The water levels on Rainy Lake and the Namakan Chain of Lakes have been controlled by dams for more than 100 years and, since 1949, according to formal rules established jointly by Canada and the U.S. through the International Joint Commission (IJC). While the dam and the “rule curves” are very familiar to people in the watershed, the way the water flows in the system, the geography and impact of the dam on water levels is often less understood. As part of the recent Rule Curve Review project done by the IJC to assess the effectiveness of the 2000 rule curves, a series of videos were developed to explain the complexities of flow in the system. The first video explains Rainy Lake and Rainy River outflows; the second video focuses on the role the dam plays in Rainy Lake water levels. These two of three planned videos are posted on the International Rainy and Namakan Lakes Rule Curves Study Board website at http://ijc.org/en_/RNLRCSB.