U.S. Geological Survey Says Yellowstone River Flooding Was a 1-in-500 Year Event

Lower Blacktail Patrol Cabin washed away. (Photo: NPS/Jacob W. Frank)

The massive flooding that happened at the Yellowstone River earlier this week represents a 1-in-500-year event, the U.S. Geological Survey said Thursday.

Why it matters: The catastrophic flood — which damaged roads and bridges at Yellowstone — has a 0.2% (or 1-in-500) chance of happening in any given year, the USGS said in a news release.

Driving the news: Katherine Chase, USGS hydrologist, said that the peak amount of water flowing in the Yellowstone River at Corwin Springs and Yellowstone River at Livingston was “higher than the 0.2% (or 1 in 500) flood” levels seen during the recent flood event.

  • Chase said the floods have been referred to as rarer than a 1-in-500 event. But “there is the same probability that they could occur in any given year,” she said.
  • Meanwhile, the streamflow at the Yellowstone River at Billings was closer to the “1% (or 1 in 100-years) and 0.2% (1 in 500-years) flood.”
  • The streamflow data is “provisional” right now until an analysis of the data is finished, the USGS said.

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SOURCE: Axios, Herb Scribner