Texas v. New Mexico, 141 S.Ct. 509

The 1949 Pecos River Compact apportions Pecos River water between New Mexico and Texas; the Court in 1988 appointed a River Master and adopted a River Master’s Manual to implement the decree.
Manual §C.5 states that when Texas allocation is stored in New Mexico “at the request of Texas,” New Mexico’s delivery obligation will be reduced by reservoir losses attributable to that storage.
In Nov. 2014 Texas requested that New Mexico store Texas’s portion of flood flows at Brantley Reservoir; New Mexico agreed, noting the water "belongs to Texas." A release to Texas occurred in Aug. 2015, but ~21,000 acre-feet evaporated while stored.
The States negotiated how to account for evaporation; the River Master’s 2015 reports deferred resolution of the issue with neither State objecting to that procedure.
New Mexico filed a motion in 2018 seeking delivery credit for the evaporated water; the River Master denied Texas’s timeliness challenge and awarded credit under §C.5.
The Supreme Court denied Texas’s motion for review, holding the motion was timely and §C.5 covers evaporative losses when water was stored at Texas’s request.

Issue	Plaintiff's Argument (Texas)	Defendant's Argument (New Mexico)	Held
Timeliness of NM’s 2018 motion	NM missed decree deadlines; objections time-barred	Both States agreed to postpone resolution; River Master’s reports deferred the issue and neither objected	Motion not untimely; parties jointly accepted negotiation procedure; deadlines are not jurisdictional
Whether §C.5 covers evaporative losses	Stored water was not part of the “Texas allocation” and NM should not get credit; NM did not "store" it under §C.5	Texas requested storage of its allocation; NM held it for Texas; §C.5 therefore applies	§C.5 applies; NM entitled to credit for evaporated water held at Texas’s request
Scope/timing of Texas’s request (rescind by Mar 2015?)	Texas rescinded by Mar 2015, so evaporation after that date should be NM’s responsibility	Texas never rescinded; request persisted until release in Aug 2015	Court rejected rescission argument; NM gets credit for evaporation through release

United States v. Detroit Timber & Lumber Co., 200 U.S. 321 (syllabus is not part of the Court’s opinion)
Texas v. New Mexico, 482 U.S. 124 (prior decree finding New Mexico breached delivery obligations)
Texas v. New Mexico, 485 U.S. 388 (per curiam) (1988 amended decree appointing River Master and adopting Manual)
Henderson v. Shinseki, 562 U.S. 428 (time limits that do not speak in jurisdictional terms are not jurisdictional)
Zipes v. Trans World Airlines, Inc., 455 U.S. 385 (time limits must be read for jurisdictional language)