TERREX Lake Sonoma 100K, 50K & Trail Sisters Women's Half Marathon

Springtime in wine country meets ultra running at Lake Sonoma!

On April 11, 2026, athletes will line up amid rolling hills, oak‑dotted ridgelines, and views that stretch toward the lake below. With a Western States–qualifying 100K, a rugged 50K, and a women's Half Marathon, this event blends serious competition with community celebration.

Lake Sonoma 100K

This Western States qualifying course begins with a demanding climb up Pritchett Peak, where runners are greeted with a sunrise summit. After descending to the Lake Sonoma Visitor Center, the course climbs again to South Lake Trailhead, entering a classic out-and-back along the original Lake Sonoma 50 mile course.

The 100K is relentlessly hilly and remote, with 13 aid stations spaced along the route (8 full, 5 water-only). You’ll run through madrone groves, lakefront paths, and California carpet singletrack that requires mental and physical stamina. Finish under 19 hours to qualify for Western States 2027.

Drop bags are allowed at Woodbridge, Warm Springs and Liberty Glen. Crew support is allowed at South Lake (outbound only), Warm Springs, and Liberty Glen.

Complete info found at the LS100K website

Lake Sonoma 50K

Come run your first ultra at the Lake Sonoma 50k. Starting at the Lake Sonoma Visitor Center, the course opens with a short paved section before turning to rolling singletrack that climbs and dips through forested terrain. Aid stations include South Lake, Island View, Warm Springs, Wulfow, Liberty Glen, and Bummer, before a bridge crossing and screaming downhill lead you to the finish.

The terrain is punchy with relentless up and downs so conserve early to handle the final miles. Finish line festivities await those who conquer the climbs within the generous 11-hour cutoff. Crew is permitted at Liberty Glen. Drop bags are available at Warm Springs and Liberty Glen.

Complete info found at the LS50K website

Trail Sisters Half Marathon

This women’s half marathon event starts at Lone Rock Trailhead and finishes at the Visitor Center. The 13.1-mile route features rolling terrain, lake overlooks, and a community atmosphere that fosters encouragement among all levels. Aid stations appear roughly every 3–4 miles, and runners have 5 hours to complete the course.

Shuttle transportation is provided from the finish back to the start, and finish line drop bags are shuttled for you. Cutoff at Bummer Aid is 12:00PM.

Complete info found at the Trail Sisters Half Marathon website

Courses

Aid Stations & Support

All Races:
All distances are cupless — runners must carry their own bottle, flask, or bladder.
Aid stations are stocked with Skratch Labs hydration and chews , plus a mix of traditional ultra fare (sweet and salty snacks), sunscreen, Vaseline, and basic medical supplies.

EMT services provided by NoSoCo Fire Department.
Live timing by UltraLive.net.
Music by DJ Marco.
Pizza by Happy Cat Pizza.

100K:
13 aid stations: 8 full service and 5 water-only.
Water-only stations: Pritchett, South Lake, and Wulfow.
Crew access: South Lake (outbound only), Warm Springs, and Liberty Glen.
Drop bags allowed at Woodbridge, Warm Springs, Liberty Glen, and Lone Rock.
Headlamp required for runners leaving Warm Springs after 3:30 PM.

50K:
6 aid stations: 4 full service and 2 water-only.
Water-only stations: South Lake and Wulfow.
Crew access and drop bags allowed at Liberty Glen.
Runners should prepare for long gaps between aid — carry enough water for stretches up to 6.9 miles.

Trail Sisters Half Marathon:
3 aid stations located at Oak Knoll (mile 3.6), Archery (mile 6.2), and Bummer (mile 9.7).
Archery has a cutoff at 12:00 PM. Runners should drop here if unable to finish.
Bummer is not crew accessible.
Finish line drop bags will be transported from the start.

Across all distances, runners should monitor fluid needs carefully — especially in warm weather. Carrying at least one bottle is mandatory.

Runner Experience

Whether you’re racing or crewing, Lake Sonoma delivers more than just miles. All finishers receive a custom gift (wine bottle or non-alcoholic option), plus a race tote and post-race pizza from Happy Cat Pizza.

Expect a warm, supportive atmosphere—especially at the Trail Sisters Half—and a community steeped in the spirit of trail running. From the sunrise start over Lake Sonoma to a roaring finish line celebration, the weekend blends rugged adventure with laid-back wine country hospitality.

Practical Details

• Registration: Opens October 1
• Pricing:
  • 100K – $280 early / $300 regular
  • 50K – $185 early / $200 regular
  • Trail Sisters Half – $110 early / $115 regular
• Finisher Awards:
  • 100K & 50K: Custom bottle of wine (or non-alcoholic option)
  • Half Marathon: Trail Sisters finisher mug
• Airports: San Francisco International (approx. 94 miles), Sacramento International (approx. 128 miles)
• Parking:
  • 100K & 50K: Lake Sonoma Visitor Center lot
  • Half Marathon: Lone Rock start area with free shuttle back from the finish
• Camping: Vehicle and tent camping permitted Friday and Saturday nights in the main lot near the Visitor Center
• Mandatory Gear:
  • All runners must carry a bottle/flask/hydration system (cupless race)
  • 100K runners must carry a headlamp if leaving Warm Springs after 3:30 PM
• Pacers: Not allowed for any distance
• Crew Access:
  • 100K: South Lake (outbound only), Warm Springs, Liberty Glen
  • 50K: Liberty Glen
  • Half: No official crew locations
• GPX/Course Maps: Available Here

Event's current local time: 12:37 AM PT