The Gabe Zimmerman Davidson Canyon Trailhead parking lot provides access to the Cienega Creek Natural Preserve and Davidson Canyon. This is a 10-car lot. The trailhead is located just off Marsh Station Road. Note: A permit is required to access the preserve however, no permit is required if you are only utilizing the Arizona Trail. The permit is free. Open dawn to dusk. Details: 520-724-5000 (Pima County). Outdoor Activities: Birding, Environmental Education, Hiking trails – dogs allowed, Interpretive Programs, Wildlife Viewing.