Flood — Washington, Utah

2010-12-19 to 2010-12-23 · near Goldstrike, Washington, Utah

Event narrative

Heavy rain caused widespread significant flooding across Washington County. Rainfall and significantly increased river flows began on December 19th, with many rivers and streams around Zion National Park and St. George near bankfull. Reports of road flooding began on December 20th. SR-9 was closed in Zion National Park due to flooding between the tunnel and Mt. Carmel Junction, and flooding and rockslides occurred on SR-18 between Enterprise and Central.

The worst of the flooding occurred on December 21st, when the flow of the Santa Clara River increased to an estimated 5000 cfs, and the Virgin River near Bloomington was measured at 12400 cfs. Zion National Park was closed due to flooding, and the Zion Park Lodge was evacuated due to the danger of landslides. One historic landslide, in particular, was moving through the day as the riprap structure was eroded away. Old Highway 91 was also closed, as flooding and debris washed out and damaged much of the road. Many other roadways across the county were flooded, including many roads in the city of St. George, many rural roads along the Santa Clara, SR-18 south of Central, in Enterprise along Center Street and Main Street, and the road into Snow Canyon State Park, which closed the park to tourists. Many bridges were damaged or destroyed, including the foot bridge over the Fort Pearce Wash, the Tobin Wash Bridge near Gunlock, a foot bridge at the Sunbrook Golf Course, the bridge at 2500 South in New Harmony, and the bridge at Brookside. Residential flood damage was reported in Enterprise, Springdale, Rockville, and St. George. Contaminated water became a problem along the Virgin River, and culinary water became unavailable in the town of Gunlock. The Southgate Golf Course in St. George suffered extensive damage due to erosion.

Flooding continued on December 22nd. Flood waters damaged a bridge in New Harmony Heights, closed many roadways including a bridge near the Enterprise Reservoir, and up to 15 homes were damaged to varying degrees in Brookside. River flows stayed high on December 23rd before receding.

Damage estimates were obtained from the Utah Emergency Management Association, and included damages of $4.7 million to infrastructure and $15 million to other properties. In addition, $300,000 worth of heavy construction equipment was saved when the NWS forecast office in Salt Lake City called the Washington City Public Works, notifying of them of the upcoming high flows expected on the Virgin River. The Public Works pulled all of their equipment out of the Virgin River, which they said would have been swept away and lost if not for the phone call.

Wider weather episode

A large and very moist Pacific storm system brought widespread heavy precipitation to Utah over a five day period. The storm pulled a continuous stream of tropical moisture ahead of it and, combined with numerous embedded shortwaves, resulted in almost non-stop rainfall across many of the lower elevations and wet, heavy snow in the mountains.

View location on OpenStreetMap → (37.6046, -114.0477)

Source: NOAA Storm Events Database, event_id 275462. Narrative written by the NWS forecast office that issued the report.