1968 Map of Donleys Reservoir

About this map

Big Porcupine Creek meanders through this portion of Rosebud County, Montana, carving a complex network of coulees and drainages across the landscape. The Chicago Milwaukee St Paul and Pacific railroad cuts across the southwestern corner of the terrain, following the valley of Horse Creek. This alignment reflects the critical role of rail transport in the mid-century western ranching economy, connecting remote rangelands to larger markets. The mapping of Donleys Reservoir and various water sources like Ash Creek and Longfork highlights the essential infrastructure required for water management in this arid environment. Named drainages such as Living Machine Coulee and Crossman Coulee reveal the localized nomenclature used by generations of land users to navigate the breaks and flats above the creek beds.