In an original jurisdiction action by South Carolina seeking an equitable apportionment with North Carolina of the Catawba River's waters, the special master's grant of three nonparties' motions to intervene is affirmed in part as to two of them where: 1) the Catawba River Water Supply Project was properly permitted to intervene because it showed a compelling interest in protecting the viability of its operations, which were premised on a fine balance between the joint venture's two participating counties; and 2) Duke Energy was also properly allowed to intervene because it was likely that any equitable apportionment of the river would need to take into account the amount of water that Duke Energy needed to sustain its operations. However, the order is reversed in part where the interest of Charlotte, North Carolina was not sufficiently unique and would be properly represented by North Carolina.
Argued October 13, 2009
Decided January 20, 2010
Opinion by Justice Alito
Partial Concurrence and Partial Dissent by Chief Justice Roberts