Most Saturday mornings at Almaden Lake Park look the same. Strollers and leashed dogs circle the water. Someone's kid is on the renovated playground near the east side. A few people fish along the bank, because fishing is about the only thing the lake is legally for. Somewhere past the tennis courts, where the paved path curves south, a good number of walkers turn around, satisfied they've finished "the loop."
They haven't finished the loop. They've finished about a third of what's actually connected to it.
The lake's own trail is a modest 1.3-mile ring with almost no elevation change, the kind of route you'd do with a coffee in one hand. What that loop doesn't advertise is that Almaden Lake Park isn't really its own attraction. It's the flattest, easiest entry point into a trail corridor that keeps going well past the edge of the park, and eventually climbs into a mountain preserve that plenty of longtime Almaden Valley residents have never actually set foot in, despite living a short drive from its base.
Where the Pavement Actually Leads
The lake sits at a junction, not an endpoint. At the south end of the park, the paved path connects directly to the Los Alamitos Creek Trail, which runs 3.9 miles to Santa Teresa County Park, passing agricultural land and riparian habitat along the way. At the north end, it links to the Guadalupe River Trail, which drops below street level for a 0.9-mile stretch that continues toward a percolation pond under Highway 85.
Stitched together, that's:
- Lake Almaden Trail — 1.3 miles, paved, flat, the loop most people already know
- Los Alamitos Creek Trail — 3.9 miles south to Santa Teresa County Park, including a fitness course
- Guadalupe River Trail — 0.9 miles north, running below street grade toward the Highway 85 corridor
That's roughly six miles of connected, mostly paved trail without crossing a single major intersection. The lake loop isn't the whole story. It's the on-ramp.
Two Signs, One Lake
Ask around about why you can't swim in Almaden Lake and you'll get two different answers depending on who's posted the sign. Some say mercury. Others cite algae. Either way, the water is for looking at, not wading into, and fishing is strictly catch-and-release.
The mercury explanation, whether or not it's the current official reason, isn't a random guess. Almaden Valley and neighboring New Almaden take their names from the historic New Almaden Quicksilver Mines, once one of the largest mercury mining operations in North America. That mining history shows up in unexpected places around the neighborhood. La Foret, the French restaurant tucked into a creekside setting in Almaden Valley, started as a boarding house for miners working those same quicksilver mines before it became a farm-to-fork dining spot.
The Corridor Runs Higher Than the Foothills Suggest
Keep following the trail logic and it doesn't stop at the park boundary. Head south on Hicks Road toward Mount Umunhum Road and you reach the Bald Mountain parking area, the trailhead for Sierra Azul Open Space Preserve, more than 19,000 acres of protected land with 26 miles of multiuse trail winding through chaparral, oak woodland, and serpentine grassland.
From that lot, the Mount Umunhum Trail climbs 3.9 miles one-way to the 3,486-foot summit, gaining roughly 1,141 feet along the way. In Ohlone, the mountain's name carries its own meaning.
"Umunhum" means "resting place of the humming bird."
At the top sits the reason most South Bay residents recognize the peak on sight without knowing its name: a Cold War-era concrete radar tower, 84.5 feet tall, known locally as the Cube. It was built for the Almaden Air Force Station, which operated from 1957 to 1980. The summit stayed closed to the public for decades afterward, until a nearly ten-year cleanup effort removed the abandoned military buildings and hazardous materials, finally reopening the area in 2017.
Nearby, Almaden Quicksilver County Park adds more than 4,000 acres and 37 miles of trail to the same general corridor, including 30 miles open to horses and 16.6 miles open to mountain bikes.
None of these places feel connected when you're standing in any one of them. The lake loop feels like a neighborhood amenity. The Quicksilver park feels like a separate hiking destination. Sierra Azul feels like a mountain you'd need a special trip to visit. In practice, they're one continuous stretch of protected land, linked by trail and separated mostly by a few road crossings, running from a stroller-friendly lake all the way to a Cold War landmark visible from most of the South Bay.
A Weekend That Uses More of It
- Walk the lake loop early, then keep going onto the Los Alamitos Creek Trail toward Santa Teresa County Park before the heat sets in.
- Later in the day, drive up Hicks Road to the Bald Mountain lot and do the Umunhum out-and-back, a route that typically takes three and a half to four hours round trip.
- Save Quicksilver Park's New Almaden Trail, a 12-mile out-and-back through the old mining district, for a cooler morning with more time on the calendar.
This Month's Calendar Anchors
The Sunday farmers market at Via Valiente Plaza on Almaden Expressway is the neighborhood's default grocery run before or after a trail morning. And for anyone who wants a guided reason to walk the Los Alamitos Creek section this month, the Santa Clara Valley Bird Alliance is leading a summer birding field trip through Almaden Lake Park and the creek trail on Sunday, August 16, from 8:30 to 11:00 a.m., an easy two-mile walk suited to any skill level.
After a long trail day, Alamitos Vineyards, the only vineyard winery within San Jose city limits, sits about five minutes from La Foret, making the two an easy pairing for a Saturday that started at the lake and ended somewhere higher up the hill.
The lake loop is still a fine way to spend a morning on its own. It's also the easiest few hundred yards of a much longer corridor that most of the neighborhood drives past without noticing where the pavement actually goes next.
Megan DeVivo works this same stretch of the South Bay every day, from the Almaden foothills down to the coast. If someone in your life is weighing a move into this corner of San Jose and wants an agent who already knows where the trail turns to dirt, Let's Connect.
