Wyoming Applies Arbitrary-and-Capricious Review to Agency Legislative Rulemaking Under the WAPA (APOZ Aquifer-Protection Zoning Upheld)

1. Introduction

In Warren Livestock, LLC, et al. v. Board of County Commissioners, County of Albany, Wyoming, 2026 WY 76 (July 13, 2026), the Wyoming Supreme Court resolved consolidated challenges to Albany County’s 2023 amendments to its Aquifer Protection Overlay Zone (APOZ), adopted to protect drinking-water quality in the Casper Aquifer east of Laramie. The Appellants comprised (1) several ranching/landholding LLCs (collectively “Warren Livestock”) and (2) a large group of affected landowners (“Property Owners”). The Appellee was the Albany County Board of County Commissioners (“Board”).

The case returned to the Court after Bienz v. Bd. of Cnty. Comm'rs, Cnty. of Albany, 2024 WY 102, ¶¶ 22-25, 556 P.3d 227, 235-36 (Wyo. 2024) (“Bienz I”), which held that agency “legislative” actions are reviewable under the Wyoming Administrative Procedure Act (WAPA) even if not “contested cases.” On remand, the district court upheld the remaining “live” portions of the 2023 amendments, including the 35-acre minimum lot size within the APOZ and a distinct procedure for APOZ boundary changes.

The Supreme Court addressed four core questions: (1) whether the Board had statutory authority to adopt zoning regulations aimed at aquifer protection; (2) whether differing amendment procedures for overlay boundaries versus zoning districts violated Wyoming equal protection; (3) whether the arbitrary-and-capricious standard applies to agency legislative action; and (4) whether the 2023 APOZ amendments were arbitrary or unlawful.

2. Summary of the Opinion

The Court affirmed. It held:

  • The Board acted within its zoning authority under Wyo. Stat. Ann. § 18-5-201(a) to protect public health, safety, and welfare by safeguarding the Casper Aquifer.
  • The separate procedures for APOZ boundary amendments (as compared to zoning district amendments) survive rational basis equal protection review.
  • Critically, agency legislative action is reviewed under the arbitrary-and-capricious standard (with substantial-evidence review reserved for evidentiary findings from trial-type proceedings).
  • On this record, the 2023 amendments—especially the 35-acre minimum lot size—were not arbitrary or capricious and did not contravene Wyoming law, including statutes protecting subdivision exemptions.

A special concurrence agreed but emphasized the WAPA’s text alone compels arbitrary-and-capricious review, without needing federal analogies. A partial dissent would have held the Board lacked authority to regulate for water-quality purposes, viewing DEQ authority as exclusive absent explicit delegation.

3. Analysis

A. Precedents Cited

1) The Bienz I foundation: reviewability of legislative-type local agency action

The Court framed this appeal as a sequel to Bienz v. Bd. of Cnty. Comm'rs, Cnty. of Albany, 2024 WY 102, ¶¶ 22-25, 556 P.3d 227, 235-36 (Wyo. 2024) (“Bienz I”), which rejected the idea that “legislative” characterization defeats WAPA review. That holding set the stage for this opinion’s major doctrinal move: identifying the correct standard of review for legislative-type amendments once reviewability is established.

2) County power as delegated and strictly construed

The authority analysis rests on Wyoming’s consistent theme: counties are creatures of statute and possess only delegated powers. The Court invoked:

  • Bd. of Trs. of Laramie Cnty. v. Bd. of Cnty. Comm'rs of Laramie Cnty., 2020 WY 41, ¶ 12, 460 P.3d 251, 256-57 (Wyo. 2020) (counties have only delegated powers).
  • Seherr-Thoss v. Teton Cnty. Bd. of Cnty. Comm'rs, 2014 WY 82, ¶ 24, 329 P.3d 936, 946 (Wyo. 2014) (local zoning cannot override state law/policy).
  • Schoeller v. Bd. of Cnty. Comm'rs of Park Cnty., 568 P.2d 869, 876 (Wyo. 1977) (Dillon’s rule framing: express powers, implied powers, indispensable powers; doubts resolved against the county).

These cases supplied the interpretive posture: broad zoning language exists, but the Court must ensure no conflict with state statutory schemes.

3) Broad zoning discretion and “public welfare” zoning purposes

To characterize Wyo. Stat. Ann. § 18-5-201(a) as a “broad grant,” and to underscore county discretion in land-development regulation, the Court relied on:

  • Wilson Advisory Comm. v. Bd. of Cnty. Comm'rs, 2012 WY 163, ¶¶ 26-27, 292 P.3d 855, 862 (Wyo. 2012) (broad grant; implied power to make zoning meaningful; discretion in regulation formulation).
  • Bd. of Cnty. Comm'rs of Teton Cnty. v. Crow, 2003 WY 40, ¶ 42, 65 P.3d 720, 734 (Wyo. 2003) (county may promote welfare via zoning; “health, safety, morals, general welfare” construed broadly).

The Court also cited national authority recognizing environmental protection as a valid zoning objective (e.g., Salamar Builders Corp. v. Tuttle; Timber Trails Assocs. v. Plan. & Zoning Comm'n of Town of Sherman), reinforcing that zoning may be used to reduce pollution risks, including by minimum lot sizes intended to mitigate septic impacts.

4) State-local coexistence: when local regulation is permissible alongside state regulation

The centerpiece for harmonizing county zoning with statewide environmental regulation is River Springs Liab. Co. v. Bd. of Cnty. Comm'rs of Cnty. of Teton, 899 P.2d 1329, 1336 (Wyo. 1995), quoted for the principle that local regulation may operate “so long as regulation by the county does not conflict with a regulation by the state.” This was the Court’s principal vehicle to reject “field preemption” arguments premised on DEQ authority.

5) Equal protection framework

For equal protection, the Court applied Wyoming’s rational basis line:

  • Mills v. Reynolds, 837 P.2d 48, 53 (Wyo. 1992) (classifications must rationally relate to legitimate concerns).
  • Reiter v. State, 2001 WY 116, ¶ 26, 36 P.3d 586, 594 (Wyo. 2001) (equal protection does not require different things be treated the same).
  • State v. Johnson, 2026 WY 1, ¶ 51, 582 P.3d 380, 400 (Wyo. 2026) and Martin v. Bd. of Cnty. Comm'rs of Laramie Cnty., 2022 WY 21, ¶ 31, 503 P.3d 68, 78 (Wyo. 2022) (strong presumption of validity; heavy burden on challenger).

6) Standard-of-review doctrine: from contested cases to informal actions to rulemaking

The opinion’s doctrinal advance builds from Wyoming administrative review precedents:

  • Dale v. S & S Builders, LLC, 2008 WY 84, ¶¶ 20-23, 188 P.3d 554, 560-61 (Wyo. 2008) (substantial evidence governs evidentiary findings; arbitrary-and-capricious as “safety net”).
  • Newman v. State ex rel. Wyo. Workers' Safety & Comp. Div., 2002 WY 91, ¶ 23, 49 P.3d 163, 172 (Wyo. 2002) (source of the “safety net” concept, later modified by Dale).
  • N. Laramie Range Found. v. Converse Cnty. Bd. of Cnty. Comm'rs, 2012 WY 158, ¶ 18, 290 P.3d 1063, 1072 (Wyo. 2012) (arbitrary-and-capricious review applies to informal adjudicatory hearings lacking trial-type indicia).

Then, the Court imported the federal APA’s rulemaking review model:

  • Motor Vehicle Mfrs. Ass'n of the U.S., Inc. v. State Farm Mut. Auto. Ins. Co., 463 U.S. 29, 41-43, 103 S.Ct. 2856, 2865-66 (1983) (arbitrary-and-capricious review of informal rulemaking; agency must consider relevant data and articulate a rational connection).
  • Citizens to Preserve Overton Park v. Volpe, Bowman Transportation, Inc. v. Arkansas-Best Freight System, Inc., and Burlington Truck Lines v. United States (the “reasoned decisionmaking” lineage).

This federal reliance is not merely decorative: it supplies the “why” for using arbitrary-and-capricious review when there is no trial-type record, and it fits the WAPA’s text, which—like 5 U.S.C. § 706—expressly authorizes setting aside action that is “arbitrary” or “capricious.”

B. Legal Reasoning

1) Authority: aquifer protection fits “public health, safety, morals and general welfare” zoning

The Court treated the aquifer as a drinking water source whose protection is quintessentially linked to “health,” “safety,” and “welfare” under Wyo. Stat. Ann. § 18-5-201(a). It reasoned that nothing in the Wyoming Constitution, the Environmental Quality Act, or DEQ’s rules withdraws or preempts county zoning authority to restrict land uses in the unincorporated area for such purposes. The Board’s 35-acre minimum lot size was therefore evaluated as a land-use density control—an orthodox zoning tool—rather than as an impermissible attempt to administer DEQ’s permit program.

The key move was harmonization rather than exclusivity: DEQ sets statewide water-quality standards and permitting rules; counties may impose land-use constraints that reduce risk, so long as they do not conflict with DEQ rules. The Court emphasized DEQ’s statutory structure anticipates coordination with local entities, including possible delegation, and indeed DEQ encouraged additional protective measures.

2) Equal protection: different procedures for overlay boundary changes are rational

Warren Livestock’s primary live equal-protection claim targeted the 2023 amendment stating that ACZR zoning-district amendment procedures were “inapplicable” to APOZ boundary amendments, which instead would proceed under W.S. § 18-5-202 and the WAPA. Applying rational basis review, the Court accepted that an overlay zone serves a specialized protective function and may justifiably have tailored amendment procedures. The classification was deemed coherent: all properties within the APOZ are treated under the same overlay-boundary rules, and properties outside it remain governed by the standard district-amendment process.

The Court also found another equal-protection claim moot because later amendments removed the challenged “previously surveyed parcels” and “clear and convincing” limitations for exclusion requests.

3) The new rule: arbitrary-and-capricious review applies to agency legislative action under WAPA

The Court held the district court erred by reading Bienz I as silently excluding arbitrary-and-capricious review. The WAPA’s standards do not distinguish adjudicatory from legislative action; and the Court aligned Wyoming doctrine with the dominant administrative-law approach:

  • Substantial evidence applies when reviewing evidentiary findings made after trial-type proceedings, with arbitrary-and-capricious as a “safety net.”
  • Arbitrary-and-capricious applies to agency actions not developed through closed, trial-type evidentiary records—explicitly including legislative-type rulemaking.

The special concurrence agreed with the result but argued the Court need not go beyond the WAPA’s plain text: Wyo. Stat. Ann. § 16-3-114(c)(ii)(A) says a court “shall” set aside agency action found “arbitrary” or “capricious,” without carving out legislative action.

4) Application: the 35-acre minimum lot size survived arbitrary-and-capricious review

On the merits, the Court emphasized that arbitrary-and-capricious review is deferential and asks whether there is a rational basis in the record, not whether challengers can marshal contrary evidence. The Board’s cited studies—especially the CAPP’s explicit identification of “thirty-five acre lots” as a “large lot zoning” aquifer-protection tool, plus studies linking septic density to nitrate risk—provided a rational connection between the perceived risk and the chosen policy response.

The Court also rejected:

  • The claim that the overlay “effectively rezoned” land to agriculture: underlying zoning continues to govern uses unless the overlay is more restrictive; matching the agricultural minimum lot size does not convert the use classification.
  • The claim that 35 acres violates Wyo. Stat. Ann. § 18-5-201’s limitation protecting subdivision exemptions under Wyo. Stat. Ann. § 18-5-303(a)(i): county regulations expressly preserved those exemptions, so qualifying divisions are not barred.
  • The claim that disappointed expectations and nonconforming status make the regulation unlawful: relying on Sheridan Cnty. Comm'n v. V.O. Gold Props., LLC, 2011 WY 16, ¶ 14, 247 P.3d 48, 52 (Wyo. 2011), the Court reiterated there is no vested right in prospective land uses.

C. Impact

1) Administrative law: clarified standard of review for local “agency legislation”

The opinion’s most durable statewide effect is procedural and doctrinal: Wyoming courts reviewing agency legislative actions under the WAPA should apply the arbitrary-and-capricious standard. After Bienz I established reviewability, this decision supplies the missing piece—how to review. This will matter for counties, boards, and state agencies adopting generally applicable policies outside contested cases.

2) Land use and environmental governance: local zoning as complementary risk management

Substantively, the decision signals that Wyoming counties may use zoning tools—like minimum lot sizes and overlay zones—to mitigate environmental risks tied to land development, even when the DEQ regulates related subject matter, so long as the county does not conflict with state standards or permit systems. The Court’s use of River Springs Liab. Co. v. Bd. of Cnty. Comm'rs of Cnty. of Teton reinforces a “coexistence” framework rather than categorical preemption.

3) Litigation posture: challengers must confront the record’s rational basis

The Court’s treatment of competing nitrate data underscores that, under arbitrary-and-capricious review, challengers must do more than identify contrary studies or critique methodology; they must show the agency lacked a rational basis, ignored a critical aspect of the problem, or made an implausible choice given the evidence. That is a demanding standard, particularly where the agency can point to planning documents (like the CAPP) that recommend the very tool adopted.

4) The dissent’s warning: potential future “preemption by policy” arguments

Justice Hill’s partial dissent frames a counter-narrative likely to recur: that counties may not use zoning as a “guise” to regulate matters (water quality) comprehensively assigned to DEQ. While the majority rejected exclusivity, the dissent provides a roadmap for future challenges that emphasize: (i) strict construction of zoning authority; (ii) the EQA’s comprehensive scope; and (iii) legislative “express delegation” as the boundary of local environmental regulation.

4. Complex Concepts Simplified

  • Overlay zone (APOZ): A layer of additional rules placed over existing zoning districts. The underlying zoning (agricultural, residential, etc.) remains, but the overlay adds extra restrictions in a defined area (here, the aquifer recharge/protection area).
  • Legislative vs. adjudicatory agency action: “Legislative” actions set general, forward-looking rules for many people/properties (like zoning amendments). “Adjudicatory” actions decide specific disputes for specific parties (like a permit decision for one project).
  • Arbitrary-and-capricious review: A deferential judicial check asking whether the agency had a rational basis and considered relevant factors. The court does not decide what policy is “best,” only whether the agency’s choice is reasonably explained and grounded in the record.
  • Substantial evidence review: A more evidence-focused standard used when an agency makes factual findings after a trial-type hearing. The court asks whether enough evidence supports the finding, even if contrary evidence exists.
  • Rational basis (equal protection): When no fundamental right or suspect class is involved, a law survives if it is reasonably related to a legitimate governmental purpose. The challenger bears a heavy burden.
  • Mootness: If later events (like amended regulations) remove the disputed issue, courts generally will not decide it because the decision would have no practical effect.
  • Vested rights in land use: Generally, an owner has rights in existing lawful uses, not in hoped-for future rezoning or subdivision potential.

5. Conclusion

2026 WY 76 completes the doctrinal arc begun in Bienz I: once agency legislative action is deemed reviewable under the WAPA, courts apply arbitrary-and-capricious review to evaluate it. On the merits, the Court upheld Albany County’s aquifer-protection overlay amendments—including a 35-acre minimum lot size—finding them within the Board’s delegated zoning authority, consistent with state environmental regulation, rationally administered, and not in violation of equal protection. The decision strengthens counties’ ability to deploy zoning as an environmental risk-management tool, while also crystallizing the judicial-review framework that will govern future challenges to similarly legislative local actions.