Catastrophic Flooding in Yellowstone – Historic Destruction of Homes, Roads, and Bridges


Yellowstone National Park saw record high water levels due to snowmelt and severe rain, which wrecked buildings, roads, and bridges as well as cut off some of the gateway settlements.

For Yellowstone National Park, this year has been remarkable in a number of ways. America's first national park, established in 1872, is celebrating its 150th birthday. Rivers crested to heights not seen in a century, and it also saw exceptional floods.

A thin band of tropical moisture known as an atmospheric river saturated the Pacific Northwest during the second week of June 2022 before dumping several inches of rain on northern Wyoming and southern Montana. A warm spell that followed the flooding accelerated the melting of the thick snowpack.

According to the National Weather Service (NWS) in Billings, Montana, "this resulted in flooding seldom or never seen previously over several region rivers and streams."

Yellowstone, which covers 2.2 million acres (8,900 square kilometers) in northwest Wyoming, southwest Montana, and eastern Idaho, was shut down on June 13 and more than 10,000 people were told to leave owing to safety concerns. Roads were washed away, camps were inundated, and rocks were thrown onto streets.

The 2021–2022 water year got off to a sluggish start, but a chilly, wet spring supplied much-needed water to the area, which has been suffering from drought conditions. The Yellowstone basin saw greater than average precipitation in April, which contributed to the accumulation of the ground's snowpack, which by May had nearly reached the 30-year median.

According to the Billings NWS, the Absaroka and Beartooth ranges received between 0.8 and 5 inches of rain and 2 to almost 5 inches of snowmelt between June 10 and June 13.

Four to nine inches (10 to 22 cm) of rain, or the equivalent in snowmelt, washed over already wet soils.

The soil moisture anomaly in northern Wyoming and southern Montana during the week prior to the storm is seen on the aforementioned maps. Data from the Crop Condition and Soil Moisture Analytics (Crop-CASMA) program was used to create the maps. 

Crop-CASMA combines readings from the MODIS sensors on NASA's Terra and Aqua satellites with vegetation indices from the Soil Moisture Active Passive (SMAP) satellite. When the state was facing more severe drought conditions, from May 30 to June 5, 2021, the soil moisture conditions are depicted on the left map. From May 31 to June 6, 2022, shortly before the downpour, the graphic on the right depicts the soil moisture levels.

The Yellowstone, Stillwater, and Clarks Fork rivers as well as their tributaries were inundated by the flow. On June 13, 2022, the Yellowstone River crested at Corwin Springs, north of Gardiner, Montana, reaching a height of 13.88 feet, shattering the previous record of 11.5 feet established on June 14, 1918. According to U.S. Geological Survey stream gauges, a record river discharge of 51,400 cubic feet per second was also recorded on that day, shattering the previous record-high flow of 32,200 cubic feet per second set in 1996.

The increasing floodwaters cut off Gardiner and Cooke City to the north of the park, washed down roads and bridges, took away several homes, and inundated hundreds more. The historic city of Red Lodge, Montana, was inundated and numerous bridges were destroyed by Rock Creek. In numerous communities, the floods also damaged drinking water supplies and resulted in power outages.

The Yellowstone River changed its path, causing the biggest damage in the park's northern region where it runs through narrow valleys. It will take months to fix the major supply route into the park from Gardiner to the park headquarters near Mammoth Hot Springs, which was flooded out.

Less damage was caused by the water in the park's southern section. Old Faithful may now be accessed by visitors thanks to the reopening of the southern loop road and the west, south, and east gates on June 22, 2022. The park's northeast and north entrances are permanently closed.