What is Montezuma Well?
Somewhere under the Verde Valley a limestone cavern collapsed, and the hole it left filled with spring water. That is Montezuma Well: a round sinkhole about 368 feet across in dry mesquite country near Rimrock, holding more than 15 million gallons of water that the springs replace at roughly 1.5 million gallons a day. The water comes up warm and heavy with dissolved carbon dioxide and arsenic. Fish cannot live in it. Five creatures evolved to live in nothing else: a springsnail, a water scorpion, a leech that hunts in open water, an amphipod and a pondweed that grows deeper than any other known. Sit on the rim for ten minutes and you will see the ducks avoiding the middle.
People found it as useful as it is odd. The Hohokam were here first; a pithouse near the parking lot dates to about 1050, and they channeled the outlet into a canal that ran for miles and watered corn, beans and squash. The Sinagua came after, building more than 30 rooms along the rim and two small stone-and-adobe dwellings on a ledge inside the sinkhole, from the 1100s until they left around 1425. Settlers in 1870 reused the same canal, and it still carries water today, lined with the calcium the Well leaves behind. The Yavapai, who were here when the settlers came, hold that this is where their people emerged into the world.
The paved trail is about half a mile. It climbs to the rim overlook, drops by stairs to the swallet where the water vanishes into the cliff, then follows the outlet under big sycamores past the old Back ranch house and the picnic area. In July the outlet is 20 degrees cooler than the rim. What you get is the strangest free half hour in the Verde Valley; what you do not get is a visitor center, a swim, or anything to see from the car.
How to visit it right
Pay nothing, keep the hours. Free. Open 9 a.m. to 5 p.m. daily, closed Thanksgiving, Christmas and New Year’s Day. There is a small contact station and restrooms but no visitor center; the Castle’s visitor center covers both units, so ask your questions there.
Get there. Loop 101 north to I-17, then I-17 north about 75 miles to exit 293 (McGuireville/Rimrock). Go east through McGuireville and Rimrock following the brown signs about 4 miles to the entrance on Beaver Creek Road. About 1 hour 45 minutes from Old Town, all paved. If you are coming from Montezuma Castle, it is 11 miles and 20 minutes.
Beat the lot. It is small and has no shade. From February 28 to May 7 the Park Service may close it to vehicles needing more than one space between 10 a.m. and 2 p.m. On a spring weekend, come before 10.
Walk all of it. Most people look over the rim, take the photo and leave. The stairway down to the swallet and the shaded outlet trail along the canal are the best part, and the picnic tables under the sycamores by the ranch house are the nicest free lunch in the valley.
Heat. The rim trail is in the open at about 3,600 feet. From May through September do the rim early and spend the hot part of the day on the shaded outlet trail or under the picnic sycamores.
Water. Bring your own. Do not touch, swim in or drink the Well; it is a protected habitat and the chemistry is not friendly.
Dogs. Allowed on leash on the trails, in the picnic area and the historic pasture, never in buildings or in the car.
Make it a day. Montezuma Castle ($10, the famous cliff dwelling) is 20 minutes south, the Crane Petroglyph site at Beaver Creek is 15 minutes north up FR 618, and Tuzigoot is 40 minutes west. Together they are the best half-day of pre-Columbian Arizona you can do from Scottsdale without a permit, and a natural day trip on the way to Sedona.
Skip it if you want a ruin first and a curiosity second; the Castle is the ruin. Come here for the water.
The hole the Backs sold for a national monument
The Well is older than anything built around it by a margin that is hard to hold in your head. The Verde limestone it sits in was laid down under shallow lakes that filled the valley between 8 and 2 million years ago, in places more than 2,000 feet thick. Somewhere in that bed a cavern dissolved, the roof fell in, and springs below filled the hole. The water still comes up carrying more than 80 times the dissolved carbon dioxide of ordinary fresh water, which is why nothing with gills survives it and why five species that do, a diatom, the springsnail, the water scorpion, the amphipod and the leech, have had the place to themselves long enough to become their own.
People have been in the Verde Valley for at least 10,000 years, and the Well was useful as soon as anyone wanted to farm. The first permanent settlement dates to about 600, and by about 700 someone had cut a ditch from the outlet to the fields; it eventually ran nearly 7 miles and watered perhaps 60 acres, and the calcium in the water lined it so thoroughly that the same channel carries water today. The pithouse near the parking lot, built around 1050, is Hohokam in style, the northern edge of the irrigation culture that dug the canals under the Valley. The Sinagua who followed built more than 50 rooms inside what is now the park, the cliff rooms on the ledge inside the sinkhole among them, and were gone by 1425. The Yavapai, who were here when the Army arrived in the 1860s, tell it as the place their people came out of the earth.
The Anglo story is a ranch story. Wales and Jennie Arnold settled at the Well in 1870, ran a mail station, and put the old canal back to work on their fields. Richard Hinton’s 1878 Handbook to Arizona already listed it as a curiosity. In 1888 or 1889, the sources disagree, William Back took over the claim, and for the next sixty years two generations of Backs farmed the outlet pasture, built the ranch house that still stands by the picnic area, and ran the Well as a roadside attraction with a small museum of their own, charging admission to look at a hole in the ground. They were, in a sense, the first interpretive staff.
The federal government took its time. Montezuma Castle, 11 miles south, had been a national monument since December 8, 1906, and the Park Service ran it from 1916, but the Well stayed private through the Depression. Congress authorized its acquisition in 1943, and the purchase from the Back family closed in 1947; the Well became a detached unit of the Castle monument, which is why it has a contact station rather than a visitor center and why the fee stays at the other site. The ranch house and the pasture came with the deal and are still called historic rather than demolished.
The Park Service then did something unusual with a hole full of arsenic. In 1968 George Fischer led the first underwater archaeological survey ever conducted in a federally managed park, in the Well, looking for what a thousand years of rim dwellers had dropped in. Since then the work has been mostly ecological: counting the endemics, keeping the ducks’ pondweed from choking the surface, which takes weekly pulling, and watching the inflow, which has held near 1.5 million gallons a day through the longest drought the valley has recorded.
Why it matters
Montezuma Well is the clearest small picture of why people have lived in the Verde Valley for ten thousand years: one dependable source of water in a dry country, and a ditch leading from it that four cultures in a row have found worth keeping. It explains the Hohokam reach up the river, the Sinagua rim towns, the Yavapai emergence story and the Arnold and Back ranches in a single half-mile walk, and it is a reminder that the Park Service’s job is sometimes to protect a leech. For a Scottsdale visitor the verdict is easy: it is free, it is 20 minutes off the interstate, the outlet trail is the coolest shade in the valley in July, and nobody who walks all the way down regrets it.