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Sweetwater County Historical Floods

LocationStart DateInformation
Green River 1918 Fifty-year flood caused by overabundance of snowfall and excessive spring rain, storm sewer backup. Damage confined to street intersections and basements. Peak discharge recorded at 22,000 CFS.
Rock Springs, Bitter Creek Apr 1924 Snowmelt lasting nearly a week destroyed bridges and severely damaged or totally destroyed large number of dwellings, driving several hundred residents from their homes.
Rock Springs, Bitter Creek Jul 1926 An intense rainfall caused a flash flood resulting in interrupted rail and highway traffic, damaged bridges, eroded stream banks and cut communication lines
Rock Springs, Bitter Creek Aug 1930 Intense rainfall damaged bridges, eroded stream banks, and cut communication lines.
Rock Springs, Killpecker Creek, Bitter Creek 11-Jul-1937 Heavy rain (3 inches in 24 hours) producing a flood caused 200 residents to be evacuated and destroyed roadbed and bridges. Peak discharge of Bitter Creek upstream was approximately 10,000 CFS.
Green River 1956 Heavy snowfall and excessive spring rain caused a flood resulting in limited damage to basements and street intersections.
North Platte River tributaries near Glenrock, Douglas, upper Green River, and Laramie River 1-May-1965 Widespread rainfall combined with snowmelt runoff caused a 30- to greater than 100-year flood.
Green River 1-Sep-1965 Earthen dam holding the reservoir developed a leak, and flood gates were opened to release as much water as rapidly as possible. Discharge from Reservoir was 19,100 CFS. (Calculated 100-year flood has a flow of 25,300 CFS).
Green River 1972 Runoff coupled with heavy rains caused a flood in Green River. The river was running at 19,100 cuffs
Rock Springs-Green River area 4-Jul-1975 Torrential rains caused severe flooding in parts of Rock Springs; damage was especially heavy in the northern part of the city. Several businesses in downtown Rock Springs reported damage from water and mud. Some hail attended the storm.
Rock Springs 24-Jul-1982 A thunderstorm dumped over 2 inches of rain on the city causing local flooding of some streets and a few basements.
Rock Springs 12-Jul-1989 Weak upper-level southerly flow, very moist tropical air and an upper-level disturbance caused a slow-moving torrential rain-producing thunderstorm to hit Rock Springs on the late afternoon and early evening. The heaviest precipitation occurred just south of the town. The Rock Springs airport recorded 0.88 inches of rain along with wind gusts up to 52 mph. Dime-sized hail covered the ground to 1.5 feet deep 5 miles south of the community. As a result of Rock Springs being low relative to the terrain to their south, a tremendous surge of water and mud, up to 3 to 4 feet deep, invaded the town between 1700 MST and 1830 MST. This surge came northward into the south part of Rock Springs by way of Dead Horse Canyon Creek. The water and mud rapidly inundated the downtown section of the community. The result was catastrophic losses to homes, businesses and cars. Automobiles were washed down streets onto lawns, and basements flooded. Not including costs associated with automobiles, a preliminary total damage figure of more than $1.5 million was given by county and city officials. Rock Springs is located on a 100 year flood plain. At 1815 MST, a storm-related death occurred to a conductor who was on a westbound, Union Pacific Railroad engine cab that struck a stationary, empty rail car. The combination of the flooding waters and strong winds caused the empty rail car to lean over to the railroad tracks that the engine cab was traveling on. A brakeman was also injured in the accident. M34V.
Rock Springs 20-Aug-1991
Dead Horse Canyon, Rock Springs 22-Aug-1995 Thunderstorms produced heavy rain in Dead Horse Canyon. The rainfall caused minor flooding in Rock Springs. In addition, lightning from the thunderstorms knocked out power to a part of Rock Springs, including the airport, for 2.5 hours.
Rock Springs 12-Sep-1998 Primarily western sections of Rock Springs. Water reported to be 4 to 5 feet deep in some areas. Estimated rainfall of 1 to 2 inches in less than an hour over a small area, caused by slow-moving, intense thunderstorms.
Green River 1-Jun-1991 A series of thunderstorms moving through southern Wyoming brought funnel clouds to 3 miles north of Cheyenne at 1710 MST. At 1720 MST, 0.75-inch hail was reported 4 miles southeast of Cheyenne. Near 1800 MST, street flooding was reported at Green River, and Laramie reported heavy rain and 1.00-inch hail at 1830 MST. Hail up to 1.00 inch in diameter was reported 2 miles north of Cheyenne at 1830 MST.
Rock Springs 2-Jun-1991 An early afternoon heavy rain brought flooding to the streets of Rock Springs at 1600 MST.
Rock Springs/Green River 19-Jun-1998 Minor flooding reported on the Blacks Fork at Granger.