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The 1949 Pecos River Compact allocates the river’s water between Texas and New Mexico. In an earlier phase of this original jurisdiction litigation, concluded roughly 30 years ago, the Supreme Court resolved issues regarding how the states’ obligations were to be calculated. The Compact allocation involves a highly technical formula that depends on measurements of the river’s inflow and outflow in each water year. To effectuate its decision going forward, the Court retained jurisdiction and appointed a River Master to oversee the annual quantification of New Mexico’s delivery obligation. The current dispute arose when in fall of 2014, Tropical Storm Odile caused heavy and widespread rainfall in the Pecos River Basin. Texas requested that water be stored in the Brantley Reservoir in New Mexico because the Red Bluff Reservoir in Texas was already full. When the flood risk abated in 2015, the Bureau of Reclamation (the operator of the Brantley Reservoir) began releases that continued throughout 2015 even though Texas remained unable to store that water in the Red Bluff Reservoir. As a result, more than 40,000 acre-feet of water released from Brantley flowed downstream without any benefit to Texas. This case involves the claim by New Mexico, eventually agreed to by the River Master, that New Mexico should be given a credit toward the calculation of its 2014 and 2015 delivery obligations for evaporative losses from the Brantley Reservoir associated with the extra stored floodwater. Eventually, in the 2018 and 2019 Water Year Reports, the Water Master recognized the credits and began to apply them retroactively to lower the amount of New Mexico’s delivery obligations.