Wyoming-Montana Water Science Center
Floods of May 1981 in West-Central Montana
A series of extensive rainstorms during the month of May culminated in record flooding in west-central Montana during May 22-23, 1981. Precipitation amounts for the first half of May, which were generally well above average at most rainfall recording stations in the area, saturated the ground and raised streamflow levels to near-bankfull stages. The larger storms of May 21-22 then combined with snowmelt to produce the destructive flooding that followed. The flooding was generally centered near Helena, but affected both sides of the Continental Divide.
East of the Contintental Divide in the upper Missouri River drainage basin, the town of Belt experienced severe flood damage from Belt Creek and East Helena was damaged by flooding of Prickly Pear Creek. Lesser but still significant flood damage occurred near Helena from Tenmile Creek and in and near Bozeman from Rocky Creek, Bridger Creek, and the East Gallatin River. West of the Continental Divide, Cottonwood Creek flooded a large part of Deer Lodge, and flood damage occurred in Elliston, Avon, and Garrison from the Little Blackfoot River and along the Clark Fork near Drummond and Clinton.Transportation facilities were damaged by the flooding throughout the area as roads and railroad tracks were washed out in numerous places. Six bridges on major State highways were destroyed or extensively damaged by the flooding, and more that 25 road approaches to major bridges were washed out. A 10-county area was declared a national disaster area by Presidential proclamation. No lives were lost in the flooding.
The USGS monitors water resources in Wyoming and Montana in cooperation with State, County, local, and other Federal agencies.