The Dam Cup celebrates the friendly rivalry between the states of Oregon and Washington within the Big Sky Conference. The so-named rivalry refers to the four dams linking Oregon and Washington that one passes on the 339-mile drive from the Portland State campus to the Eastern Washington campus. Located along the Columbia River, they are Bonneville Dam, The Dalles Dam, the John Day Dam, and the McNary Dam.
The purpose of The Dam Cup is to create a rivalry between Portland State University and Eastern Washington University and provide a sense of pride between alumni in the Portland and Spokane areas. Other goals include increasing attendance at events between both schools and building school spirit among each institutions' student body. According the PSU's website, winning the Dam Cup is one of the schools' priorities. The winner of the Dam Cup will possess The Dam Trophy acknowledging the achievement for the following year.
The Dam Cup is based on a point system. Each game played in the five sports between the two schools has a point value. Points are only rewarded for regular season contests. The annual football game is worth four points, the women’s soccer match is worth one point, each women’s volleyball match is worth two points for a total of four points possible, and each men’s and women’s basketball game is worth two points for a total of four points possible in each sport, The total points possible are 17 which means that to win the cup a school would need to win at least 9 points.
Starting with the 2013-2014 athletic season, fans of each team were given the ability to earn points for their schools through social media, by following the teams on Facebook, Twitter, Instagram and YouTube while also using their respective hashtags when posting. The winner of the Dam Cup Fan Challenge collects two points to add to their respective team's total for the year, raising the total amount of available points to 19 and the minimum to win the cup to 10.