Sedona Westerners in the Red Rock News

September 20, 2013

Inner Basin - Flagstaff


by Kevin O‘Connor

The San Francisco Peaks surrounding the Inner Basin were named in honor of St Francis of Assisi by Franciscan friars at the Orabi Hopi village in the mid-17th century, 150 years before the City-By-The-Bay was named. But the story begins in pre-history and that period sets the stage for what we experience in the 21st century. An eruption one million years ago began the formation of a stratovolcano; steep sides, viscous flows, short-range lava flows. Mts Vesuvius, Krakatoa, Pinatubo, St. Helens, Rainer & Hood & Fuji are of this type. However, according to my research, only the San Francisco range is lacking the tectonic subduction zone found at other locations, and geologists still speculate on how this might have occurred. It is estimated that the peak of the stratovolcano, in its development stage, was in excess of 14,000 ft. Single or multiple eruptions, possibly similar to that of Mt St Helen's, reduced the stratovolcano to what we see today.

The largest peak, Mt Humphreys, towers to 12,600 ft, the highest mountain in Arizona. Five additional peaks form the ringing edge of the remaining caldera with the Inner Basin opening to the north east. The internal structure of a stratovolcano, combined with the caldera formation made the area an ideal subterranean aquifer. While prehistoric native Americans likely came to understand this advantage over centuries of agrarian activity, it was not until the late 19th century that the Inner Basin was recognized as a natural and renewable water source.

Early settlers, in particular those involved in the railroad and lumbering industries, recognized the value of a spring water source to a growing community, and in the late 19th century taped the Inner Basin with a 15 mile 6" clay tile pipeline. In 1914 the Santa Fa railroad constructed an additional 8" tile pipeline. It was at this time that the pipeline access road to the Inner Basin was first constructed. About 1925 the city of Flagstaff upgraded the pipeline to a 15" concrete pipe. Beginning in 1986, the City began upgrading the concrete pipeline to a 16" iron pipe. These pipelines have provided Flagstaff with an average of ~13% of the city water needs, peaking in the summer at ~30%. There are at least 13 drilled well casings in the Inner Basin, three of which are currently in production.

Katsina Peaks Wilderness Area of the Coconino National Forest was established in 1984 and encloses the Inner Basin. Parts of this wilderness have been seriously compromised by wildfire, the latest being the Schultz Pass fire of 2010.

Hiking to the Inner Basin begins at Lockett Meadow campground, about 3 miles off Rt 89A and immediately opposite the turn for Sunset Crater. A good mile of this route is a narrow, mountain hugging, single lane road where on-coming traffic is unwelcome! The trail, beginning at 8600 ft, winds through a mixed hard and softwood forest for about 2.5 miles. In climbing about 2200', you meander, via many switch-backs, through spectacular Aspen forests that are evermore amazing during the October color changes. The alluvial soil and decaying vegetation, dampened by the intense monsoon rains, burst forth a multitude of mushrooms and toad stools in all the colors of the rainbow.

Allow on the order of 4-5 hours to make this round trip hike and to enjoy the scenery. Take lunch near the upper pump-house at 9800'. For the adventurous, continue on up the trail for another mile or so and another 1000 ft in elevation to the junction of the Weatherford trail. It's all down hill on the way back, so enjoy the views, and remember: take only pictures & leave only memories!

The Westerners always welcome new members. If you are interested in joining the club, log onto our website: You may also join by attending a monthly meeting, our next one will be on Thursday, October 10th 11AM at Red Rock State Park for the fall cookout.