The late nineteenth and twentieth centuries witnessed profound transformations in the organization of North Dakota’s Native American communities. The end of the fur trade, depleting timber resources, and the passage of the Dawes Act in 1887 led to the eventual fissioning of the coalescent community of Like-A-Fishhook Village. Despite their co-residence at the site for almost three decades, the Mandan, Hidatsa, and Arikara people reestablished ethnically distinct villages in the bottomlands of the Missouri River within the Fort Berthold Reservation. Most of the Arikara population settled on allotments in the Nishu area until it was inundated by the Garrison Dam in the early 1950s. Through interviews with Arikara elders, this collaborative project documents the lived experience of Nishu, now under the waters of Lake Sakakawea and visually inaccessible to their descendants. It investigates the role of spatiality and temporality in community construction—specifically, how the persistence of Arikara memory and tradition empowered residents to navigate changes wrought by the assimilative policies of the U.S government. This research revealed that Arikara memories of these submerged lands embody a dialectic of pervasive nostalgia about living there and profound trauma about being forced to leave. Through this dialectic, it elucidates how time, movement, and place are complicit in residents’ sense of belonging, and discusses the inherent challenges in (re)constructing a community’s memory of “erased” heritage.