Teaming up with Jim Haglund, Mertes helped to revitalize Wenatchee Valley College's booster club, known as the Quarterback Club, into an organization to promote all WVC athletics. Renaming the club "KnightBoosters", Mertes and Haglund set about building the membership as well as generating financial support for WVC's burgeoning athletic program that included football, men's and women's basketball, women's volleyball, men's and women's track and tennis.
Although only in their mid-20's, Mertes and Haglund alternated as club presidents for a decade beginning in 1975 during a time of perhaps the college's greatest overall athletic success with dominating men's and women's basketball squads and highly competitive football and track teams. As well as through KnightBoosters memberships, Mertes and Haglund also worked together to develop several successful fund raisers including an annual golf tournament, a 10k run to lead off the Apple Blossom Festival parade, and sponsorships along with increasing season ticket sales.
While working at the Wenatchee World, and later through his advertising agency, Adco, Mertes promoted Wenatchee Valley College athletics and developed logo identities and advertising that helped the college lead the NWAACC in season attendance at football and men's and women's basketball games for many years. Later, as an influential member of Wenatchee North Rotary, he was a driving force in the club's donation of $25,000 to build the softball facility on the WVC campus.