Annadel Half Marathon

APR

18

2026

Celebrate Earth Week with trail runs through Annadel State Park at Spring Lake Regional Park in Santa Rosa. This nonprofit fundraiser features half marathon, 10K and 5K distances, low waste aid stations, and supports local park stewardship.

Sat 18 Apr 2026

Santa Rosa, California

Registration

Half Marathon 10 kilometers 5 kilometers

Always double-check with the organizer's website! This page may contain affiliate links.

Event overview

The Annadel Half Marathon is a non-profit fundraising race held on April 18, 2026, at Spring Lake Regional Park, 5585 Newanga Avenue, Santa Rosa, CA. The event has operated for about 15 years and donates a portion of proceeds to Trione-Annadel State Park and the Sonoma County Parks Foundation. Organizers describe the course using the trails of Annadel State Park and emphasize park stewardship and low-waste practices in honor of Earth Day (April 22).

Race details

Distances offered:

Half Marathon
10K
5K

The Half Marathon has a 4-hour cut-off time. Each participant receives a race medal, an event shirt, and post-race beverages and snacks. The event uses cup-free aid stations and refill options to reduce waste. Registration is non-refundable. Visit the organization's website for the most recent information.

Half Marathon

10 km

10k

5 km