2021 Map of Iona NW

About this map

Lake Francis Case dominates the eastern half of this landscape, tracing the county line between Lyman and Brule counties. The confluence of the White River and the reservoir creates a complex network of wetlands and shifting shorelines, including the broad alluvial plains of Peterson Bottoms and the isolated Bird Island. The terrain is defined by dramatic drainage patterns where Bull Cr, Waterhole Cr, and Nicholas Cr carve deep draws into the Missouri River breaks. The modern infrastructure of 252nd St and Canyon Rd provides limited access to these riverine lowlands, illustrating the persistent isolation of the South Dakota prairie where the river system continues to dictate the local geography.