Earlier footage from #ocpublicworks of Trabuco Creek. Mandatory Evacuations remain in place for Trabuco Creek. Your public safety agencies continue to monitor the weather and potential for these mud/debris flows. #ocsd #ocsheriff pic.twitter.com/ywkjxqbAfn

TRABUCO CANYON, CA —Closures and evacuations remained in effect for the Trabuco Creek area Thursday, according to Orange County Fire Authority. This sobering flash flood video shows just how quickly a dry wash under a bridge can fill up with rushing water.

As they watched, water raced from the mountain under the bridge. The video was posted just after noon on Thursday, during heavy rain. "Watch, (the water is) going to block underneath!" the videographer says.

Within seconds, debris clogs the spillway under the Trabuco Creek Bridge, and flood water splashes up and over the bridge. All the while, more rain continues to flow down the mountain stream. Flash flood water is heavily laden with topsoil which is no longer held in place by roots after the Holy Fire destroyed the mountainside. That soil loosens with the rain until it reaches a critical, viscous mass of mud, debris, and water.



"Your public agencies will continue to monitor the weather and potential for these mud and debris flows," OCFA Capt. Tony Bommarito told Patch. Residents of Trabuco Creek were under a mandatory evacuation, while residents of Rose Canyon were under voluntary evacuation, as of 1:30 p.m. Thursday.

Hard road closures remained in effect at Trabuco Canyon, Rose Canyon, Trabuco Canyon Road, and Robinson Ranch Road, the Orange County Sheriff's Department reported.

An emergency operations center hotline was activated and residents should call 714-628-7085 for the latest information.