United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued January 11, 2017 Decided August 4, 2017

No. 15-5332

AMERICAN WILD HORSE PRESERVATION CAMPAIGN, ET AL.,

APPELLANTS

v.

SONNY PERDUE, SECRETARY, U.S. DEPARTMENT OF 

AGRICULTURE, ET AL.,

APPELLEES

Appeal from the United States District Court

for the District of Columbia

(No. 1:14-cv-00485)

David Zaft argued the cause for appellants. With him on 

the briefs was William S. Eubanks II. Katherine A. Meyer

entered an appearance.

Mark R. Haag, Attorney, U.S. Department of Justice, 

argued the cause for appellees. With him on the brief were 

John C. Cruden, Assistant Attorney General at the time the 

brief was filed, Meredith L. Flax and Stuart Gillespie, 

Attorneys, U.S. Department of Justice, and Steven F. Hirsch, 

Attorney-Advisor, U.S. Department of Agriculture. 

Caroline Lobdell was on the brief for defendantsintervenors-appellees. 
2

Before: TATEL, MILLETT, and WILKINS, Circuit Judges.

Opinion for the Court filed by Circuit Judge MILLETT.

MILLETT, Circuit Judge: Since 1975, the United States 

Forest Service has protected and managed wild horses in the 

Devil’s Garden section of the Modoc National Forest in 

Northern California. That wild horse territory originally 

consisted of two separate tracts of land of roughly 236,000 

acres. But at some point in the 1980s, a Forest Service map 

added in an approximately 23,000 acre tract of land known as 

the Middle Section and, in so doing, linked the two territories 

into a larger and unified wild horse territory of approximately 

258,000 acres. For more than two decades, the Service 

continued to describe the territory as a single contiguous area 

and to manage wild horses in the Middle Section. 

In 2013, the Forest Service publicly acknowledged the 

cartographic confusion, declared the expansion reflected in the 

1980s map to be an administrative error, and without further 

analysis redrew the wild horse territory’s lines to exclude the 

Middle Section and to revert to two disjoined tracts of land. 

The American Wild Horse Preservation Campaign and other 

plaintiffs filed suit alleging that the Service’s revamping of the 

territorial lines violated numerous federal laws. We agree. A 

23,000 acre tract of land and two decades of agency 

management cannot be swept under the rug as a mere 

administrative mistake. We accordingly reverse in part and 

remand for the Service to address rather than to ignore the 

relevant history. 

I

The Modoc National Forest comprises approximately 1.6

million acres of federally managed land in Northern California. 
3

Included within the Forest are several hundred thousand acres 

of protected wild horse land that make up the Devil’s Garden 

Wild Horse Territory. The Forest Service’s management of the 

Devil’s Garden Wild Horse Territory is subject to a 

Matryoshka doll of nesting federal statutes.

First, the Wild and Free-Roaming Horses and Burros Act

of 1971 (“Wild Horses Act”), 16 U.S.C. § 1331 et seq., charges 

the Secretaries of Interior and Agriculture with “protect[ing]

and manag[ing] wild free-roaming horses and burros” on 

federal lands, id. § 1333(a). The Secretaries “may designate 

and maintain specific ranges on public lands as sanctuaries for 

their protection and preservation,” and “shall manage wild 

free-roaming horses and burros in a manner that is designed to 

achieve and maintain a thriving natural ecological balance[.]” 

Id. The Secretaries also “shall maintain a current inventory” 

and set “appropriate management levels” for “wild freeroaming horses and burros,” to ensure a “thriving natural 

ecological balance” and to “protect the range from the 

deterioration associated with overpopulation.” Id. 

§ 1333(b)(1), (2). Wild horses are to be treated “in the area 

where presently found” as an integral component “of the 

natural system of the public lands.” Id. § 1331. 

The Service is responsible for implementing the Wild 

Horses Act within the National Forest System. 36 C.F.R. 

§ 222.60(a). In 1980, the Service promulgated regulations 

providing that it “shall: * * * [e]stablish wild horse and burro 

territories” (“Wild Horse Territories”), and then “[a]nalyze,” 

“develop[,] and implement a management plan” for each Wild 

Horse Territory. Id. § 222.61(a)(3)–(4). The Service may 

“update[]” the Wild Horse Territory Plans “whenever needed, 

as determined by conditions on each territory.” Id.

§ 222.61(a)(4). The Service must also “[m]aintain a current 

inventory of [wild horses] on each [Wild Horse Territory] to 
4

determine * * * where excess animals exist[,]” id.

§ 222.61(a)(5), set “appropriate management levels” for those 

horses and burros, and “remov[e] or destr[oy] * * * excess 

animals,” id. § 222.61(a)(6); see also id. § 222.69.

Service regulations further define “[w]ild free-roaming 

horses and burros” to mean “all unbranded and unclaimed 

horses and burros and their progeny that” either “have used 

lands of the National Forest System on or after December 15, 

1971,” or that “do hereafter use these lands as all or part of their 

habitat.” 36 C.F.R. § 222.60(b)(13). Those animals retain 

federal protection even if they “move to lands of other 

ownership or jurisdiction as a part of their annual territorial 

habitat pattern or for other reasons.” Id. § 222.65. 

Second, the National Forest Management Act of 1976

(“Forest Management Act”), 16 U.S.C. § 1600 et seq.,

“requires the Secretary of Agriculture to ‘develop, maintain, 

and, as appropriate, revise land and resource management plans 

for units of the National Forest System.’” Ohio Forestry Ass’n 

v. Sierra Club, 523 U.S. 726, 728 (1998) (quoting 16 U.S.C. 

§ 1604(a)). The Secretary has delegated his authority under the 

Act to the Service. 36 C.F.R. § 200.3(b).

The Forest Management Act establishes a two-step 

procedure for managing National Forest System lands. The 

Service must (i) “develop, maintain, and, as appropriate, revise 

land and resource management plans” for national forests

(“Forest Plans”), and (ii) ensure that all “[r]esource plans and 

permits, contracts, and other instruments for the use and 

occupancy of National Forest System lands,” including Wild 

Horse Territory Plans, are “consistent with the [Forest Plans].” 

16 U.S.C. § 1604(a), (i). 

The Forest Management Act sets out several general 

conditions with which the development of Forest Plans must 
5

comply. See 16 U.S.C. § 1604(f). For instance, the Service 

must “provide for public participation in the development, 

review, and revision of [Forest Plans].” Id. § 1604(d). In 

addition, the Plans must “be embodied in appropriate written 

material, including maps and other descriptive documents,” id.

§ 1604(f)(2), and “be prepared by an interdisciplinary team,” 

id. § 1604(f)(3). The Forest Service may amend Forest Plans 

“in any manner whatsoever after final adoption[.]” Montanans

for Multiple Use v. Barbouletos, 568 F.3d 225, 227 (D.C. Cir. 

2009) (quoting 16 U.S.C. § 1604(f)(4)); see also 36 C.F.R. 

§ 219.13(a). But if an “amendment” of a Forest Plan “would 

result in a significant change,” the amendment process must 

comply with heightened procedural requirements. See 16 

U.S.C. § 1604(f)(4). Regardless of whether an amendment is 

significant, however, the Forest Service must allow for public 

participation in the amendment process. Id. 

Service regulations elaborate upon the procedures for 

developing and amending Forest Plans. 36 C.F.R. §§ 219.1–

219.19. As relevant here, the Service must develop Forest 

Plans in coordination with the statutorily required 

interdisciplinary team, extensive public participation and 

comment, and related efforts of other federal agencies, state 

and local governments, and Indian tribes. Id. §§ 219.4, 219.5. 

Formulation of such Plans must take into consideration, inter 

alia, “fish and wildlife species,” “grazing and rangelands,” 

“habitat and habitat connectivity,” “[h]abitat conditions,” and 

“[l]and status and ownership, use, and access patterns relevant 

to the [Forest Plan] area.” Id. § 219.10(a). The Plan must also

“maintain the diversity of plant and animal communities” 

within the forest. Id. § 219.9. 

Third, the National Environmental Policy Act (“NEPA”), 

42 U.S.C. § 4321 et seq., obligates federal agencies to analyze 

the environmental consequences of proposed federal actions. 
6

See generally id. § 4332. Under NEPA, federal agencies must 

conduct an Environmental Assessment to determine whether a 

proposed federal action will have a significant effect on the 

environment. 40 C.F.R. §§ 1508.9(a), 1508.13. If that 

Assessment indicates that the environmental impacts will not 

be significant, the agency must issue a “finding of no 

significant impact,” id. § 1501.4(e), explaining why the agency 

action will not substantially affect the environment, id.

§ 1508.13. But if the Assessment indicates that the proposed 

action will “significantly affect[] the quality of the human 

environment,” the agency must prepare an Environmental 

Impact Statement detailing: “(i) the environmental impact of 

the proposed action, (ii) any adverse environmental effects 

which cannot be avoided should the proposal be implemented, 

(iii) alternatives to the proposed action, (iv) the relationship 

between local short-term uses of [the] environment and the 

maintenance and enhancement of long-term productivity, and

(v) any irreversible and irretrievable commitments of resources 

which would be involved in the proposed action should it be 

implemented.” 42 U.S.C. § 4332(C); see also 40 C.F.R. 

§ 1502.2.

Fourth, the Administrative Procedure Act, 5 U.S.C. § 551 

et seq., prohibits arbitrary and capricious actions by federal 

agencies and mandates that they give reasoned explanation for 

the actions that they do take. See, e.g., Motor Vehicle Mfrs. 

Ass’n v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 42–52 

(1983); see also Public Citizen, Inc. v. FAA, 988 F.2d 186, 197 

(D.C. Cir. 1993) (“The requirement that agency action not be 

arbitrary or capricious includes a requirement that the agency 

adequately explain its result[.]”).
7

II

While this dispute concerns a 2013 decision by the Service

to change the boundaries of the Devil’s Garden Wild Horse 

Territory, the origins of the controversy reach back four 

decades. 

A

In 1975, the Service issued its first Devil’s Garden Wild 

Horse Territory Plan. The Wild Horse Territory specified in 

that plan consisted of two separate areas of land totaling 

approximately 236,000 acres. The Territory did not include a 

parcel of land of approximately 23,000 acres, known as the 

Middle Section, which conjoined those two separate tracts. 

Sometime in the 1980s, a Forest Service map depicted the 

Devil’s Garden Wild Horse Territory as a single contiguous 

area of land that included the Middle Section. According to the 

Service, the map’s “revised boundary” “incorporated about 

another 23,631 acres of land,” resulting in a Wild Horse 

Territory of “approximately 258,000 acres in size.” J.A. 261. 

Then, in 1991, the Service issued a Forest Plan for the 

Modoc National Forest. While the Plan did not include a map 

of the Wild Horse Territory, the Forest Plan acknowledged that 

the Service “is legally obligated to manage horses within a 

258,000-acre wild horse territory,” J.A. 584, and announced 

that “[t]he Forest has one wild horse territory of about 258,000 

acres,” J.A. 585. 

The 1991 Forest Plan also stated that the Service “prepared 

the Wild Horse [Territory] Plan in 1985, which identifies a 

population objective of 275–335 animals to manage.” J.A. 
8

585–586.1 The interdisciplinary team that prepared the 1991 

Forest Plan expressly denominated the “Wild Horse [Territory] 

Plan” to be “consistent with, and still appropriate for, the 

[1991] Forest Plan.” J.A. 578. As a result, the Wild Horse 

Territory Plan, which the interdisciplinary team understood to 

include a single 258,000 acre territory, was expressly 

“incorporated by reference” into the 1991 Forest Plan. J.A. 

578; see also J.A. 588 (describing “Wild Horse [Territory] 

Plan” as an “[e]xisting [p]lan[] [r]etained and [i]ncorporated by 

[r]eference into the [1991] Forest Plan and [u]pdated to be 

[c]onsistent”) (emphasis added). When the 1991 Forest Plan 

was finally approved, it “supersede[d] most previous Forest 

resource management plans.” J.A. 578. 

Over the next two decades, the Service actively managed

and recorded wild horses in the Middle Section, as evidenced 

by official Wild Horse Inventory Reports from that time period. 

B

The Modoc National Forest is divided into grazing 

“allotments.” Generally speaking, the Wild Horse Territory 

boundaries do not hew precisely to those of the grazing 

allotments. Rather, the Wild Horse Territory covers portions 

of various allotments. The disputed Middle Section consists of 

portions of five allotments: the Triangle, Avanzino, Carr, 

Timbered Mountain, and Big Sage Allotments. In 1971, when 

the Wild Horses Act was adopted, two portions of allotments 

in the Middle Section were privately held: the Triangle

portion, and the Avanzino portion. In total, those private lands 

covered approximately 5,923 acres. The other portions—the 

Carr, Timbered Mountain, and Big Sage portions—were 

publicly held in 1971. Consequently, as stipulated by the 

 1 The Service denies that there was a 1985 Wild Horse Territory 

Plan. 
9

Service, the “majority of the lands in the [Middle Section] were 

publicly held in 1971[.]” J.A. 66.

In 1976, the Service acquired the Triangle Allotment as 

public land. That means that, in 1991, when the Service 

adopted the Forest Plan that included the Middle Section in the 

Wild Horse Territory, only one portion of the Middle Section 

was privately held: the Avanzino portion. That private land 

covered approximately 10% of the Middle Section’s acreage. 

C

In July 2011, the Service issued a scoping letter proposing 

to update the Devil’s Garden Wild Horse Territory Plan. That 

letter indicated that the Wild Horse Territory was 

“approximately 268,750 acres in size,” J.A. 757, and included 

a map depicting the Wild Horse Territory as a single, 

contiguous area of land including the Middle Section. 

A year later, the Service turned its attention to the 

discrepancy between the Wild Horse Territory boundaries in 

the 1991 Forest Plan and the boundaries in the original 1975 

Wild Horse Territory Plan. The Forest Service issued a new 

scoping letter in December 2012 stating that, “[d]uring the mid1980’s, the [Modoc National Forest’s Devil’s Garden and 

Doublehead Ranger Districts] appear[] to have adjusted the 

[Wild Horse Territory] boundary for administrative 

convenience” to “incorporate[] about [an additional] 23,631 

acres of land.” J.A. 731. The December 2012 scoping letter 

called this an “administrative error” and “propose[d] to return 

to the management of wild horses within the [Wild Horse 

Territory] boundary established in 1975.” J.A. 732.

In August 2013, the Service released a Final 

Environmental Assessment to accompany its proposed 

revisions to the size of the Wild Horse Territory. Like the 
10

scoping letter, the Final Environmental Assessment labeled the 

inclusion of the Middle Section “[a]n administrative error,” 

J.A. 264, 708, and “propose[d] to return to the management of 

wild horses within the [Wild Horse Territory] boundary” as 

originally established, J.A. 264, 710. The Service also issued 

a Decision Notice and Finding of No Significant Impact, 

incorporating the Final Environmental Assessment by 

reference. That Decision formally adopted the proposed action 

set forth in the Final Environmental Assessment and concluded

that contracting the Wild Horse Territory as proposed would 

not have a sufficiently significant environmental impact to 

necessitate an Environmental Impact Statement. 

Also in August 2013, the Service issued its new Devil’s 

Garden Wild Horse Territory Plan. The 2013 Wild Horse 

Territory Plan indicated that the boundaries of the Wild Horse 

Territory would mirror those of the 1975 Wild Horse Territory 

Plan, which did not include the disputed Middle Section. 

D

After exhausting their administrative remedies, plaintiffs, 

the American Wild Horse Preservation Campaign, Return to 

Freedom, and Carla Bowers (collectively, “Campaign”), all of 

which advocate for the protection of wild horses, filed suit in 

the United States District Court for the District of Columbia. 

They contend that the Service’s 2013 revision of the Devil’s 

Garden Wild Horse Territory violated the Administrative 

Procedure Act, the Wild Horses Act, the Forest Management 

Act, and NEPA. See American Wild Horse Preservation 
11

Campaign v. Vilsack, No. 14-0485, Docket Entry No. 1 

(D.D.C. Mar. 24, 2014) (Compl. ¶¶ 58–91).

2

On September 30, 2015, the district court granted 

summary judgment for the Service. American Wild Horse 

Preservation Campaign v. Vilsack, 133 F. Supp. 3d 200 

(D.D.C. 2015). The court concluded that the Service 

permissibly found that the Middle Section was never 

incorporated into the Wild Horse Territory, and that any 

reference to a single, contiguous Wild Horse Territory was a 

mere “administrative error.” Id. at 212; see also id. at 212–218. 

The district court also ruled that the Service’s redrawing of the 

boundaries of the Wild Horse Territory did not amount to a 

“significant” amendment warranting formal procedures under 

the Forest Management Act, as the Service was already 

managing the Wild Horse Territory as two noncontiguous 

units. Id. at 219–220. The district court similarly reasoned 

that, because the Service’s “boundary adjustment simply 

corrected an administrative error and resulted in the continued 

management of the [Middle Section] as distinct from the [Wild 

Horse Territory],” the Service reasonably determined that its

boundary correction would not significantly affect the quality 

of the human environment, within the meaning of NEPA. Id.

at 221. 

III

We review the district court’s grant of summary judgment 

de novo. Theodore Roosevelt Conservation P’ship v. Salazar, 

661 F.3d 66, 72 (D.C. Cir. 2011). Under the Administrative 

Procedure Act, we must set aside the Service’s actions if they 

are “arbitrary, capricious, an abuse of discretion, or otherwise 

 2 The Campaign also originally challenged the management 

level for horses set by the Service, but does not press that issue on 

appeal.
12

not in accordance with law.” 5 U.S.C. § 706(2)(A). That 

standard obligates the agency to examine all relevant factors 

and record evidence, and to articulate a reasoned explanation 

for its decision. See State Farm, 463 U.S. at 52. Generally, a

rule is arbitrary and capricious if the agency: “(1) ‘has relied 

on factors which Congress has not intended it to consider,’ (2) 

‘entirely failed to consider an important aspect of the problem,’ 

(3) ‘offered an explanation for its decision that runs counter to 

the evidence before the agency,’ or (4) [offers an explanation 

that] ‘is so implausible that it could not be ascribed to a 

difference in view or the product of agency expertise.’” United 

States Sugar Corp. v. EPA, 830 F.3d 579, 606 (D.C. Cir. 2016) 

(quoting State Farm, 463 U.S. at 43). 

We hold that the Service’s decision to eliminate the 

Middle Section of the Devil’s Garden Wild Horse Territory 

Plan was arbitrary and capricious in two respects. First, the 

Service failed to acknowledge and adequately explain its 

change in policy regarding the management of wild horses in 

the Middle Section as part of a single, contiguous protected 

Wild Horse Territory. Second, the Service failed to consider 

adequately whether an Environmental Impact Statement was 

required under NEPA. Accordingly, we reverse the district 

court’s grant of summary judgment for the Service.

A

A central principle of administrative law is that, when an 

agency decides to depart from decades-long past practices and 

official policies, the agency must at a minimum acknowledge 

the change and offer a reasoned explanation for it. See Encino 

Motorcars, LLC v. Navarro, 136 S. Ct. 2117, 2126 (2016)

(“[A]n ‘[u]nexplained inconsistency’ in agency policy is ‘a 

reason for holding an interpretation to be an arbitrary and 

capricious change from agency practice[.]’”) (second alteration 
13

in original) (quoting National Cable & Telecomms. Ass’n. v. 

Brand X Internet Servs., 545 U.S. 967, 981 (2005)); Lone 

Mountain Processing, Inc. v. Secretary of Labor, 709 F.3d 

1161, 1164 (D.C. Cir. 2013) (“[A]n agency changing its course 

must supply a reasoned analysis indicating that prior policies 

and standards are being deliberately changed, not casually 

ignored. Failing to supply such analysis renders the agency’s 

action arbitrary and capricious.”) (internal quotation marks and 

citation omitted); United Mun. Distribs. Grp. v. FERC, 732 

F.2d 202, 210 (D.C. Cir. 1984) (“[A]gencies must give a 

reasoned analysis for departures from prior agency practice[.]”)

(citing Greater Boston Television Corp. v. FCC, 444 F.2d 841, 

852 (D.C. Cir. 1970)).

3

For that reason, we have long held that “[a]n agency may 

not * * * depart from a prior policy sub silentio[.]” United 

States Telecom Ass’n v. FCC, 825 F.3d 674, 707 (D.C. Cir. 

2016) (quoting FCC v. Fox Television Stations, Inc., 556 U.S. 

502, 515 (2009)); Verizon v. FCC, 740 F.3d 623, 636 (D.C. Cir. 

2014) (same); Comcast Corp. v. FCC, 600 F.3d 642, 659 (D.C. 

Cir. 2010) (same).

 3

 See also Mistick PBT v. Chao, 440 F.3d 503, 512 (D.C. Cir. 

2006) (“Where an agency departs from established precedent without 

a reasoned explanation, its decision will be vacated as arbitrary and 

capricious.”) (quoting Ramaprakash v. FAA, 346 F.3d 1121, 1130 

(D.C. Cir. 2003)); Nuclear Energy Inst., Inc. v. EPA, 373 F.3d 1251, 

1296 (D.C. Cir. 2004) (“If an agency decides to change course * * *

we require it to supply a reasoned analysis indicating that prior 

policies and standards are being deliberately changed, not casually 

ignored.”) (internal quotation marks and citation omitted); National

Classification Comm. v. United States, 779 F.2d 687, 696 (D.C. Cir. 

1985) (“[A]n agency may depart from past policies or practices if the 

agency also provides a reasoned explanation for its actions.”) 

(emphasis added).
14

The Service’s main defense in this case, however, has been

to insist that nothing changed in 2013. In the Service’s view, 

the Middle Section was never part of the Devil’s Garden Wild 

Horse Territory, and so there was nothing to change. That 

argument flatly defies the plain text of the official 1991 Forest 

Plan, repeated official agency statements, and two decades of 

agency practice. Blinders may work for horses, but they are no 

good for administrative agencies. 

The Service argues secondly that the inclusion of the 

Middle Section must be ignored because it lacked the legal 

authority to add it in the mid-1980s. That argument never even 

leaves the starting gate.

1

The Service tries to shrug off its inclusion of the Middle 

Section in the Wild Horse Territory as some sort of 

inconsequential and passing “administrative error,” as though 

that label nullifies any agency duty to reasonably explain its 

about-face. But there is no “oops” exception to the duty of 

federal agencies to engage in reasoned decisionmaking. 

Accordingly, the Service’s decision runs aground on both the 

facts and the law. 

As a matter of factual reality, this case involves far more 

than an errant map. The Service’s inclusion of the Middle 

Section in the Wild Horse Territory is well documented in the 

administrative record, and it was reconfirmed repeatedly by 

two decades of agency practice and official pronouncements. 

Most significantly, the official 1991 Forest Plan formally 

documented that the Modoc National Forest “has one wild 

horse territory of about 258,000 acres,” J.A. 585, and that the 

Service “is legally obligated to manage horses within [that]

258,000-acre wild horse territory,” J.A. 584. That language 
15

was no divagation. The Forest Plan was the product of more 

than ten years of formal study by the Service involving 

participation by: (i) hundreds of members of the public who 

submitted numerous comments and gave 105 testimonials at 

almost 50 public meetings, (ii) five other federal government 

agencies, (iii) eleven state agencies, (iv) various local 

governments, agencies, and elected officials; (v) four tribal 

communities, and (vi) various industry and non-profit groups. 

Such extensive study and wide participation renders fanciful 

the notion that 23,000 acres of wild horse territory simply 

slipped in unnoticed. 

The Service notes that the record contains no affirmative 

indications that the Service “intended to expand the boundaries 

of the existing Territory when it adopted the [1991] Forest 

Plan.” Service’s Br. 16. True. But that is because the Forest 

Plan treated the determination of the Wild Horse Territory’s 

size as a decision that had already been made in an earlier 

Service plan. See J.A. 585–586 (“The [Modoc National] Forest 

has one wild horse territory of about 258,000 acres * * * *

Fulfilling requirements of the [Wild Horse] Act the [Service] 

prepared the Wild Horse Management Plan in 1985[.]”). To be 

sure, the Service denies that there was such a 1985 plan. 

Service’s Br. 15 n.7. But that misses the point: The 1991 

Forest Plan that the Service drafted, and in the formulation of 

which it was the key player, described the Wild Horse 

Territory’s expanded 258,000 acreage as a fait accompli by 

1991. So the absence of expansion talk in the Forest Plan is no 

surprise.

What the 1991 Forest Plan did do was formally document

a single, contiguous, 258,000 acre Wild Horse Territory that 

could only exist through inclusion of the Middle Section, 

incorporate that status into the Plan through a notice-andcomment process, and set a herd management level within that 
16

territory of “275–335 animals to manage,” J.A. 586. In 

addition, the Forest Plan’s explicit description of the size and 

management levels for the Wild Horse Territory largely

repudiates the Service’s claims that the plan was “of no 

practical consequence for the management of the disputed area 

because the Forest Service never set appropriate management 

levels for horses on the [portions of allotments] within the 

disputed area.” Service’s Br. 44. 

The Service also argues that it did not intend to expand the 

territory. But after-the-fact claims about agency intentions do 

not work when agency actions evince the opposite. And the 

Service’s actions for at least twenty years corroborated the 

Middle Section’s inclusion in the Wild Horse Territory.

More specifically, Wild Horse Inventory Reports for the 

Devil’s Garden Wild Horse Territory documented the

Service’s treatment of portions of the Middle Section as part of 

the Territory after the 1991 Forest Plan. In 1992 and 1993, the 

Wild Horse Inventory Reports counted the “total [number of] 

horses[,] mules & burros” in ten regions within the Modoc 

National Forest. J.A. 859, 861. Big Sage, which is partially 

contained within the Middle Section, and Boles Meadow,

which is entirely within the Middle Section, were both

excluded from the original 1975 Wild Horse Territory 

boundaries. But they are listed as two of the ten main regions 

that Service observers surveyed for wild horses in 1992 and 

1993. The 1992 Wild Horse Inventory Report documented 33 

horses in Big Sage and Boles Meadow combined—more than 

ten percent of the total headcount of 321 horses for the entire 

Wild Horse Territory. The 1993 Wild Horse Inventory Report 

documented five horses in Big Sage and Boles Meadow

combined, out of 58 horses in total. 
17

In addition, statements accompanying the 1992 and 1993 

Wild Horse Inventory Reports implicitly treated Big Sage and 

Boles Meadow as within the Wild Horse Territory. For 

example, in the 1992 Wild Horse Inventory Report, the Service 

noted that some of the wild horses spotted were located outside 

the Wild Horse Territory. See, e.g., J.A. 862 (1992 Wild Horse 

Inventory Report: “Ten horses were observed in the West 

Grizzlie * * * Allotment. This area is outside of the wild horse 

territory. Every effort should be made to return these animals 

to the territory and/or [have them] removed.”). By implication, 

the remaining wild horses that the Service counted—including 

those wild horses in Big Sage and Boles Meadow—were 

considered to be inside the Wild Horse Territory. Moreover, 

the 1993 Wild Horse Inventory Report recommended that 

certain wild horses found outside the Wild Horse Territory be

relocated to Boles Meadow. J.A. 860 (1993 Wild Horse 

Inventory Report: “There are 3 [wild horses] in the Blue Mtn. 

Allotment that need to be relocated to the Boles [Meadow]. 

The Blue Mtn. Allotment is outside of the Territory.”) 

(emphasis added). That has to mean that the Service 

considered Boles Meadow (in the Middle Section) to be within 

the Wild Horse Territory. Why else would the Service devote 

scarce resources to shuffling horses from one location outside 

the Territory to another one also outside the Territory?

Starting in 1994, the Wild Horse Inventory Reports began

not only reporting the number of wild horses identified in 

specific areas, but also listing “designated management herd 

minimum size[s]” (which appear to be analogous to what the 

Service now terms “appropriate management levels”) for each 

region. Those post-1994 reports continued to treat portions of 

the Middle Section as part of the Wild Horse Territory by 

designating a management herd minimum size for “Big Sage” 

and “Boles [Meadow].” J.A. 857.
18

All subsequent Wild Horse Inventory Reports in the 

record—for the years 1996, 1997, 1998, 2002, 2004, and 

2010—also established “designated management herd 

minimum sizes” for Big Sage and Boles Meadow. See, e.g.,

J.A. 851.4

 On top of that, the 2002 and 2010 Wild Horse 

Inventory Reports listed “Avanzino”—also contained in the 

Middle Section—as one of the regions surveyed. 

The pattern continues in the post-1994 Wild Horse 

Inventory Reports. For instance, the 1998 Wild Horse 

Territory Report recommended the relocation of wild horses 

found in Boles Meadow. See J.A. 852 (1998 Wild Horse 

Inventory Report: “Our plans in 1999 are to capture and 

relocate 100 adult horses on the Emigrant Spring, Boles, Pine 

Springs, [and] Surveyor’s Valley allotments.”) (emphasis 

added). Other Wild Horse Inventory Reports recommended 

that wild horses found outside the Wild Horse Territory be 

relocated to Boles Meadow. See, e.g., J.A. 856 (1996 Wild 

Horse Inventory Report: “Horse sign has been observed in the 

Garden Tank and Lower Fletcher Creek areas. Th[ese] area[s] 

[are] outside of the Wild Horse Territory and these horses 

should be moved back over to the Timbered Ridge Area (Boles 

[Meadow]).”) (emphasis added); J.A. 858 (same for 1994 Wild 

Horse Inventory Report). 

Further, the 1997 Wild Horse Inventory Report 

inventoried 289 wild horses in total, but noted that 40 of those 

wild horses were found in the “Mtn. Dome Area,” which was 

“outside * * * the * * * Devil’s Garden Wild [H]orse 

Territor[y].” J.A. 854. The remaining 249 wild horses—

including 17 wild horses in Big Sage and 36 wild horses in 

 4 If, as it appears, “designated management heard minimum 

sizes” are synonymous with “appropriate management levels,” the 

presence of those figures contradicts the Service’s claim that levels 

were never set. 
19

Boles Meadow—were deemed to be “within the territory.” 

Compare J.A. 853 (inventory chart), with J.A. 854 (“Actual 

horses counted were 249 head within the territory.”). 

Similarly, in the 2002 Wild Horse Inventory Report, the 

Service stated that the “[a]ctual horses counted were 500 head 

within the wild horse territory.” J.A. 850 (emphasis added). 

The inventory report shows that this 500 figure included 88 

wild horses in Big Sage, 11 wild horses in Avanzino, and 64 

wild horses in Boles Meadow. J.A. 850. Further, to reduce this

500 figure, the Service planned “to capture and adopt 160 adult 

horses on the Emigrant Spring, Big Sage, and Avanzino 

allotments.” J.A. 850. And “additional * * * horses [would] 

need to be removed to be compliant with the Devil’s Garden 

[Wild Horse Territory Plan].” J.A. 850 (emphasis added).5

 

The Service does not deny what the Inventory Reports say 

or their treatment of wild horses in the Middle Section. Instead, 

the Service says we should pay no mind to those reports 

because those horses were “included solely for administrative 

convenience.” Service’s Br. 36–37. For that proposition, the 

Service points to a 2014 e-mail from a retired Service employee

who purportedly was responsible for creating the 1980s-era 

Service map that first depicted the single, contiguous Wild 

Horse Territory. The email states that the retired employee

“assigned Administrative [Appropriate Management Levels] to 

the Grazing Allotments for ease of managing the existing 

horses & the areas they were inhabiting.” J.A. 767 (emphasis 

omitted). The email further states that “[t]he Administrative 

 5 The Wild Horse Inventory Reports also consistently surveyed, 

and set appropriate management levels for, wild horses in the 

Timbered Mountain Allotment. Most of the Timbered Mountain 

Allotment is part of the original two-part Wild Horse Territory, but 

part of it is in the Middle Section. The pasture within the Timbered 

Mountain Allotment that is most heavily used by wild horses 

includes area within the Middle Section.
20

map & [Appropriate Management Levels] were never intended 

to change the [Wild Horse Territory] Plan,” and were only 

made “for ease of managing the existing situation within the 

[Wild Horse Territory].” J.A. 767. 

That email is at best a post hoc rationalization that was not 

part of the record before the Service when it issued its 2013 

decision, and thus cannot help the Service here. See District

Hosp. Partners v. Burwell, 786 F.3d 46, 55 (D.C. Cir. 2015)

(“To ensure that we review only those documents that were 

before the agency, we do not allow parties to supplement the 

record unless they can demonstrate unusual circumstances 

justifying a departure from this general rule.”) (internal 

quotation marks and citation omitted); American Wildlands v. 

Kempthorne, 530 F.3d 991, 1002 (D.C. Cir. 2008).

On top of that, the email explanation makes little sense. 

What administrative ease or convenience is there for counting 

in an inventory horses that should not count? Clearly the 

Service understood the relevant boundaries of Big Sage and 

Boles Meadow; otherwise, it could not have counted the wild 

horses in those areas when preparing the Wild Horse Inventory 

Reports. So if Big Sage and Boles Meadow were simply not 

part of the Wild Horse Territory, all the Service had to do was 

not include those wild horses in the Wild Horse Inventory 

Reports, or note that Big Sage and Boles Meadow were not part 

of the Wild Horse Territory. That was not hard to do; the 

Service repeatedly did it for other wild horses found outside the 

Wild Horse Territory. Convenience alone, then, does not 

explain why the Service not only monitored and managed wild 

horses in the Middle Section, but did so at the same time it 
21

refused to count all of the other horses that it deemed to be 

outside of the Wild Horse Territory.6 

In sum, the formal and published 1991 Forest Plan along 

with at least two decades of official Wild Horse Inventory 

Reports and the management activities they document together 

demonstrate that for twenty years the Service officially treated 

portions of the Middle Section as part of a single, contiguous 

Devil’s Garden Wild Horse Territory. Given that longstanding 

practice, it is unsurprising that the Service’s 2011 scoping letter 

for the revision at issue here treated the Middle Section as part 

of the Wild Horse Territory. While the agency tries to whistle 

past that factual graveyard, the established pattern of agency 

conduct and formalized positions cannot be evaded. The 

Service’s failure even to acknowledge its past practice and 

formal policies regarding the Middle Section, let alone to 

explain its reversal of course in the 2013 decision, was arbitrary 

and capricious. See, e.g., Encino Motorcars, 136 S. Ct. at

2126; West Deptford Energy, LLC v. FERC, 766 F.3d 10, 12 

(D.C. Cir. 2014) (vacating agency action because, inter alia, 

the agency “provided no reasoned explanation for how its 

decision comports with * * * prior agency practice”); accord

Northwest Envtl. Def. Ctr. v. Bonneville Power Admin., 477 

F.3d 668, 687, 690 (9th Cir. 2007) (invalidating an agency 

action because the agency “depart[ed] from its long-standing 

 6 That is just the beginning of the e-mail’s credibility problems. 

For instance, the email states that the retired employee “developed 

the Administrative map lumping the [Wild Horse] [T]erritory into 

one in the early 1990’s.” J.A. 767 (emphasis omitted). But the 

parties agree that the map in question actually originated in the 

1980s. The email further asserts that, “[i]n the early 1980’s Triangle 

was acquired through a land exchange,” and “[b]ecause we had 

horses in the areas,” he “lump[ed] them in with [the Wild Horse 

Territory].” J.A. 767. But there is no dispute that the Service 

acquired the Triangle lands in 1976. 
22

practice” and “two-decade-old precedent without supplying a 

reasoned analysis for its change of course”).

2

The Service also trots out would-be legal impediments to 

the Forest Plan’s inclusion of the Middle Section in the Wild 

Horse Territory, insisting that it lacked the legal authority to 

incorporate the Middle Section and failed to comply with the 

procedural requirements for such a measure. But the Service’s 

supposed failure to comply with all of the applicable laws for 

amending the boundaries of a Wild Horse Territory a quarter 

century ago does not mean that the expansion never happened. 

A failure to comply with the requirements of the Wild Horses 

Act or Administrative Procedure Act would not render the 

change to the territory void from its inception. 

The Service’s assumption that a purported past mistake 

would excuse the agency’s current missteps is wrong. In 

administrative law, as elsewhere, two wrongs do not make a

right. In addition, regardless of whether the Service’s original 

decision was lawful, the Service never grappled with the 1991 

Forest Plan’s formal recognition of the unitary wild horse 

territory, the inventory reports, or its actions monitoring and 

regulating wild horses in the Middle Section for twenty years. 

Accordingly, whatever the Service’s past transgressions, “we 

cannot condone the ‘correction’ of one error by the 

commitment of another.” Gray v. Mississippi, 481 U.S. 648, 

663 (1987); see also Natural Res. Def. Council v. Thomas, 805 

F.2d 410, 435 (D.C. Cir. 1986). 

3

Of course, the Service is free to change its policies going 

forward if doing so is reasonable. But the agency first must at 

least “display awareness that it is changing position” and 
23

“show that there are good reasons for the new policy.” Fox 

Television, 556 U.S. at 515. If instead “an agency glosses over 

or swerves from prior precedents without discussion it may 

cross the line from the tolerably terse to the intolerably mute.” 

Greater Boston, 444 F.2d at 852, quoted in State Farm, 463 

U.S. at 57; see also Encino Motorcars, 136 S. Ct. at 2125

(“Agencies are free to change their existing policies so long as 

they provide a reasoned explanation for the change.”).

7

Accordingly, if the Service wishes now to formally revert 

to the 1975 territorial lines, it must acknowledge that it is 

actually changing course and explain its reasons for doing so. 

Whatever the cause of the initial incorporation of the Middle 

Section into the Wild Horse Territory, that action morphed into

a multi-decade agency policy—formalized in part by the 1991 

Forest Plan—that cannot be abandoned without some reasoned 

explanation. The Service’s attempt to slam shut the barn door 

after the horse already bolted is not sufficient.

B

The Campaign next challenges the Service’s 

determination that the removal of the Middle Section did not 

constitute a significant amendment under the Forest 

Management Act. The Forest Management Act provides that,

if “amendment” of a Forest Plan “would result in a significant 

change in such [Forest Plan],” the Service must comply with 

heightened procedural requirements including public 

participation through a three-month study, public meetings, 

 7

 See also Atchison, Topeka & Santa Fe Ry. Co. v. Wichita Bd. 

of Trade, 412 U.S. 800, 808 (1973) (plurality opinion) (“Whatever 

the ground for the departure from prior norms, however, it must be 

clearly set forth [by the agency] so that the reviewing court may 

understand the basis of the agency’s action and so may judge the 

consistency of that action with the agency’s mandate.”).
24

and compliance with the Multiple Use Sustained Yield Act of 

1960, 16 U.S.C. §§ 528–531. See 16 U.S.C. § 1604(d), (e),

(f)(4) (emphasis added). 

In its Final Environmental Assessment, the Service 

concluded that amending the 1991 Forest Plan to redraw the 

Wild Horse Territory boundary was a “non-significant” action,

and thus did not trigger the formal amendment process. The 

Service instead complied with the Act’s less rigorous 

procedural requirements for alterations to a Forest 

Management Plan, 16 U.S.C. § 1604(d); see id. § 1604(f)(4).

The Campaign argues that excision of the Middle Section 

from the Wild Horse Territory made a “significant” change to 

the Forest Plan itself, and thus triggered the Forest 

Management Act’s more formal and elaborate review process. 

That is not correct. While elimination of the Middle Section 

worked an important and consequential change in the Wild 

Horse Territory itself, the removal of those 23,000 acres had no 

material impact on the 1991 Forest Plan governing 1.6 million 

acres of the Modoc National Forest.

In interpreting the Forest Management Act, the Forest 

Service has explained that non-significant changes include 

“[a]djustments of management area boundaries or management 

prescriptions resulting from further on-site analysis when the 

adjustments do not cause significant changes in the multipleuse goals and objectives for long-term land and resource 

management.” FOREST SERV., U.S. DEP’T OF AGRICULTURE,

FOREST SERVICE MANUAL § 1926.51 (2015). By contrast, to 

constitute a “significant change” to a Forest Plan, the change 

would have to “significantly alter the long-term relationship 

between levels of multiple-use goods and services originally 

projected,” “have an important effect on the entire [Forest 

Plan],” or “affect land and resources throughout a large portion 
25

of the planning area during the planning period.” Id.

§ 1926.52.8

Viewed against the comprehensive scope and operation of 

the 1991 Forest Plan, the Service’s reworking of the Wild 

Horse Territory boundaries was not a significant change. The 

1991 Forest Plan governs the entire Modoc National Forest. In 

formulating the plan, the Service balanced a panoply of 

considerations, including air quality, cultural resources, 

biodiversity, fire management, mineral leasing, pest control, 

range conditions, range management, livestock grazing, 

recreational uses, riparian resources, soil and water quality, 

timber clearance, and wildlife protection. 

Within the Forest Plan, wild horse management is just one 

consideration, among a multitude of others, that fall within the 

broader consideration of the Plan’s range-management subcomponent. Other factors that the Service considers in 

developing a range management program are livestock 

management and diversity of ecological conditions. For 

instance, one objective of range management is “to produce 

desired expressions of” “herbaceous, shrub, and forest 

vegetation” through livestock grazing. J.A. 585. And even 

within the subject of wild horse management, the physical 

dimensions of the wild horse territory are just one element.

In other words, wild horse management is a factor of a 

factor of a factor that the Service considered when developing 

the Modoc Forest Plan. In addition, the Service’s proposed 

reduction of the Wild Horse Territory by approximately 23,000 

 8 The Forest Service Manual is a compendium of “legal 

authorities, responsibilities, delegations, and general instruction[s],” 

36 C.F.R. § 216.2(a), that “establish[es] the general framework for 

the management and conduct of Forest Service programs,” id.

§ 216.2(c). 
26

acres represents at most a 1.5% change in the status of an area 

that will still remain within the federally managed Modoc 

National Forest. Even then, the Service will continue to 

superintend the remaining Wild Horse Territory, balancing 

wild horse management against livestock management and 

range biodiversity, and then balancing all of those rangemanagement considerations against such concerns as air, soil,

and water quality, and all of the other aspects of forest 

management. 

When viewed in that context, the Service reasonably 

concluded that its proposed modification of the Wild Horse 

Territory’s boundaries would likely have at most a slight effect 

on the “multiple-use” goals of the Forest Plan in the “longterm,” and will not affect the “entire” Forest Plan or a “large 

portion” of the planning area.9

Finally, because we hold that the boundary change was not 

a “significant” change for purposes of the Forest Management 

Act, we need not address the Campaign’s argument that NEPA 

requires an Environmental Assessment for significant changes

under the Forest Management Act.

C

The Campaign’s final argument arises under NEPA and 

the APA. Specifically, the Campaign argues that the Service’s 

failure to prepare an Environmental Impact Statement 

addressing the boundary changes violated NEPA and was the 

product of arbitrary and capricious decisionmaking. We agree. 

 9 The Campaign does not challenge the criteria set forth in the 

Forest Service Manual for a “significant” change. Accordingly, we 

need not determine what level of deference is properly afforded to 

the Service’s interpretation of the Act. Cf. Baptist Mem’l Hosp.-

Golden Triangle v. Sebelius, 566 F.3d 226, 228 (D.C. Cir. 2009).
27

In finding no significant environmental impact that would 

warrant an Environmental Impact Statement, the Service’s 

NEPA analysis never came to grips with its departure from past 

practice, and thus never analyzed the potential environmental 

significance of its 2013 decision to contract the boundaries of 

the Wild Horse Territory by approximately ten percent.

Our “role in reviewing an agency’s decision not to prepare 

an [Environmental Impact Statement] is a ‘limited’ one, 

‘designed primarily to ensure that no arguably significant 

consequences have been ignored.’” Myersville Citizens for a 

Rural Community, Inc. v. FERC, 783 F.3d 1301, 1322 (D.C. 

Cir. 2015) (quoting TOMAC v. Norton, 433 F.3d 852, 860 

(D.C. Cir. 2006)). Our task in particular is to ensure that the 

Service, in finding no significant impact, (i) “accurately 

identified the relevant environmental concern,” (ii) took a 

“hard look at the problem” in making its decision, (iii) has 

made “a convincing case for its finding of no significant 

impact,” and (iv) “has shown that even if there is an impact of 

true significance, an [Environmental Impact Statement] is 

unnecessary because changes and safeguards in the project 

sufficiently reduce the impact to a minimum.” Sierra Club v. 

Van Antwerp, 661 F.3d 1147, 1154 (D.C. Cir. 2011) (quoting 

TOMAC, 433 F.3d at 861); see also Sierra Club v. Department 

of Transp., 753 F.2d 120, 127 (D.C. Cir. 1985). 

The Service failed that task because its environmental 

analysis did not “accurately identif[y] the relevant

environmental concern.” Van Antwerp, 661 F.3d at 1154

(emphases added; internal quotation marks and citation 

omitted). Here, the relevant environmental concern was the 

effect of the boundary modification on the wild horse 

population in the Devil’s Garden area. The Service not only 

failed to address that concern, it denied its very existence. The 

Service insisted that the redrawn boundary lines would have 
28

“no effect” on the ground because it was only “correct[ing] a 

boundary established for administrative convenience.” J.A. 

372. That is, the only sense in which the Service “identified” 

the effect of the boundary modification on wild horses was by 

insisting that there was “no effect” and that nothing had ever 

really changed. That head-in-the-sand approach to past agency 

practice is the antithesis of NEPA’s requirement that an 

agency’s environmental analysis candidly confront the relevant 

environmental concerns.

10 

More to the point, because the Service actually managed 

wild horses within portions of the Middle Section for two 

decades as though they were within the Wild Horse Territory, 

the 2013 boundary change entailed far more than scratching out 

a few lines in the 1991 Forest Plan. Yet the Service refused to

even consider the possibility of that broader, real-world impact. 

Thus, while the Service “identifie[d]” some effects on wild 

horses as an environmental concern, the Service did not 

forthrightly and “accurately identif[y] the relevant

environmental concern”—the actual effects of the boundary 

modification on wild horses in the Devil’s Garden area. Van 

Antwerp, 661 F.3d at 1154 (emphases added; internal quotation 

marks and citation omitted).

Likewise, the Service’s Finding of No Significant Impact 

not only failed to take a “hard look” at the consequences of the 

boundary change, it averted its eyes altogether. Van Antwerp, 

661 F.3d at 1154. As a result, the Service’s analysis entirely 

omitted a “discussion of the relevant issues and opposing 

viewpoints,” Myersville, 783 F.3d at 1325 (internal quotation 

 10 In its August 2013 Environmental Assessment, the Service 

also referred to the inclusion of the Middle Section as an 

“administrative error.” J.A. 264. Saying something was both done 

for “administrative convenience” and because of “an administrative 

error” is incoherent. The former is purposeful; the latter is not. 
29

marks and citation omitted), because the Service refused even 

to entertain the opposing premise that the boundary 

modification did more than correct a few stray lines of text in 

the 1991 Forest Plan. The Service’s decision thus failed to 

“make a convincing case for its finding of no significant 

impact.” Van Antwerp, 661 F.3d at 1154 (internal quotation 

marks and citation omitted). 

For those reasons, the Service’s environmental analysis 

and Finding of No Significant Impact were arbitrary and 

capricious.

11 

* * * * *

“Facts are stubborn things.”12 But record facts are the grist 

of reasoned agency decisionmaking. In this case, the Service 

brushed aside critical facts about its past treatment of and 

 11 The Campaign, in a footnote, also lobs an accusation of 

prejudgment and bad-faith at the Service, charging it with acting at 

the behest of the Farm Bureau. The Campaign has not come close to 

meeting the high bar necessary to prove such allegations. See, e.g.,

Air Transp. Ass’n of America, Inc. v. National Mediation Bd., 663 

F.3d 476, 487–488 (D.C. Cir. 2011). Regardless, its footnoted 

allegation is insufficient to preserve this argument on appeal. See

CTS Corp. v. EPA, 759 F.3d 52, 64 (D.C. Cir. 2014) (“A footnote is 

no place to make a substantive legal argument on appeal; hiding an 

argument there and then articulating it in only a conclusory fashion 

results in forfeiture.”).

12 See Statement of John Adams Made When Defending the 

Accused British Regulars at the Boston Massacre Trial, quoted in

WILLIAM GORDON, THE HISTORY OF THE RISE, PROGRESS, AND 

ESTABLISHMENT, OF THE INDEPENDENCE OF THE UNITED STATES OF 

AMERICA: INCLUDING AN ACCOUNT OF THE LATE WAR; AND OF 

THE THIRTEEN COLONIES, FROM THEIR ORIGIN TO THAT PERIOD, 

Vol. 1, p. 296 (1788).
30

official statements about the boundaries of the Devil’s Garden 

Wild Horse Territory. As a result, the Service failed: (i) to 

acknowledge and adequately explain its change in course

regarding the size of the Devil’s Garden Wild Horse Territory

and its management of wild horses within the Middle Section, 

and (ii) to consider or to adequately analyze the environmental 

consequences of those changes. Accordingly, we reverse the 

district court’s grant of summary judgment in part and direct 

the district court to remand to the Service for further 

consideration. 

So ordered.