☎ (888) 264-7050
← Back to Blog Environmental

Thirty Dry Days: How the 2026 WOTUS Supplemental Proposal Redefines Relatively Permanent Waters

EPA's September 2026 WOTUS supplemental proposal would define relatively permanent waters as perennial, with a single 30-day dry period. Comments close October 9.

by iSi Environmental

A channel on your site either holds water every day of the year or it does not, and under a proposal published September 9, 2026, that sentence could carry a jurisdictional consequence. EPA and the Department of the Army published a supplemental notice of proposed rulemaking at 91 FR 57284 proposing that “relatively permanent” waters of the United States means perennial bodies of water, defined as standing or continuously flowing water every day of the year under ordinary conditions. For ordinary, predictable dry spells, one exception survives: a single dry period of up to 30 consecutive days in a year. Day 31 breaks it.

Very few facilities have the record to argue either side of that line. A quarterly site walk and a memory of the east ditch in July will not carry a jurisdictional determination. What carries it is a date-stamped photograph from a fixed station, a gauge reading, and a Drought Monitor screenshot covering the same dates. Comments close October 9, 2026, and the 30-day cap is what the agencies asked about.

A note on older coverage here. An earlier post on the 2020 Navigable Waters Protection Rule described that rule as operative; it was vacated in 2021. Jurisdiction today runs through Sackett v. EPA, 598 U.S. 651, plus either the 2023 amended rule at 88 FR 61964 or the pre-2015 regime, depending on the state. Treat this page as the current state of play.

What does “relatively permanent” mean under the 2026 WOTUS supplemental proposal?

The September 9, 2026 SNPRM (91 FR 57284) proposes that “relatively permanent” means “perennial bodies of water,” and that perennial means “having standing or continuously flowing water every day of the year during ordinary conditions.” It is offered alongside, not in place of, the broader “year-round or at least during the wet season” language the agencies proposed in November 2025 at 90 FR 52498; the EPA fact sheet says the supplemental text “does not change or modify the options considered in the 2025 proposed rule.”

One word is doing all the work. The November 2025 proposal’s definition let a feature qualify on wet-season flow; the supplemental option deletes that path. A channel that runs hard from March through June and sits dry in August qualifies under the 2025 proposal and drops out under the 2026 supplemental option. The proposal would amend 33 CFR 328.3 for the Corps and 40 CFR 120.2 for EPA, on top of Sackett v. EPA, which requires a relatively permanent water connected to traditional navigable waters and a continuous surface connection for an adjacent wetland.

How many consecutive dry days can a stream have and still be a federal water?

Thirty. Under 91 FR 57284, a water keeps relatively permanent status if it dries “for no more than a single period of up to 30 consecutive days in any given year” from non-anomalous causes such as low tide or a regularly occurring dry spell. That is one period per year rather than a cumulative total, so day 31 breaks jurisdiction.

The qualifiers are where the site-level arguments will happen. “A single period” means a channel dry for 20 days in July and another 15 in September has already blown past the allowance, even though neither stretch reaches 30. The count is consecutive days, and the preamble notes the dry period may span two calendar months as long as it does not exceed 30 days. Drying from anomalous events is treated separately, below.

Does a creek that dries up during a drought lose Clean Water Act jurisdiction?

Not if the drying is anomalous. Under the supplemental option, a water keeps relatively permanent status when it dries up from “anomalous events such as drought or dry spell.” In the preamble, the agencies say they are considering counting only extreme (D3) and exceptional (D4) U.S. Drought Monitor classifications as anomalous drought, and only for up to five continuous years. They tie that five-year ceiling to the five-year expiration of a Corps approved jurisdictional determination. The preamble also leaves room for a dry spell short of categorical drought to count as anomalous.

If the agencies adopt that approach, the test runs in two steps. Was the channel dry for more than 30 consecutive days, and if so, does the Drought Monitor show D3 or D4 for that county across those dates. A moderate (D1) or severe (D2) classification would not carry the drought argument on its own; the case would then rest on showing the dry spell itself was anomalous.

The flow record that answers the 30-day question

The EPA fact sheet explains the options the agencies are weighing. It does not tell you how to document a site, and the evidence set is short:

  • Date-and-time-stamped photographs from a fixed station, shot from the same spot each visit so the frames compare.
  • Gauge readings, or a pressure transducer logging continuously on a feature contested enough to justify the instrument.
  • U.S. Drought Monitor screenshots for the same dates as the dry-period photographs, retained with the photo log.
  • Historic aerial photography and the county soil survey, which answer what the channel was before it was a channel.

Frequency is the part people get wrong. A monthly visit cannot resolve a 30-day question, because a 30-day dry period can open and close between two visits and leave nothing behind. The interval has to be short enough to catch a 30-day event, and the record has to start before the final rule lands.

Is a drainage ditch at my facility a water of the United States?

Under the 2026 supplemental option, only if it carries perennial flow that connects to a traditional navigable water. The proposed exclusion at 40 CFR 120.2(b)(3) covers ditches “constructed or excavated entirely in dry land” (90 FR 52498). A ditch cut through a wetland or a captured stream channel falls outside that exclusion, and the proposed tributary definition still requires relatively permanent flow plus a bed and banks.

The load-bearing word is “entirely.” A roadside ditch scraped out of dry pasture is excluded. A channel cut through a wet meadow, one that relocated a stream, or one that captured an existing swale is not, however engineered it looks today. Historic aerials and the soil survey answer that; standing on the bank does not. Pull aerials from before the ditch was built, look at what occupied the alignment, and check for hydric soils. A ditch following a line that already carried water has a weak exclusion argument.

When does a wetland on my site have a “continuous surface connection”?

Under the 2026 supplemental option, when the wetland holds “perennial surface water … continuously connected with the surface water in the jurisdictional water such that it is difficult to determine where the jurisdictional water ends and the wetland begins” (91 FR 57284). The March 12, 2025 joint EPA and Army field guidance requires the wetland to directly abut the jurisdictional water, with no separating uplands, berm, or dike.

Two tests have to be satisfied, which is easy to miss. The tributary has to qualify on its own as relatively permanent, and then the wetland has to abut it. Under the supplemental option, a wetland abutting a channel that only runs seasonally would not be jurisdictional, because the channel drops out first. Under the pre-2015 practice in force today, a seasonal tributary can still qualify.

How do I get a written determination that a site feature is not a federal water?

Request an approved jurisdictional determination (AJD) from your Corps district under RGL 16-01 and 33 CFR 331.2. An AJD is definitive, administratively appealable, and valid five years. A preliminary JD is non-binding, cannot be appealed, and a permit decision based on one treats every aquatic resource the activity would affect as jurisdictional. RGL 16-01 asks for the information in its Appendix 1 “Request for Corps JD” with every JD request.

RGL 16-01 lets a requester elect a PJD to move faster toward a permit, but the tradeoff is real: impacts and mitigation are computed as if every affected aquatic resource were jurisdictional, and there is nothing to appeal. Then check dates. An AJD issued before May 25, 2023 rests on a test Sackett replaced, and one issued under the 2015 rule or the 2020 Navigable Waters Protection Rule rests on a standard that no longer exists.

Three definitions of “relatively permanent” are live right now

The agencies have put three readings on the table in eighteen months, and all three are still in play. The March 12, 2025 field memorandum restates the 2008 Rapanos Guidance, under which relatively permanent tributaries “typically flow year-round or have continuous flow at least seasonally (e.g., typically three months).” The November 2025 proposed rule said year-round or at least during the wet season. The September 2026 supplemental proposal offered alongside that proposal, says every day of the year. In the 26 states under the pre-2015 regime, including Kansas, districts apply the oldest of the three today, because neither proposal is in force.

The courts have not followed the Federal Register either. In United States v. Andrews, No. 24-1479 (2d Cir. March 19, 2025), a non-precedential summary order, the panel wrote that the Clean Water Act “does not require surface water but only soil that is regularly ‘saturated by surface or ground water.’” The Supreme Court denied certiorari on June 1, 2026. The agencies’ own regulatory impact analysis says they “are unable to quantify these changes with any reliable accuracy at this time,” so anyone quoting you a percentage of features that will leave federal jurisdiction is inventing it.

When does the comment period on the 2026 WOTUS supplemental proposal close?

October 9, 2026, thirty days after the September 9 publication at 91 FR 57284. That is two-thirds of the 45-day window the agencies gave the November 2025 proposal. Comments go to Docket ID EPA-HQ-OW-2025-0322 at regulations.gov, by email to OW-Docket@epa.gov, or by mail to the EPA Water Docket, Mail Code 28221T, 1200 Pennsylvania Avenue NW, Washington, DC 20460.

Roughly 220,000 comments were filed on the November 2025 proposal, and the follow-up was a shorter window on a narrower option. If your site has a feature that runs most of the year but goes dry for 45 consecutive days in an ordinary year, that is the comment to file, with the flow record attached. EPA’s WOTUS page gives no target date for a final rule, and the July 2026 final-rule target in the Fall 2025 Unified Agenda (RIN 2040-AG44) has already passed.

What is the penalty for discharging to a water of the United States without a permit?

Up to $68,445 per day per violation in a civil judicial action under 33 U.S.C. 1319(d), per the current 40 CFR 19.4 table at amounts effective January 8, 2025 (90 FR 1377). Administrative routes run $27,378 per violation with a $68,445 cap for Class I, and $27,378 per day with a $342,218 cap for Class II.

Those are 2025 levels carried into 2026. No amendment to part 19 has been published since January 8, 2025, so re-verify in January 2027. Enforcement volume is climbing while the definition narrows: EPA concluded 2,127 civil enforcement cases in FY2025, the highest in nine years and assessed more than $650 million in civil penalties. That report publishes no Section 404 or wetlands line item, so treat any statute-level Clean Water Act number in trade press as unsourced.

The expensive mistake available here is unilateral reliance on a proposal: stopping monitoring, stopping reporting, or filling a channel because proposed text says the feature may not qualify. Nothing in 91 FR 57284 changes an obligation today.

Which states use the pre-2015 WOTUS definition instead of the 2023 rule?

Twenty-six states, including Kansas, Oklahoma, Missouri, Nebraska and Texas. The 2023 amended rule (88 FR 61964, effective September 8, 2023) applies in 24 states plus the District of Columbia and the territories. Kansas, Oklahoma, Missouri and Nebraska fall under the April 12, 2023 District of North Dakota injunction, and Texas under the March 19, 2023 Southern District of Texas injunction.

If your site sits in one of those five states, your baseline is already the pre-2015 regime read through Sackett. The features a further narrowing removes are the ones you were probably treating as borderline anyway. Colorado is the exception: the 2023 amended rule applies there.

If my ditch is not a federal water, is it still regulated in Kansas?

Almost certainly. K.A.R. 28-16-28b(sss) defines surface waters to include “streams, including rivers, creeks, brooks, sloughs, draws, arroyos, canals, springs, seeps,” and subsection (ttt) reaches “all surface waters occurring within the borders of the state of Kansas.” The definition is written by state boundary rather than by federal jurisdiction, and it expressly names draws and arroyos.

A draw and an arroyo are, by definition, features that do not carry water every day of the year, which makes them exactly what the perennial test would strip of federal status. Kansas named them anyway, and KDHE’s authority under K.S.A. 65-171d does not move when the Corps’ does. KDHE runs two permitting programs: the NPDES program it administers on EPA’s behalf for direct discharges to streams, rivers, lakes, and reservoirs, and the Kansas Water Pollution Control permit program for wastewater systems that do not discharge to surface waters, regulated solely under state authority. A feature leaving federal jurisdiction does not leave the state definition. For the state permit side, see our post on Kansas water pollution control permit requirements.

The rest of the footprint reads the same way, with one real exception:

  • Oklahoma reaches drainage systems, irrigation systems, and artificial and private waters, surface and underground, under OAC 252:730-1-2 and 82 O.S. § 1084.2(3).
  • Texas covers all bodies of surface water, natural or artificial, navigable or nonnavigable, under Texas Water Code § 26.001.
  • Nebraska is explicit: DWEE “has authority and responsibility under Title 117 for all non-jurisdictional wetlands and waterbodies in Nebraska” (DWEE Section 401 page).
  • Colorado switches on when federal jurisdiction switches off. Regulation 87 took effect March 30, 2026, general conditions September 1, 2026, and CDPHE requires state authorization when USACE determines a feature lacks WOTUS status.
  • Missouri holds the one genuine narrowing. RSMo 644.016 excludes waters entirely confined on land controlled by a single owner or joint owners, so a contained on-site impoundment can fall outside the state definition.

Outside Missouri’s single-owner carve-out, federal narrowing mostly changes which regulator writes the letter, not whether one does.

Does maintaining an existing drainage ditch require a Section 404 permit?

No. 33 CFR 323.4(a) exempts “maintenance (but not construction) of drainage ditches,” along with normal farming, farm and stock ponds, and irrigation ditches, under CWA 404(f). Construction of a new ditch is not exempt, and the recapture provision at 33 CFR 323.4(c) pulls work back under permitting if it converts waters to a new use that impairs flow or reduces reach.

The maintenance line is where jobs get into trouble. Restoring an existing ditch to its original cross-section and grade reads as maintenance. Deepening, widening, extending or re-aligning it starts reading as construction, and crews rarely know where that line sits. Check coverage against the current nationwide permits first: the Corps reissued 56 NWPs and added one new permit at 91 FR 768, effective March 15, 2026 through March 15, 2031. NWP 46 covers discharges in certain ditches up to a one-acre loss of waters, and NWP 43 covers stormwater management facilities up to a half-acre loss of non-tidal waters.

Does a narrower WOTUS definition change my SPCC plan obligation?

Not automatically. SPCC applicability at 40 CFR 112.1(b) turns on a reasonable expectation of discharging harmful quantities of oil “into or upon the navigable waters of the United States or adjoining shorelines,” and the thresholds at 112.1(d) are 1,320 gallons aggregate aboveground in containers of 55 gallons or larger, and 42,000 gallons completely buried. The agencies’ regulatory impact analysis estimates roughly 550,000 facilities are covered. Re-run applicability on its own.

Part 112 defines “navigable waters” by cross-reference to 40 CFR 120.2 (40 CFR 112.2), so a narrower WOTUS definition does feed into SPCC applicability once it is final. It still does not retire a plan by itself: applicability turns on whether oil could reasonably be expected to reach any jurisdictional water, and a favorable call on one ditch does not settle the other paths off the site. EPA counts roughly 3,800 facilities under Facility Response Plan rules, keyed to the same definition.

What to do before October 9

The comment window is the only dated opportunity on the board. The rest holds whether or not the rule is finalized.

  1. File a comment to Docket EPA-HQ-OW-2025-0322 by October 9, 2026, with the flow record attached.
  2. Check every jurisdictional determination against May 25, 2023. Anything older rests on a superseded test.
  3. Start the photo log and gauge readings on each feature you expect to contest.
  4. Pull historic aerials and the soil survey for every ditch you assume is excluded.
  5. Keep every permit obligation running as written, because monitoring and reporting follow the rule in effect.
  6. Run the state check in parallel: K.A.R. 28-16-28b, OAC 252:730-1-2, Texas Water Code § 26.001, RSMo 644.016, Nebraska Title 117, Colorado Regulation 87.
  7. Calendar the 2022 Construction General Permit expiration on February 16, 2027 if construction runs into Q1 2027.

Most of that list only gets done if somebody owns it, and at a lot of manufacturing sites the person who would own it is also running safety, training, waste, and air reporting. That is where iSi fits. Our environmental compliance program support keeps the obligations that do not wait on a final rule running as written: stormwater permit monitoring and reporting, SPCC plan applicability and upkeep, air permitting, state permit requirements, and the training behind them.

If you want a second look at how your stormwater, SPCC, and state permit obligations line up while the definition is in flux, contact us.

Sources

Tags: