Tonto Natural Bridge State Park

Tonto Natural Bridge State Park, in the Tonto Natural Forest north of Payson in central Arizona, protects the world’s largest known natural travertine bridge — a 183-foot-high arch (wider and taller than the Statue of Liberty) spanning a 400-foot-long tunnel carved by Tonto Creek through a travertine deposit, forming a massive natural bridge over a lush canyon with clear green swimming pools, waterfalls and the rushing sound of Tonto Creek.

The bridge is the world’s largest travertine bridge and one of the most geologically unusual and visually surprising geological features in Arizona — an intimate, lush, water-carved canyon in the middle of the Sonoran Desert highlands, completely unexpected in the dry Arizona landscape. Tonto Natural Bridge State Park is a treasured geological icon of central Arizona.

Tonto Natural Bridge State Park offers walking the trails to and through the bridge (the primary experience — three main trail viewpoints: the Viewing Platform (wheelchair-accessible) for the classic arch view from above; the Pine Creek Trail (steep, 0.25 miles) descending to the creek and the base of the arch, where you can walk under the bridge through the 400-foot tunnel on a wet, slippery trail through the arch; and the Waterfall Trail (0.3 miles) for the view of the waterfall falling through the arch), swimming in the creek pools (the turquoise-green pools in and below the arch are one of the finest natural swimming holes in Arizona — cold, clear water; rope swings; waterfalls; a completely unexpected oasis), picnicking at the park facilities, and photography of the arch (the light through the arch arch at different times of day creates extraordinary photography conditions). The swimming under the arch and the tunnel walk are the singular experiences.

Spring (April through June) and fall (September through October) are the finest seasons — the creek pools are at their most inviting water temperatures (cool but swimmable), the arch is surrounded by green vegetation, the waterfall is at good flow, and the temperatures are comfortable. Summer (June through August) is hot on the approach trail but the creek pool swimming is spectacular — the pools stay cool (65-70°F) while the surrounding temperatures exceed 95°F. The creek is at its highest flow in spring after snowmelt; the waterfall is most dramatic. Summer for the swimming, and spring for the highest water flow and the most dramatic waterfall, are the highlights.

The Tonto Natural Bridge was known to the Apache people and to early American miners and prospectors in the area. It was formally discovered by Scottish prospector David Gowan in 1877 (Gowan fled an Apache war party and hid in the canyon, discovering the bridge). His nephew Frank Vance later homesteaded the site and operated it as a tourist destination; the Vance family operated the site until the state of Arizona acquired it in 1991 and established Tonto Natural Bridge State Park. The original Vance homestead lodge (still standing in the park) is one of the oldest structures in central Arizona. The Vance family homestead represents the park’s unique history of private ownership and public conservation.

Tonto Natural Bridge is a travertine bridge — formed by the precipitation of calcium carbonate from spring water as it outgasses CO2, building up deposits of travertine over thousands of years. Unlike a natural sandstone arch (formed by wind and water erosion) or a natural sandstone bridge (formed by stream undercutting), Tonto Natural Bridge was formed by travertine building — a freshwater spring deposited travertine around and over a pre-existing creek channel, gradually building the bridge structure while the creek continued to flow through it. The result is a massive travertine vault over the creek channel. The bridge is still growing as travertine continues to precipitate from the spring water. The travertine deposition, the spring hydrology and the creek channel created the bridge.

Tonto Natural Bridge State Park’s riparian canyon and spring-fed creek support a rich desert-oasis wildlife community — black hawks (Zone-tailed Hawks — a Sonoran Desert raptor — nesting in the sycamores), belted kingfishers, canyon towhees, black phoebes (catching insects at the water’s edge), Arizona toads (common in the pools), longfin dace (a native Arizona fish in the creek), mule deer (drinking at the creek), javelinas (peccaries — common in the surrounding Sonoran Desert), and Arizona black rattlesnakes (present; watch your step). The creek-side riparian woodland (Fremont cottonwood, Arizona sycamore, Arizona walnut) is disproportionately diverse for its size.

Tonto Natural Bridge State Park’s ecological significance is the travertine-spring system and the riparian creek corridor in the Sonoran Desert highlands — a permanent water source in an otherwise dry landscape, supporting a disproportionately rich plant and animal community. The travertine bridge itself is an actively growing feature — the spring water continues to deposit calcium carbonate on the bridge surface; protecting the bridge from physical damage (people breaking off travertine, uncontrolled foot traffic on the arch) is the most critical conservation priority. The longfin dace (an Arizona native fish) in Tonto Creek is a conservation concern; the creek water quality must be protected.

Tonto Natural Bridge State Park holds a treasured place among the geological icons of Arizona — the world’s largest known natural travertine bridge, a stunning oasis canyon in the Sonoran Desert highlands, an accessible swimming-hole paradise in central Arizona, and a historical homestead site of rare authenticity. Its combination of the massive travertine arch, the cold swimming pools, the waterfall and the lush canyon makes it one of the finest and most surprising state parks in Arizona. Tonto Natural Bridge is a cherished natural icon.

Tonto Natural Bridge State Park is 10 miles north of Payson, Arizona, on AZ-87 (the Beeline Highway), then 3 miles west on a paved but steep and narrow road (the descent to the park is not recommended for vehicles longer than 30 feet; check the park website for vehicle restrictions before visiting). Payson (10 miles south) has full services. Phoenix is about 90 miles south via AZ-87. An Arizona State Parks fee applies. Check Arizona State Parks for current hours, fees and any seasonal closures (the park may close the inner trail access in high water; check current conditions). The pool area and trails can be slippery when wet.

Arizona State Parks manages Tonto Natural Bridge State Park. The travertine bridge is the most critical conservation feature — do not chip or break off any travertine from the bridge; do not walk on any fragile or roped-off travertine surfaces; the bridge is irreplaceable and actively growing. Sunscreen and insect repellent in the swimming pools can damage the aquatic ecosystem and the travertine precipitation chemistry — the park requests no sunscreen or insect repellent in the swimming areas. The riparian creek corridor is sensitive; stay on designated trails. Pack out all trash. The park is small and intimate — visitor behavior directly affects the experience of every other visitor; be respectful of others and the environment.

The inner trail through the bridge tunnel is wet, slippery, and requires some hand-and-foot scrambling — wear appropriate footwear (water sandals with ankle support or trail shoes); do not attempt in flip-flops. The descent to the creek on all trails is steep — take your time on the ascent (returning from the creek to the parking area is strenuous). The swimming pools are cold (65-70°F) and fed by spring water — the current in the creek can be strong in spring high-water; check the creek conditions before entering the water. Arizona black rattlesnakes are present; watch where you step and put your hands. Respect the slippery trail, the cold creek current, and the rattlesnakes.

Arizona State Parks vehicle fee required. Vehicle length restriction: vehicles over 30 feet not recommended on the access road (check park for current rules). No sunscreen or insect repellent in the swimming areas. Stay on designated trails. No collecting of travertine or rocks. Swimming is at your own risk (no lifeguard). Pets on leash; not allowed in the swimming areas. Pack out all trash. Check Arizona State Parks for current hours, fees, water conditions and any seasonal closures before visiting.

The town of Payson (10 miles south — the gateway to the Mogollon Rim country; the Rim Country Museum and the Zane Grey Cabin; Payson has excellent services), the Mogollon Rim (the dramatic 200-mile-long escarpment defining the southern edge of the Colorado Plateau, accessible from AZ-87 north of Payson with sweeping views of the Sonoran Desert below), Tonto Natural Forest (surrounding the park, with hiking, trout fishing and dispersed camping), the Christopher Creek and Woods Canyon Lake area (northeast of Payson, with the finest trout fishing in central Arizona), and Sedona (about 80 miles northwest) define the region. Tonto Natural Bridge is the finest single geological stop in central Arizona’s Mogollon Rim country.

Wear your swimming gear under your hiking clothes and plan to swim through the arch tunnel — the experience of wading and swimming through the 400-foot tunnel under the world’s largest travertine bridge in cold, clear turquoise water, with the waterfall falling through the arch above you, is extraordinary and completely unlike anything else in Arizona. Arrive when the park opens (check current hours) to beat the summer heat and the crowds in the pool — by midday the pool area is busy. The descent to the creek on the Pine Creek Trail is short (0.25 miles) but steep; the ascent back up (especially in summer heat) is strenuous — pace yourself and carry water. The viewing platform overlook is accessible to all abilities and provides the classic arch view for those who don’t descend to the creek.