The Lower Colorado River Accounting System

The Colorado River, which has its headwaters as far north as Wyoming, discharges into the Gulf of California in Mexico. The Colorado River basin includes about 638,953 square kilometers (246,700 square miles) in the United States. The Colorado River basin is divided into upper and lower basins at Lee Ferry, Arizona. The lower basin includes parts of Arizona, California, Nevada, New Mexico, and Utah. The Colorado River is the principal source of water for irrigation and domestic use in Arizona, southern California, and southern Nevada. Within this area, accounting for the use and distribution of water from the lower Colorado River is required by the U.S. Supreme Court Decree of 1964 (Supreme Court Decree) in Arizona v. California. In addition to its other requirements, the Supreme Court Decree directs the Secretary of the Interior (Secretary) to provide detailed and accurate records of diversions, return flows, and consumptive use of water diverted from the mainstream "stated separately as to each diverter from the mainstream, each point of diversion, and each of the States of Arizona, California, and Nevada." These records are provided annually by The Bureau of Reclamation (Reclamation) in a report entitled, "Compilation of Records in Accordance with Article V of the Decree of the Supreme Court of the United States in Arizona v. California Dated March 9, 1964".