Ice Jam Flooding


Idaho Office of Emergency Management
For immediate release January 4, 2017
Contact: Elizabeth Duncan
(208) 258-6595

Extreme Winter Weather Poses Flooding Risks

Prolonged Freezing Conditions Followed by Warm Temperatures Could Cause Significant Flooding


BOISE – The Idaho Emergency Operations Center (IDEOC) is now activated to Heightened Awareness. This comes in response to extreme cold weather and record snowfall in parts of Idaho this week and the likelihood of flooding once temperatures warm. Temperatures are expected to be above freezing by Sunday.

Currently the Lemhi River, Big Wood River and Snake River at Weiser are all experiencing ice jam related minor flooding. Ice jams happen when shallower areas of rivers freeze faster than deeper areas and the ice gets stuck where the river bends or curves.

Lemhi County is experiencing minor to moderate flooding in low areas near the Salmon River north of the city of Salmon. A high risk area for flooding in the southeastern part of the state includes the Snake River above the American Falls reservoir.

“One of Idaho’s major hazards is flooding following significant snowfall and subsequent rapid thawing,” said Idaho Office of Emergency Management Deputy Director Brad Richy. “In fact, in 1997 melting snow caused by similar weather conditions, led to a statewide Presidential Disaster Declaration. Being aware of the potential dangers and making sure both your car and your home have emergency kits is critically important.”


  • Drivers should never attempt to cross flooded roads in a vehicle. Turn around Don’t Drown. This is just as important in winter as it is in spring.
  • Assess the safety of your route. Some roadways heading toward Nevada and Oregon may be impassable. Road condition information can be found at
  • If you are traveling, make sure your vehicle is equipped with emergency supplies. A list of emergency supplies, including water, snack foods, flashlights, extra batteries, blankets and booster cables can be found at


Urban areas of the state also face challenging weather related conditions. Storm drains can be backed up once the snow starts melting. Snow and ice-covered tree branches can fall on both power lines and structures, especially where there is thawing and then a return to sub-freezing temperatures.

Heightened Awareness in the IDEOC means the threat level is moderate, with a chance of developing into a state level emergency disaster.


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The Idaho Office of Emergency Management is a Division of the Idaho Military Division. The services we provide are to facilitate emergency management in Idaho, and to assist neighboring states. The men and women of this Division are dedicated to their mission of protecting the lives and property of the people of Idaho, as well as preserving the environmental and the economic health of Idaho.


Original Release