Annadel Half Marathon
Santa Rosa, United States • 18 Apr 2026
Event overview
The Annadel Half Marathon is a non-profit fundraising event held at Spring Lake Regional Park, 5585 Newanga Avenue, Santa Rosa, California. The event includes a half marathon, a 10K, and a 5K, and has raised funds to support Trione-Annadel State Park and the Sonoma County Parks Foundation over the past 14 years. The races use the trails around Annadel State Park and include participant amenities such as a race medal, an event shirt, and post-race beverages and snacks.
Race details
- Half Marathon
- 10K
- 5K
The half marathon has a 4-hour cut-off time. The event is organized as a low-waste effort in honor of Earth Day, with cup-free aid stations and refill options and an emphasis on park stewardship. A portion of event proceeds is donated to Trione-Annadel State Park and the Sonoma County Parks Foundation. Registration uses tiered pricing: the listed half marathon fees range from $108.98 to $130.38; the 10K from $60.83 to $76.88; and the 5K from $55.49 to $66.18. The event policy states that refunds are not available. Visit the organization's website for the most recent information.