United States v. New Mexico Environment Department

• Court: Court of Appeals for the Tenth Circuit
• Decided: June 16, 2026
• Docket: 22-2132
• Status: Unpublished

Opinion

Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 1 FILED United States Court of Appeals UNITED STATES COURT OF APPEALS Tenth Circuit

FOR THE TENTH CIRCUIT June 16, 2026 _________________________________ Christopher M. Wolpert Clerk of Court UNITED STATES OF AMERICA,

Plaintiff - Appellant,

v. No. 22-2132 (D.C. No. 2:19-CV-00046-KG-SMV) NEW MEXICO ENVIRONMENT (D. N.M.) DEPARTMENT; JAMES KENNEY, Secretary, in his official capacity,

Defendants - Appellees. _________________________________

ORDER AND JUDGMENT * _________________________________

Before HOLMES, Chief Judge, MURPHY, and McHUGH, Circuit Judges. _________________________________

The Resource Conservation and Recovery Act (“RCRA”) authorizes the

Environmental Protection Agency (“EPA”) to regulate the disposal of hazardous

waste. Under RCRA, subject to EPA approval, states may administer their own

hazardous-waste disposal regimes. See 42 U.S.C. § 6926(b). To facilitate states’

enforcement of their regimes against federal entities, Congress supplemented RCRA

with a sovereign-immunity waiver subjecting federal entities to state requirements,

“both substantive and procedural,” regarding the control, abatement, disposal, and

* This order and judgment is not binding precedent, except under the doctrines of law of the case, res judicata, and collateral estoppel. It may be cited, however, for its persuasive value consistent with Fed. R. App. P. 32.1 and 10th Cir. R. 32.1. Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 2

management of hazardous waste “in the same manner, and to the same extent, as any

[other] person.” 42 U.S.C. § 6961(a); see Federal Facility Compliance Act of 1992,

Pub. L. No. 102–386, 106 Stat. 1505 (1992).

The EPA has approved New Mexico’s regime, known as the Hazardous Waste

Act (“HWA”). 40 C.F.R. § 272.1601. The HWA applies by operation of 42 U.S.C.

§ 6961(a) to Cannon Air Force Base (“Cannon”), a federal facility near Clovis, New

Mexico. Cannon sued the New Mexico Environment Department (“NMED”) in

federal district court, claiming that certain requirements of Cannon’s latest HWA

permit exceeded the regulatory authority that § 6961(a) confers on New Mexico and,

consequently, effectively trespassed beyond the boundaries of RCRA’s waiver of

Cannon’s sovereign immunity. Under N.M. STAT. ANN. § 74-4-14(A), the HWA

vests jurisdiction in the New Mexico Court of Appeals to resolve challenges to final

administrative actions of the NMED. Nevertheless, Cannon maintains that federal

jurisdiction is proper under 28 U.S.C. § 1345 because its challenge to HWA’s permit

amounts to a “civil action[] . . . commenced by the United States.”

This appeal presents the following jurisdictional question: does 42 U.S.C.

§ 6961(a)’s procedural-requirements language include state judicial-review

mechanisms that mandate exclusive state-court jurisdiction over challenges to state

administrative action? The district court concluded that (1) state judicial-review

mechanisms are procedural requirements, so (2) § 6961(a) subjects federal entities to

state judicial-review mechanisms implicated by § 6926(b), even where those

mechanisms provide for exclusive state-court jurisdiction, and therefore (3) § 6961(a)

2 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 3

impliedly repeals § 1345. In the alternative, the district court determined that, even if

it could properly exercise jurisdiction under § 1345, abstention was appropriate under

the Colorado River doctrine. 1 Consequently, the district court held that it lacked

§ 1345 jurisdiction and sua sponte dismissed Cannon’s complaint.

We conclude the district court erred and hold that state judicial-review

provisions are not procedural requirements under § 6961(a). We likewise reject the

district court’s alternative holding that the Colorado River doctrine justified its

abstention from the exercise of § 1345 jurisdiction. We thus reverse the district

court’s dismissal and remand for further proceedings.

Our decision proceeds in five parts. First, we recount the relevant factual and

procedural background. Second, we acknowledge our jurisdiction and state the

applicable standards of review. Third, we address and reject the district court’s

conclusion that it lacked § 1345 jurisdiction to hear Cannon’s HWA challenge.

Fourth, we consider and express our disagreement with the district court’s Colorado

River analysis. Fifth, we conclude.

I

A

Cannon Air Force Base sits atop the Llano Estacado, approximately thirty

thousand square miles of arid tablelands, bounded by Texas’s Caprock Escarpment to

1 See Colo. River Water Conservation Dist. v. United States, 424 U.S. 800, 817–21 (1976). 3 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 4

the east and New Mexico’s Mescalero Ridge to the west. Cannon shares its perch on

these stockaded plains with the town of Clovis.

Since the 1970s, Cannon has utilized foam containing perfluoroalkyls

chemicals or PFAS, colloquially known as “forever chemicals,” to extinguish fires on

the base. Runoff from Cannon’s PFAS use has leached into nearby Clovis’s

groundwater. This case concerns the State of New Mexico’s attempts to address

Cannon’s PFAS pollution.

RCRA, enacted by Congress in 1976, authorizes the EPA to regulate disposal

of “solid” and “hazardous” wastes. 42 U.S.C. § 6901 et seq. More specifically,

RCRA requires the EPA to “promulgate regulations identifying the characteristics of

hazardous waste, and listing particular hazardous wastes . . . , which shall be subject

to” the rigorous cradle to grave waste management provisions of RCRA Subtitle C.

42 U.S.C. § 6921. Although the EPA has proposed rules that would list PFAS as a

hazardous constituent subject to RCRA regulations, see 89 Fed. Reg. 8606 (Feb. 8,

2024), the EPA has yet to formally designate PFAS as a “hazardous waste.”

However, RCRA offers states the option of administering and enforcing their

own hazardous-waste disposal programs with RCRA’s imprimatur, subject to EPA

approval. 42 U.S.C. § 6926(b). To ensure that state RCRA enforcement actions have

“the same force and effect” as EPA enforcement actions, 42 U.S.C. § 6926(d),

Congress supplemented RCRA with a waiver of sovereign immunity entitling states

to enforce their RCRA regimes against federal polluters like Cannon. See 42 U.S.C.

§ 6961(a).

4 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 5

While RCRA demands that state waste management programs satisfy certain

federal minima, the statute “does not preclude a state from adopting more stringent

requirements” than the federal regime. United States v. Colorado, 990 F.2d 1565,

1569 (10th Cir. 1993); see 42 U.S.C. § 6929; 40 C.F.R. § 271.1(i)(1). But the HWA,

New Mexico’s EPA-approved RCRA regime, prohibits New Mexico from

“identify[ing] or list[ing] any solid waste or combination of solid wastes as a

hazardous waste that has not been listed and designated” as such by the EPA. N.M.

STAT. ANN. § 74-4-4(A)(1).

So, though RCRA itself does not preclude New Mexico from listing PFAS as a

hazardous waste or constituent, New Mexico’s HWA binds state regulators to federal

standards, which have thus far declined to include PFAS within RCRA’s regulatory

purview. 2 Nonetheless, in Cannon’s 2018 HWA permit, the NMED designated PFAS

as a hazardous waste requiring corrective action.

B

The United States, on behalf of the Air Force, sued the NMED in federal

district court, alleging that the 2018 permit’s definition of “hazardous waste” was

2 New Mexico subsequently amended the HWA to define the PFAS- containing flame retardant that Cannon uses as a “hazardous waste.” See Order, No. 22-2132, at *1 (10th Cir., filed Apr. 18, 2025). We requested supplemental briefing to confirm that the intervening New Mexico legislation would not affect this appeal’s justiciability. The parties agree that this appeal—which centers on the scope of § 6961(a)’s procedural-requirements language, and not the propriety of the 2018 HWA permit—has not been rendered moot or otherwise non-justiciable by the HWA amendment. And we agree.

5 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 6

“inconsistent with the HWA.” Aplt.’s App. ¶ 21 at 14 (Compl., filed Jan. 17, 2019).

More technically, the government pleaded that the 2018 permit constituted “‘final

administrative action’ subject to judicial review pursuant to section 74-4-14.A of the

HWA,” and that “[t]he definition of ‘hazardous waste’ for the purposes of corrective

action stated in [the 2018 permit] is arbitrary, capricious, or an abuse of discretion,

not supported by substantial evidence in the record, or otherwise not in accordance

with law.” Id. ¶¶ 17, 28 at 41, 43 (Am. Compl., filed Apr. 2, 2021) (quoting N.M.

STAT. ANN. § 74-4-14(A)). The government pleaded that the district court’s

jurisdiction over its HWA claim was proper under both 28 U.S.C. §§ 1331 and 1345. 3

The government nonetheless filed a parallel action in the New Mexico Court of

Appeals, which remains stayed pending disposition of the federal case. See United

States v. N.M. Env’t Dep’t, Case No. A-1-CA-37887 (N.M. Ct. App., filed Jan. 17,

2019).

After denying the NMED’s motion to dismiss and receiving cross-motions for

summary judgment, the district court sua sponte “determine[d] it lack[ed] jurisdiction

. . . and dismisse[d] the case without prejudice.” Aplt.’s App. at 207 (Mem. Op. and

Order, filed Aug. 18, 2022). The district court also rendered an alternative holding:

even if federal jurisdiction were proper, it would decline to exercise such jurisdiction

under Colorado River Water Conservation District v. United States, 424 U.S. 800

(1976).

3 Because we conclude that the district court had jurisdiction under § 1345, we decline to address the parties’ § 1331 arguments. 6 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 7

The district court’s jurisdictional analysis proceeded in three steps. First, the

district court held that the HWA vests in the New Mexico Court of Appeals exclusive

jurisdiction to hear disputes over HWA permitting decisions. See N.M. STAT. ANN.

§ 74-4-14(A). Second, the district court concluded that “[t]he HWA, by vesting

exclusive jurisdiction for permit appeals in the New Mexico Court of Appeals,

precludes other courts from adjudicating such claims.” Aplt.’s App. at 208. Noting

that Congress may “statutorily vest exclusive administrative appellate jurisdiction in

specific courts at the expense of district courts’ ordinary jurisdiction” where

“Congress’[s] intent to preclude district court jurisdiction is ‘fairly discernible in the

statutory scheme,’” id. (quoting Sec. People, Inc. v. Iancu, 971 F.3d 1355, 1362 (Fed.

Cir. 2020)), the district court held that RCRA’s provisions permitting states to

fashion their own RCRA regimes (i.e., 42 U.S.C. § 6926(b)) and waiving federal

sovereign immunity against state RCRA enforcement (i.e., 42 U.S.C. § 6961(a))

evidenced Congress’s intent to strip federal jurisdiction over HWA appeals.

Third, and based on the foregoing, the district court concluded that it lacked

jurisdiction over the government’s action since § 6961(a) had impliedly repealed

§ 1345. Aplt.’s App. at 212 (“Congress’[s] general and qualified grant of jurisdiction

in 28 U.S.C. § 1345 must give way to Congress’[s] specific and unqualified waiver of

sovereign immunity subjecting federal facilities to authorized state hazardous waste

permitting schemes.”). In other words, the district court held that the HWA’s

judicial-review provision qualified as a “procedural” requirement “respecting control

and abatement of solid waste or hazardous waste disposal and management” which

7 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 8

was binding on the federal government by virtue of the sovereign-immunity waiver.

42 U.S.C. § 6961(a).

Alternatively, the district court reasoned that, even if jurisdiction were proper,

it would conclude that Colorado River counseled abstention “in deference to the

parallel state proceeding already before the New Mexico Court of Appeals.” Aplt.’s

App. at 213. The district court’s Colorado River analysis turned on the perceived

“danger of piecemeal litigation.” Id. at 215 (quoting D.A. Osguthorpe Fam. P’ship v.

ASC Utah, Inc., 705 F.3d 1223, 1234 (10th Cir. 2013)). Recognizing that “there is

not an immediate risk of piecemeal litigation” owing to the stay of the New Mexico

action, the district court nevertheless concluded that the very “threat” of parallel

litigation justified abstention, especially because “[f]ederal law does not provide the

rule of decision in this case.” Id.

The district court thus denied the parties’ summary judgment motions and

dismissed the case for lack of jurisdiction. The government timely appealed.

II

We have jurisdiction over the government’s appeal from the district court’s

final order under 28 U.S.C. § 1291. “We review the dismissal of a complaint for lack

of subject matter jurisdiction de novo.” Chapman v. Oklahoma, 472 F.3d 747, 749

(10th Cir. 2006). We review a district court’s exercise of Colorado River abstention

for an abuse of discretion. Moses H. Cone Mem’l Hosp. v. Mercury Constr. Corp.,

460 U.S. 1, 19 (1983) (“Under . . . Colorado River, of course, the decision whether to

defer to the state courts is necessarily left to the discretion of the district court in the

8 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 9

first instance.”); D.A. Osguthorpe, 705 F.3d at 1231 n.11 (“We review district court

decisions regarding deferral under the Colorado River Doctrine for abuse of

discretion.”).

III

Section 1345 vests in the federal courts “original jurisdiction of all civil

actions, suits or proceedings commenced by the United States.” 28 U.S.C. § 1345.

But § 1345 jurisdiction is subject to exceptions “as otherwise provided by Act of

Congress.” Id. Because the United States commenced these proceedings, § 1345 by

default provides for federal jurisdiction. The question is whether an “Act of

Congress” (here, RCRA) “otherwise provide[s]” an exception to the default rule. Id.

RCRA explicitly contemplates the “[a]pplication of Federal, State, and local

law to Federal facilities” like Cannon. 42 U.S.C. § 6961. Section 6961(a)

unambiguously provides that federal executive branch departments:

shall be subject to, and comply with, all Federal, State, interstate, and local requirements, both substantive and procedural (including any requirement for permits or reporting or any provisions for injunctive relief and such sanctions as may be imposed by a court to enforce such relief), respecting control and abatement of solid waste or hazardous waste disposal and management in the same manner, and to the same extent, as any person is subject to such requirements, including the payment of reasonable service charges.

(emphases added). The statute clarifies that the state requirements to which federal

executive departments are subject “include, but are not limited to, all administrative

orders and all civil and administrative penalties and fines.” Id. (emphasis added).

9 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 10

Section 6961(a) thus functions as an express waiver of federal sovereign immunity

with respect to state RCRA enforcement in “State or Federal Court.” Id.

RCRA thus waives Cannon’s immunity from HWA enforcement. But that

waiver of sovereign immunity merely establishes the predicate for the jurisdictional

question before us. Specifically, the question is whether § 6961(a) contemplates that

the HWA could confer exclusive jurisdiction on the New Mexico Court of Appeals to

hear Cannon’s permitting dispute with the NMED, thereby effectively displacing

§ 1345’s default grant of federal jurisdiction over suits commenced by federal

agencies.

Congress can strip § 1345 jurisdiction in two ways. See Colo. River, 424 U.S.

at 808. First, Congress can pass legislation containing an “affirmative showing” of

the legislature’s “intention to repeal” § 1345. Id. (quoting Morton v. Mancari, 417

U.S. 535, 550 (1974)). Alternatively, Congress can effect a “repeal by implication”

by enacting a statute that is “irreconcilable” with § 1345 jurisdiction. Id. (quoting

Morton, 417 U.S. at 550). The NMED wisely concedes that RCRA does not

affirmatively repeal § 1345. So, we confine our analysis to the implied-repeal

inquiry.

Repeal by implication is disfavored. Radzanower v. Touche Ross & Co., 426

U.S. 148, 154 (1976). “[W]henever possible, statutes should be read consistently.”

Kremer v. Chem. Constr. Corp., 456 U.S. 461, 468 (1982). Thus, we find implied

repeal only “where provisions in the two acts are in irreconcilable conflict.” Id.

(quoting Radzanower, 426 U.S. at 154). “Since an implied repeal must ordinarily be

10 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 11

evident from the language or operation of a statute,” absent a “manifest

incompatibility” between the statutes, there is no implied repeal. Id. at 470.

In this case, in assessing § 6961(a) and § 1345 for manifest incompatibility, we

are bound, “absent a clearly expressed congressional intention to the contrary, to

regard each [statute] as effective.” Morton, 417 U.S. at 551; see Yellowfish v. City of

Stillwater, 691 F.2d 926, 928 (10th Cir. 1982) (“[T]he intent of the legislature must

be ‘clear and manifest’ to uphold an implied repeal.” (quoting Posadas v. Nat’l City

Bank of N.Y., 296 U.S. 497, 503 (1936))). In other words, if we discern any plausible

means of harmonizing two statutes, they are not manifestly incompatible.

Consequently, to uphold the district court’s interpretation of § 6961(a)’s effect on

federal-agency jurisdiction under § 1345—which would impliedly repeal the latter—

it would not be enough for us to conclude that the court’s interpretation is a plausible

one. Instead, the district court’s interpretation must be the only plausible

construction of the interaction between the two statutes.

The government attacks the district court’s determination that Congress, by

passing § 6961(a), “otherwise provided” for exclusive state-court jurisdiction.

Aplt.’s Opening Br. at 13. Acknowledging that “RCRA requires federal agencies to

comply with state procedural requirements,” the government nonetheless maintains

that “the HWA’s assignment of jurisdiction to state courts of appeals to review state

permits is not such a requirement.” Id.

11 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 12

The government begins by emphasizing the breadth of § 1345’s jurisdictional

language: “Because § 1345 provides district courts with subject-matter jurisdiction in

all civil cases in which the United States is the plaintiff, the United States may ‘sue

in the federal court irrespective of subject matter.’” Id. at 15 (quoting United States

v. S. Fla. Water Mgmt. Dist., 28 F.3d 1563, 1569 (11th Cir. 1994)). True, § 1345 is

subject to exceptions “as otherwise provided by Act of Congress.” Id. at 16 (quoting

28 U.S.C. § 1345). But, as the government reasons, “the Supreme Court has

recognized that the standard for stripping jurisdiction under this language in § 1345 is

high.” Id. (citing Colo. River, 424 U.S. at 808–09).

Acknowledging the dearth of authority addressing § 6961(a)’s jurisdictional

import, the government directs us to United States v. Puerto Rico, 721 F.2d 832 (1st

Cir. 1983), which held that an analogous provision of the Clean Water Act (“CWA”),

33 U.S.C. § 1323(a), 4 “does not foreclose the United States from challenging state

4 The relevant CWA provision provides that:

Each department, agency, or instrumentality of the executive, legislative, and judicial branches of the Federal Government . . . shall be subject to, and comply with, all Federal, State, interstate, and local requirements, administrative authority, and process and sanctions respecting the control and abatement of water pollution in the same manner, and to the same extent as any nongovernmental entity including the payment of reasonable service charges. The preceding sentence shall apply (A) to any requirement whether substantive or procedural (including any recordkeeping or reporting requirement, any requirement respecting permits and any other requirement, whatsoever), (B) to the exercise of any Federal, State, or local administrative authority, and (C) to any process and sanction, whether enforced in Federal, State, or local courts or in any other manner. 12 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 13

administrative actions in federal court under § 1345.” Aplt.’s Opening Br. at 22.

The government acknowledges that the First Circuit bolstered its holding by

highlighting that the CWA included a bespoke federal removal provision, something

the relevant portion of RCRA lacks. But the government urges us to look beyond

that distinction, since “the lack of a removal provision is irrelevant to what forum the

government may choose as a plaintiff”—i.e., when the government is “on offense.”

Id. at 23–24 (first emphasis added). Besides, says the government, “even if the

United States were on defense, removal would be proper under 28 U.S.C. § 1442.”

Id. at 24.

On the other hand, the NMED reads § 6961(a) as dictating that “federal

facilities must not be treated any differently than any other party.” Aplee.’s Resp.

Br. at 7–8 (emphasis added). Consequently, the NMED construes the government’s

invocation of the district court’s § 1345 jurisdiction as “a request for special

treatment that is irreconcilable with Congress’[s] command that federal facilities be

subject to ‘substantive and procedural’ requirements ‘in the same manner, and to the

same extent, as any person is subject to such requirements.’” Id. at 8 (quoting 42

U.S.C. § 6961(a)). The NMED’s argument flows from the premise that “[t]he

procedural-requirements language in § 6961(a) necessarily includes state judicial

review procedures that are part of the statutory scheme through which states enforce

RCRA.” Id.

33 U.S.C. § 1323(a) (emphases added). 13 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 14

Conceding that “there is no binding caselaw holding that § 6961(a) includes

state judicial-review procedures in its procedural-requirements language,” the NMED

nevertheless distinguishes the government’s reliance on Puerto Rico by homing in on

the CWA’s bespoke removal provision. Id. at 16, 19. In New Mexico’s view,

“Congress’[s] eschewal of a removal provision in § 6961(a) leads to the only

permissible conclusion that, had Congress wanted to immunize the United States

from following the same judicial review procedures as other parties when it waived

such immunity for other state procedures, it would have said so.” Id. at 22.

C

For the reasons detailed below, we conclude that § 6961(a) does not impliedly

repeal § 1345. Consequently, the district court properly had jurisdiction over

Cannon’s lawsuit, and its decision to dismiss sua sponte the action for lack of

jurisdiction was erroneous.

The district court held that § 6961(a) contemplates exclusive state-court

jurisdiction by defining state judicial-review mechanisms—including those vesting in

state courts exclusive jurisdiction over state RCRA enforcement—as procedural

requirements to which the government is subject under § 6961(a). Even accepting for

purposes of this discussion that the district court’s reading of what § 6961(a)

contemplates is plausible, it is not the only plausible reading of that statute. We

discern another interpretation of § 6961(a) that contemplates that the statute’s

procedural-requirements language refers to (as relevant here) a state’s procedural

mechanisms—like permitting regimes—for enforcing the substantive environmental

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standards of the state, and not to the state’s judicial-review mechanisms. Under this

statutory reading, federal courts are not impliedly stripped of their jurisdiction under

§ 1345 by operation of § 6961(a); federal agencies may invoke the jurisdiction of

those courts under § 1345.

This is not to say that those federal agencies may not seek relief against state

environmental enforcement efforts in state courts, as Cannon has here. After all, by

operation of § 6961(a), those agencies are without sovereign immunity and subject to

EPA-approved state environmental regimes and their procedural requirements. But it

is to say that state courts may not exercise anything more than concurrent jurisdiction

over such federal agencies because the procedural-requirements language of

§ 6961(a) does not encompass a state’s judicial-review mechanisms, and, thus, it does

not impliedly repeal federal courts’ jurisdiction over actions by federal agencies

under § 1345. In sum, “[t]here is no irreconcilability [between § 6961(a) and § 1345]

in the existence of concurrent state and federal jurisdiction.” Colo. River, 424 U.S. at

809. It ineluctably follows that the district court’s determination of implied repeal

was error. See Morton, 417 U.S. at 551.

The district court’s conclusion that § 6961(a) contemplates exclusive state

court jurisdiction flows from its analytically antecedent determination that

§ 6961(a)’s procedural-requirements language includes state judicial-review

mechanisms. Although § 6961(a) does not define the term “requirement,” we have

previously held that the term encompasses the procedural means by which

substantive environmental standards are implemented. United States v. New Mexico,

15 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 16

32 F.3d 494, 497 (10th Cir. 1994). We thus previously concluded that § 6961(a)

empowers the NMED to enforce HWA permitting conditions against federal

facilities. Id. at 498–99. But it does not inescapably follow from that interpretation

of “requirement” that § 6961(a)’s procedural-requirements language must be read to

include state judicial-review mechanisms. Quite to the contrary.

The First Circuit’s assessment of the analogous CWA provision is persuasive

and instructive in this regard. In Puerto Rico, the First Circuit held that 33 U.S.C.

§ 1323(a), which requires federal actors to “comply with” state “requirement[s]

whether substantive or procedural” “in the same manner, and to the same extent as

any nongovernmental entity” did not impliedly repeal § 1345’s grant of federal

jurisdiction. 721 F.2d at 837–38. Congress’s objective in passing § 1323(a) was

much the same as its objective in passing § 6961(a). Just as Congress passed

§ 6961(a) to prevent federal facilities from “dragging their feet by asserting

sovereign immunity” rather than face state RCRA enforcement, H.R. Rep. No. 102-

111, at 9 (1991), Congress passed § 1323(a) to “[e]nsure that federal facilities

comply fully with apposite state laws and regulations” respecting water pollution,

Puerto Rico, 721 F.3d at 838 (citing S. Rep. No. 95–370, at 67 (1977)). In other

words, Congress passed both provisions to prevent federal facilities from leveraging

sovereign immunity to frustrate compliance with EPA-approved pollution regimes.

But, as Puerto Rico strongly suggests, that immunity-stripping congressional purpose

does not necessarily stand in tension with allowing federal agencies to invoke the

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jurisdiction of federal courts to hear challenges to state enforcement of substantive

environmental standards.

We read the language of § 6961(a) as having a similar effect to the one the

First Circuit discerned in the language § 1323(a)—that is, to permit state

environmental regulations to be applied to federal entities without impliedly

repealing federal courts’ jurisdiction under § 1345 to entertain federal entities’

challenges to those state regulations. In other words, Congress’s passage of both

provisions reflects its conclusion that federal compliance with state environmental

regimes would be effectuated by waiving federal sovereign immunity with respect to

the procedural components of enforcing state substantive requirements, e.g.,

permitting conditions. But, as in Puerto Rico, this rationale does not necessarily

mean Congress contemplated that federal compliance could only be assured by

vesting exclusive jurisdiction in state tribunals to adjudicate federal-agency

challenges to state regulatory commands. More specifically, we do not think

Congress necessarily intended to effectuate its purpose of subjecting federal agencies

to state environmental regulatory regimes by including state judicial-review

mechanisms within the procedural-requirements language of § 6961(a).

Instead, as in Puerto Rico, we conclude here that state-court adjudication is not

“so critical to the teleology of federal compliance that the dictates of 28 U.S.C.

§ 1345 must necessarily be overridden.” 721 F.3d at 838; see North Carolina v.

United States, 7 F.4th 160, 164 (4th Cir. 2021) (noting that concurrent federal

jurisdiction “does not prevent states from bringing enforcement actions or levying

17 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 18

penalties against federal facilities” under an analogous provision of the Clean Air

Act, 42 U.S.C. § 7604(e)). It is true that, unlike RCRA, the CWA contains a bespoke

removal provision that “unequivocally grants to the United States the right to remove

compliance proceedings brought against it to the district courts.” Puerto Rico, 721

F.3d at 838. But whatever weight the First Circuit placed on the CWA’s removal

provision, RCRA’s lack of an analogous provision presents a distinction without a

difference. This case does not concern a compliance proceeding brought against the

government, but a pre-enforcement action brought by the government. Consequently,

the government’s removal options are irrelevant. 5

In sum, we read § 6961(a)’s procedural-requirements language as not

including state judicial-review provisions. Accordingly, we reject the district court’s

holding that RCRA impliedly repealed § 1345’s grant of concurrent federal

jurisdiction.

5 Even if this case did concern a state-court compliance proceeding, while the government would be without a RCRA-specific removal provision, it would still remain entitled to removal under 28 U.S.C. § 1442(a)(1), which provides for removal of “[a] civil action . . . that is commenced in a State court and that is against or directed to. . . . [t]he United States or any agency thereof.” Section 6961(a) does not impliedly repeal § 1442 for the same reasons it does not impliedly repeal § 1345: federal compliance with state environmental regulations is not contingent on state courts’ monopoly control of enforcement actions. See North Carolina, 7 F.4th at 164. 18 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 19

IV

We now address and reject the district court’s alternative conclusion that

Colorado River abstention was appropriate. “[F]ederal courts have a ‘virtually

unflagging obligation . . . to exercise the jurisdiction given them’” by Congress.

Moses H. Cone, 460 U.S. at 15 (quoting Colo. River, 424 U.S. at 817); see Cohens v.

Virginia, 19 U.S. 264, 404 (1821). Our obligation stems from the “undisputed

constitutional principle that Congress, and not the Judiciary, defines the scope of

federal jurisdiction.” New Orleans Pub. Serv., Inc. v. Council of New Orleans, 491

U.S. 350, 359 (1989). The obligation is virtually unflagging, but the Supreme Court

has recognized “exceptional circumstances” under which federal courts should

abstain from exercising jurisdiction “for reasons of wise judicial administration.”

Colo. River, 424 U.S. at 813, 818. The coexistence of parallel proceedings in federal

and state courts is a necessary predicate for Colorado River abstention. See Fox v.

Maulding, 16 F.3d 1079, 1082 (10th Cir. 1994).

We have identified a list of non-exhaustive factors bearing on the propriety of

Colorado River abstention. See id. Those factors include:

1. “[W]hether either court has assumed jurisdiction over property”;

2. “[T]he inconvenience of the federal forum”;

3. “[T]he desirability of avoiding piecemeal litigation”;

4. “[T]he order in which the courts obtained jurisdiction” (i.e., priority);

19 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 20

5. “[T]he vexatious or reactive nature of either the federal or the state action”;

6. “[W]hether federal law provides the rule of decision”;

7. “[T]he adequacy of the state court action to protect the federal plaintiff’s rights.”

Id. “No single factor is dispositive.” Id. Moreover, the factors are not a

“mechanical checklist.” Id. (quoting Moses H. Cone, 460 U.S. at 16). Instead, courts

should carefully balance the factors as they apply to the facts of a given case, with a

heavy thumb on the scale weighing against abstention. Id.

The government maintains that “by declining to decide the fully briefed

federal case at the expense of reactivating the long-dormant state-court litigation, the

district court’s dismissal wastes judicial resources contrary to the efficiency principle

at the core of Colorado River.” Aplt.’s Opening Br. at 14. More specifically, the

government argues that the district court’s alternative abstention holding relied

primarily on the “avoidance of piecemeal[-]litigation” factor, but “misunderstood

what types of ‘piecemeal litigation’ the Colorado River doctrine is designed to

avoid.” Id. at 32.

The district court deemed the risk of piecemeal litigation substantial because

this case requires a federal court to apply state law, which could entail certifying

state-law questions to the New Mexico courts. Id. at 33; see Aplt.’s App. at 216

(citing Erie R. Co. v. Tompkins, 304 U.S. 64 (1938)). But on the government’s read,

Colorado River’s piecemeal-litigation factor is concerned not with the applicable rule

20 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 21

of decision, but instead with avoiding duplicative litigation. The government

maintains that its protective filing of a long-dormant action in New Mexico court

does not raise a serious threat of duplicative litigation.

The NMED, by contrast, contends that (1) the district court correctly

interpreted Colorado River’s piecemeal-litigation factor to include the “risk of

developing a body of [state common law] which applies to all permit holders except

the United States,” and (2) the threat of piecemeal litigation would persist even if the

government prevails in federal court, because dismissal of the state action is not

guaranteed. Aplee.’s Resp. Br. at 28–29 (quoting Aplt.’s App. at 216).

Even if we were to conclude that abstention under Colorado River was not

appropriate, the NMED would urge us to affirm under two alternative abstention

doctrines: those articulated in Brillhart v. Excess Ins. Co. of Am., 316 U.S. 491

(1942), and Burford v. Sun Oil Co., 319 U.S. 315 (1943). Though it recognizes that

neither party nor the district court addressed Brillhart or Burford below, the NMED

nevertheless maintains we may in our discretion affirm under either of its late-

blooming abstention theories. The government urges us not to reach the NMED’s

Brillhart and Burford arguments.

We conclude that the district court abused its discretion by misinterpreting

Colorado River’s piecemeal-litigation factor and, accordingly, determine that its

abstention ruling was erroneous. At the outset, we decline, in our discretion, to

21 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 22

address the NMED’s late-blooming Brillhart and Burford arguments, leaving the

district court free to address those doctrines (if applicable) on remand.

The necessary predicate for Colorado River abstention—parallel state and

federal proceedings—is patent. Here, the government sued the NMED in both New

Mexico and federal court alleging that the terms of Cannon’s 2018 HWA permit

exceeded the NMED’s authority. The parties are litigating “substantially the same

issues in different forums,” New Beckley Mining Corp. v. Int’l Union, UMWA, 946

F.2d 1072, 1073 (4th Cir. 1991); so, the proceedings are parallel for Colorado River

purposes.

The district court concluded that the threat of piecemeal litigation “tip[ped] the

scales strongly in favor of abstention.” Aplt.’s App. at 215. Specifically, the district

court determined this was so because the circumstance before it was “unique”—

where a state-law issue must be “analyzed under state-law standards” and where

“Congress has expressly waived sovereign immunity.” Id. at 216. In such a

circumstance, the district court reasoned, “it is wise that the state courts adjudicate

the issue.” Id. But, in our view, the district court fundamentally misapprehended

“the danger of piecemeal litigation” in the Colorado River context. D.A. Osguthorpe,

705 F.3d at 1234.

The piecemeal-litigation factor is not designed to prevent federal courts from

applying state law but instead to prevent duplicative litigation that wastes judicial

resources and portends inconsistent federal and state interpretations of identical rules

of decision. See id. at 1233–34. The district court acknowledged that “avoidance of

22 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 23

duplicative litigation . . . is at the core of the Colorado River doctrine,” Aplt.’s App.

at 213–14 (quoting D.A. Osguthorpe, 705 F.3d at 1233), but nonetheless abstained

because it could not discern, “without further consideration,” whether the New

Mexico law questions presented by this case would “necessitate reasoned guesses, or

may even require certification,” id. at 216.

In view of a district court’s well-established obligation to exercise its

congressionally endowed jurisdiction, Cohens, 19 U.S. at 404, we deem the district

court’s step back from exercising its jurisdiction to avoid predicting state law

mistaken and improper. We thus remand for further consideration of the relevant

state-law questions. The district court’s analysis reflects a misunderstanding of the

piecemeal-litigation factor of our Colorado River analysis. See United States v. Ellis,

23 F.4th 1228, 1238 (10th Cir. 2022) (“An error of law is per se an abuse of

discretion.” (quoting United States v. Lopez-Avila, 665 F.3d 1216, 1219 (10th Cir.

2011))). Even if Erie predictions or certifications to state court are required,

Colorado River abstention remains inappropriate. And so long as the state litigation

brought by the government remains dormant, there is simply no risk of duplicative—

i.e., “piecemeal”—litigation.

Thus, we reject the district court’s alternative holding that Colorado River

abstention was justified.

23 Appellate Case: 22-2132 Document: 64-1 Date Filed: 06/16/2026 Page: 24

V

For the foregoing reasons, we reverse the district court’s order dismissing this

action and remand for further proceedings consistent with this order and judgment.

Entered for the Court

Jerome A. Holmes Chief Judge