In just a few short years, Lyons-based Spring Creek Bluegrass Band has become one of the most popular traditional bluegrass groups in Colorado. While the pairing of the words "popular" and "traditional" may seem at odds--especially considering the success of  New Grass bands that incorporate elements of rock, jazz, and electronic music--Spring Creek conveys infectious, youthful exuberance without straying from bluegrass' roots. And it plays those roots without coming across like a historical reenactment. Banjoist Chris Elliott, bassist and fiddler Jessica Smith, guitarist Taylor Sims, and mandolin player Alex Johnstone share vocal duties, pick their instruments with impressive skill, and sing with a whole lot of soul. When the group plays Swallow Hill tonight, it'll perform tracks from its new album, Way Up on a Mountain. Spring Creek's minty fresh LP was released by Rebel Records, a long-standing, Virginia-based bluegrass label that delivers the music of legends like Ralph Stanley. This is a major accomplishment for a Colorado bluegrass band. As the Rebel website points out, Spring Creek is the first band "west of the Mississippi" to be on the storied label. The Blue Maddies, a five-piece Longmont group featuring KC Groves (founding member of the all-female string band Uncle Earl), will open the show. Sat, June 6, 8 p.m. Daniels Hall at Swallow Hill, 71 E. Yale Ave., 303-777-1003 $15/adv, $18/dos, all ages