Texas v. New Mexico

Background

The dispute is between the State of Texas and the State of New Mexico over division of the Pecos River under a 1949 compact. The compact’s Article 111(a) required New Mexico not to reduce river flow at the state line below what Texas had under the “1947 condition,” but the compact did not set a fixed annual amount. The Pecos River Commission could not resolve differences because it needed both States’ agreement. After years of negotiation, Texas sued in 1974 and the Court appointed Special Masters who in 1979 and 1984 defined the 1947 condition and an inflow‑outflow method to calculate deliveries.

Reasoning

The Court addressed whether New Mexico had failed to meet its Article 111(a) duty and what remedy should follow. The Special Master found New Mexico underdelivered 340,100 acre‑feet from 1950–1983 and recommended making up the shortfall by delivering 34,010 acre‑feet yearly for ten years. The Court accepted the Master’s calculations, rejected the idea that only future relief is allowed, and held that remedies may include additional water deliveries or monetary damages if appropriate. The Court also approved appointing a River Master to apply the approved formula and make periodic calculations.

Real world impact

The Court enjoins New Mexico to deliver water each year using the Court‑approved inflow‑outflow equation and retains authority to enforce and modify that order. A River Master will make annual calculations and report to both States, and if the Commission later agrees on a different formula the States may seek modification. The Court kept jurisdiction to decide whether monetary payment may substitute for water and to provide other relief needed to make Texas whole.