Trione-Annadel State Park is a 5,092-acre wilderness preserve located at 6201 Channel Drive on the eastern edge of Santa Rosa, California, at the northern gateway to the Sonoma Valley. Established in 1971 and renamed in 2016 after a major preservation gift from the Henry Trione family, the park protects a rugged landscape of volcanic hills, second-growth coast redwoods, Douglas fir groves, open meadows, and seasonal streams. Centuries before European settlers quarried its basalt cobblestones to pave the streets of San Francisco, Indigenous Pomo and Wappo peoples harvested the park’s abundant obsidian deposits to craft arrowheads and cutting tools. Today, travelers and Sonoma County locals visit for its 40-plus miles of multi-use trails, spring wildflower displays, and catch-and-release bass and bluegill fishing at Lake Ilsanjo.
What to Expect at Trione-Annadel State Park
Unlike heavily developed recreational parks, Trione-Annadel State Park leaves its interior largely untouched by paved roads, allowing hikers, mountain bikers, and equestrians to explore its backcountry terrain on dirt fire roads and rocky singletrack paths. The central destination inside the park is Lake Ilsanjo, a 26-acre man-made reservoir constructed in the 1950s and named by combining the first names of former property owners Ilsa and Joe Coney. Reaching the lake requires a 2.5-mile hike or ride up either the shaded Warren Creek Trail or the wider Canyon Trail. Anglers carrying a valid California fishing license cast from the shoreline for largemouth bass and panfish, while swimmers and picnickers spread out along the grassy banks beneath coast live oaks and black oaks.
From late February through June, the park’s varying microclimates produce one of Sonoma County’s premier botanical displays. Damp seeps near Ledson Marsh support endangered Sebastopol meadowfoam and buttercups, while sunny chaparral slopes along the North Burma Trail and Rough Go Trail bloom with California poppies, purple lupines, calypso orchids, and red larkspur. Visitors can check seasonal trail maps, geological displays, and wildlife sightings at the volunteer-staffed Visitor Center near the Channel Drive entrance before setting out toward Bennett Mountain, the park’s highest peak at 1,887 feet.
- Lake Ilsanjo Loop: A 26-acre backcountry reservoir encircled by the 1.2-mile Lake Trail, offering shoreline fishing for largemouth bass and bluegill alongside quiet lakeside picnic spots.
- Over 40 Miles of Multi-Use Trails: Interconnected singletrack and fire roads—including Canyon Trail, Cobblestone Trail, and Lawndale Trail—celebrated by Northern California trail runners, hikers, and technical mountain bikers.
- Historic Basalt Cobblestone Quarries: Abandoned late-19th-century and early-20th-century quarry pits visible along the Cobblestone Trail, where workers cut volcanic stone for San Francisco’s cable car tracks and roadways.
- Ledson Marsh & Spring Wildflowers: High-elevation vernal wetlands and open meadows that bloom each spring with yellow buttercups, iris, shooting stars, and rare endemic flora.
- Warren Richardson Trail & Redwood Groves: Shaded canyon corridors near the Channel Drive staging area featuring mature Douglas firs, bay laurels, and coast redwoods with picnic tables and vault toilets.
Trione-Annadel State Park at a Glance
| Detail | Information |
|---|---|
| Address | 6201 Channel Drive, Santa Rosa, CA 95409 |
| Neighborhood / Area | Eastern Santa Rosa / Bennett Valley / Sonoma Valley North |
| Operating Hours | Daily from 8:00 AM to sunset (hours vary seasonally up to 8:30 PM in summer) |
| Admission / Price Range | $7–$10 day-use vehicle parking fee at Channel Drive ($); free walk-in and bike-in entry |
| Recommended Visit Duration | 2 to 4 hours |
| Nearest Transit / Parking | Paid main parking lot on Channel Drive; Sonoma County Transit and Santa Rosa CityBus stops along Montgomery Drive |
| Official Website & Phone | California State Parks Official Page | +1 707-539-3911 |
Visiting Tips, Getting There & Nearby Pairings
The primary vehicle entrance to Trione-Annadel State Park sits along Channel Drive off Montgomery Drive in eastern Santa Rosa, where a day-use parking fee applies to cars parking at the Warren Richardson Trailhead and Visitor Center lot. Because the main lot fills quickly on sunny spring weekends, arrive before 9:00 AM or access the trail network from perimeter staging areas at neighboring Spring Lake Regional Park (via Newanga Avenue or Violetti Road) or along Lawndale Road in Kenwood. Carry plenty of drinking water and downloaded offline trail maps, as potable water faucets and flush restrooms are limited to the Channel Drive entrance area, with only rustic pit toilets located near Lake Ilsanjo. Due to protected wildlife habitats, dogs are strictly prohibited on all dirt trails inside the state park, though leashed dogs are permitted solely on the paved Channel Drive roadway.
Regarding physical accessibility, the Channel Drive staging area provides designated ADA parking spaces, accessible restrooms, and level picnic tables beneath the oaks, though the park’s unpaved, rocky interior trails gain steep elevation and require sturdy footwear or all-terrain mobility equipment. After a morning hike, visitors are within a 5-to-10-minute drive of Howarth Park and Spring Lake Regional Park, which connect directly to Trione-Annadel’s western boundary and offer paved lakeside walking paths. For post-hike dining and wine tasting, head ten minutes west to the Montgomery Village shopping and dining district on Sonoma Avenue, or drive ten minutes southeast along Highway 12 into the heart of Kenwood’s Sonoma Valley wineries.
Frequently Asked Questions
What are the opening hours and best season to visit Trione-Annadel State Park?
Trione-Annadel State Park is open from 8:00 AM until sunset year-round, with summer evening hours extending until 8:30 PM. March through May is the ideal window to experience lush green hills, flowing creeks, and peak wildflower blooms around Lake Ilsanjo and Ledson Marsh, while autumn brings golden black oak foliage and crisp hiking weather.
How much does parking cost at Trione-Annadel State Park?
Day-use vehicle parking at the main Channel Drive lot costs between $7 and $10 per vehicle, payable at the entrance kiosk or self-pay station, and California State Parks passes (including the California Explorer Pass and Golden Poppy Pass) are accepted. Hikers, trail runners, and cyclists entering on foot or by bicycle pay no admission fee.
How much time should I budget for a hike to Lake Ilsanjo?
Plan on 2.5 to 3.5 hours to hike the popular 6-to-7-mile round-trip loop from the Channel Drive trailhead up Canyon Trail, around Lake Ilsanjo, and back down via Warren Creek Trail or Spring Creek Trail. Visitors seeking a shorter outing can spend 60 to 90 minutes exploring the lower redwood and fir groves near the Warren Richardson Trailhead.
Are dogs or mountain bikes allowed on the trails at Trione-Annadel State Park?
Mountain bikes and horses are permitted on almost all of the park’s 40 miles of fire roads and singletrack trails, making it one of Northern California’s premier cycling destinations. However, dogs are not allowed on any dirt trails or in the backcountry; leashed dogs are restricted exclusively to the paved Channel Drive entrance road and parking area.
When planning your Santa Rosa travel guide or comparing verified attractions and parks in Santa Rosa, pair this stop with standout local spots including Ca'Bianca, Vintners Resort, Crane Creek Regional Park, and Spring Lake Park (1.3 km away).
