Bourbanis Dam: The Spring 2022 Emergency Response and Moving Forward to Mitigate Future Risk

ABSTRACT ONLY - The spring flood of 2022 came seemingly out of nowhere. By early April, an uneventful spring runoff season was already beginning to subside in the Tongue River Watershed. Conditions rapidly changed when much of North Dakota received a late season snowstorm in mid-April with snowfall accumulations anywhere from 12 inches to upwards of 30 inches within the Tongue River Watershed. Snow rapidly melted in late April/early May due to spring rains, causing 10 flood control dams within the watershed to nearly reach, and in some cases exceed, storage capacity.One such dam that exceeded capacity was Bourbanis Dam, located in eastern Cavalier County, ND. The dam is owned and operated by the Pembina County Water Resource District (PCWRD). The flood pool quickly rose to the auxiliary spillway, resulting in a partial failure of the earthen grass-lined spillway. Bourbanis Dam is considered a high-hazard structure, meaning that failure has potential to result in loss of life downstream. Also compounding concern were downstream dams already at capacity as well as severe flooding occurring further downstream along the Tongue River including the community of Cavalier, ND. Rapid, emergency response was undertaken to reduce risk of a full dam failure. Luckily, the efforts were successful.While the immediate risk was resolved, the PCWRD was then faced with the questions of “what’s next?”. There were two main considerations: 1) how to mitigate the immediate risk of a partially failed structure, and 2) how to ensure the long-term viability of flood control within the watershed. The talk will provide background on conditions leading up to the 2022 flood event, actions taken during the emergency response, and next steps that the PCWRD is taking to move forward.