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. Open dawn to dusk. Details: 520-877-6000 (Pima County). Call (520) 877-6158 for permit information. These permits are free.
From I-10 east or west, take exit 279 (Vail/Wentworth), head north on Colossal Cave Road approximately 2.6 miles to parking lot on right side just before bridge.
http://www.tripleblaze.com/trail.php?c=3&i=8097