Fossil Creek ( or ) is a perennial stream accessed by forest roads near the community of Camp Verde in the U.S. state of Arizona. Primary access is from Forest Road 708 off Arizona State Route 260 east of Camp Verde. A tributary of the Verde River, Fossil Creek flows from its headwaters on the Mogollon Rim to meet the larger stream near the former Childs Power Plant.
Fossil Springs, near the headwaters, emits upwards of per minute that flow into the creek year-round. Calcium carbonate, precipitating from the water from the springs, creates travertine dams and deposits for several miles downstream. The Fossil Creek system is the fourth largest producer of travertine in the United States.
Fossil Creek is one of only two streams in Arizona included in the National Wild and Scenic Rivers System. The creek and its riparian corridor provide habitat for a wide variety of flora and fauna, some listed as endangered or otherwise imperiled. Its former power-plant complex is listed as a National Historic District. Since restoration of the stream's natural flow in 2008, an increase in recreational visits has raised concerns about overuse and has led to road closings and other restrictions. Parking is available only by advanced permit between April 1 and October 1.
Course
Fossil Springs, the head water of Fossil Creek, arises at an elevation of above sea level on the Mogollon Rim in Coconino County north of Strawberry. For about the first , the creek's flow is intermittent.
From high on the rim, the creek runs generally north, entering Gila County almost immediately. It continues north through the wilderness to the confluence of an intermittent stream in Calf Pen Canyon, which enters from the right. Turning west, the creek receives another intermittent stream from the right in Sandrock Canyon, at the head of Fossil Creek Canyon. Before it reaches Fossil Springs, the creek becomes the boundary between Gila County on the stream's left and Yavapai County on its right, and it remains the boundary all the way to the Verde River.
The perennial stretches of the stream begin at Fossil Springs, at river mile (RM) 14 or river kilometer (RK) 23, in the Fossil Springs Wilderness of the Coconino National Forest at an elevation of about . Below the springs, the creek flows west and southwest, passing the remnants of a former dam. Unnamed intermittent streams enter from left and right. Before Fossil Creek reaches the former Irving Power Plant, it leaves the Fossil Springs Wilderness, and below the plant, it enters the Mazatzal Wilderness of the Tonto National Forest. Forest Road 708 (Fossil Creek Road) follows the creek for along this stretch, crossing the creek once at Fossil Creek Bridge.
After Cimarron Creek Wash enters from the right, Fossil Creek turns sharply south. In the next stretch, Stehr Lake is to the right and Deadman Mesa to the left. Hardscrabble Creek enters from the left just before Fossil Creek turns west again and enters the Verde River.
Discharge
The flow of water from Fossil Springs has been estimated to range from (320–420 gal/s) year-round, and it emerges from underground at a constant . The United States Geological Survey installed a stream gauge at the Fossil Creek Bridge in 2010. The maximum daily discharge at that station was on February 19, 2011, and the minimum was on August 6, 2011.
Geology
Fossil Creek Canyon is about deep and varies in width from at Fossil Springs to less than in places further downstream. Rocks in the canyon vary in age from the Precambrian through the Cenozoic. North of the springs the canyon cuts through Paleozoic sedimentary rocks including the Redwall Limestone, Naco Group, Supai Group, Schnebly Hill Formation, Coconino Sandstone, and Kaibab Formation. South of the springs, the rocks of the canyon are Tertiary volcanics, mostly dark-gray basalt and yellow-gray tuff.
Fossil Springs, the source of about 80 percent of the water in Fossil Creek, issues from several vents in close proximity to one another at the base of the Mogollon Rim. The rim is the southern edge of the Colorado Plateau. Water percolating through limestone layers in the rim becomes laden with dissolved carbon dioxide and calcium carbonate. When the water emerges at the springs, it begins to release carbon dioxide as a gas and calcium carbonate as travertine, a porous form of calcite often found around hot springs such as Mammoth Hot Springs in Yellowstone National Park. The release, affected by stream turbulence and other factors, does not occur all at once but continues downstream.