RUSTON, La. -- Louisiana Tech athletic director Bruce Van De Velde announced on Thursday that he is stepping down.

Van de Velde did not immediately go into detail about the reasons for his decision. His resignation, effective Monday, comes at the end of an academic year in which the Bulldogs' football team missed out on a bowl game despite a nine-win season, and then lost coach Sonny Dykes, who left to coach California.

The Bulldogs were left out of college football's post season after Van De Velde declined to quickly accept an invitation from the Independence Bowl in Shreveport, holding out for other opportunities that never materialized.

Dykes left soon after Van De Velde said publicly he would not get into a bidding war to keep the coach and suggested that Cal consider another candidate.

Louisiana Tech spokesman Dave Guerin said university policies prevent officials from discussing details of personnel decisions. In a written release, Louisiana Tech President Dan Reneau thanked Van De Velde for his contributions, which included the hiring of Dykes and men's basketball coach Mike White, who both had their teams ranked in the Top 25 in their most recent seasons.

The university also highlighted student-athletes' good academic performance during Van De Velde's tenure.

"My experience at Louisiana Tech has been both rewarding and challenging," said Van De Velde, who took over in March 2010. "I am proud of my contributions to the competitive and academic success of our student-athletes and coaches."

Louisiana Tech is leaving the Western Athletic Conference and next fall will begin competing in Conference USA.

Reneau said Louisiana Tech will immediately start forming a search committee, led by incoming Louisiana Tech President Les Guice, to find Van De Velde's replacement.