Flood & Drought Risk Assessment and 2022 Flood Response for Billings, MT Water Treatment Plant Along the Yellowstone River

The Billings, MT, USA water treatment plant (WTP) is located adjacent to the Yellowstone River and serves a population of over 100,000 people. FEMA floodplain maps show much of the WTP within the 100-year floodplain. Further, previous low water events had created difficulty to use the preferred side channel intake. Plant staff were concerned that future high and low water events on the Yellowstone River could have significant impacts to WTP operations. It was also unclear which facilities were most at risk and what would be the most effective emergency response plan. AE2S prepared a hydrologic and hydraulic model of the Yellowstone River to evaluate that risk. The analysis showed that the WTP was at risk to both high and low water events. Following the analysis, the 2022 flood of record occurred, and the risk assessment helped plant staff prepare and respond to maintain water supply to the city.