Monsoonal moisture interacted with a strong upper-level low on September 11th, producing heavy rain and flash flooding in many locations across southern Utah. The most significant event of the day was the failure of the Laub Dike in Santa Clara, causing flooding in many area homes and businesses.

Flash Flood in WASHINGTON, UTAH
From 11-SEP-12 11:00:00 to 11-SEP-12 12:30:00 (MST-7)
Location: ZION LODGE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Flash flooding was reported in multiple locations across Zion National Park, including in the Narrows. The North Fork of the Virgin River rose from 52 cfs to 1004 cfs in one hour. Large waterfalls coming off of cliffs closed numerous hikes and temporarily stranded hikers.

Flash Flood in WASHINGTON, UTAH
From 11-SEP-12 09:30:00 to 11-SEP-12 12:30:00 (MST-7)
Location: SANTA CLARA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

Flooding was reported over the bridge where old US Highway 91 crosses the Santa Clara River. This flooding caused the road to be closed for a few hours in the late morning and early afternoon.

Flash Flood in KANE, UTAH
From 11-SEP-12 11:30:00 to 11-SEP-12 13:30:00 (MST-7)
Location: ALTON SWAINS ARPT
Flood cause: Heavy Rain
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

Flash flooding was reported along Stout Creek. This flooding damaged a fly fishing operation along the creek, including filling a pond with silt, damaging a small bridge, and causing some erosion damage.

Flash Flood in WASHINGTON, UTAH
From 11-SEP-12 12:15:00 to 11-SEP-12 15:15:00 (MST-7)
Location: SANTA CLARA
Flood cause: Dam / Levee Break
Property damage: 7.50M
Crop damage: 0.00K
Reported by: County Official

An extended period of moderate to heavy rainfall occurred in southwest Utah on the morning of September 11th, during which 3.24 inches of rainfall was measured in Ivins, Utah. In nearby Santa Clara, an earthen dike (called the Laub Dike) burst, releasing all of the water in the associated retention pond. This water and mud flowed into nearby homes and businesses, damaging both public infrastructure and private properties. A total of $3.8 million in damage was done to public infrastructure, including damage to the dike, streets, and sidewalks. The flood also damaged 16 businesses and 63 homes; some of these buildings had internal damage due to water and mud flowing into them, while other buildings experienced serious structural damage.

Flash Flood in WASHINGTON, UTAH
From 11-SEP-12 10:00:00 to 11-SEP-12 13:00:00 (MST-7)
Location: SHIVWITS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Beaver Dam Wash experienced a flash flood, with the reading on the gauge along the wash increasing from 96 cfs to 4367 cfs in one hour.

Flash Flood in WAYNE, UTAH
From 11-SEP-12 13:00:00 to 11-SEP-12 17:00:00 (MST-7)
Location: TORREY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Flash flooding was reported in multiple locations across Capitol Reef National Park. Flooding occurred along Sulphur Creek, and water also flowed across the Scenic Drive, causing park officials to temporarily close the road.