Montezuma Well (Yavapai: Ahakaskyaywa), a detached unit of Montezuma Castle National Monument, [1] is a natural limestone sinkhole near Rimrock, Arizona through which some 1,400,000 US gallons (5,300,000 L) of water flow each day through two underground springs. It is located 11 miles (18 km) northeast of Montezuma Castle. The well measures in at 368 feet (112 m) across and 55 feet (17 m) deep. The water is highly carbonated and contains high levels of arsenic. At least five endemic species live (only) in the Well: the diatom, the springtail, the water scorpion, the amphipod (Hyalella montezuma), and the leech (Erpodbella montezuma) -- the most endemic species in any spring in the Southwestern United States.[2] It is also home to the Montezuma Well springsnail.
Montezuma Well's outflow has been used for irrigation since the 8th century. Part of a prehistoric canal is preserved at the picnic ground, and portions of the original Sinagua canal are still in use today.
The existence of the well was almost unknown to Anglo Americans before the publishing of Handbook to America by Richard J. Hinton in 1878. In 1968, Montezuma Well was the subject of the first ever underwater archaeological survey to take place in a National Park, led by archaeologist George R Fischer.
The Yavapai people believe they emerged into this world through the well, and as such, it is a very sacred place to them.[3]
In recent years Illinois Pondweed (Potamogeton illinoensis) has invaded the well. Weekly maintenance is required to keep water from the well flowing.[1]