A significant spring storm impacted south central Montana May 8-11 as a moist and slow moving storm system impacted the region. Rain began to move into the region late Sunday, May 8th with the heaviest rainfall Monday into Tuesday. Some embedded thunderstorms enhanced rainfall across portions of the region late on Monday, the 9th. Widespread rainfall amounts of 2-4 inches occurred. The heavy rainfall also combined with some mid elevation snowmelt from nearby mountains to enhance flooding in some foothill locations. As a result, widespread lowland flooding was reported along with some damage to roads and structures.

Flood in YELLOWSTONE, MONTANA
From 10-MAY-11 10:30:00 to 11-MAY-11 07:00:00 (MST-7)
Location: BULL MTN
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Significant flooding occurred in the Briarwood Subdivision and golf course in South Billings along Blue Creek. Several homes, structures and barns were inundated with water with evacuations required in the area. Damage occurred to the golf course due to the flooding and several bridges washed out on the course.

Flood in PARK, MONTANA
From 10-MAY-11 01:05:00 to 17-MAY-11 12:00:00 (MST-7)
Location: HOOPERS
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Park County officials reported flooding on Billman and Trail Creeks southwest of Livingston due to heavy rainfall and mid elevation mountain snowmelt. Numerous roads flooded (Miller, Trailer Creek, Old Yellowstone, Cokedale, Rendezvous Trail) in the region with water overtopping them with lowland flooding in nearby farmland. Several homes and trailers flooding. Several farms were cutoff and unreachable because of flooded raodways. The Shields River in central Park County ran high and out of it's banks, flooding nearby farmland.

Flood in ROSEBUD, MONTANA
From 10-MAY-11 07:00:00 to 11-MAY-11 07:00:00 (MST-7)
Location: BRANDENBERG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread flooding resulting in road closures occurred across the northern half of Rosebud County. Flooding in low lying areas along Reservation Creek west of Forsyth was reported. Across northwest Rosebud County, flooding on Home Creek resulted in significant water over Bascom Road.

Flood in CUSTER, MONTANA
From 10-MAY-11 07:00:00 to 11-MAY-11 07:00:00 (MST-7)
Location: MIZPAH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Widespread flooding resulted in road closures occurring across Custer County with numerous roads reported as washed out. Significant flooding was reported along the Powder River as well as its tributaries. Dry, Spring, Strevel and Mizpah Creeks all reported flooding. Major flooding occurred from north of Powderville to Mizpah. Water overtopped Pumpkin Bridge on Pumpkin Creek. A storm spotter 16 miles south of Miles City on Highway 59 indicated this was the worst flooding that they had seen in that area in 25 years. There was significant lowland flooding in the Yellowstone Valley area of Northeast Miles City where Emergency Travel Only was declared for a time. A water rescue was required when a paper carrier in the valley washed off the road.
Tongue River flooding on May 10-11th resulted in Custer County declaring a flood disaster and a water rescue due to Graveyard Creek washing out Kinsey Road. A levee system was damaged in Miles City. In addition, Custer County ran out of road closed signs due to extent of washed out roads.

Flood in TREASURE, MONTANA
From 10-MAY-11 10:30:00 to 11-MAY-11 07:00:00 (MST-7)
Location: SANDERS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several roads across Treasure County flooded, especially northeast of Hysham area.

Flood in BIG HORN, MONTANA
From 10-MAY-11 10:30:00 to 12-MAY-11 08:00:00 (MST-7)
Location: ST XAVIER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous reports of small stream and lowland flooding were reported along streams and creeks across Big Horn County. Water was reported over highway 313 towards the Fort Smith area. As a result of the flooding, a few homes were evacuated.