Boulder Rez Marathon

Boulder, United States • 15 Aug 2026

Boulder Rez Marathon

The Boulder Rez Marathon takes place at Boulder Reservoir in Boulder, Colorado, on August 15, 2026. The running course follows the shoreline of the reservoir and remains mostly on dirt roads and trails. The course is described as flat with only about 200 feet of elevation gain and provides views of the Boulder Reservoir and the Rocky Mountains.

The event offers several distance options and relay entries. Distances available include:

  • Marathon
  • 3/4 Marathon
  • Half Marathon
  • 10K
  • Marathon relay captain entry
  • Marathon relay member entry

The event program notes packet pick up and registration and awards for each distance. The stated venue address is Boulder Reservoir, Boulder, Colorado 80301. Visit the organization's website for the most recent information.

Race information

26 mi
Marathon
26 mi
Marathon Relay
20 mi
3/4 Marathon
13 mi
Half Marathon
10 km
10k Run
Visit the organization's website for the most recent information.
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