An artist's rendition of the proposed Watana Dam on the Susitna River. (Image courtesy Alaska Energy Authority)For decades, the Susitna–Watana Hydroelectric Project has occupied a liminal space in Alaska’s energy conversations — too large, expensive and controversial to move forward, yet too potentially transformative to fully dismiss. In many ways, it has become shorthand for the state’s uneasy relationship with mega-projects that promise to re…