“ The case before us today involves a claim by Kansas for damages based on Colorado's violations of that Compact.
2 The Compact was designed to " [s] ettle existing disputes and remove causes of future controversy" between the two States and their citizens concerning waters of the Arkansas River and to " [e] quitably divide and apportion" those waters and the benefits arising from construction and operation of the federal project known as the "John Martin Reservoir." Arkansas River Compact, Art. I, reprinted in App. to Brief for Kansas A-1, A-2. ”