Trione-Annadel State Park: The Complete Guide

View of the clouds at Trione-Annadel State Park

Harminder Dhesi / CC BY-NC-ND 2.0 / Flickr

Map card placeholder graphic

Trione-Annadel State Park

6201 Channel Dr, Santa Rosa, CA 95409, USA
Phone +1 707-539-3911

Made up of over 5,000 acres on the northern edge of Sonoma Valley in California, Trione-Annadel State Park is known for its springtime wildflower displays and expansive network of hiking, cycling, or horseback riding trails. At the heart of the park, the man-made Lake Ilsanjo (formed by a dam in the 1950s) offers opportunities for fishing, while the rainy winter season forms a series of waterfalls and creeks that flow from the hillsides for an extra splash of natural ambiance.

Trione-Annadel was once occupied by the Wappo and Pomo people, and while no traces of permanent settlements have been found in the park, the area is believed to have been an important site for trading and a source of obsidian. Additionally, the park’s majestic groves of northern oaks are considered by biologists as some of the best-preserved woodlands in the region. 

Things to Do

Most visitors come to Trione-Annadel to tackle its hiking trails or fish in Lake Ilsanjo. Many of the hiking trails are suitable for horseback riding and mountain biking as well, perfect for both quick workouts and all-day sessions.

The diverse range of plant communities, which include meadows, grasslands, and forests, help provide habitats for wildlife like birds, deer, and even coyotes that are often spotted by park visitors. In addition to the lake, the park also houses Ledson Marsh—originally built as a reservoir to provide water to eucalyptus groves. Water collects here during the winter months and overflows into Schultz Canyon, bringing along native grasses and safe haven for vulnerable species (like the rare California red-legged frog).

Wildflower Season

Peak wildflower season ranges from early spring until early summer, with the flowers especially condensed to around Lake Ilsanjo. A small selection of flowers bloom early in the year starting in January and as late in the year as September, though the best months to see wildflowers in general are still considered April and May.


The 26-acre Lake Ilsanjo is full of bluegill and black bass—some as heavy as nine pounds—but those wanting to fish will need to hike in with their fishing gear. According to park officials, bass prefer purple-colored plastic bait, while bluegill fish favor garden worms, small crayfish, and grubs. A California fishing license is required for those 16 years and older. 

Best Hikes & Trails

The 40-plus miles of hiking trails, which include an 8.5-mile section of the popular Bay Area Ridge Trail, are what attracts most visitors to the state park. The trails traverse through dense, shaded forests and open meadows, past rolling hills and seasonal streams, all with different degrees of difficulty.

  • Rough-Go Trail: It’s not hard to guess how this 6-mile loop hike got its name. Not only does the Rough-Go Trail feature a steep path through rough terrain, but it also has full southwestern exposure and plenty of switchbacks. The strenuous hike takes visitors past massive rock formations and meadows before culminating at the lake.
  • Warren Richardson Trail: Named for a prominent cattle rancher and hop farmer, the Warren Richardson Trail starts from the parking lot at the end of Channel Drive and travels uphill past groves of Douglas-fir, bay, and redwood trees. After hiking to a 900-foot elevation about two miles in, visitors will reach the lake and can choose to venture around it to turn the trail into a 6-mile loop.
  • Canyon Trail: A 2-mile journey that begins at the intersection of Spring Creek Trail near the bridge, the Canyon Trail is a favorite of horseback riders and those in search of an incredible view. After a steady climb, the trail offers panoramic views of Santa Rosa and Mount Saint Helena in the distance.
  • Marsh Trail: Popular with mountain bikers and hikers, the Marsh Trail spans just over 4 miles skirting the northern slope of Bennett Mountain. Climbing higher, the trail runs through forests of oak and coastal redwoods to eventually offer vast views of Lake Ilsanjo and the Mayacamas Mountains.

Where to Stay Nearby

Although there are no camping facilities inside the park itself, nearby landscapes at Spring Lake and Sugarloaf Ridge State Park have campgrounds about 10 miles east via Highway 12 and Adobe Canyon Road. Otherwise, nearby Sonoma and Santa Rosa offer plenty of options for accommodations.

  • Beltane Ranch: The luxurious-yet-cozy Beltane Ranch is located just 10 miles from Trione-Annadel State Park. The 19th-century bed and breakfast here is set on a working ranch complete with vineyards and orchards complemented by a peacefully lush garden and clean, farmhouse-chic guest rooms overlooking the property.
  • The Jack London Lodge: This charming Victorian-era accommodation is found in a quiet spot overlooking Sonoma Creek and adjoins the Jack London Saloon. The Jack London Lodge is known for its rustic decor and outdoor swimming pool that attracts visitors looking for a peaceful setting among the forested, small town of Glen Ellen.
  • Vintners Resort: On the other side of the state park about 10 miles away in the city of Santa Rosa, the Vitners Resort is a four-star hotel set on a large vineyard among 92 acres of land. Visitors who require a bit more amenities will feel right at home here thanks to its on-site restaurant, cafe, bar, spa, hot tub, and pool.

How to Get There

Trione-Annadel State Park is located about 60 miles north of San Francisco in east Santa Rosa. It can be found south of Highway 12 on Channel Drive via Montgomery Drive and Highway 101 north.


There are two accessible picnic tables and an accessible portable restroom off the main parking lot at the end of Channel Drive inside the boundaries of the park. The parking lot also has several designated accessible parking spots. 

Tips for Your Visit

  • Dogs are only allowed in the park’s developed areas, such as Channel Drive. They are not allowed on any trails, dirt roads, or in backcountry spaces (except for service animals).
  • Park hours are 8 a.m. to sunset every day.
  • Because of its low altitude, snow and fog are very rare inside the park, but rainfall averages about 30 inches per year mainly throughout winter and early spring.
  • Since there is no camping allowed in the park and the property is in a high wildfire zone, there are no fires, camp stoves, or barbecues allowed inside.
  • Some trails will be marked for “no use” by horses and cyclists.
  • Aside from the drinkable water fountain located near the visitor center and in the main parking lot at east Channel Drive, there is no potable water available inside the park. Come prepared with your own water bottles and stock up before heading out, especially if you plan to hike or participate in any other strenuous activities.
  • In addition to Trione-Annadel State Park, there are several other state parks located in the surrounding area nearby. These include Sugarloaf Ridge State Park, Jack London State Park, Sonoma State Historic Park, and Petaluma Adobe State Historic Park.
Back to Article

Trione-Annadel State Park: The Complete Guide