STAY ALERT A wood stove and chimney collapsed and surrounding woodlands were scorched at this Boulder Creek home during the CZU August Lightning Complex fires. Officials are now fearing debris flows as seasonal rains start up. — Tarmo Hannula/The Press Banner file

STAY ALERT A wood stove and chimney collapsed and surrounding woodlands were scorched at this Boulder Creek home during the CZU August Lightning Complex fires. Officials are now fearing debris flows as seasonal rains start up. — Tarmo Hannula/The Press Banner file


San Lorenzo Valley may soon experience another natural disaster, following the CZU August Lightning Complex fire. County officials are stepping up in their efforts to warn residents about life-threatening debris flows that “our experts have determined are highly likely,” said Fifth District Supervisor Bruce McPherson.

Throughout several virtual town halls county officials have impressed the importance of heeding evacuation alerts this winter. Debris Flow Town Halls were held online on Nov. 12 for District 5 residents and Nov. 13 for District 3 residents.

The County will host another virtual town hall on Nov. 21 from 11am to 12:30pm. Visit for more information on the event.

The previous events were hosted by district supervisors with presentations from County officials. Recordings of the previous town halls, information and contacts for the recovery team are available

A debris flow, according to Carolyn Burke, the Department of Public Works senior civil engineer and environmental planner, occurs when “intense” rainfall saturates loose rock and soil high up in the mountains, creating a moving mass with trees and other trapped debris that travels downslope. 

They can travel more than 30 mph, destroying everything in their path.

These mudslides are directly correlated with the CZU Lightning Complex, said Kent Edler, County Public Works assistant director.

“Wildfires burn trees, leaves, litter and other organic matter which leaves a waxy residue on soils making them virtually water repellent,” he said. “Rainfall does not percolate into the ground, which means all this water is delivered directly down slope. By the time you see it, it’s too late.”

The Santa Cruz County Sheriff’s Office has announced these thresholds will trigger the evacuation response: 

  • 0.30 inches of precipitation in 15 minutes

  • 0.50 inches of precipitation in 30 minutes and/or

  • 0.70 inches an hour

When forecasts predict weather similar to the above conditions, the Sheriff’s Office will begin evacuation procedures, with a “warning” issued 48 hours in advance and an “order” 24 hours in advance, if there is no change to the forecast. These alerts will be sent out via Nixle and CodeRed, opt-in emergency alert systems. After issuing the alerts, Sheriff deputies and other staff will go door-to-door to check on residents’ evacuation status.

“We’re asking people to take these evacuation orders seriously. We know it’s a burden to people living in the County to have to pack up their belongings and animals, especially after they’ve already done so earlier this year,” Sheriff’s Office spokeswoman Ashley Keehn said. “But we saw in Montecito that this debris flow can be deadlier than the wildfire.”

Keehn refers to the debris flows in Montecito in 2018, after several wildfires. While three lives were lost in the wildfires, only 28% of residents evacuated during the mudslides, leading to 23 more deaths. This incident proved the great need for debris flow awareness and preparation, which the County has spent the past few months advancing.

Among County preparations, the Community Emergency Response Team (CERT) will visit door-to-door throughout San Lorenzo Valley, checking on residents’ preparedness beginning this week. They will hand out surveys and promote emergency alert registration, to help expedite the evacuation process.

Many community members have voiced frustration over lack of evacuation alerts during the CZU Complex. Keehn said the Sheriff’s Office is “always looking to improve emergency alerts as they are vital in times of crisis. Testing out the emergency alert is definitely under consideration.”

Santa Cruz County Emergency Services Manager, Rosemary Anderson, expanded on preliminary tests of the system.

“We’ll send out a public service message to debris flow areas about our CERT teams,” she said. “We’ll use that as a test of the alert system, with CERT individuals checking in to see if residents have received those alerts, and if not, advise them on how to sign up.”

Other than checking in with CERT volunteers, County officials encouraged residents to take these steps: 

  • Review your evacuationzone

  • Sign up for emergency alert services, likeNixle andCodeRED

  • Pay attention to weather forecasts, especially if you don’t have internet or cell reception at home

  • Have a to-go bag

  • Don’t wait for an order to evacuate. If you feel uncomfortable or will need extra time to evacuate, leave earlier

  • Know your evacuation route and a backup if possible 

  • Stay alert during a storm that can potentially cause an evacuation

  • Update your neighbors

  • Have a plan for a post evacuation shelter

Keehn also said Santa Cruz Mountain residents should keep a close eye on the national weather service in the coming months.

“Things are remote in the Santa Cruz Mountains, that’s one of the great parts of living here, but you don’t always have cell service or WiFi,” Keehn said. “We’re asking residents in more remote locations to stay as informed as they can on weather systems in the coming months.” 

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