The Republican River originates in Colorado; crosses the northwestern corner of Kansas into Nebraska and cuts back into northern Kansas. The river drains a 24,900-square-mile watershed, called the Republican River Basin. The Basin contains substantial farmland, producing wheat and corn. At the prodding of the federal government, the States negotiated and ratified the Republican River Compact; and in 1943, as required under the Constitution, Art. I, 10, cl. 3, Congress approved that agreement. The Compact gives each State a set share water: 49% to Nebraska, 40% to Kansas, and 11% to Colorado. The States created the Republican River Compact Administration (RRCA). The RRCAs chief task is to calculate the Basins annual virgin water supply by measuring stream flow throughout the area and to determine (retrospectively) whether each States use of that water has stayed within its allocation. Kansas complained to the Supreme Court about Nebraska's increased pumping of groundwater, resulting from that States construction of thousands of wells hydraulically connected to the Republican River and its tributaries. A Special Master was appointed by the Supreme Court and favored the Kansas interpretation of the Compact. The States then entered into negotiations. In 2002, the States signed a Final Settlement Stipulation (Settlement). The Settlement established detailed mechanisms to promote compliance with the Compacts terms. By 2007, Kansas and Nebraska each had complaints about how the Settlement was working. Kansas sought redress in the Supreme Court, petitioning for both monetary and injunctive relief. The case was again referred to a Special Master. The Special Master issued his report and recommendations. It concluded that Nebraska had knowingly failed to comply with the Compact. To remedy that breach, the Master proposed awarding Kansas $3.7 million for its loss, and another $1.8 million in partial disgorgement of Nebraska's still greater gains. Kansas and Nebraska each filed exceptions.