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Wyoming Floods

Floods can and have caused significant damage in Wyoming and are one of the more significant natural hazards in the state. They can cause millions of dollars in damage in just a few hours or days. Every county and many communities in the state have experienced some kind of flooding after spring rains, heavy thunderstorms, or winter snow thaws. Additionally, floods can also occur because of ice jams or dam failures, both of which have occurred in Wyoming.


The documented flood history for Wyoming extends back to July 1895 in Casper, Wyoming. The flood produced a 20-foot-high wall of water sweeping down Garden Creek, wiping out a camp of settlers at present-day Westwood School. Three people drowned.

The most damaging flood in Wyoming's history was the August 1, 1985 flood in Cheyenne. The dollar property loss was $65 million. In 2004 dollars the damage would be nearly $112.9 million. Twelve deaths and 70 injuries were associated with that event. The greatest loss of life associated with flooding, however, did not occur in 1985. In September 1923, five days of widespread rainfall caused a 60- to greater than 100-year flood resulting in a railroad bridge being washed out east of Casper. The event took 18 lives on September 27, 1923.

Another significant flood was on May 15, 1978. Heavy wet snow and record rains did very extensive damage to property, crops, and livestock in 12 counties (Park, Big Horn, Campbell, Converse, Crook, Johnson, Natrona, Sheridan, Washakie, Weston, Hot Springs, and Niobrara). Hundreds of homes were damaged, and many totally destroyed. Numerous bridges and sections of roads were washed out; power lines were downed, with much damage to cars and personal property. Total estimated damages came to $15.5 million. In 2004 dollars, damages would be over $44.4 million.

In more recent times, on August 27, 2002 the town of Kaycee in Johnson County was inundated by flash flooding from a storm that struck the southern part of the county. The flooding caused significant devastation, with the Wyoming Office of Homeland Security [then WEMA] reporting a final count on Wednesday, August 28, 2002 of $459,166 in damage, including 19 trailers, 22 houses, and 12 of Kaycee's 15 businesses.

More flood history information can be found by selecting the "Flood Histories" tab.


Floods and flood damage have occurred in every county in Wyoming. The following figure shows the distribution of the number of floods, number of deaths, and the amount of crop and property damage in reported dollars. The total documented flood damage for 1905 to present is nearly $126.7 million. In 2004 dollars the damage would be almost $332.7 million This web page is designed to provide important information for the residents of Wyoming regarding floods and preparedness to reduce the effects of flooding and to provide important information on current flood related topics within the state.

The National Flood Insurance Program (NFIP): A Federal Program enabling property owners in participating communities to purchase insurance protection against losses from flooding.

Map Modernization: The Federal Emergency Management Agency's Flood Hazard Map Modernization Program of modernizing flood insurance rate maps nationwide.

FIRM/DFIRM Panels: Flood Insurance Rate Maps and Digital Flood Insurance Rate Maps for Wyoming communities.

Ordinances: Flood plain management ordinances for Wyoming communities participating in the National Flood Insurance Program.

Flood Histories: Photographs and concise flooding histories for Wyoming counties.

Frequently Asked Questions: Questions and answers pertinent to Wyoming flooding.

Links: Important flood related links

Contacts: Important contacts