Texas v. New Mexico

Background

The dispute involves the States of Texas and New Mexico over how much water New Mexico may use from the Pecos River without reducing flow to Texas below what was available under the “1947 condition.” Texas sued after negotiations failed, claiming New Mexico used more water than allowed and arguing that the 1947 routing study should remain the baseline despite known errors. A Special Master issued a report interpreting the Compact’s “1947 condition,” and both States filed exceptions to that report.

Reasoning

The central question was what the Compact meant by the phrase “1947 condition” and how compliance should be measured. The Special Master defined the term as the man-made depletions produced by the level of development at the start of 1947, including certain augmented acreage, and said errors in the old routing study had to be corrected before use. The Court, in a per curiam decision, overruled all exceptions and confirmed the Special Master’s report and his interpretation of the 1947 condition, leaving the Master’s measurement approach in place and rejecting Texas’s objections.

Real world impact

This ruling fixes how the Compact’s baseline will be interpreted for measuring New Mexico’s water use at the New Mexico–Texas state line. It affects which years and calculations are compared when deciding if New Mexico has overused water, and it preserves the Special Master’s approach unless the Compact’s agreed method is later changed.

Dissents or concurrances

Justice Stevens dissented, arguing that the Compact incorporated the 1947 routing study as an ``artificial’’ baseline adopted by the parties, and he would have sustained Texas’s objections to the Master’s definition.