Management options to address flood impacts on visitor safety and park facilities in the Cedar Pass area of Badlands National Park (TAR #29930)

Schook, Derek

Flooding in the Cedar Pass area of Badlands National Park (BADL) threatens park infrastructure and visitor safety. After rainstorms, sediment-laden water flows overland and through two drainage channels. This runoff frequently overtops the banks of the drainages then encounters park facilities located within the adjacent floodplain areas. This flooding is a natural process in the geomorphically evolving badlands landscape, so there are inherent risks to any use of the landscape. BADL staff contacted the Water Resources Division (WRD) to help develop ideas to mitigate flood impacts, and WRD visited the site in August 2023. Six flooding issues were identified: 1) East Drainage culvert underpass of Hwy 240, 2) Ben Reifel Road flooding, 3) Cedar Pass Lodge cabins flooding, 4) Cedar Pass Lodge courtyard flooding, 5) West Drainage flooding of the Cedar Pass campground (the most dangerous issue), and 6) Ponding in the campground. NPS management policies discourage development within flood-prone areas, but in some instances it is not practicable to (re)locate developments to outside of the floodplain. This report develops management alternatives that could mitigate impacts and risks associated with continued use of flood-prone areas at Cedar Pass. These alternatives include adjustments to the at-risk infrastructure or its usage, constructing earthen berms to protect park facilities from floodwaters, and excavating drainage ditches or channels to convey water away from areas of conflict and reclaim some of the historical topographic drainage systems. The alternatives presented would require different levels of floodplain and wetland compliance. This report includes preliminary development of options, although further planning and quantitative analyses should be undertaken before implementation of any approach. WRD will be available for further guidance.