Introduction

TEXAS v. NEW MEXICO, 141 S. Ct. 509 (2020), adjudicated by the Supreme Court of the United States on December 14, 2020, addresses a significant dispute between Texas and New Mexico concerning the allocation of evaporated water under the Pecos River Compact of 1949. This case centers on whether New Mexico is entitled to delivery credit for water that evaporated while being stored at Texas's request during a flood control operation initiated after a destructive tropical storm.

Summary of the Judgment

The Supreme Court upheld the River Master's determination that New Mexico is entitled to delivery credit for water that evaporated while stored in New Mexico reservoirs at Texas's request during a 2014 flood event caused by Tropical Storm Odile. The Court found that New Mexico's motion for credit was timely and that the evaporation fell under §C.5 of the River Master's Manual, which governs such scenarios. Consequently, the Court denied Texas's motion for review, affirming the River Master's decision.

Analysis

Precedents Cited

The Court referenced its prior decision in TEXAS v. NEW MEXICO, 485 U.S. 388 (1988), which established the framework for the Pecos River Compact and the role of the River Master in adjudicating disputes. This precedent underscored the importance of adhering to the Compact's mechanisms for equitable water division and reaffirmed the River Master's authority in interpreting the Compact’s provisions.

Legal Reasoning

The Court's legal reasoning was grounded in the explicit language of §C.5 of the River Master's Manual, which states that water stored in New Mexico at Texas's request will have the delivery obligation reduced by the amount of reservoir losses due to storage. The Court emphasized that:

• Texas explicitly requested storage of its water, thereby invoking §C.5.
• New Mexico retained the understanding that the stored water was Texas's property and that evaporative losses should be borne by Texas.
• The procedural history showed that both states agreed to postpone resolution pending negotiations, which were ultimately unsuccessful, validating the River Master's decision to grant the credit.

The Court dismissed Texas's arguments by clarifying that:

• The term "stored" was used in its ordinary sense, aligning with §C.5.
• The evaporation occurred during the period when the water was under Texas's allocation as per the Compact.
• The motion for credit was not subject to the 30-day deadline due to the agreed postponement of the dispute resolution.

Impact

This judgment reinforces the adherence to interstate compacts and the authority of designated officials like the River Master in managing water disputes. It sets a clear precedent that states must honor procedural agreements made within such frameworks and underscores the importance of explicit contractual language in interstate agreements. Future cases involving water allocation under similar compacts will likely reference this decision to determine entitlement and obligations concerning water loss during storage.

Complex Concepts Simplified

Interstate Compacts

Interstate compacts are agreements between two or more U.S. states that are approved by those states' legislatures and, in some cases, by Congress. They are used to manage shared resources, such as rivers, to ensure fair and equitable usage.

River Master's Manual (§C.5)

The River Master's Manual is a set of guidelines adopted under the Pecos River Compact to facilitate the management and allocation of water between Texas and New Mexico. Section C.5 specifically deals with scenarios where Texas requests New Mexico to store water, stipulating that any evaporation losses during storage will adjust New Mexico's water delivery obligations.

Delivery Credit

Delivery credit refers to an accounting adjustment that reduces a state's water delivery obligations based on losses like evaporation. In this case, it means that New Mexico does not have to deliver the full amount of water initially allocated to Texas if some of it evaporated while being stored.

Inflow-Outflow Method

This method calculates water delivery obligations by comparing the amount of water flowing into New Mexico with the amount flowing out to Texas. It ensures that Texas receives an equitable share of the river’s water based on availability.

Conclusion

The Supreme Court’s decision in TEXAS v. NEW MEXICO serves as a pivotal interpretation of the Pecos River Compact, particularly regarding how evaporative losses are handled when water is stored at one state's request. By affirming the River Master's authority and the procedural agreements between the states, the Court has reinforced the mechanisms for equitable water distribution and interstate cooperation. This judgment not only resolves the immediate dispute but also provides a clear framework for similar future cases, ensuring that water resource management remains fair and consistent under established interstate agreements.