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In June 2022, unprecedented amounts of rainfall caused substantial flooding, rockslides, and mudslides within Yellowstone National Park. Historic water levels caused severe damage to roads, water and wastewater systems, power lines, and other critical park infrastructure. (Video includes natural sounds only: no narration.)
BackgroundOn the morning of June 13, 2022, Yellowstone experienced a 500-year flood event. Northern parts of the park received a combined 7.5-9.5 inches of rain and snowmelt in a 24-hour period. The flood destroyed several sections of the North Entrance Road between Mammoth Hot Springs, Wyoming, and Gardiner, Montana, and three sections of the Northeast Entrance Road between Lamar Valley and Cooke City/Silver Gate, Montana.
The park immediately set a range of life and safety objectives to ensure all employees and visitors were safe and accounted for, restore power, divert damaged wastewater systems, and help local communities with emergency response. Within 36 hours of the event, the park evacuated all visitors in developed areas and conducted initial damage assessments. Within 48 hours, the park restored power, diverted severed wastewater lines, and planned for recovery and resumption of operations when and where possible. The south loop of the park reopened on June 22, 2022, nine days after the flood event. As repairs continued, additional sections of road and backcountry trails opened throughout the summer.
Mammoth Wastewater System
A sewer line adjacent to the road that carried wastewater from Mammoth Hot Springs to a sewage treatment plant in Gardiner ruptured. Staff quickly rerouted the wastewater into percolator ponds used between the 1930s and 1960s, allowing for summer day-use visitors and residents to stay in the area. A new wastewater treatment system is being built to serve the Mammoth area with an anticipated spring 2023 completion.
Temporary North Entrance Road
Northeast Entrance Road
Last updated: November 21, 2022