Tenth Circuit: “Overall Project Purposes” Under CWA § 404 May Include Multiple Interrelated Applicant Goals

Case: Save The Colorado v. Graham (Nos. 25-1137, 25-1231 & 25-1299)
Court: United States Court of Appeals for the Tenth Circuit
Date: September 15, 2026
Author: TYMKOVICH, Circuit Judge

1) Introduction

This consolidated appeal arises from the Army Corps of Engineers’ 2017 issuance of a Clean Water Act (“CWA”) § 404 permit authorizing Denver Water to place fill material in South Boulder Creek to raise Gross Dam and expand Gross Reservoir (the “Moffat System Collection Project”). Environmental organizations (Save the Colorado and others) challenged the permit and the accompanying NEPA process, alleging that the Corps’ fourteen-year review improperly narrowed the project’s purpose, used an inadequate cost methodology, and failed to sufficiently account for climate change’s effects on streamflow and project feasibility.

The district court agreed, vacated the permit, and permanently enjoined enlargement of the reservoir (including tree removal and water diversion). By the time of appeal, construction to raise the dam was complete, but Denver Water could not fill the reservoir because of the injunction. The Tenth Circuit reversed, holding that the Corps permissibly defined “overall project purposes” to include multiple related goals, and that the Corps’ cost and climate-change analyses were reasonable under deferential APA review.

2) Summary of the Opinion

3) Analysis

A. Precedents Cited (and How They Drove the Result)

1. NEPA’s role as procedural “informer,” not a substantive veto

• Seven Cnty. Infrastructure Coal. v. Eagle County, 605 U.S. 168 (2025)
  The court invoked Seven Cnty. repeatedly to frame NEPA as procedural—EISs “inform agency decisionmaking, not paralyze it”—and to justify “substantial deference” in NEPA compliance review. This backdrop supported upholding the Corps’ choices on both alternatives framing and how far to go with climate modeling.
• Dep't of Transp. v. Pub. Citizen, 541 U.S. 752 (2004)
  Cited in describing when an EIS is required (versus FONSI), reinforcing the court’s focus on NEPA’s structured process rather than an outcome mandate.

2. APA deference and the “hard look” in technical domains

• Am. Wild Horse Campaign v. Raby, 144 F.4th 1178 (10th Cir. 2025) and New Mexico ex rel. Richardson v. Bureau of Land Mgmt., 565 F.3d 683 (10th Cir. 2009)
  These cases supplied the standard APA “arbitrary-and-capricious” formulation (failure to consider an important aspect, explanation counter to evidence, etc.). The panel used that framework to reject the district court’s approach and to re-center review on whether the Corps’ explanations were reasonable.
• Hillsdale Env't Loss Prevention, Inc. v. U.S. Army Corps of Eng'rs, 702 F.3d 1156 (10th Cir. 2012)
  The lynchpin for CWA § 404 review in this opinion. The panel relied on Hillsdale for two key propositions: (i) “partial relief” on remand (including new mitigation) can defeat mootness; and (ii) for the “clearly demonstrate” LEDPA burden, the Corps need only take “a hard look” and reach a “meaningful conclusion based on the evidence,” not satisfy a court’s preferred methodology.
• W. Watershed Project v. U.S. Bureau of Land Mgmt., 76 F.4th 1286 (10th Cir. 2023)
  Cited to reinforce deference to agency technical judgments, particularly when an agency explains model uncertainty and methodological limits.

3. Defining project purpose in § 404 alternatives analysis

• Greater Yellowstone Coal. v. Flowers, 359 F.3d 1257 (10th Cir. 2004) (quoting Sylvester v. U.S. Army Corps of Eng'rs, 882 F.2d 407 (9th Cir. 1989))
  These cases established that the Corps must account for the applicant’s objectives when analyzing alternatives, while avoiding a purpose statement that “preclude[s] the existence of” alternatives by definition. The panel used them to validate the Corps’ applicant-goal-sensitive “overall project purposes,” and to rebut the claim that the purpose statement was outcome-determinative (emphasizing that many alternatives remained after screening).
• Del. Riverkeeper Network v. U.S. Army Corps of Eng'rs, 869 F.3d 148 (3d Cir. 2017) and Friends of Santa Clara River v. U.S. Army Corps of Eng'rs, 887 F.3d 906 (9th Cir. 2018)
  Cited for the textual point that “overall project purposes” appears in the plural, supporting the court’s reading that multiple purposes may be considered.

4. Climate change modeling discretion

• Nat'l Audubon Soc'y v. U.S. Army Corps of Eng'rs, 991 F.3d 577 (4th Cir. 2021)
  Used to support the proposition that an agency may decide not to engage in quantitative modeling when it reasonably explains uncertainty and limitations—especially where the scientific link is contested or not sufficiently reliable for the decision at hand.

5. Mootness (constitutional and prudential) and post-completion NEPA/CWA cases

• Rio Grande Silvery Minnow v. Bureau of Reclamation, 601 F.3d 1096 (10th Cir. 2010) and Wyoming v. U.S. Dep't of Agric., 414 F.3d 1207 (10th Cir. 2005)
  Provided the “some effect in the real world” test for redressability and constitutional mootness.
• Audubon of Kan., Inc. v. U.S. Dep't of Interior, 67 F.4th 1093 (10th Cir. 2023)
  Used for the proposition that redressability must persist throughout litigation or the matter becomes moot.
• Caddo Nation of Okla. v. Wichita & Affiliated Tribes, 877 F.3d 1171 (10th Cir. 2017) and Airport Neighbors All., Inc. v. United States, 90 F.3d 426 (10th Cir. 1996)
  Supported the rule that completion of an action often moots NEPA claims, but not when partial relief (like enjoining use/operation pending further analysis) remains possible.
• Sierra Club v. U.S. Army Corps of Eng'rs, 803 F.3d 31
  Reinforced that injunctions against operation/use pending further analysis can still supply effective relief post-construction.
• Winzler v. Toyota Motor Sales U.S.A., Inc., 681 F.3d 1208 (10th Cir. 2012) and Sierra Club, Inc. v. Bostick, 787 F.3d 1043 (10th Cir. 2015)
  Framed prudential mootness as discretionary, but the panel declined to reach it because it resolved the case on the merits.

6. Appellate jurisdiction and “practical finality”

• Rocky Mountain Wild v. Dallas, 98 F.4th 1263 (10th Cir. 2024), W. Energy All. v. Salazar, 709 F.3d 1040 (10th Cir. 2013), and Ausmus v. Perdue, 908 F.3d 1248 (10th Cir. 2018)
  These cases supplied the “administrative-remand rule” and the “practical-finality exception.” The panel reasoned that a permanent injunction effectively dictated an outcome and could render appellate review impracticable later, thus allowing review despite potential remand-finality concerns.

7. Textual interpretation and deference to agency interpretations

• Ysleta Del Sur Pueblo v. Texas, 596 U.S. 685 (2022) (quoting Henson v. Santander Consumer USA, Inc., 582 U.S. 86 (2017))
  Grounded the “different words, different meanings” presumption used to distinguish “basic purpose” from “overall project purposes.”
• Kisor v. Wilkie, 588 U.S. 558 (2019)
  The panel rejected reliance on Auer deference because it found § 230.10(a)(2) unambiguous; Kisor limits deference to genuinely ambiguous regulations.

8. Cost analysis in EIS/alternatives review

• Utahns for Better Transp. v. U.S. Dep't of Transp., 305 F.3d 1152 (10th Cir. 2002) and Habitat Educ. Ctr., Inc. v. U.S. Forest Serv., 673 F.3d 518 (7th Cir. 2012)
  These cases supported the view that agencies need “more than nothing” but not exhaustive precision, and that agencies have discretion to decide when information is sufficient to proceed.

B. Legal Reasoning

1. The opinion’s central doctrinal move: “basic purpose” ≠ “overall project purposes”

The court treated the regulatory text as determinative. Under 40 C.F.R. § 230.10(a)(3), “basic purpose” matters for the threshold question whether a project is water dependent. But under § 230.10(a)(2), “overall project purposes” (plural) informs practicability (cost, technology, logistics) and alternatives screening. The Corps applied that distinction: it defined the project’s “basic purpose” broadly (“to provide supplemental water supply”)—triggering the non-water-dependent presumption—while defining “overall project purposes” more specifically to include Denver Water’s interconnected goals (increasing firm yield to the Moffat Collection System and addressing system imbalance/overreliance).

The panel held the Environmental Groups’ “interchangeable phrases” reading incompatible with:

• textual cues (plural “purposes”);
• the canon that different terms ordinarily carry different meanings; and
• regulatory context (water-dependency screening requires generality; alternatives practicability requires specificity).

2. LEDPA “clearly demonstrate” burden did not convert review into de novo judgment

Although everyone agreed the project was non-water-dependent (so the Corps had to “clearly demonstrate” the LEDPA and overcome a presumption that less damaging practicable alternatives exist), the court emphasized that judicial review remains deferential. The question was not whether judges found the LEDPA “clearly demonstrated” in the first instance, but whether it was arbitrary and capricious for the Corps to find it had done so—an approach the panel linked to Hillsdale Env't Loss Prevention, Inc. v. U.S. Army Corps of Eng'rs.

3. Cost methodology: acceptability of planning-level comparative estimates

The Corps’ RDC approach (capital “ROM” costs plus a 50% contingency factor for land, engineering, legal/financial, etc.) was upheld because the agency:

• explained why alternative-by-alternative precision was “implausible” at early screening stages;
• supported the 50% factor with component estimates and comparison to other projects; and
• used the figures for comparison, not as a final budget.

The court treated these explanations as sufficient under APA review, particularly given the breadth of the initial alternatives universe (303 proposals) and the need for consistent comparative assumptions.

4. Climate change: “considered and explained” can be enough without quantification

The Corps acknowledged potential climate impacts (earlier runoff timing; reduced flows; evapotranspiration; drought) and addressed comments urging quantitative modeling. It nonetheless declined to model impacts, citing lack of “generally accepted” methods for translating temperature changes into incremental streamflow/reservoir changes at the relevant scale, plus model uncertainty and data limitations. The panel characterized the Corps’ conclusions as reasoned technical judgment, entitled to deference, particularly where the agency evaluated proffered studies and explained why they were not sufficiently reliable for decisive quantification.

C. Impact

1. Purpose statements in § 404/NEPA reviews: greater room for multi-goal framing

The most consequential aspect of the decision is its explicit textual holding that “overall project purposes” in 40 C.F.R. § 230.10(a)(2) can encompass multiple interrelated applicant goals, and that the Corps may define those purposes more specifically than the “basic purpose.” Practically, this tends to:

• give applicants (and the Corps) more flexibility to define the “purpose” used to screen alternatives, so long as goals are related and supported in the record; and
• make it harder for challengers to force agencies into a single “most general” purpose that broadens the alternatives set.

2. Comparative cost screening: endorsement of standardized multipliers at early stages

For future permitting and NEPA documents, the decision supports the use of planning-level, standardized contingencies to compare alternatives—provided the agency documents why precision is impracticable and why the chosen method is reliable enough for comparative screening.

3. Climate change analysis: reinforces discretion over “how” to analyze, not whether to mention

The court did not say climate change is irrelevant; it upheld the Corps because it discussed climate change and explained why quantification was not methodologically dependable. The decision thus reinforces a pattern: agencies reduce litigation risk by (i) acknowledging climate risks, (ii) engaging comments, and (iii) explaining uncertainty and methodological choice—rather than ignoring the subject.

4. Post-construction litigation: partial-relief theory can keep cases alive

On mootness, the opinion underscores that even when the permitted discharge is complete, claims may remain live if a remand could produce meaningful mitigation or modified permit conditions. That is significant for long-duration infrastructure projects where litigation outlasts construction.

4) Complex Concepts Simplified

• CWA § 404 permit: Federal authorization required to place dredged or fill material into “waters of the United States,” including certain wetlands and streams.
• LEDPA (Least Environmentally Damaging Practicable Alternative): The Corps may permit a discharge only if no other practicable alternative would cause less aquatic harm (and not create other significant adverse consequences).
• “Practicable” (40 C.F.R. § 230.10(a)(2)): An option is practicable if it is available and can be done considering cost, technology, and logistics in light of the project’s overall purposes.
• “Basic purpose” vs. “overall project purposes”:
  • Basic purpose = high-level essence used to decide whether the project is water-dependent.
  • Overall project purposes = more specific articulation (can be plural) used to evaluate which alternatives are practicable.
• Non-water-dependent presumption (40 C.F.R. § 230.10(a)(3)): If a project doesn’t inherently need to be in the aquatic site, the Corps must “clearly demonstrate” the LEDPA, and less damaging practicable alternatives are presumed available unless shown otherwise.
• NEPA / EIS: NEPA requires an Environmental Impact Statement for major federal actions significantly affecting the environment; it is primarily procedural (disclose impacts and alternatives), not a mandate to choose the greenest option.
• APA arbitrary-and-capricious review: Courts generally uphold agency decisions if the agency considered relevant factors and reasonably explained its choices—especially on technical issues.
• Constitutional vs. prudential mootness:
  • Constitutional mootness asks whether a court can still provide any effective relief.
  • Prudential mootness asks whether relief would be so marginal or disruptive that the court should decline to decide (a discretionary doctrine).

5) Conclusion

Save The Colorado v. Graham is a major Tenth Circuit decision on CWA § 404 and NEPA litigation involving large water infrastructure. Its key doctrinal contribution is a textual, regulation-focused holding: “overall project purposes” under 40 C.F.R. § 230.10(a)(2) can include multiple interrelated applicant goals and need not collapse into the “basic purpose” used for water-dependency analysis. Coupled with emphatic APA deference on cost screening and climate-change methodology, the decision raises the bar for challengers seeking to invalidate § 404 permits based on disputes over purpose formulation and the level of quantitative modeling. At the same time, the court’s mootness discussion confirms that post-construction environmental cases can remain live where remand may still produce mitigation or other partial relief.