Lake Sonoma 100K

Lake Sonoma 100K, 50K and Trail Sisters Half Marathon

The event takes place at Lake Sonoma near Healdsburg/Geyserville on April 11, 2026. It includes three trail races that share the Lake Sonoma landscape and visitor center as the primary venue.

Distances

• 100K (Western States qualifier)
• 50K
• Trail Sisters Half Marathon women only

The 100K begins with a climb to Pritchett Peak and follows an out-and-back on the original Lake Sonoma route, passing madrone groves and lakefront singletrack. The course has 13 aid stations (8 full, 5 water-only); finishing the 100K in under 19 hours provides Western States qualifying eligibility for 2027. Crew access and drop bag locations are designated at several points on the course.

The 50K starts near the Visitor Center, travels rolling singletrack past named aid stations and crosses the Lake Sonoma bridge before a steep final descent. Crew access and drop bag options are available at Liberty Glen.

The Trail Sisters Half Marathon is a women-only out-and-back course that starts near Lone Rock and finishes at the Visitor Center; a shuttle runs from the finish back to the start. Aid stations appear along the route and organizers describe a supportive, community-focused environment.

Practical details include a cupless policy requiring runners to carry their own bottle or hydration system, EMT coverage on site, on-course nutrition and basic medical supplies at aid stations, visitor center parking for the 100K and 50K, and permitted vehicle and tent camping in the main lot on Friday and Saturday nights. Finishers receive a custom bottle of wine or a non-alcoholic option and event merchandise. Visit the organization's website for the most recent information.