Document: 88th Congress, 1st Session, Senate, Document No. 20, Determination of the Rights of the States of the Lower Colorado River Basin to Waters of the Main Stream of the Colorado River, Opinion of the United States Supreme Court in the Case of State of Arizona, Plaintiff, v. State of California et al, Rendered June 3, 1963, Presented by Mr. Hayden, June 4, 1963, page 3937 ARIZONA v. CALIFORNIA. necessary for it to acquire water rights or vested interests therein. But the acquisition of water rights must not be confused with the operation of federal projects. As the Court said in Nebraska v. Wyoming, supra, at 615: 'We do not suggest that where Congress has provided a system of regulation for federal projects, it must give way bef...