Geologic report warns Centerville of potential canyon catastrophe

CENTERVILLE — A new report by the Utah Geological Survey shows that Deuel Creek in Centerville Canyon, given the right conditions, could dump 196,000 cubic yards of mud on Centerville homes.

The last time Deuel Creek had a devastating debris flow event was, well, never.

But creeks in similar canyons to the north of Centerville Canyon have produced debris flows, which are characterized by large amounts of mud, rocks, trees and boulders. That's different from a flood, says UGS geologist Rich Giraud, which is mostly water with some eroded material.

A debris flow is a catastrophic change, Giraud says, caused by rapid runoff, rapid snowmelt or a landslide up the canyon, particularly after a wildfire or overgrazing lays the ground bare.

As debris comes tearing out of a canyon, it is deposited in a fan-shaped area at the canyon's mouth, known as an alluvial fan.

Centerville Canyon's alluvial fan is completely developed.

Centerville Canyon has managed to escape recent wildfires that have plagued other Davis County canyons, said Davis County public works director Kirk Schmalz. That means the hillsides aren't barren and don't present an immediate hazard to the community.

"It's something we need to pay attention to," Schmalz said.

Centerville and Davis County public works officials are teaming up to build a debris basin in Centerville Canyon. The basin would function like a dam to slow down a torrent of debris from causing widespread devastation.

Farmington Pond, located on Farmington Creek, is designed as a debris basin, Giraud said. Other basins, built of concrete, exist along most creeks coming out of the Wasatch Mountains in Davis County and are designed to maintain a creek's normal flow.

In 1983, a debris flow out of Farmington's Rudd Canyon damaged 50 homes — 15 of them severely — and dealt $3 million in damage to the area. Mud and rocks spread out over 19 acres, Giraud said.

Depending on where a debris flow originates in Centerville Canyon, 75,000 to 196,000 cubic yards of debris could spill out into Centerville.

Nearby canyons in Davis County have produced flows between Rudd Canyon's 83,707 cubic yards in 1983 to Farmington Canyon's 690,492 cubic yards in 1923.