Calero Bald Peaks

El Toro and the Diablo Range from the Bald Peaks Trail

10 miles loop, 2000 feet elevation gain
Difficulty: Moderate
Access: Paved road to trailhead, no entrance fee required

The Bald Peaks Loop in Calero County Park south of San Jose, California is an enjoyable though ordinary hike through grassy hills with views of the Santa Cruz Mountains and Santa Clara Valley. Calero County Park centers on water recreation on Calero Reservoir, which supplies water to Santa Clara County, but this enjoyable hike follows the ridge behind the reservoir for a nice day-long outing. This hike starts from the McKean Road entrance to the park and follows the Pena, Vallecito, and Canada del Oro Trails to the top of the ridge, then travels along a scenic stretch of the Bald Peaks Trail before returning to the trailhead via the Chisnantuck, Cottle, and Serpentine Trails. This hike is best in winter and spring when the grassy hillsides of the Bald Peaks are green, although the trail can get muddy after rain. Summer hiking here is typically dry, hot, and unpleasant. This loop is popular with mountain bikers as well as hikers.

I hiked the Bald Peaks Loop in Calero County Park on a nice December day, after recent rains had renewed the green grasses of the hills. Calero County Park lies south of San Jose; I reached the McKean Road entrance by following US 101 south from San Jose to exit 373 for Bailey Road. I headed west on Bailey Road, following it into the foothills of the Santa Cruz Mountains until Bailey Road ended at a junction with McKean Road. Here, I turned left and followed McKean Road south for just under a mile to the entrance to Calero County Park on the right side of the road. Turning right into Calero County Park, I parked at the large, open parking area across from the start of the Pena Trail. Although Calero County Park does charge an entrance fee at Calero Reservoir, there was no fee to park at this trailhead.

I started the loop by crossing the road and taking the Pena Trail, a dirt road trace which was initially flat as it traveled through grassland until reaching a fork with the Figueroa Trail at 0.2 miles. I took the right fork at this junction to follow the Pena Trail up into some gently rolling hills, passing a small manmade pond shortly after the junction. The Pena Trail undulated with the hills until reaching a junction with the Los Cerritos Trail at 0.6 miles; here, the Pena Trail turned sharply and began ascending up an open, grassy ridge. This earliest stretch of the hike was quite muddy during my visit.

Pena Trail winds through grassy hills in Calero County Park

I followed the Pena Trail along its steep ascent up the grassy ridge, with lovely views of Mount Hamilton and Coyote Valley quickly opening up behind me. 

Diablo Range views from the Pena Trail

At 0.9 miles, I came to the junction with the Vallecito Trail; I went left at the junction and took the single-track Vallecito Trail, which descended down a grassy slope to the bottom of a valley and followed a stream through oak woodlands. This was a pretty if ordinary stretch of the hike, particularly nice because it was single track rather than the more common road traces in the Bay Area hills.

Oaks and grasslands on the Vallecito Trail

The Vallecito Trail ended at a junction with the Figueroa Trail, a road trace, at one and a third miles into the hike. I turned left at this junction and followed the Figueroa Trail for a brief hundred meters to reach the junction with the Canada del Oro Trail. Here, I turned right and began to follow the Canada del Oro Trail uphill through oak forest. The Canada del Oro Trail was the first part of this hike’s most extended ascent, climbing 650 feet in just over a mile. The Canada del Oro Trail had no views as the trail was completely in the woods here; the steep incline made this a good and vigorous workout. I came to a fork in the Canada del Oro Trail at 2.2 miles, with the Canada del Oro cutoff trail heading to the left and the Canada del Oro Trail turning to the right. I stayed on the Canada del Oro Trail, heading right and enjoying a short reprieve from the ascent before a final uphill through the forest brought me to the top of an open ridge and the junction with the Bald Peaks Trail at 2.5 miles.

Canada del Oro Trail through the forest

I began to follow the Bald Peaks Trail west (to the right) and the components of this ridge’s lovely views slowly started unfolding. First came views of Loma Prieta, the communications tower-topped summit that is the highest point in the Santa Cruz Mountains and was the epicenter of a 1989 earthquake that caused significant damage and fatalities in the Bay Area. The dirt road trace of the Bald Peaks Trail ran above a small basin holding a seasonal pond that made an interesting foreground to Loma Prieta’s tree-covered form in the distance.

Loma Prieta rises above a pond on the Bald Peaks Trail

The Bald Peaks Trail continued the steep ascent that had started on the Canada del Oro Trail. The trail climbed through most openly meadows with a few scattered oaks, with improving views to the east of Mount Hamilton and Coyote Valley. At 3.1 miles, the trail reached a junction with the Needlegrass Trail coming up from the Rancho Canada del Oro Open Space Preserve. Immediately after this junction, the trail arrived atop a first high point along the Bald Peaks Trail. Views over the next hundred meters of the Bald Peaks Trail, which followed the crest of the grassy ridge, were wonderful. Loma Prieta and Mount Umunhum lay to the west, rising ahead of the Bald Peaks Trail; the view north into San Jose and Santa Clara Valley was unfortunately hampered by some low-level smog but I could see Black Mountain and the rest of the Santa Cruz Mountains marching up the Peninsula. Views to the south encompassed both the Santa Cruz Mountains and the Diablo Range rising on either side of the unseen town of Gilroy.

Mount Umunhum and Black Mountain rising in front of the Bald Peaks ridge

The trail descended from this first high point, reaching a saddle at 3.5 miles where a cut in the hillside revealed some unusually red rock and soil. The Almaden Valley area and the foothills of the Santa Cruz Mountains around Mount Umunhum and Loma Prieta are known for their cinnabar-bearing bedrock. In fact, the nearby New Almaden mine was one of the earliest European-American mining operations in California, preceding the 1849 Gold Rush; decades of mining eventually caused severe contamination of the landscape here, with the Environmental Protection Agency declaring the former mine a Superfund site. Such contamination is not unusual for Santa Clara County, which at the moment has more active Superfund sites than any other county in the United States, most related to contaminants from early semiconductor manufacturing operations by Fairchild and HP.

Leaving the saddle, I followed the Bald Peaks Trail through a short but steady ascent to the second high point of the hike. At a large clockwise turn in the trail, a social path led from the Bald Peaks Trail to the second high point. The views from this point were the most comprehensive of the hike. Looking to the southeast, I had lovely views of El Toro near Morgan Hill dwarfed by the Diablo Range, which led south from Mount Hamilton to a cluster of high peaks in the Hollister area. Loma Prieta stood high to the west and the hazy sprawl of San Jose lay to the north. It really was unfortunate that the day of my hike was so hazy: I’m sure this view would extend to Mission Peak and perhaps all the way to the San Francisco skyline and the North Bay mountains on a very clear day.

Bald Peaks of Calero County Park

Leaving the high point, the Bald Peaks Trail dropped slightly as it headed north and arrived at a junction with the Chisnantuck Trail at 3.8 miles. Here, the Bald Peaks Trail continued to the west, heading into the Rancho Canada del Oro Open Space Preserve. I took the right fork for the Chisnantuck Trail, a single track trail that left the open, grassy ridge crest for the oak woodlands on the north slopes of the ridge. At the junction, there was a bench with a nice view of the San Jose skyline, which was a bit hazy on the day of my hike.

View towards downtown San Jose

Departing from the bench, the Chisnantuck Trail largely stuck to the woods as it descended very gently over the next 2.5 miles. In fact, I found the grade of this trail excessively gentle- which was nice on my knees, but at times felt frustrating because a half mile or more of trail could easily have been shaved off here. In a few spots, the trail emerged into clearings with views towards Mount Hamilton and partial views of Calero Reservoir below. I met quite a few mountain bikers both ascending and descending this trail, so I listened carefully for fast bikers as this was a single track trail with some blind turns.

Mount Hamilton

Grassy oak woodlands on the Chisnantuck Trail

At 6.3 miles, the Chisnantuck Trail emerged into a meadow and intersected with the Cottle Trail shortly afterwards at the Cottle Rest Site, where there was water for horses. The Cottle Trail was a former road trace that followed Cherry Canyon Creek down a canyon towards Calero Reservoir. The Cottle Trail was surprisingly steep, with grades far harsher than anything I encountered on the Chisnantuck Trail as it dropped downhill to the side of the creek, which was flowing nicely during my December visit.

The Cottle Trail emerged into a large clearing and intersected with the Lisa Killough and Oak Cove Trails at 7.3 miles into the hike. I turned right onto the Oak Cove Trail at this intersection; just a hundred meters later, I came to a second junction where the Serpentine Loop Trail split off to the right from the Oak Cove Trail. Here, I once again took the right fork, leaving the much longer Oak Cove Trail for the Serpentine Loop Trail, which returns to the parking lot in a shorter distance. The Serpentine Loop Trail immediately began an uphill ascent, which was broken just two hundred meters in when the two branches of the Serpentine Loop split. I took the left fork, which stayed a little lower but offered some views over Calero Reservoir.

The Serpentine Loop Trail was very muddy, a situation made worse by the cows that had trampled over many parts of the trail. After an initial stretch of uphill through the oak woods, the trail leveled out as it headed east. I came to the Calero Bat Inn at 7.9 miles: this was one of the park’s most unusual features, a small tower designed specifically to provide a daytime shelter for these nocturnal creatures.

Continuing along the Serpentine Loop, I came to a more open stretch of the trail at 8.2 miles, where I caught a couple of rare glimpses of the Calero Reservoir, along with views of the foothills of the Santa Cruz Mountains and of Mount Umunhum.

Calero Reservoir from the Serpentine Trail

Muddy Serpentine Trail

At 8.6 miles, I came to a four-way junction where the Figueroa Trail, the other branch of the Serpentine Loop, and the Pena Trail intersected. Here, I took the left fork for the Pena Trail to return to the trailhead. The Pena Trail began a short but steep climb from the intersection, crossing a grassy ridge and delivering views behind me of Mount Umunhum and Loma Prieta rising over the rolling hills of Calero County Park.

Mount Umunhum rises over the pastoral landscape of the Serpentine Trail

I passed a water tank and the junction with the Los Cerritos Trail at 8.9 miles; I stayed on the Pena Trail, which now began a steep and constant descent down a ridge. At just over 9 miles, the Pena Trail passed the fork for the Vallecito Trail that I had taken that morning to start the loop. I finished up the hike by following the Pena Trail downhill to the trailhead.