FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

FRIENDS OF THE INYO; 

WESTERN WATERSHEDS 

PROJECT; CENTER FOR 

BIOLOGICAL DIVERSITY; 

SIERRA CLUB, 

Plaintiffs-Appellants, 

 v. 

UNITED STATES FOREST 

SERVICE; LEEANN MURPHY, 

Defendants-Appellees, 

KORE MINING, LTD., 

Intervenor-DefendantAppellee.

No. 23-15492 

D.C. No. 

2:21-cv-01955-

KJM-KJN 

OPINION

Appeal from the United States District Court

for the Eastern District of California

Kimberly J. Mueller, Chief District Judge, Presiding

Argued and Submitted August 24, 2023

San Francisco, California

Filed May 21, 2024
2 FRIENDS OF THE INYO V. USFS

Before: Patrick J. Bumatay, Lucy H. Koh, and Roopali H. 

Desai, Circuit Judges. 

Opinion by Judge Desai; 

Dissent by Judge Bumatay 

SUMMARY*

Environmental Law 

The panel reversed the district court’s summary 

judgment in favor of the U.S. Forest Service and KORE 

Mining Ltd. in an action brought by environmental groups 

challenging the Forest Service’s approval of the Long Valley 

Exploration Drilling Project, a mineral exploration project 

on land in the Inyo National Forest in California. 

An agency can comply with the National Environmental 

Policy Act’s environmental requirements by invoking a 

Categorical Exclusion (“CE”) to avoid preparing an 

Environmental Impact Statement or an Environmental 

Assessment, two of which are at issue here: CE-6, which 

allows timber stand or wildlife habitat improvement 

activities that do not use herbicides or require more than 1 

mile of low standard road construction; and CE-8, which 

allows certain short-term mineral, energy, or geophysical 

investigations and their incidental support activities. 

* This summary constitutes no part of the opinion of the court. It has 

been prepared by court staff for the convenience of the reader.
FRIENDS OF THE INYO V. USFS 3

The parties disputed whether the Forest Service 

regulation enumerating CEs, 36 C.F.R. § 220.6, allowed the 

Forest Service to combine two CEs to approve a proposed 

action, where no single CE could cover the proposed action 

alone.

The panel held that the two-phase Project was a single 

proposed action. The Forest Service properly analyzed the 

Project as one proposed action because Forest Service 

regulations prohibit artificially bifurcating reclamation from 

a proposed plan of operations, and all parties treated 

KORE’s mineral exploration and reclamation as one 

proposal.

Neither CE-6 nor CE-8 alone could cover the proposed 

action. The plain language of the regulation, and its history, 

structure, and purpose, supported finding that § 220.6 

prohibited combining CEs, where no single CE could cover 

a proposed action alone. The panel held that the Forest 

Service’s error in combining CE-6 and CE-8 was not 

harmless, and remanded for district court to enter summary 

judgment on behalf of plaintiffs, vacating the agency’s 

decision.

Dissenting, Judger Bumatay would hold that any error in 

applying the CEs here was harmless because the Project 

would disturb less than an acre of land and no one has 

identified any significant impact on the environment.
4 FRIENDS OF THE INYO V. USFS

COUNSEL

Roger Flynn (argued), Western Mining Action Project, 

Lyons, Colorado; Talasi B. Brooks, Western Watersheds 

Project, Boise, Idaho; for Plaintiffs-Appellants. 

Ezekiel Peterson (argued), Tyler M. Alexander, and Robert 

P. Stockman, Assistant United States Attorneys; Todd Kim, 

Assistant Attorney General; United States Department of 

Justice, Environment and Natural Resources Division, 

Washington, D.C.; Jamie Rosen, Attorney, United States 

Department of Agriculture, Office of General Counsel, 

Washington, D.C.; for Defendants-Appellees United States 

Forestry Service and Leeann Murphy. 

Kerry Shapiro (argued), Daniel Quinley, and Lena Streisand, 

Jeffer Mangels Butler & Mitchel LLP, San Francisco, 

California, for Intervenor-Defendant-Appellee Kore Mining 

LTD. 
FRIENDS OF THE INYO V. USFS 5

OPINION

DESAI, Circuit Judge:

In 2021, the United States Forest Service approved the 

Long Valley Exploration Drilling Project (the “Project”), a 

mineral exploration project on land in the Inyo National 

Forest. Plaintiffs Friends of the Inyo, Western Watersheds 

Project, Center for Biological Diversity, and Sierra Club 

(collectively, “Friends”) sued under the National 

Environmental Policy Act (“NEPA”), arguing that it was 

unlawful for the United States Forest Service (“Forest 

Service”) to approve the Project by combining two 

categorical exclusions, when neither one alone could justify 

approval of the Project. KORE Mining Ltd. (“KORE”), the 

entity that proposed the Project, intervened as a defendant. 

The district court granted summary judgment in favor of the 

Forest Service and KORE and denied Friends’ motion for 

summary judgment. For the reasons discussed below, we 

reverse the decision of the district court.

BACKGROUND

I. National Environmental Policy Act

“Congress enacted NEPA to establish a national policy 

for the environment.” Mountain Cmtys. for Fire Safety v. 

Elliott, 25 F.4th 667, 674 (9th Cir. 2022). NEPA requires 

federal agencies to perform environmental analysis before 

taking any “major Federal actions significantly affecting the 

quality of the human environment.” Env’t Prot. Info. Ctr. v. 

Carlson, 968 F.3d 985, 987–88 (9th Cir. 2020) (quoting Ctr. 

for Biological Diversity v. Salazar, 706 F.3d 1085, 1094 (9th 

Cir. 2013)). NEPA “does not mandate particular results,” but 

“imposes only procedural requirements to ensure that the 
6 FRIENDS OF THE INYO V. USFS

agency, in reaching its decision, will have available, and will 

carefully consider, detailed information concerning 

significant environmental impacts.” Id. at 988 (quoting 

Winter v. Nat. Res. Def. Council, 555 U.S. 7, 23 (2008)). An 

agency can comply with NEPA in three ways: (1) it can 

prepare an Environmental Impact Statement (“EIS”); (2) it 

can prepare an Environmental Assessment (“EA”); or (3) it 

can invoke a Categorical Exclusion (“CE”) to avoid 

preparing an EIS or EA. Id. This case involves the invocation 

of CEs. 

CEs represent a “more expedited track available for a 

limited set of agency actions . . . ‘that normally do not have 

a significant effect on the human environment.’” Earth 

Island Inst. v. Muldoon, 82 F. 4th 624, 632 (9th Cir. 2023) 

(quoting 40 C.F.R. § 1501.4(a)). Invoking an exclusion 

allows an agency to avoid preparing an EIS or EA so long as 

no “extraordinary circumstances” indicate that the action 

will nonetheless have a significant environmental effect. Id. 

To approve a project using a CE, the Forest Service must 

issue a “decision memo” supported by a project record or 

case file. § 220.6(e).

The Forest Service promulgated 25 categories of CEs in 

36 C.F.R. § 220.6(e). Two CEs are at issue here: (1) CE-6 

allows “[t]imber stand and/or wildlife habitat improvement 

activities that do not include the use of herbicides or do not 

require more than 1 mile of low standard road construction,” 

36 C.F.R. § 220.6(e)(6) (“CE-6 (habitat improvement)”); 

and (2) CE-8 allows “[s]hort-term (1 year or less) mineral, 

energy, or geophysical investigations and their incidental 

support activities that may require cross-country travel by 

vehicles and equipment, construction of less than 1 mile of 

low standard road, or use and minor repair of existing roads,” 
FRIENDS OF THE INYO V. USFS 7

Id. § 220.6(e)(8) (“CE-8 (mineral operations less than 1 

year)”).

II. Mining Activities on Forest Service Administered 

Land

The General Mining Law of 1872 confers a statutory 

right to prospect, explore, and mine minerals on certain 

public lands, including National Forests. 30 U.S.C. § 22, 

amended by Surface Resources Act of 1955, 30 U.S.C. 

§ 612; 16 U.S.C. § 482. Such activities, known as 

“operations,” must be “conducted so as to minimize adverse 

environmental impacts on National Forest System surface 

resources.” 36 U.S.C. § 228.1. “Operations” are defined as 

“[a]ll functions, work, and activities in connection with 

prospecting, exploration, development, mining or 

processing of mineral resources and all uses reasonably 

incident thereto . . . .” § 228.3(a).

Under the Forest Service’s mineral regulations, any 

person proposing “operations which might cause significant 

disturbance of surface resources” must file “a notice of intent 

to operate” with the Forest Service District Ranger with 

jurisdiction over the operations area. 36 C.F.R. § 228.4. If

the District Ranger finds that any operation will likely cause 

“significant disturbance of surface resources,” the operator 

must submit a “proposed plan of operations” to the Forest 

Service for approval. 36 C.F.R. § 228.4. No operations can 

be conducted until a plan of operations is approved. 36 

C.F.R. § 228.4.

A plan of operations must provide, among other things, 

a description of how the operations will be conducted and

the “measures to be taken to meet the requirements for 

environmental protection in § 228.8.” 36 C.F.R. § 228.4. In 

turn, § 228.8, titled “[r]equirements for environmental 
8 FRIENDS OF THE INYO V. USFS

protection,” requires an operator to “reclaim the surface 

disturbed in operations by such measures as will prevent or 

control . . . damage to the environment and forest services

including . . . reshaping and revegetation of disturbed areas” 

and “rehabilitation of fisheries and wildlife habitat.” 

228.8(g), (g)(4)–(5). Once the Forest Service receives an 

operator’s proposed plan of operations, the agency must 

complete “an environmental analysis in connection with 

[the] proposed operating plan” to “determine whether an 

environmental statement is required.” § 228.4(f), (a)(4), (b); 

§ 228.5(a)–(b).

III. The Long Valley Exploration Drilling Project 

East of Mammoth Lakes, California, there is a wide 

expanse of public land covered by shrubs and small trees 

within the Inyo National Forest. The Long Valley 

Exploration Drilling Project is a proposed mineral 

exploration project on this Forest Service-managed land. 

The Project would proceed in two phases. The approved Plan 

of Operations would first allow KORE to build 12 temporary 

drilling pads in the Project area, which would be used for 

one year or less. Then, for up to three years after drilling, 

experts would monitor and tend to the Project area to ensure 

environmental rehabilitation is successful. 

Each drilling pad would include up to 3 core, angle 

borings, which will reach depths from about 580 to 1,424 

feet. KORE would use existing public roads and build up to 

.32 miles of temporary access roads for the Project. Between 

the temporary roads and drilling pads, KORE estimates the 

Project would directly disturb about .82 acres within the 

Project area. Friends allege that the Project’s impact will be 

much larger because construction will be scattered 

throughout the Project area and will disrupt the region with 
FRIENDS OF THE INYO V. USFS 9

loud noises and visual intrusions. The parties also dispute 

whether the Project’s drill depths will reach or disrupt the 

regional ground water aquifer. 

IV. Procedural Background 

KORE began investigating the Project in 2019. The 

proposed site was 1,848 acres in Mono County, where other 

entities bored hundreds of holes in previous explorations in 

the 1980s and 1990s. Although the previous holes only 

reached a few hundred feet, KORE believed that deeper 

exploration, which had previously not been technically 

possible, could be fruitful. KORE proposed drilling fewer, 

deeper holes in the periphery of the same area. KORE would 

then refill the holes without extracting any resources. 

KORE submitted a required notice of intent to the Forest 

Service in the summer of 2020. The Forest Service requested 

a more detailed plan of operations because KORE’s 

“proposed mining activities” were “likely to cause 

significant disturbance of surface resources.” KORE

prepared and submitted a plan of operations that summer. 

Initially, the Forest Service determined that KORE needed 

to prepare an EA to assess the Project’s environmental

impact. In a July 2020 letter to KORE, the Forest Service 

concluded: “Our initial review of the Plan of Operation 

indicates that an Environmental Assessment will need to be 

completed for this project.” 

In August 2020, KORE sent a letter to the Forest Service 

objecting to the need for NEPA review. KORE wrote that it 

was “hopeful that [the Forest Service] can help [KORE] get 

through this initial exploration stage on a quicker timeline.”

In an email to KORE in November 2020, the Forest Service 

informed KORE that the agency was “trying to fit the project 

into a Categorical Exclusion for the NEPA process . . . .” 
10 FRIENDS OF THE INYO V. USFS

The same day, the Forest Service reversed course, informing 

KORE that NEPA review was unnecessary because the 

Project could be approved via CE-8 (mineral operations less 

than 1 year). 

On January 2, 2021, the Forest Service listed the Project 

“as a proposal on the Inyo National Forest Schedule of 

Proposed Actions (SOPA).” The Forest Service solicited 

public comment on the proposed Project and received over 

1,500 comments. Commenters raised “potential impacts to 

tourism, wildlife, cultural resources, water quality and 

recreation.” Many comments warned that the Project could 

disrupt several species in and around the Project area. 

Among these were objections to the Project based on 

potential disruption to the Bi-State sage-grouse and the 

Owens Tui Chub. The Bi-State sage grouse is a ground 

nesting bird recognized by the Forest Service as a Species of 

Conservation Concern. Commentors expressed concerns 

that the Project would allow destruction of the sage grouse’s 

habitat and lead to disruption of mating and nesting. The 

Owens Tui Chub is an endangered species of fish. Although 

the Project area does not contain surface water, two 

populations of endangered chub live near the Project area 

and depend on groundwater. The Forest Service received 

many comments expressing concern that the Project would 

impact ground and surface waters. Commentors also 

objected to the Forest Service’s reliance on CE-8 (mineral 

operations less than 1 year) because the Project’s 

reclamation period would take up to three years, and thus the 

Project could not be completed within one year. 

After receiving public comments, in July 2021, the 

Forest Service altered its analysis of the Project. In the 

agency’s draft Public Involvement Scoping Summary 

Report, the Forest Service acknowledged that commentors 
FRIENDS OF THE INYO V. USFS 11

were concerned that the Project could not be approved using 

CE-8 (mineral operations less than 1 year) because “some 

activities would continue beyond one year, particularly 

monitoring and re-seeding as necessary, and other habitat 

restoration activities.” The Forest Service stated that “[t]hese

concerns were considered” and, ultimately, the agency 

“add[ed] another CE category to cover the minor activities 

that may occur to support rehabilitation, which may include 

additional seeding or planting vegetation, and leaving fences 

in place around revegetated areas.”

Internally, Forest Service Environmental Coordinator 

Erin Noesser shared an updated version of a draft decision 

memo approving the Project. The updated memo relied on a 

combination of CE-6 and CE-8 to approve the Project 

without an EA or EIS. She explained in an internal email: “I 

added the new CE category and an explanation, so see if you 

think it’s logical. I’m sending it to our attorneys and NEPA 

people today to look at that section, so they may ask for some 

changes if they don’t like it.” The updated memo relied on 

a combination of CE-6 and CE-8 to approve the Project 

without an EA or EIS. It concluded that “[r]eclamation

activities that do not involve grading, or major ground 

disturbance may continue past one year as needed for 

satisfactory reclamation” and “fall under support activities 

necessary for mineral exploration.” A redlined note in the 

draft explained that the Forest Service District Ranger was 

approving the project under an additional CE, CE-6 (habitat 

improvement), because “I want to be sure that I explicitly 

acknowledge that these restoration activities may take more 

than one year and that we have analyzed both the positive 

and negative impacts of the restoration activities.” 

After these drafts, the Forest Service formally approved 

the Project in a final decision memo. The decision memo 
12 FRIENDS OF THE INYO V. USFS

continued to rely on the combination of two CEs, but it 

reversed its description of the Project’s reclamation plan, 

finding that post-one-year reclamation efforts “are not 

support activities necessary for mineral exploration.” As 

approved, the Project was divided into two phases. In phase 

one, covered by CE-8 (mineral operations less than 1 year), 

KORE will complete its mineral exploration and initial site 

reclamation. Phase one will last one year, and at the end of 

the one-year period, all equipment will be removed, and 

exploration activities will be complete. In phase two, 

covered by CE-6 (habitat improvement), for up to three years 

after phase one, experts will monitor and tend to the Project 

area to ensure revegetation is successful. 

The Forest Service found that the Project’s plan of 

operations would avoid any significant effects on the 

environment. The final decision memo concluded that 

“impacts to the [sage grouse], should they be present, would 

be minor and temporary,” and “will not result in any impacts 

to the species that would affect their viability within the 

Project area or the Inyo National Forest.” It found that 

drilling may cause “physiological stress, reduced foraging 

success, and exposure to higher predation rates,” but that, 

with the implementation of avoidance and minimization 

measures, any impact would be “short-term and spatially 

limited.” The decision memo also evaluated risks to 

groundwater and concluded based on a historical 

groundwater analysis that “there is a very low potential for 

any effect to surface or groundwater quality or quantity from 

this exploration project.” 

Friends sued the Forest Service after it approved the 

Project, alleging that the Forest Service violated NEPA by 

approving the Project using a combination of two CEs where 

neither CE alone could be invoked to avoid an EIS or EA. 
FRIENDS OF THE INYO V. USFS 13

Both sides moved for summary judgment. The district court 

granted the Forest Service and KORE’s motions for 

summary judgment and denied Friends’ motion for summary 

judgment. Friends appealed to this court. 

STANDARD OF REVIEW

A district court’s grant of summary judgment is reviewed 

de novo. 350 Mont. v. Haaland, 50 F.4th 1254, 1263 (9th 

Cir. 2022). We review NEPA claims under the standards set 

forth in the Administrative Procedure Act and must set aside 

agency action if we find it to be “arbitrary, capricious, an 

abuse of discretion, or otherwise not in accordance with 

law.” Idaho Sporting Cong., Inc. v. Rittenhouse, 305 F.3d 

957, 964 (9th Cir. 2002) (citing 5 U.S.C. § 706). Arbitrary 

and capricious review is “highly deferential” and presumes 

that the agency action is valid if “a reasonable basis exists” 

for the agency’s decision. Ranchers Cattlemen Action Legal 

Fund v. U.S. Dep’t of Agric., 499 F.3d 1108, 1115 (9th Cir. 

2007). But we defer to an agency’s decision only if it is 

“fully informed and well-considered,” Save the Yaak Comm. 

v. Block, 840 F.2d 714, 717 (9th Cir. 1988) (quoting Jones 

v. Gordon, 792 F.2d 821, 828 (9th Cir. 1986)), and our 

review is limited to “the grounds that the agency invoked 

when it took the action.” Michigan v. EPA, 576 U.S. 743, 

758 (2015).

ANALYSIS

The parties dispute whether the Forest Service regulation 

enumerating CEs, 36 C.F.R. § 220.6, allows the Forest 

Service to combine two CEs to approve a proposed action, 

where no single CE could cover the proposed action alone. 

To answer this question, we must define the scope of the 

proposed action here, then decide whether the Forest Service 

properly combined CE-6 and CE-8. Based on the plain 
14 FRIENDS OF THE INYO V. USFS

language of § 220.6, we hold that the two-phase Project was 

a single proposed action, and that § 220.6 prohibits 

combining two CEs, when neither CE would cover a 

proposed action alone. 

I. The Project is a single proposed action. 

We first define the scope of the proposed action 

considered by the Forest Service. Under § 220.6, “A 

proposed action may be categorically excluded from further 

analysis and documentation in an EIS or EA only if there are 

no extraordinary circumstances related to the proposed 

action and if . . . [t]he proposed action is within a category 

listed in § 220.6(d) and (e).” Section 220.6 thus requires 

NEPA compliance for each “proposed action” considered by 

the agency. Here, the agency evaluated the two-phase 

Project as a single proposed action. The Forest Service 

properly analyzed the Project as one proposed action 

because Forest Service regulations prohibit artificially 

bifurcating reclamation from a proposed plan of operations.

Forest Service NEPA regulations do not define 

“proposed action.” 36 C.F.R. § 220.6. However, the term 

“proposed action” must be read alongside the Forest 

Service’s mineral regulations, which establish that 

reclamation cannot be bifurcated from other mineral 

exploration efforts. Specifically, the mineral regulations 

govern mineral exploration “operations.” 36 C.F.R. pt. 

228.3(a). Operations encompass “[a]ll functions, work, and 

activities in connection with” mineral exploration. 

§ 228.3(a). This definition necessarily includes reclamation 

because mineral operations are required under § 228.8 to 

meet certain environmental protection procedures, including 

revegetation and wildlife habitat rehabilitation. § 228.8(g). 

In fact, operators must submit a “proposed plan of 
FRIENDS OF THE INYO V. USFS 15

operations” to the Forest Service that describes “measures to 

be taken to meet the requirements for environmental 

protection in § 228.8,” § 228.4(c)(3), and the Forest Service 

must then review the plan’s environmental impact, 

§§ 228.4(a)(4), (b), 228.5(a)–(b). The Forest Service thus 

necessarily reviews mineral exploration and reclamation as

a single proposed project. Under this framework, in the 

mineral exploration context, the “proposed action” is the 

proposed plan of operations as a whole—not its component 

parts. The entire Project is thus subject to NEPA review, and 

KORE’s proposed plan of operations must fit within “a 

category” of CE under § 220.6. 

That KORE’s plan of operations was a single proposed 

action is further evidenced by the fact that all parties treated

KORE’s mineral exploration and reclamation as one 

proposal, not piecemeal proposals. For example, KORE

described the Project in its plan of operations as comprising 

both exploration and remedial activities. And throughout the 

approval process, the Forest Service and KORE presented 

one Project to the public for comment and referred to the 

Project as the proposed action in letters, announcements, 

reports, internal documents, and the plan of operations itself.

The Forest Service’s final decision memo then ultimately 

approved KORE’s plan of operations as a single proposal.

The record thus shows that the Forest Service and KORE 

understood the Project to be a single action. Indeed, at oral 

argument, the Forest Service agreed that it had approved a 

single proposed action to be completed in two phases.

Although the agency’s final decision memo divided the 

Project into two phases, the Forest Service considered the 

entire Project as the proposed action by conducting a single 

analysis of the potential extraordinary circumstances related 

to the Project. Because the agency considered only the 
16 FRIENDS OF THE INYO V. USFS

combined effect of the action, we must accept the agency’s 

treatment of the entire Project as the proposed action in our 

analysis. See Ctr. for Biological Diversity v. U.S. Fish & 

Wildlife Serv., 33 F.4th 1202, 1223 (9th Cir. 2022) (“It is 

black-letter law ‘that an agency’s action may not be upheld 

on grounds other than those relied on by the agency.’” 

(quoting Nat’l R.R. Passenger Corp. v. Bos. & Me. Corp., 

503 U.S. 407, 420 (1992))).1

We thus hold that the Project was a single proposed 

action. 

II. Neither CE-6 nor CE-8 alone could cover the 

proposed action. 

The parties agree that neither CE applied by the Forest 

Service covers the Project alone. CE-8 applies to “[s]hortterm (1 year or less) mineral, energy, or geophysical 

investigations and their incidental support activities.” 36 

C.F.R. § 220.6(e)(8). But the proposed action, which 

includes two phases, exceeds one year. The decision memo 

found that after reclamation activities occur for “up to one 

year,” the “minimum monitoring time” for the rehabilitation 

1 To hold otherwise would require us to define the proposed action 

differently at different points in the regulation. The proposed action 

evaluated for a categorical exclusion must be the same proposed action 

evaluated for extraordinary circumstances. See 36 C.F.R. § 220.6 (“A 

proposed action may be categorically excluded from further analysis and 

documentation in an EIS or EA only if there are no extraordinary 

circumstances related to the proposed action and if . . . [t]he proposed 

action is within a category listed in § 220.6(d) and (e).” (emphasis 

added)); Prieto-Romero v. Clark, 534 F.3d 1053, 1061 n.7 (9th Cir. 

2008) (“[W]ords or phrases are presumed to have the same meaning 

when used in different parts of a statute.” (internal quotation marks 

omitted)). Not even the Forest Service asks us to reach this inconsistent 

result. 
FRIENDS OF THE INYO V. USFS 17

phase is three years. For its part, CE-6 applies to “[t]imber 

stand and/or wildlife habitat improvement activities.” 36 

C.F.R. § 220.6(e)(6). It cannot cover the full Project because 

phase one includes drilling and exploratory activities that are 

not remedial in nature. Both the Forest Service and KORE 

thus argue only that each phase of the Project could be 

covered by a different CE, not that one of the CEs applied 

by the Forest Service was sufficient alone. 

III. Section 220.6 prohibits combining CEs to approve 

a proposed action.

Because both phases of the Project are a single proposed 

action and the parties do not dispute the scope of either 

exclusion, we must decide whether the agency properly 

combined CE-6 (habitat improvement) and CE-8 (mineral 

operations less than 1 year) to approve the proposed action. 

We hold that 36 C.F.R. § 220.6 unambiguously prohibits 

combining CEs to approve a proposed action, where no 

single CE could cover the proposed action alone. 

“Regulations are interpreted according to the same rules 

as statutes, applying traditional rules of construction.” 

Mountain Cmtys. for Fire Safety, 25 F.4th at 676 (quoting 

Minnick v. Comm’r of Internal Revenue, 796 F.3d 1156, 

1159 (9th Cir. 2015)). “Our ‘legal toolkit’ includes careful 

examination of ‘the text, structure, history, and purpose of a 

regulation.’” Amazon.com, Inc. v. Comm’r of Internal 

Revenue, 934 F.3d 976, 984 (9th Cir. 2019) (quoting Kisor 

v. Wilkie, 139 S. Ct. 2400, 2415 (2019)). “But, of course, ‘the 

starting point of our analysis must begin with the language 

of the regulation.’” Mountain Cmtys. for Fire Safety, 25 

F.4th at 676 (quoting Wards Cove Packing Corp. v. Nat’l 

Marine Fisheries Serv., 307 F.3d 1214, 1219 (9th Cir. 

2002)). Both the plain language of the regulation, and its 
18 FRIENDS OF THE INYO V. USFS

history, structure, and purpose, support finding that § 220.6 

prohibits combining CEs, where no single CE could cover a 

proposed action alone.2

A. The text of § 220.6 prohibits the Forest Service 

from combining CEs to approve a proposed 

action when no CE alone is sufficient. 

The plain text of § 220.6 prohibits the Forest Service 

from combining CEs to approve a proposed action when no 

CE alone is sufficient. That regulation provides: 

A proposed action may be categorically 

excluded from further analysis and 

documentation in an EIS or EA only if there 

are no extraordinary circumstances related to 

the proposed action and if: (1) The proposed 

action is within one of the categories 

established by the Secretary at 7 CFR part 

1b.3; or (2) The proposed action is within a 

category listed in § 220.6(d) and (e).

36 C.F.R. § 220.6(a). This language uses singular nouns: “a

proposed action” may be categorically excluded if “the

proposed action” is “within a category.” Id. (emphasis 

added). In other words, the regulation’s language indicates 

2 The Forest Service concedes that Auer deference does not apply here. 

Under Auer, if a regulation is genuinely ambiguous, we defer to the 

agency’s reasonable interpretation of its own regulation. Auer v. 

Robbins, 519 U.S. 452, 461 (1997). But we only defer to interpretations 

that are “the agency’s ‘authoritative’ or ‘official position,’ rather than 

any more ad hoc statement not reflecting the agency’s views.” Kisor, 139 

S. Ct. at 2416 (quoting United States v. Mead, 533 U.S. 218, 237–38 & 

n.6 (2001)). The Forest Service agrees it made no such authoritative 

statement here.
FRIENDS OF THE INYO V. USFS 19

that a single “proposed action” must fall within a single

“category” for it to be categorically excluded. As explained 

in Niz-Chavez v. Garland, the “decision to use the indefinite 

article ‘a’” is evidence of intent to use a term “as a discrete, 

countable thing.” 141 S. Ct. 1474, 1480 (2021) (considering 

the ordinary meaning of a statute governing the stop-time 

rule, and reasoning: “To an ordinary reader . . . ‘a’ notice 

would seem to suggest just that: ‘a’ single document 

containing the required information, not a mishmash of 

pieces with some assembly required”); see also United 

States v. Randall, 34 F.4th 867, 876 (9th Cir. 2022) (finding 

that the “phrasing ‘an offense’” is a “singular construction” 

that “tells us that each ‘offense’ requires a separate 

assessment” (emphasis in original)), cert. denied, 143 S. Ct. 

1061 (2023). There, like here, if the statute had “meant to 

endow the government with the flexibility it supposes” it 

could have indicated so. Niz Chavez, 141 S. Ct. at 1480. We 

thus credit the singular construction of § 220.6. 

The canon of statutory construction that “singulars 

normally include plurals,” codified by Congress in the 

Dictionary Act, does not render this singular construction 

plural. Schott v. Comm’r, 319 F.3d 1203, 1206 (9th Cir. 

2003). Although the Act tells us to assume “words importing 

the singular include and apply to several persons, parties, or 

things” unless the statutory context indicates otherwise, 1 

U.S.C. § 1, it “does not transform every use of the singular 

‘a’ into the plural ‘several.’ Instead, it tells us only that a 

statute using the singular ‘a’ can apply to multiple persons, 

parties, or things.” Niz-Chavez, 141 S. Ct. at 1482.3

3 Moreover, “[o]n the rare occasions when we have relied on this rule, 

doing so was ‘necessary to carry out the evident intent of the statute,’” 
20 FRIENDS OF THE INYO V. USFS

Section 220.6(a)’s singular language is also consistent 

with the rest of the Section. When the Forest Service applies 

a CE enumerated in Subsection 220.6(e), it must prepare a 

decision memo that includes the “rationale for using the 

category.” 36 C.F.R. § 220.6(f)(2)(ii). And when “more than 

one category could have been used,” the decision memo 

must explain “why the specific category was chosen.” Id. 

Thus, though § 220.6 lists multiple exclusions, it explicitly 

directs the agency to explain why it picked the chosen 

category.

Although § 220.6(a)(2)’s “within a category” language 

is different from § 220.6(a)(1)’s directive that the proposed 

action must be “within one of the categories established” by 

7 C.F.R. 1b.3, 36 C.F.R. § 220.6(a), neither subsection 

permits the agency to combine CEs when no CE alone could 

cover a proposed action. The “a category” language is 

instead consistent with this court’s finding that CEs “may 

overlap” and more than one CE may apply to one set of facts. 

See Mountain Cmtys. for Fire Safety, 25 F.4th at 680 & n.9 

(“[I]n selecting a CE for a project, the Forest Service only 

needs to cite and rely on one CE, even if other CEs may 

apply.”). But the proposed action must be covered by the 

chosen exclusion. In short, even if the dissent were correct 

that “one” and “a” have different meanings, neither allows 

the agency to combine CEs. Section 220.6(a)’s language 

thus establishes that exclusions cannot be combined to 

United States v. Hayes, 555 U.S. 415, 422 n.5 (2009) (quoting First Nat. 

Bank in St. Louis v. Missouri, 263 U.S. 640, 657 (1924)). Reading 

§ 220.6(a)’s singular language to include plurals is not necessary to carry 

out the regulation’s intent—in fact, as discussed below, it would serve 

only to circumvent NEPA’s procedural requirements and would thus 

contradict NEPA’s intent.
FRIENDS OF THE INYO V. USFS 21

approve a proposed action, where no single CE could cover 

the project alone. 

B. The history, structure, and purpose of § 220.6 

lead to the same result. 

Although the plain language of § 220.6 alone prohibits 

the Forest Service from combining CEs, the structure, 

history, and purpose of the Section further reinforce our 

conclusion. 

First, the history of § 220.6 shows that its CE categories 

were intentionally enumerated independently, rather than as 

a grab bag of combinable exclusions. In 1991, when the 

Forest Service first proposed CE-6 (habitat improvement), it 

stated that the previously existing CE, a broad “category of 

low impact silvicultural activities,” would be separated into 

“precise, clearly understood categories of proposed actions.” 

National Environmental Policy Act Revised Policy and 

Procedures, 56 Fed. Reg. 19720–21 (Apr. 29, 1991). 

Accordingly, the Forest Service established four new 

“categories of proposed actions” eligible for exclusion: 

(1) Proposals to harvest or salvage timber 

which remove one million board feet or less 

of merchantable wood products; require one 

mile or less of new road construction; assure 

regeneration of harvested or salvaged areas, 

where required; (2) Proposals to thin 

merchantable timber from over-stocked 

stands which require one mile or less of new 

road construction; (3) Proposals to artificially 

regenerate areas to native tree species, 

including needed site preparation not 

involving the use of pesticides; and 
22 FRIENDS OF THE INYO V. USFS

(4) Proposals to improve vegetation or timber 

conditions using approved silvicultural or 

habitat management techniques, not 

including the use of herbicides.

Id. at 19721. The Forest Service did not list these categories 

of proposed actions as subcategories under a single CE. 

Instead, it divided the prior exclusion into four new CEs, one 

for each category of action. In doing so, the drafters clearly 

intended for the Forest Service to consider each CE 

independently. See id.; 36 C.F.R. § 220.6(e). Allowing the 

Forest Service to combine CEs after the fact would 

undermine this effort. 

Second, the structure of § 220.6 shows that CEs cannot 

be combined, where one CE alone cannot cover a proposed 

action. Each CE is separately defined by the Section, and 

many include time and space limitations that would be futile 

if they could be duplicated or combined. E.g., 36 C.F.R. 

§ 220.6(e)(3) (“Approval, modification, or continuation of 

special uses that require less than 20 acres of NFS lands.”); 

§ 220.6(e)(6) (“Timber stand and/or wildlife habitat 

improvement activities that do not include the use of 

herbicides or do not require more than 1 mile of low standard 

road construction”); § 220.6(e)(8) (“Short-term (1 year or 

less) mineral, energy, or geophysical investigations and their 

incidental support activities”); § 220.6(e)(11) (“Post-fire 

rehabilitation activities, not to exceed 4,200 acres”). Some 

enumerated CEs also directly conflict with one another and 

could not meaningfully be applied together. CE-23, for 

example, permits “[r]oad management activities” on 

National Forest Service roads, but “cannot include 

construction or realignment.” 36 C.F.R. § 220.6(e)(23). But 

CE-24 permits “[c]onstruction and realignment of up to 2 

miles of NFS roads and associated parking areas.” 
FRIENDS OF THE INYO V. USFS 23

§ 220.6(24). Combining these exclusions would undermine 

their limits and violate the basic principle that “[a] statute or 

regulation should be construed so that effect is given to all 

its provisions, so that no part will be inoperative or 

superfluous, void or insignificant.” Nacarino v. Kashi Co., 

77 F.4th 1201, 1210 (9th Cir. 2023) (quoting United States 

v. Grandberry, 730 F.3d 968, 981–82 (9th Cir. 2013)). 

Finally, the purpose of NEPA and § 220.6 also support 

our holding that CEs may not be combined, where no one 

CE could cover a proposed action alone. NEPA is a 

procedural statute, but its mandates are a “basic national 

charter for protection of the environment.” Ctr. for 

Biological Diversity v. U.S. Forest Serv., 349 F.3d 1157, 

1166 (9th Cir. 2003) (quoting Blue Mountains Biodiversity 

Project v. Blackwood, 161 F.3d 1208, 1215–16 (9th Cir. 

1998)). Under the regulations implementing NEPA, an 

agency must “prepare an environmental assessment for a 

proposed action that is not likely to have significant effects 

or when the significance of the effects is unknown unless the 

agency finds that a categorical exclusion (§ 1501.4) is 

applicable or has decided to prepare an environmental 

impact statement.” 40 C.F.R. § 1501.5(a). This requirement 

ensures that agencies consider “detailed information 

concerning significant environmental impacts.” See

Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 

349 (1989).

CEs are designed to streamline this process when a class 

of proposed actions has been found to have little to no effect 

on the environment. See Env’t Prot. Info. Ctr., 968 F.3d at 

988. But when an agency applies CEs in a way that 

circumvents NEPA’s procedural requirements and renders 

the environmental impact of a proposed action unknown, the 

purpose of the exclusions is undermined. That is the case 
24 FRIENDS OF THE INYO V. USFS

here. The district court acknowledged the potentially 

“absurd results” that might flow from allowing a patchwork 

application of CEs to a single proposed action: 

Consider a six-month mining exploration 

project. On its own, the project may very well 

have no “significant effect on the human 

environment,” 40 C.F.R. 1501.4(a), and so it 

might be excluded categorically under CE-8, 

but if the Forest Service also planned to 

relocate administrative and recreational 

buildings under CE-21 and 22, see id.

§ 220.6(e)(21)–(22), to realign two miles of 

the surrounding roads under CE-24, see id.

§ 220.6(e)(24), to widen other parts of the 

surrounding roads and replace a bridge under 

CE-23, see id. § 220.6(e)(23), to fell and sell 

the surrounding trees under CE-12, see id.

§ 220.6(e)(12), to construct telephone and 

utility lines under CE-2, see id. § 220.6(e)(2), 

and to modify the course of a nearby stream 

under CE-7, see id. § 220.6(e)(7), could the 

Forest Service reasonably claim no 

significant effects were expected? Or could 

the Forest Service indefinitely extend a 

supposedly “short-term” exploratory project 

under CE-8 by approving a new six-month 

project every six months?

That this is not such an extreme case does not nullify the 

potential consequences of the rule moving forward. Any 

project can be broken down into seemingly innocuous 

independent acts. The fact that the Forest Service has found 

CEs “normally do not have a significant effect on the human 
FRIENDS OF THE INYO V. USFS 25

environment,” 40 C.F.R. 1508.1(d) (emphasis added), does 

not mean they have no effect, and combining carefully 

defined exclusions renders these calculated risks unknown. 

The Forest Service asks us to adopt a view of categorical 

exclusions that will swallow the protections of NEPA. We 

decline to do such violence to NEPA’s procedural 

safeguards. See Griffin v. Oceanic Contractors, Inc., 458 

U.S. 564, 575 (1982) (“[I]nterpretations of a statute which 

would produce absurd results are to be avoided if alternative 

interpretations consistent with the legislative purpose are 

available.”).

* * *

Based on the text, history, structure, and purpose of 

§ 220.6, we thus conclude that the Forest Service cannot 

combine categorical exclusions to approve a proposed 

action, when no single CE would cover a proposed action 

alone. 

IV. The Forest Service’s error was not harmless. 

Finally, the Forest Service and KORE suggest that, even 

if we find that the agency erred by combining CE-6 and CE8, its failures were, at most, harmless error. Here, even 

cursory review of the Forest Service’s actions demonstrates 

the agency’s error was not harmless. “The harmless-error 

analysis asks whether the failure to consult materially 

impeded NEPA’s goals—that is, whether the error caused 

the agency not to be fully aware of the environmental 

consequences of the proposed action, thereby precluding 

informed decisionmaking and public participation, or 

otherwise materially affected the substance of the agency’s 

decision.” Idaho Wool Growers Ass’n v. Vilsack, 816 F.3d 

1095, 1104 (9th Cir. 2016). We have found harmless error 

when an agency’s decision contains clerical or insubstantial 
26 FRIENDS OF THE INYO V. USFS

errors. See, e.g., Cal. ex rel. Imperial Cnty. Air Pollution 

Control Dist. v. U.S. Dep’t of the Interior, 767 F.3d 781, 794 

(9th Cir. 2014) (declining to remand when an error was a 

“scrivener’s error” and the necessary documents were 

“plainly incorporated by reference”); Laguna Greenbelt, 

Inc. v. U.S. Dep’t of Transp., 42 F.3d 517, 527 (9th Cir. 

1994) as amended on denial of reh’g (Dec. 20, 1994) 

(finding a “technical non-disclosure does not require 

reversal” because “we must look to the ultimate harm NEPA 

seeks to prevent: the risk of damage to the environment that 

results if the agency fails to properly and thoroughly 

evaluate the environmental impacts of a proposed project”). 

But errors are not harmless if “they prevented a proper, 

thorough, and public evaluation of the environmental impact 

of [a] Project.” Lands Council v. Powell, 395 F.3d 1019, 

1037 n.25 (9th Cir. 2005). In California Wilderness 

Coalition v. U.S. Department of Energy, for example, an 

agency failed to prepare an EIS or an EA, and we found its 

proffered reasons for doing so were “not persuasive as a 

matter of law and [were] not supported by the record.” 631 

F.3d 1072, 1106 (9th Cir. 2011). Because the agency had not 

“taken the requisite ‘hard look’ at the environmental 

consequences” of the project, the error could not be 

harmless. Id.

So too here. The Forest Service failed to prepare either 

an EIS or an EA for the Project. And its proffered reason for 

doing so—that it could combine two CEs to approve a 

project that no single exclusion could cover—is 

unpersuasive as a matter of law. The agency thus failed to 

take the requisite “hard look” at the proposed action that 

NEPA requires. Id. Because NEPA is a procedural regime 

promulgated to ensure that federal agencies “carefully 

consider . . . detailed information concerning significant 
FRIENDS OF THE INYO V. USFS 27

environmental impacts,” Robertson, 490 U.S. at 349, we find 

no support for the agency’s position that it is harmless to 

wholly circumvent this process. 

Where, as here, the agency completely fails to undertake 

the required environmental analysis, conclusions about the 

environmental impact of the under-evaluated project are 

speculation. The fact that each CE represents a category of 

actions that “normally do[es] not have a significant effect on 

the human environment,” 40 C.F.R. § 1508.1(d), does not 

undermine this conclusion. While the dissent quips that 

“zero plus zero is zero,” this circular math assumes that 

because the agency has found each category of risk 

acceptable, their impact will not change when combined. As 

set forth above, the sometimes-conflicting time and space 

limitations in 220.6’s enumerated CEs undercut this 

assumption. E.g., 36 C.F.R. § 220.6(e)(23) (allowing “[r]oad 

management activities” on National Forest Service roads, 

but not “construction or realignment”); § 220.6(24) 

(allowing “[c]onstruction and realignment of up to 2 miles 

of NFS roads and associated parking areas.”). The dissent’s 

back-of-the-envelope math thus cannot replace the “hard 

look” NEPA requires.

The dissent also attempts to cast the Forest Service’s lack 

of analysis as a clerical error by concluding that the Forest 

Service could have successfully proceeded with the same 

project had it been formally divided into two proposed 

actions. But as explained above, remediation cannot be 

artificially bifurcated from mineral exploration. See 36 

C.F.R. §§ 228.3(a), 228.8(g). Nor can this court speculate on 

how experts may have evaluated each phase of the Project 

independently. Michigan, 576 U.S. at 758 (explaining that 

this court’s review is limited to “the grounds that the agency 

invoked when it took the action.”). Given the decision memo 
28 FRIENDS OF THE INYO V. USFS

itself suggests that the Forest Service believed that post oneyear reclamation activities may be needed for satisfactory 

reclamation,4 the agency’s misapplication of CEs was not 

harmless. 

CONCLUSION

In an earlier order, we reversed the district court’s order 

denying Plaintiffs’ motion for summary judgment and 

granting Defendants’ and Defendant-Intervenors’ motions 

for summary judgment. We now remand for the district court 

to enter summary judgment on behalf of Plaintiffs, vacating 

the agency’s decision. 

REVERSED and REMANDED with 

INSTRUCTIONS. Defendants shall bear costs on appeal. 

BUMATAY, Circuit Judge, dissenting: 

Straddling California and Nevada, the Inyo National 

Forest covers around two million acres of forest. Most of it 

lies on the eastern slope of the Sierra Nevada Mountains, 

offering spectacular views. The Inyo National Forest also 

teems with wildlife. Among other species, it is home to the 

Bi-State sage-grouse. The sage-grouse is a ground-nesting 

bird famous for its mating dance. This sage-grouse 

subpopulation exists in only five counties in Nevada and 

three counties in California. Given its limited geographic 

spread, the Bi-State sage-grouse is considered a “species of 

4 In fact, an internal draft of the Forest Service’s decision memo 

acknowledged that “restoration activities do fall under support activities 

necessary for mineral exploration” and “would not be limited to one 

year” under CE-8 (mineral operations less than 1 year). 
FRIENDS OF THE INYO V. USFS 29

conservation concern,” though it is not classified as an 

endangered or threatened species under federal law.

The Inyo National Forest is also potentially rich in 

minerals. Under federal law, citizens have a right to explore 

for mineral resources on public lands. See General Mining 

Law of 1872, ch. 152, 17 Stat. 91 (codified as amended at 30 

U.S.C. §§ 21–54). In the 1980s and 1990s, parts of the 

Forest were explored, which included constructing roads and 

drilling hundreds of cores. In 2020, KORE Mining Limited 

sought to conduct additional mineral investigation at the 

periphery of the prior mineral exploration site. This new 

project would involve building twelve temporary drilling 

pads. Each drill pad would be active for only three to twelve 

days. Because roads already exist in the area, only 0.32 

miles of new temporary access roads would need to be 

constructed. The whole project would only impact about 

0.82 acres out of the 2 million acres of the Forest. And to 

mitigate concerns for the sage-grouse, the exploration will 

begin after the sage-grouse breeding and nesting season ends 

and will be prohibited in sage-grouse breeding grounds.

After completing the exploration, KORE would 

immediately refill any bore holes and revegetate the drill 

pads and temporary access roads with native seed mix. All 

mineral exploration, from installing to removing the drilling 

equipment, would be completed within one year. No actual 

mining would be involved. This project would solely permit 

mineral exploration. As shown below, the total disturbed 

area would be minimal.
30 FRIENDS OF THE INYO V. USFS

After considering KORE’s proposal, the Forest Service, 

which manages Inyo, added several requirements. To 

minimize any environmental effects, the Forest Service will 

require KORE to conduct a post-project restoration for 

habitat improvement. The reclamation will require KORE 

to re-seed, install sage-grouse friendly fences, monitor 

revegetation, and pull weeds. If monitoring were to show 

that revegetation was inadequate, the Forest Service would 

mandate that KORE renew its reclamation efforts. And to 

ensure adequate rehabilitation, the Forest Service will not 

limit the reclamation phase to one year—it would take up to 

three years. 

After KORE agreed to these requirements, the Forest 

Service approved the project. It did not conduct an 

environmental impact statement or an environmental 

assessment. Instead, after notifying the public and receiving 

thousands of comments about the project, the Forest Service 

issued an 18-page decision memo. This memo assessed that 

the project fell within the regulatory definition of two 
FRIENDS OF THE INYO V. USFS 31

categorical exclusions, thus alleviating the need for a more 

extensive environmental analysis. 

Friends of the Inyo and other environmental advocacy 

groups challenge the Forest Service’s decision to allow 

KORE to explore the park without an environmental impact 

statement or assessment. While the district court affirmed 

the Forest Service’s decision, the majority reverses. Given 

that this project would disturb less than an acre of land and 

no one has identified any significant impact on the 

environment, any error made by the Forest Service was 

harmless. 

For this reason, I respectfully dissent.

I.

A.

The National Environmental Policy Act (“NEPA”) 

requires agencies to conduct an environmental analysis 

before taking any “major Federal actions significantly 

affecting the quality of the human environment.” 42 U.S.C. 

§ 4332(2)(C). Agencies have three ways to meet NEPA’s 

requirements: (1) develop an environmental impact 

statement, (2) prepare an environmental assessment, or 

(3) invoke a categorical exclusion. Env’t Prot. Info. Ctr. v. 

Carlson, 968 F.3d 985, 988 (9th Cir. 2020). The first two 

methods require an agency to analyze a project’s impact on 

the environment—with varying levels of detail. Compare 40 

C.F.R. § 1508.1(h) (2020) (an “environmental assessment” 

is a “concise public document”) with id. § 1508.1(j) (an 

“environmental impact statement” is a “detailed written 

statement”).

Of the three, a categorical exclusion is the least onerous 

because it is limited to agency action that “normally do[es] 
32 FRIENDS OF THE INYO V. USFS

not have a significant effect on the human environment.” Id.

§ 1508.1(d). This results in a “more expedited track” since 

“an agency need not prepare an environmental assessment or 

environmental impact statement for an action that it 

concludes fits within the exclusion, so long as no 

‘extraordinary circumstances’ indicate that the action will 

nonetheless have a significant effect.” Earth Island Inst. v. 

Muldoon, 82 F.4th 624, 632 (9th Cir. 2023) (quoting 40 

C.F.R. § 1501.4(b)). Categorical exclusions free agencies to 

focus on major projects that may result in a significant 

environmental impact. See 48 Fed. Reg. 34263–66 (July 28, 

1983); see also 40 C.F.R. § 1500.4(a) (2020) (requiring 

agencies to use categorical exclusions when possible to 

reduce excessive paperwork). We uphold an agency’s use 

of a categorical exclusion whenever “the application of the 

exclusions to the facts of the particular action is not arbitrary 

or capricious.” Safari Club Int’l v. Haaland, 31 F.4th 1157, 

1178–79 (9th Cir. 2022) (simplified). 

Like other agencies, the Forest Service has promulgated 

regulations governing its use of categorical exclusions. 

Under its regulations, absent “extraordinary circumstances,” 

“[a] proposed action may be categorically excluded from 

further analysis and documentation in an [environmental 

impact statement] or [environmental assessment] . . . if . . . 

[t]he proposed action is within a category listed in § 220.6(d) 

and (e).” 36 C.F.R. § 220.6(a)(2) (2020). The Forest Service 

then promulgated 37 different categorical exclusions in 

paragraphs (d) and (e). See id. § 220.6(d)–(e).

In this case, the Forest Service invoked two exclusions— 

• Categorical Exclusion-8: The mining 

exploration phase fell within the exclusion 

for “[s]hort-term (1 year or less) mineral, 
FRIENDS OF THE INYO V. USFS 33

energy, or geophysical investigations and 

their incidental support activities.” Id. 

§ 220.6(e)(8). The exclusion includes 

projects that “require cross-country travel by 

vehicles and equipment, construction of less 

than 1 mile of low standard road, or use and 

minor repair of existing roads.” Id. 

• Categorical Exclusion-6: The revegetation 

phase came within the exception for “wildlife 

habitat improvement activities that do not 

include the use of herbicides or do not require 

more than 1 mile of low standard road 

construction.” Id. § 220.6(e)(6). 

The issue here is whether the Forest Service may invoke

two categorical exclusions for one project to avoid preparing 

an environmental impact statement or assessment. Friends 

of the Inyo and the other groups argue that it cannot and that 

the Forest Service artificially bifurcated the project into two 

to get around NEPA. The Forest Service and KORE counter 

that the regulations do not preclude using two categorical 

exclusions when a project has two distinct phases, as here. 

As a textual matter, this question is a challenging one. 

Recall that, under the regulation, a categorical exclusion is 

appropriate if “[t]he proposed action is within a category 

listed in § 220.6(d) and (e).” Id. § 220.6(a)(2). So we focus 

on the meaning of “within a category.” 

i.

Several reasons support reading the regulation as 

permitting only one categorical exclusion.
34 FRIENDS OF THE INYO V. USFS

First, as the majority holds, § 220.6(a)(2) refers to “a 

category” in the singular. Sometimes, a statute’s “singular 

construction” is “significant” of meaning. United States v. 

Randall, 34 F.4th 867, 876 (9th Cir. 2022). But, of course, 

this isn’t dispositive.

Second, the term “within” gives us another clue. 

Normally, when we say something is “within” another thing, 

it is “inside” it. See Within, American Heritage Dictionary 

(3d ed. 1996). Take a car. We wouldn’t say a car is “within” 

a garage if half of it is sticking out onto the driveway. So an 

action falling “within a category” naturally means that the 

action falls wholly inside the category. 

Third, construing § 220.6(a)(2) to require one category 

offers a nice parallel with § 220.6(a)(1). Section 220.6(a)(1) 

establishes another group of categorical exclusions for the 

Forest Service, but expressly limits the agency to only “one” 

exclusion. It permits a categorical exclusion if “[t]he 

proposed action is within one of the categories established 

by the Secretary at 7 CFR part 1b.3.” 36 C.F.R. 

§ 220.6(a)(1) (2020). The Secretary then established seven 

categories of activities, ranging from policy planning to 

criminal law enforcement, that don’t require an 

environmental assessment or impact statement. See 7 C.F.R. 

§ 1b.3(a)(1)–(7). So reading both subparagraphs to allow 

only one category would give them a parallel structure.

Fourth, the provision governing the Forest Service’s 

“decision memos” on categorical exclusions contemplates 

that the agency should explain “why the specific category 

was chosen.” 36 C.F.R. § 220.6(f)(2)(ii) (emphasis added). 

This is required even if “more than one category could have 

been used.” Id. Again, this suggests only one category could 

be used. 
FRIENDS OF THE INYO V. USFS 35

And finally, the Forest Service did not appear to believe 

it could use multiple categorical exclusions for one project 

given its attempt to change § 220.6(a)’s language. See 84 

Fed. Reg. 27544, 27546 (June 13, 2019). In 2019, the Forest 

Service proposed an amendment to its NEPA regulations to 

“clarify . . . that a proposed action may be categorically 

excluded if it is within one or more of the categories” listed 

in the regulations. Id. The proposed change sought to ensure 

that “[w]here a proposed action consists of multiple 

activities, and all of the activities that comprise the proposed 

action fall within one or more [categorical exclusions], the 

responsible official may rely on multiple categories for a 

single proposed action.” Id. This proposed rule change was 

not implemented, but it shows that the Forest Service did not 

think it had the authority to bifurcate actions under the 

existing regulation. 

So the requirement that a “proposed action” fall “within 

a category” may mean that the Forest Service can select only 

one categorical exclusion for a proposed action. 

ii.

But some persuasive arguments exist on the other side 

too. 

First, there’s the long-established rule of interpretation 

that “singulars normally include plurals.” Schott v. Comm’r 

of Internal Revenue, 319 F.3d 1203, 1206 (9th Cir. 2003). 

This “rule is simply a matter of common sense and everyday 

linguistic experience[.]” Antonin Scalia & Bryan A. Garner, 

Reading Law: The Interpretation of Legal Texts 130 (2012). 

After all, it would hang so much on the mere use of the 

singular article “a” in § 220.6(a)(2). So we could read the 

regulation’s text to mean that a “proposed action” is 

excluded if it is “within categories listed.” 
36 FRIENDS OF THE INYO V. USFS

Second, the adjacent § 220.6(a)(1) uses different 

language. As stated above, it refers to “one of the 

categories.” This more expressly limits the Forest Service to 

picking one and only one category. That § 220.6(a)(2) uses 

different language from § 220.6(a)(1) may signify a different 

meaning. See SEC v. McCarthy, 322 F.3d 650, 656 (9th Cir. 

2003) (“It is a well-established canon of statutory 

interpretation that the use of different words or terms within 

a statute demonstrates that Congress intended to convey a 

different meaning for those words.”) (simplified); Scalia & 

Garner, Reading Law, at 156 (“[A] material variation in 

terms suggests a variation in meaning.”). For whatever 

reason, the regulation may intend for the Forest Service to 

pick one category under § 220.6(a)(1) but allow multiple

categories under § 220.6(a)(2).

Finally, the regulatory definition of a “categorical 

exclusion” supports using multiple categories. The previous 

NEPA regulations defined a categorical exclusion as “a 

category of actions which do not individually or 

cumulatively have a significant effect on the human 

environment[.]” 40 C.F.R. § 1508.4 (2017) (emphasis 

added). Today, regulations define categorical exclusions as 

“categories of actions that normally do not have a significant 

effect on the human environment.” 40 C.F.R. § 1508.1(d) 

(2020). If the proposed actions would not significantly 

affect the environment cumulatively, why not allow the use 

of multiple categories? 

* * *

Ultimately, however, this textual debate is unnecessary 

to resolve. I explain why next.
FRIENDS OF THE INYO V. USFS 37

B.

We don’t need to resolve this tricky regulatory debate 

because any error in applying the categorical exclusions here 

was harmless. Even if the Forest Service erred by invoking 

two categorical exclusions to justify the mineral exploration 

project, the record supports that the overall project would not 

significantly affect the environment. As the district court 

reasoned, it would be “pointless to set aside the Forest 

Service’s decision in this case if its sole error was a failure 

to process KORE’s proposal as two ‘actions’ rather than 

one.” So relying on two categorical exclusions to satisfy 

NEPA constitutes, at most, harmless error.

We do not just freely vacate agency decisions at the 

slightest inkling of error. Instead, our review of NEPA 

violations is limited to “prejudicial error.” Idaho Wool 

Growers Ass’n v. Vilsack, 816 F.3d 1095, 1104 (9th Cir. 

2016) (quoting 5 U.S.C. § 706). So we ask whether any error 

“caused the agency not to be fully aware of the 

environmental consequences” of its action. Id. We focus on 

whether violating NEPA would have “somehow materially 

altered the environmental review process, not whether a 

constituent body was harmed by the agency’s ultimate 

decision.” Id. at 1105. 

Friends of the Inyo and the other environmental groups 

have identified no prejudice from the Forest Service 

invoking two categorical exclusions here. As stated above, 

categorical exclusions are reserved for “categories of actions 

that normally do not have a significant effect on the human 

environment[.]” 40 C.F.R. § 1501.4(a) (2020); see also 

Alaska Ctr. for Env’t v. U.S. Forest Serv., 189 F.3d 851, 859 

(9th Cir. 1999) (categorical exclusions are “limited to 

situations where there is an insignificant or minor effect on 
38 FRIENDS OF THE INYO V. USFS

the environment”). The groups do not show that the Forest 

Service overlooked a significant effect on the environment 

based on the use of the two categorical exclusions. At most, 

they complain that the Forest Service did not prepare an 

environmental assessment. But it is uncontested that the 

project’s two phases fit neatly into Categorical Exclusion-8 

(short-term mineral investigation) and Categorical 

Exclusion-6 (wildlife improvements). Given that each phase 

would have no significant environmental impact 

individually or cumulatively, see 40 C.F.R. § 1508.4 (2017), 

analyzing the project as one would not yield any greater 

environmental impact. As the district court put it, “zero plus 

zero is zero.”

And contrary to the majority’s assumption, this harmless 

error analysis is neither speculative nor back-of-theenvelope. Indeed, nothing shows that the Forest Service 

failed to take the “hard look” that NEPA requires. N. Alaska 

Env’t Ctr. v. Kempthorne, 457 F.3d 969, 975 (9th Cir. 2006). 

The district court rightfully noted that “the Forest Service 

[didn’t] ignore[] the project’s environmental effects” nor 

“attempt[] to obscure the project’s environmental effects.” 

In analyzing the project for any “extraordinary 

circumstances” under § 220.6(a)(2), the Forest Service 

extensively evaluated the project’s impact on the Inyo’s 

wildlife, botany, water, noise, and cultural heritage. It 

concluded none existed.

• The Forest Service found that any impact on 

the sage-grouse would be “minor and 

temporary” given that the bird would avoid 

the immediate vicinity of the drill sites. 

While it acknowledged that the drilling could 

lead to “physiological stress, reduced 
FRIENDS OF THE INYO V. USFS 39

foraging success, and exposure to higher 

predation rates” for the sage-grouse, the 

Service concluded the effect would be shortterm and not affect their viability in the 

project area. 

• The Forest Service also concluded that the 

project would have no long-term impact on 

the migration corridor of local wildlife, like 

the mule deer, given the small area involved. 

• The Forest Service foresaw no impact on 

plant species of conservation concern. 

• The Forest Service saw no effect on surface 

water, floodplains, wetlands, or groundwater.

• The Forest Service consulted local Indian 

tribes and invited tribal monitors to observe 

the project’s implementation. It also 

analyzed any impact on religious, cultural, 

archaeological, and historical sites and found 

none.

• The Forest Service further considered the 

impact on riparian conservation, recreational 

management, and scenery. Again, it 

concluded the project would have little to no 

impact on these areas.

So after considering all this, it is hard to see what further 

environmental analysis would uncover. 

If anything, it was the Forest Service’s hypervigilance as 

the Inyo’s environmental steward that caused this issue. 

After all, it was the Forest Service’s insistence that the 

mineral-exploration phase be followed with re-habitation 
40 FRIENDS OF THE INYO V. USFS

and revegetation efforts that took the project out of 

Categorical Exclusion-8’s one-year time limit. If KORE 

was allowed to proceed without the Forest Service-mandated 

reclamation, then § 220(a)(2) would have easily been 

satisfied. So even if the Forest Service erred by relying on 

two categorical exclusions, it didn’t materially alter the 

environmental review process and thus any “error” was 

harmless.

Think of it this way: The Forest Service could have 

complied with § 220.6(a)(2) by simply breaking the mineral 

exploration project into two separate “proposed actions.” 

Remember the regulation excuses an environmental impact 

statement or assessment if “[t]he proposed action is within a 

category listed in § 220.6(d) and (e).” 36 C.F.R. 

§ 220.6(a)(2). But the regulation doesn’t directly define 

what constitutes a “proposed action.”1 So the Forest Service 

could have just said that the mineral exploration phase 

constituted one “proposed action” and that the reclamation 

phase was another “proposed action.” Under that approach, 

the two “proposed action[s]” would have easily fallen into

the two separate categorical exclusions.

Indeed, the Forest Service’s decision memo all but says 

that the two phases are two distinct “action[s].” According 

to the decision memo, despite the majority’s assumption, the 

“[restoration] activities are not required to support the 

mineral exploration activities.” As a result, the Forest 

1 Under the regulations, “Major Federal action or action” broadly 

includes any “new and continuing activities, including projects and 

programs entirely or partly financed, assisted, conducted, regulated, or 

approved by federal agencies; new or revised agency rules, regulations, 

plans, policies, or procedures; and legislative proposals.” 40 C.F.R. 

§ 1508.1(q)(2) (2020).
FRIENDS OF THE INYO V. USFS 41

Service determined it would “us[e] an additional [categorical 

exclusion] category to cover these [restoration] activities.” 

It makes sense to consider the two phases as different 

“proposed action[s]” because the habitat restoration would 

come only after the mining operation had been completed 

and all equipment removed. While this approach might not 

work for all projects, it does here and so any error in reading 

§ 220.6(a)(2) was harmless.

II.

Because any error in relying on two categorical 

exclusions was harmless, I respectfully dissent.