In late January, many Phoenix area residents awoke to the sight of snow in the McDowell Mountains.  Snowfall occurs infrequently enough to be a source of interest to hikers, photographers, and other outdoor enthusiasts.  While beautiful in any circumstances, when covered in snow the landscape in the Sonoran Desert becomes something entirely enchanting. 

Many people who sought out the trails in the McDowell Sonoran Preserve on this morning were disappointed to be turned away at popular trailheads such as Tom’s Thumb, Granite Mountain, and Brown’s Ranch.  The City of Scottsdale closed these trails temporarily to protect them from the potentially damaging combination of excessive moisture and human traffic, which are the two greatest threats to the integrity of trails in the Preserve.

The Preserve has approximately 225 miles of trails. Much of the responsibility for maintaining these trails rests with the volunteer stewards who staff the McDowell Sonoran Conservancy, a non-profit organization that supports the City of Scottsdale in maintaining the Preserve.  These volunteers work primarily on drainage, mitigation, and clearance projects.  

Drainage work ensures that flowing water from rain and melting snow does not erode the trails.  Erosion is a particular problem in the Tom’s Thumb area of the Preserve, where granite is the primary stone.  The decomposition of granite has covered the trails in loose sand and gravel that is poor at absorbing moisture.  Poor absorption and steep slopes create more running water, which causes more erosion.  In addition, human traffic on wet trails, particularly from horses and bikes, can result in semi-permanent rutting once the trails dry and harden. 

The Conservancy also works to keep visitors on the official trails and minimize the number of visitors who create their own trails as shortcuts or pathways to interesting geologic features. This effort is referred to as mitigation.  After all, the goal of the Preserve is to “preserve” the natural state of the desert as much as possible, while also allowing responsible human recreational use. Mitigation activities often involve installing plants and rocks as natural barriers where unofficial trails have begun to take shape. 

Finally, Conservancy Stewards work to keep trails clear, passable, and safe for hikers, bikers, and horses. This involves, among other things, pruning bushes, removing obstacles, and addressing potentially dangerous trail conditions that may have arisen due to erosion, fallen cacti or rocks, or other factors.  

The McDowell Sonoran Preserve is an amazing resource for the citizens of Scottsdale and visitors to the City. Ongoing effort by the City and the Conservancy, supported by informed and respectful use by the public, will ensure that it remains a tremendous resource for years to come.