include … intermittent streams which do not typically flow year-round."[14]

However, the guidance asserted jurisdiction over "waters that have a continuous flow at least seasonally (e.g., typically three months)," based on the "seasonal rivers" footnote in Rapanos.[15] The agencies also drew no distinction between natural and man-made channels when it comes to the amount of water flow.[16]

The agencies have followed this general approach ever since, through the Bush, Obama, first Trump and Biden administrations.[17] The effect of the inclusion of "seasonal" streams and channels is to assert jurisdiction over most channels that are regularly dry or lack water flow for much of the year.

The agencies' approach to intermittent streams seems clearly inconsistent with the Rapanos plurality opinion.

First, it allows the "seasonal rivers" footnote exception to swallow the "intermittent stream" rule. The plurality opinion repeatedly stated that intermittent streams are not regulated, yet the agencies continue to assert jurisdiction over most intermittent streams.

Second, the agencies' distinction between "seasonal" and "intermittent" streams is inconsistent with its own acknowledgment that those two terms generally mean the same thing: Seasonal flow is a type of intermittent flow.[18]

Third, the agencies' inclusion of "seasonal" ditches is inconsistent with a separate Rapanos footnote that treats man-made channels differently than natural streams and indicates that they are only regulated if they are always wet.[19]

The agencies' approach also seemingly runs counter to the plain meaning of the plurality's use of the phrase "relatively permanent." Something is "permanent" if it is always there.[20]

"Relatively" means "to a relative degree; somewhat."[21] Together "relatively permanent" would seem to mean that water is always there or something close to it.[22]

A seasonal river that is wet for more than nine months a year (the example in the Rapanos "seasonal rivers" footnote) fits that language, but a river that is dry for nine months of the year (the example used in the 2008 guidance) is not. The disconnect between the agencies' guidance and the Rapanos plurality makes it easy to understand why the Supreme Court in Sackett stated that "the agencies issued guidance that sought to minimize [the court decisions'] impact" and refused to defer to the agencies' understanding of the Clean Water Act's jurisdictional reach.[23]

The Path From Here

Despite the disconnect, lower courts have for the most part accepted the agencies' approach to this issue, and have found that streams that are wet for only a few months of the year are waters of the United States.[24]

Most of these decisions came before the Supreme Court in Sackett, when a majority of the court adopted the Rapanos plurality opinion and admonished lower courts not to defer to the agencies' interpretation of the waters of the United States. However, some courts continue to find that intermittent streams are waters of the United States.[25]

Others are finding that intermittent streams, especially ditches that flow only intermittently, are not waters of the United States.[26] This issue therefore remains in flux.

The current Trump administration has announced that it intends to revise the regulations defining the phrase "waters of the United States." President Donald Trump issued a presidential memorandum directing the agencies to review their regulations based on Sackett.

In a Federal Register notice, the agencies asked for input on "the scope of 'relatively permanent' waters and to what features this phrase applies," and requested "feedback on whether certain characteristics, such as flow regime, flow duration, or seasonality should inform a definition of 'relatively permanent.'"[27]

This suggests that the agencies are at least considering whether to change their approach toward intermittent streams and channels. However, there may be significant institutional resistance within the agencies to changing an approach that has been followed for nearly two decades.

The agencies have indicated that they expect to issue a proposed new rule this fall. If the agencies do not change their regulations on this issue, then property owners' only resort will be to the courts, where some litigants are starting to find success.

Whether or not intermittent streams and ditches are regulated matters more than many people realize. Since Sackett, wetlands are only regulated if they have a "continuous surface connection" with a relatively permanent water.[28]

If "relatively permanent waters" include intermittent, seasonal streams and ditches, then the number of jurisdictional wetlands increases dramatically. Also, many properties have intermittently wet ditches and streams, and if such channels are jurisdictional, then those property owners will need a federal Clean Water Act permit before starting projects that could affect them.

This issue therefore is both important and poorly understood by many involved in the debate over the proper scope of the waters of the United States.

Reprinted with permission from Law360.

[1] See, e.g., 51 Fed. Reg. 41206 (Nov. 13, 1986) (Corps rule promulgating 33 CFR 328.3(a)(5) that defined the "waters of the United States" to include tributaries of otherwise jurisdictional waters).

[2] E.g., Treacy v. Newdunn Assoc., 344 F.3d 407, 410 (4th Cir. 2003).

[3] E.g., United States v. Eidson, 108 F.3d 1336, 1340-42 (11th Cir. 1997).

[4] E.g., Community Assn. for Restoration of Envt. v. Henry Bosma Dairy, 305 F.3d 943, 954-55 (9th Cir. 2002); Headwaters, Inc. v. Talent Irrigation Dist., 243 F.3d 526, 534 (9th Cir. 2001).

[5] E.g., Quivira Mining Co. v. EPA, 765 F.2d 126, 129 (10th Cir. 1985); Save Our Sonoran, Inc. v. Flowers, 408 F.3d 1113, 1118 (9th Cir. 2005).

[6] Sackett v. EPA, 598 U.S. 651, 671 (2023) (quoting Rapanos v. United States, 547 U.S. 715, 739 (2006)).

[7] See, e.g., 80 Fed. Reg. 37076 (June 29, 2015) (Obama WOTUS rule) ("Intermittent streams are those that have both precipitation and groundwater providing part of the stream's flow, and flow continuously only during certain times of the year (e.g., during certain seasons such as the rainy season)."); 85 Fed. Reg. 22276 (April 21, 2020) (Trump WTOUS rule) ("The term 'intermittent' in the final rule means surface water flowing continuously during certain times of the year and more than in direct response to precipitation (e.g., seasonally when the groundwater table is elevated or when snowpack melts).").

[8] 80 Fed. Reg. at 37076 ("Ephemeral streams have flowing water only in response to precipitation events in a typical year, and are always above the water table."); 85 Fed. Reg. at 22275 ("The term 'ephemeral' in the final rule means surface water flowing or pooling only in direct response to precipitation, such as rain or snow fall.").

[9] E.g., Rapanos, 547 U.S. at 733; see also id. at 733-34 ("[t]he restriction of 'the waters of the United States' to exclude channels containing merely intermittent or ephemeral flow also accords with the commonsense understanding…"); 734 ("In applying the definition to 'ephemeral streams,' … the Corps has stretched the term 'waters of the United States' beyond parody"). 734 (the Clean Water Act "confers jurisdiction over only relatively permanent bodies of water. … at a bare minimum, the ordinary presence of water"), 737 ("Even if the phrase 'the waters of the United States' were ambiguous as applied to intermittent flows, our own canons of construction would establish that the Corps' interpretation of the statute is impermissible."), 739 ("[O]n its only plausible interpretation, the phrase 'the waters of the United States' … does not include channels through which water flows intermittently or ephemerally, or channels that periodically provide drainage for rainfall.").

[10] Rapanos, 547 U.S. at 734.

[11] Rapanos, 547 U.S. at 733 n.5 (emphasis in original).

[12] Id. at 736 n.7 (distinguishing "between continuously flowing 'waters' and [man-made] channels containing only an occasion or intermittent flow").

[13] Clean Water Act Jurisdiction Following the U.S. Supreme Court Decision in Rapanos v. United States & Carabell v. United States, at 7 (Dec. 2, 2008).

[14] Id.

[15] Id. at 6-7.

[16] Id. at 6 n.24 ("A tributary includes natural, man-altered, or man-made water bodies that carry flow directly or indirectly into a traditional navigable water.").

[17] See, e.g., 85 Fed. Reg. at 22268, 22286 (April 21, 2020) (Trump WOTUS rule) ("[b]oth the plurality and Justice Kennedy would have included some seasonal or intermittent streams as waters of the United States," pointing to the seasonal rivers footnote in Rapanos; its rule included as "tributaries" natural watercourses that are "perennial or intermittent in a typical year"); 88 Fed. Reg. 3004, 3084-85 (Jan. 18, 2023) (Biden WOTUS rule) (relatively permanent tributaries include "surface waters that have flowing or standing water year-round or continuously during certain times of year").

[18] See, e.g., 85 Fed. Reg. at 22275 (Trump WOTUS rule) ("The term 'intermittent' … means surface water flowing continuously during certain times of year and more than in direct response to precipitation (e.g., seasonally…"); 88 Fed. Reg. 3004, 3085 (Jan. 18,
2023) (Biden WOTUS rule) ("many definitions of intermittent incorporate 'seasonal' flow").

[19] Rapanos, 547 U.S. at 736 n.7.

[20] Permanent, Merriam-Webster.com ("continuing or enduring without fundamental or marked change: Stable").

[21] Relatively, Merriam-Webster.com.

[22] Rapanos, 547 U.S. at 734 (the Clean Water Act "confers jurisdiction only over relatively permanent bodies of water … [which requires], at bare minimum the ordinary presence of water") (emphasis in original).

[23] Sackett, 598 U.S. at 666, 679.

[24] See, e.g., United States v. Brink, 795 F.Supp.2d 565, 578-79 (S.D. Tex. 2011) (citing cases that creeks with flow for as little as two months of the year are "relatively permanent waters");

[25] See, e.g., San Francisco Baykeeper v. City of Sunnyvale, 2023 WL 8587610, *4 (N.D. Cal. 2023) (finding seasonal creeks and manmade channels are regulated based on the "seasonal rivers" footnote in Rapanos).

[26] See, e.g., United States v. Sharfi, 2024 WL 5244351, 2024 WL 4483354 (S.D. Fla. 2024); Ragsdale v. JLM Construction Servs., Inc., 737 F.Supp. 3d 449 (W.D. Tex. 2024) ("wet weather creek" where there was evidence of water flow only twice during site visits is not WOTUS); Lewis v. United States, 2025 WL 338296 (M.D. La. 2025) (holding that intermittent streams are not WOTUS based on language in Rapanos).

[27] 90 Fed. Reg. 13428, 13430 (March 24, 2025) (seasonally wet ditches are not WOTUS).

[28] Sackett, 598 U.S. at 678.