USGS study says winter rains bring high risk of huge debris flows in Calif. wildfire area

Study finds risk of mud flows in Calif. fire area

PASADENA, Calif. — The U.S. Geological Survey says winter rains could release huge flows of mud and debris in the vast area of the Angeles National Forest burned by a wildfire, affecting San Gabriel Mountain foothill communities.

A report released Tuesday indicated high probabilities of large debris flows in both scenarios it examined: a three-hour thunderstorm and a 12-hour storm.

The USGS says rainwater roaring through canyons in the nearly 251-square-mile burn area could move up to 100,000 cubic yards of mud, rocks and vegetation — enough debris to cover a football field 60 feet deep.

The August and September fire burned from the northeastern corner of Los Angeles eastward above the suburbs of La Crescenta, La Canada Flintridge, Altadena and Pasadena.