In the promotion of health, fun, and fitness, the Calarat Challenge Trail Running Festival comprises a half marathon, 10k, 5k, and 1k trail race that supports the Cal-Wood Education Center; a non-profit with the mission to increase outdoor education and provide life-transforming experiences for low-income communities. Trail Runners. This half-marathon course takes runners along a variety of different trails throughout the Cal-Wood and Balarat Outdoor Education Center properties. Taking place during Labor Day weekend in early September, participants can expect mild and pleasant temperatures. Jamestown is a beautiful mountain town situated at the Foothills of the Colorado Rocky Mountains, just miles from Boulder, widely known for its scenic nature and tight-knit community atmosphere. Starting and finishing at the Cal-Wood Education Center, this is a looping course on dirt trails that’s fairly flat throughout.