What did the 1963 U.S. Supreme Court decision decide about lower Colorado River water rights?

In 1963, the U.S. Supreme Court issued a landmark decision that clarified the allocation of water from the lower Colorado River basin. The ruling explicitly defined the specific amounts of water apportioned among the lower-basin states—Arizona, California, and Nevada—and affirmed Arizona’s right to approximately 2.8 million acre-feet of water annually from the Colorado River, in addition to the entire flow of the Gila River.12

Furthermore, the decision identified and quantified the amounts of water that had been implicitly "reserved" for Indian tribes and federal public lands. By settling these long-standing disputes, particularly the conflict between Arizona and California, the ruling provided the legal certainty necessary to secure funding for the Central Arizona Project, a major infrastructure system designed to transport water to the cities of Phoenix and Tucson.12