In 2003, Koehl, who had been a star football player at Midland High School, announced his commitment to play college football for the University of Houston.[3] He was a linebacker for the Houston Cougars football team from 2003 to 2006. A four-year starter, Koehl had 300 tackles in his playing career at Houston.[4] He was named to watch lists for both the Butkus Award (awarded to the nation's best collegiate linebacker) in 2004 and the Lombardi Award (awarded to the nation's top lineman, including tight ends and linebackers) in 2005.[5][6] In 2006, Koehl helped lead Houston to its first Conference USA championship in a decade and a berth in the Liberty Bowl.[2]
Koehl also received multiple honors for his academic performance and community service. He was a unanimous choice for the Conference USA All-Academic team in 2006.[7][8] He was also named to ESPN The Magazine's Academic All-District First-team, a finalist for the Wuerffel Trophy, and a semifinalist for the Draddy Award, also known as "the academic Heisman."[4]
In April 2007, Koehl signed a contract to play professional football in the National Football League for the New Orleans Saints.[9] He was released by the Saints before the start of the 2007 regular season. He next signed to in the All American Football League (AAFL) for Team Texas.[10] However, in March 2008, the AAFL announced that its 2008 season had been cancelled.[11]