Lake Sonoma 100K

Event overview

The Lake Sonoma weekend in Healdsburg, California includes three trail races on April 11, 2026:

• 100K
• 50K
• Trail Sisters Half Marathon (women’s only)

The 100K is a Western States qualifier (finish under 19 hours to qualify for Western States 2027). All races use Lake Sonoma area trails and start or finish at the Lake Sonoma Visitor Center. The Trail Sisters Half Marathon starts at Lone Rock and finishes at the Visitor Center with a shuttle back to Lone Rock.

Courses and support

The 100K begins with a climb to Pritchett Peak, follows an out-and-back along the original Lake Sonoma route, and passes through madrone groves and lakefront singletrack. The 50K follows rolling singletrack, crosses the Lake Sonoma bridge, and finishes near the Visitor Center. The Trail Sisters half is an out-and-back with rolling hills and lake overlooks.

All races are cupless; runners must carry a bottle, flask, or hydration system. Aid station service and locations vary by distance: the 100K has 13 stations (8 full, 5 water-only), the 50K has 6 stations, and the half has 3 stations. EMT services are provided on course. Drop bag and crew access rules differ by race.

Logistics and notes

Parking for the 100K and 50K is at the Visitor Center lots; the half uses Lone Rock parking with a shuttle to the finish. Vehicle and tent camping is permitted in the main lot on Friday and Saturday nights. Pacers are not allowed. Finishers receive a custom bottle of wine or a non-alcoholic option, and other finisher items vary by distance. Registration fees differ by event. Visit the organization's website for the most recent information.