Every Trail Tells a Story

Annadel State Park

Warren Richardson, Steve’s S Trails
Annadel State Park
To Lake Ilsanjo is 5 miles round trip with 500-foot elevation gain; circling the lake adds an additional 2 miles
Why Go

A wilderness fix just minutes from suburban Santa Rosa.

Lake Ilsanjo—perfect for picnics, fishing, or just lazing on the shore.

Trails that weave through obsidian history, wildflower meadows, and shady fir forests.

The Story

Annadel is the wild backyard that Santa Rosa never knew it needed. Pressed right up against the suburbs, yet sprawling over 5,000 acres with more than 45 miles of trails, it’s a surprise of oak woodlands, meadows, rocky ridges, and one very popular lake—Ilsanjo, where locals hike, picnic, and even fish for bass and bluegill.

The lake’s name sounds old-world Spanish, but it’s actually a mash-up of Ilsa and Joe, the Coneys who dammed the creek in 1956. The waters may be modest, but ask any kid who’s reeled in a bluegill here—Ilsanjo looms large in local legend.

Long before the Coneys or the park service, though, people came for rocks. Pomo and Wappo tribes prized Annadel’s obsidian, flaking it into arrowheads and knives. Settlers quarried basalt in the late 1800s and early 1900s—tons of it hauled south to build San Francisco, and then again after 1906 to rebuild what the earthquake brought down. Annadel’s hillsides bear those scars, but the forests and grasses have since softened them.

The land passed through ranchers’ and farmers’ hands—part of the vast Rancho Los Guilicos land grant—before becoming a state park in 1971. In 2016, it was renamed Trione-Annadel State Park to honor the Trione family, who played a key role in preserving open space in Sonoma County.

Today, Annadel is a patchwork of natural and cultural history where trail runners, mountain bikers, equestrians, and hikers all converge. (If you’re a hiker, be ready to share the trail and maybe step aside as a Lycra-clad cyclist zooms past shouting, “On your left!”).

Despite being so close to town, Annadel feels expansive, with a trail network dense enough to keep you exploring for days. And while you can enter from multiple trailheads—Oakmont, Lawndale, Spring Lake—the classic approach is from Channel Drive and the Warren Richardson Trail, a wide dirt road named for a cattle rancher and horseman who loved these hills. From there, you can make your way to Ilsanjo, loop around the lake, or connect to a lattice of side trails that wind up to rocky ridges and wildflower meadows.

Directions

Trione-Annadel State Park is located at 6201 Channel Drive in Santa Rosa. The park office is at the entrance; trailhead parking is a mile farther down the road.

The Hike

From the Channel Drive lot, head south on the short connector to wide Warren Richardson Trail. You’ll pass an interpretive display on Native use of acorns, then see the junction with Steve’s S Trail—your return route.

The wide trail ambles 0.75 mile through oak and fir before swinging into a hairpin and climbing more steadily. Sword ferns and bay laurels line the way, and the canopy offers shady relief. Past a junction with Louis Trail, the route drops gently, and Lake Ilsanjo comes into view. Cross a meadow and stroll down to the lakeshore—a favorite picnic stop.
If you’re satisfied with a five-mile out-and-back, linger by the water, maybe toss in a line. If you want more, continue around the lake by connecting Rough Go Trail and Middle Steve’s S Trail. In spring, blue-eyed grass carpets the lakeshore.

For your return, take Steve’s S Trail up the east side of the meadow. The narrow singletrack climbs, then dips through Douglas fir forest before delivering you back to Warren Richardson Trail and the start.