## Facts

- The dispute arose in Colorado’s San Luis Valley within the Rio Grande and Conejos River basins, where surface rights were long-established and over-appropriated and later groundwater development reduced artesian pressure and affected surface flows.
- Colorado was obligated under the Rio Grande Compact to deliver specified quantities of water at the Colorado–New Mexico state line, and an interstate stipulation required Colorado to curtail uses to meet delivery obligations.
- The State Engineer adopted administrative rules under (1) statutory authority to issue regulations enabling compact compliance and (2) general authority to administer and regulate state waters through rules.
- The rules: (a) imposed separate compact delivery obligations for the Rio Grande mainstem and the Conejos River system; (b) treated the compact as applying to all tributaries within the basin; and (c) would effectively phase out all wells unless each well owner proved no material injury to senior surface rights or supplied an approved plan of augmentation.
- Well owners and allied entities challenged the rules in the water court, which approved the separate-delivery approach, rejected the blanket well phase-out/augmentation scheme, and concluded the compact applied to all tributaries.

## Issues

1. Whether the Rio Grande Compact applies to all tributaries within the basin such that tributary appropriators may be directly curtailed to satisfy compact deliveries.
2. Whether the State Engineer may administer separate compact delivery obligations for the Conejos River system and the Rio Grande mainstem.
3. Whether rules effectively phasing out all wells unless each well owner proves no material injury or provides augmentation are valid under the State Engineer’s statutory authority and Colorado water law.
4. Whether rules issued under the compact-compliance and water-administration statutes are reviewable in the water court for legality and equity.

## Decision

- The Colorado Supreme Court reversed the water court’s ruling that the compact applies broadly to all tributaries within the basin.
- The Court affirmed approval of rules that administered separate delivery obligations for the Conejos River system and the Rio Grande mainstem.
- The Court affirmed disapproval of rules that would phase out all wells absent individualized proof of non-injury or an augmentation plan.
- The Court held that rules issued under both the compact-compliance statute and the general water-administration statute fall within the water court’s jurisdiction and are subject to judicial review.

## Legal Principles

- The State Engineer may promulgate rules to meet interstate compact obligations, but such rules must remain within the compact’s terms and must be legal and equitable as among Colorado appropriators required to curtail.
- Rules adopted to assist in administering and regulating state waters are reviewable in the water court and must conform to Colorado’s constitutional prior-appropriation system and the statutory policy favoring maximum beneficial use (often described as maximum utilization).
- The Rio Grande Compact’s obligations are determined by its text, delivery schedules, and measurement structure; it does not automatically impose direct, uniform obligations on all tributaries.
- A blanket regulatory scheme presuming all wells materially injure senior surface rights—thereby shifting to each well owner the burden to disprove injury or fund augmentation—may be invalid where unsupported by an adequate hydrologic basis and where it produces inequitable curtailment burdens inconsistent with Colorado water policy.

## Conclusion

The court upheld separate compact accounting for the Conejos River and Rio Grande mainstem but rejected both an expansive reading of compact coverage over all tributaries and a rule set that would broadly shut down wells absent individualized proof or augmentation, emphasizing compact fidelity, equitable administration, and consistency with Colorado’s prior-appropriation and maximum-beneficial-use policies.


Alamosa-La Jara Water Users Prot. Ass’n v. Gould, 674 P.2d 914 (Colo. 1983)