## Facts

- The Colorado River Municipal Water District applied for a permit to impound over 500,000 acre-feet of water at the Stacy Dam site and to divert and use 113,000 acre-feet annually from the Colorado River.
- The Texas Department of Water Resources, acting through the Texas Water Commission, granted the permit.
- The administrative record included extensive hydrologic studies, plus existing certificates of adjudication, permits, certified filings, and recognized riparian rights on the Colorado River.
- Measured by the recorded (face) quantities of existing rights, the Colorado River was fully appropriated, and often overappropriated, for much of the year.
- The Department and the applicant relied on a computer model based on historic river operations and actual use, concluding substantial water was physically unused and therefore “available.”
- Lower Colorado River Authority and irrigation companies contested the permit, arguing § 11.134 requires availability of legally uncommitted water and that unused portions of existing rights cannot be treated as “unappropriated.”
- The Travis County district court upheld the permit; the Third Court of Appeals affirmed, accepting the agency’s reliance on historic usage rather than recorded rights.

## Issues

1. Under Texas Water Code § 11.134, does “unappropriated water” mean water not actually used under existing rights (based on historic use and projections), or water remaining only after accounting for all existing uncancelled permits and filings at their recorded amounts?
2. If the recorded amounts of existing rights fully allocate the supply, may the agency nonetheless issue a new permit based on modeled nonuse by existing right holders?

## Decision

- The Texas Supreme Court reversed the judgments affirming the permit and remanded.
- The court held the Department and lower courts misconstrued § 11.134 by treating historically unused water under existing rights as “unappropriated water.”
- “Unappropriated water” under § 11.134 is the amount remaining after accounting for all existing uncancelled permits and filings valued at their recorded levels.
- Because the record showed no unappropriated water when existing rights were counted at face value, issuance of the permit was improper.

## Legal Principles

- Texas Water Code § 11.134 requires an agency finding that “unappropriated water is available” and that existing rights will not be impaired as a prerequisite to permitting.
- “Unappropriated water” is a rights-based measure: available supply minus all existing uncancelled permits and filings at their recorded quantities, not a physical measure based on actual historical usage.
- Existing water rights remain enforceable up to their recorded limits unless modified or canceled through lawful procedures; an agency may not reduce their effective scope by reallocating “unused” portions through modeling.
- Administrative technical assessments and efficiency concerns cannot override the statutory allocation method established by the Legislature.

## Conclusion

The court required the permitting agency to determine “unappropriated water” by subtracting all existing uncancelled rights at their recorded amounts, rejecting an approach that relied on historic nonuse to justify new appropriations, and it set aside the permit due to the absence of legally available water under that standard.


Lower Colo. River Auth. v. Tex. Dep’t of Water Res., 689 S.W.2d 873 (Tex. 1984)