The Vallecito Lake Heavy Half Marathon is a beautiful and scenic course around Vallecito Lake. Nestled in the heart of the San Juan Mountains in Colorado, our race course takes runners completely around the picturesque Vallecito Reservoir with a special section that runs right across Vallecito Dam. Grab a few friends and spend the weekend in the beautiful Vallecito Valley. More than just a great race, this event is a fundraiser for local non profits.