The Colorado River Compact is an agreement signed in 1922 at a meeting at Bishop's Lodge, near Santa Fe, New Mexico, by representatives of the seven Colorado River Basin states governing the allocation of water from the Colorado River. The compact divides the water between four Upper Basin States—Colorado, New Mexico, Utah and Wyoming—and three lower basin states—Nevada, Arizona and California. The compact requires the Upper Basin states to deliver water at a rate of 7.5 million acre feet per year (293 m³/s), averaged over a moving ten-year average. The compact enabled the development of water works projects such as Hoover Dam. But the amount of water allocated was based on an expectation that the river's average flow was 16.4 million acre feet per year (641 m³/s). Subsequent tree ring studies have concluded that the long-term average water flow of the Colorado is approximately 13.5 million acre feet per year (528 m³/s).

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