In considering risk forecasting in light of anthropological and interdisciplinary impact assessment literature, this article demonstrates that impact assessment in Canada's tar sands sector is about designing the future, legitimizing future energy development, and rendering defense of foraging economies into technical, rather than political, channels. Impact assessment is a future-oriented, modeling-based practice, with a problematic relationship to empirical research methods such as ethnography. While purportedly foregrounding the knowledge of expert forecasters over that of impacted people, impact assessment documents and processes actually raise serious questions about forecasters' expertise and impartiality. Using three case studies of traditional land use reports from the tar sands region, this article draws on literature from the Anthropology of the Future to understand and critique the construction of expert knowledge and predictive power in the tar sands region through social impact assessment documents.