Entry No. 172 — the Denver file — filed under: outdoor
Sleepy Lion Trail to Button Rock Dam
Most people aiming for "a hike near Boulder" never turn down the dirt road to Button Rock Preserve, which is exactly why it stays quiet. You start on a flat service road tracing North St. Vrain Creek past tiny Longmont Reservoir, then the Sleepy Lion Trail peels off and climbs through ponderosa and Douglas fir into a high rolling meadow with views toward Longs Peak and Mt. Meeker. It's named for a ranger who found a mountain lion napping on a rock here. Bighorn sheep, reintroduced in the 1980s, and wintering elk move through these slopes. The loop closes at Button Rock Dam, where water roars off a granite cliff into a pool. Big country, almost nobody on it.
The move: Skip the crowded flatirons-selfie hikes and make the drive itself the date. Pack water and a snack, leave the dog at home (not allowed here), and walk in past the gate together. The first easy stretch along the creek is for talking; the climb up Sleepy Lion is for working a little; the meadow at the top is where you stop, sit, and watch for bighorn while the whole Front Range opens up. Finish at the dam, feel the spray, and let the quiet do the rest. A real adventure that takes a half day, not a whole one.
📍 Before you go Full loop is roughly 5 miles round trip with about 850 ft of gain, rated moderate; the first half-mile is flat service road before the real climb begins. Trailhead: from Lyons, US-36 west ~4 mi, left on Boulder County Road 80 ~3 mi to the gated lot (about 45 min from central Denver). Free entry, no permit to hike; a separate fishing permit is required only for Ralph Price Reservoir. No dogs allowed in the preserve since 2023 (watershed protection). Best from late spring through fall — wildflowers and wildlife peak in spring/early summer. The northwest section closes Dec 1–Mar 31 to protect wintering elk, and snow, ice, and afternoon mountain storms are real risks shoulder-season and summer; carry layers and water, and turn back if thunder builds. The lot holds about 60 cars and fills early on weekends; roadside parking gets ticketed or towed.
- 📍 Lyons / Button Rock Preserve (northwest of Boulder)
- 💸 Free
- ⚡ Up for anything
- 🌗 Outdoors
Where: Button Rock Preserve Trailhead, Lyons. From Denver/Longmont, take US-66 west to Lyons, then US-36 west ~4 miles, turn left onto Boulder County Road 80 (Longmont Dam Road) and continue ~3 miles to the gate. Park in the lot at the gate (about 60 cars, fills early on weekends); the preserve is walk-in only past that point.
Hours: Day-use, free. Best season: Late spring through fall. Confirm trail & road conditions before you go.
⚠ Seasonal or scheduled — always check before you go.
Plan a visit & invite your people →
Proof: source 1 · source 2 · source 3 · source 4
last checked: 2026-06-10