Mercer Spring
Mercer Spring flows at 77°F in the Santa Catalina Mountains above Tucson, running 14 degrees warmer than the surrounding 63°F environment. Within Coronado National Forest's open-access lands, it creates a thermal oasis in the high desert woodland.
The spring emerges at 4,460 feet elevation along a short 600-foot walk from North General Hitchcock Highway. Oak and pine forest surrounds the feature, with cool mountain air and seasonal streams characterizing the landscape. The approach winds through typical Sonoran Desert transition forest typical of the Catalina range.
Mercer Spring's thermal waters reflect the Coronado National Forest's complex geology, where multiple fault systems allow deep groundwater circulation to reach hot rock layers. The region's mining and ranching history shaped human use of these mountains for over a century.
Access is straightforward via North General Hitchcock Highway year-round. The short walk makes this suitable for casual visitors. Winter offers pleasant temperatures; summer heat is moderate at this elevation. The nearby Molino Campground (1.2 miles) offers convenient overnight facilities.
Is Mercer Spring worth visiting?
Best for
- Overnight camping trips
Overview Visitors are drawn to Molino Campground for its group camping area, scenic mountain surroundings and hiking and mountain biking opportunities. While most other campgrounds in the Catalina Mountains are closed in winter, Molino Campground and its picnic area are open in late fall, winter and early spring. The pleasant winter weather at this elevation makes it a great time to visit. Molino Basin is conveniently located 5.5 miles from the base of Mt. Lemmon on the Catalina Highway, and...