Screengrab from Wednesday's town hall.
Recovery & Reopening

Evacuation debrief: Does the lack of debris flow mean the threshold should change?

In the first of two town hall meetings, Santa Cruz county officials met with 70 community members who offered up questions, comment and criticism about the evacuation of 5,000 people during last week’s storm.

A week after an “atmospheric river” rainstorm pulsed over Santa Cruz County, and the vulnerable burn scar left by the CZU Lightning Complex Fire, county officials met with nearly 70 residents to discuss how the evacuation process went and, as 5th District Supervisor Bruce McPherson said, “inform, listen and learn.”

The main topic addressed by the 12 residents who spoke at Wednesday’s virtual town hall: Was the evacuation of 5,000 people due to fears of debris flow in the burn scar areas the right move given that nobody was hurt, and no property was damaged?

“We know it’s tough and our community has already been through this,” McPherson said, noting the mass fire evacuations of just six months ago.
“Our number one goal is to keep our community safe.”

While Monterey County experienced significant damage from debris flow, the storm didn’t linger over Santa Cruz, and the mountains were largely spared. Experts at the meeting reminded residents that weather forecasting is laden with uncertainty. County geologist Jeff Nolan called it “a black art.”

Even still residents wanted to know: Since debris flow didn’t materialize as predicted, would the county reconsider the rainfall thresholds it used to trigger evacuations?

Nolan said thresholds are set to capture the initiation point for debris flow, not the point where people would expect to see significant movement of infrastructure, rock and soil.

“The experts felt like we were just starting to see debris flows in areas where we just met the thresholds, so I think their confidence in those thresholds is actually reinforced by this last storm,” said Nolan, who’s consulted with multiple state and national geological agencies on the subject.

“I don’t think anybody has the inclination to adjust those thresholds up or down at this point, but we certainly may if we see another storm and get a few more data points,” he said.

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The decision to evacuate San Lorenzo Valley residents after the first major storm event of the year was set in motion last fall when the California Geological Survey and Cal Fire assessed the area that burned in the Complex Fire and established a threshold for the amount of rainfall needed to trigger evacuations.

Chief Ian Larkin of Cal Fire said his agency worked with the National Weather Service in the days before the storm to determine that the rainfall threshold would indeed be met. Evacuation warnings went out, at 6 p.m. on Jan. 24. By 9 a.m. on Jan. 25, sheriff’s deputies were issuing evacuation orders door-to-door.

Some at the meeting expressed gratitude to the county officials who evacuated them; others raised concerns about the process.

One Ben Lomond resident said she never received an evacuation warning. Another expressed concern for elderly residents who waited outside and in their cars, seeking hotel vouchers. Another wrote that “the people staffing the so-called debris flow hotline did not always have correct or complete information.”

Those who spoke, and those who didn’t get a chance, were encouraged to submit feedback about their evacuation experience here.

There will be another town hall tonight from 5:30 p.m. to 7 p.m. and it will focus on the 3rd District, which is overseen by supervisor Ryan Coonerty and includes the Davenport/Swanton areas that also received evacuation orders. The meeting link: