Moun­tain towns fear mud­slides next cri­sis

San Francisco Chronicle - Late Edition (Sunday) - - NEWS - By Mal­lory Moench

BOUL­DER CREEK, Santa Cruz County — Pa­trick and An­gela Aure­lio call it the “dooms­day sce­nario.”

The cou­ple worry that in a strong win­ter storm, the hill­side burned by the CZU Light­ning Com­plex fires be­hind their home along High­way 9 near down­town could hur­tle down at up to 30 mph, pick­ing up mud, boul­ders and even red­woods, block­ing the only way out. In the worstcase sce­nario, the mud­slide could bury them and their two tod­dlers.

The Aure­lios con­sulted two ge­ol­o­gists, spent sleep­less nights do­ing re­search and texted each other ar­ti­cles about past lethal dis­as­ters as they de­cided what to

do. With rain in the fore­cast last week, they made their choice to take mort­gage for­bear­ance and rent a home in Ap­tos for the next six months. The idea was to avoid, at the very least, evac­u­at­ing ev­ery time there was a win­ter storm — and per­haps to save their lives.

“In the end it’s all about whether you can sleep,” said Pa­trick Aure­lio on a re­cent af­ter­noon as he stood out­side the fam­ily’s home. “We will al­ways be able to come back — as long as the house is still stand­ing.”

Ex­perts say it’s likely not a mat­ter of if, but when, in­tense rain­fall trig­gers mud­slides that threaten the prop­er­ties and lives of thou­sands of peo­ple in the Santa Cruz Moun­tains. The area has seen th­ese dis­as­ters be­fore: In Jan­uary 1982, the Love Creek mud­slide killed 10 peo­ple near Ben Lomond. But the CZU Light­ning Com­plex, larger than any fire in the re­gion’s recorded his­tory, cre­ated an un­prece­dented haz­ard.

That’s why county of­fi­cials, first re­spon­ders and ge­ol­o­gists are scram­bling to de­velop an evac­u­a­tion and emer­gency re­sponse plan for the area to avoid a re­peat of the 2018 Mon­tecito mud­slides that killed at least 20 peo­ple af­ter the Thomas Fire ripped into Santa Bar­bara County. Of­fi­cials warn that you can’t fight, out­run or out­drive a mud­slide if you’re in its path.

“De­bris flow is some­thing you re­ally can’t plan for,” said Ian Larkin, Cal Fire San Ma­teoSanta Cruz unit chief. “The only plan­ning you do for it is to get peo­ple out of its way. ... It’s go­ing to hap­pen, and when it does hap­pen it’s in­stan­ta­neous and dan­ger­ous.”

Of­fi­cials now have to con­vince res­i­dents of the se­ri­ous­ness of the is­sue and alert those in re­mote ar­eas who lost communicat­ion ser­vices be­cause of the fire. They’re also wor­ried that mul­ti­ple win­ter storms might spark evac­u­a­tion fa­tigue.

“I don’t ex­pect to be able to re­lax un­til spring,” Santa Cruz County ge­ol­o­gist Jeff Nolan said.

The CZU Light­ning Com­plex scorched more than 86,500 acres, reach­ing High­way 9 in the east and the Pa­cific Ocean in the west. The fire stripped hill­sides of veg­e­ta­tion, leav­ing only rocks, clay and ash, which can’t ab­sorb much wa­ter. That in­creases the risk of mud­slides, which oc­cur when high­in­ten­sity rain­fall sat­u­rates loose soil, cre­at­ing a mass that is ca­pa­ble of pick­ing up trees, boul­ders, cars and even houses

Prob­a­bil­ity of land­slide

Mud­slide high- risk ar­eas

Of­fi­cials said this pre­lim­i­nary as­sess­ment from the state likely un­der­es­ti­mates the risks on the ground. as it moves down­hill, said Santa Cruz County Se­nior Civil En­gi­neer Carolyn Burke.

A quar­ter inch of rain­fall in 15 min­utes can trig­ger a mud­slide. The Na­tional Weather Ser­vice is­sues flash flood warn­ings within 24 hours for a fore­cast of a fifth of an inch in 15 min­utes. That level of rain­fall usu­ally oc­curs be­tween three and five times a year in the burn area, me­te­o­rol­o­gist Ryan Wal­brun said.

The risk is higher on the west side of the CZU burn zone, es­pe­cially on Swan­ton Road, but the area is sparsely pop­u­lated, said David Longstreth, a ge­ol­o­gist with the Cal­i­for­nia Ge­o­log­i­cal Sur­vey who worked on a pre­lim­i­nary re­port af­ter the fire. The greater pos­si­bil­ity for loss of life and prop­erty is on the steeper east side along the High­way 9 cor­ri­dor.

Creek drainages all the way from Shin­gle Mill Creek south of Fel­ton to China Grade Road north of Boul­der Creek are a con­cern, said Nolan, with the high­est threat from Clear Creek near Brook­dale up High­way 9 and up High­way 236 to Jami­son Creek.

The most dan­ger­ous ar­eas are not al­ways the most ob­vi­ous ones. On a re­cent af­ter­noon, re­tired Stan­ford ge­ol­o­gist Gail Ma­hood stood at the in­ter­sec­tion of High­way 9 and Clear Creek Road, next to the iconic Brook­dale Lodge, and ex­plained that the build­ings lie in an al­lu­vial fan, a flat area cre­ated from past mud­slides. In the case of an­other flow, the hill­side could come down Clear Creek and spread out be­fore reach­ing the San Lorenzo River.

It could also take out in­fra­struc­ture

MTNS. for the San Lorenzo Val­ley Wa­ter District and dirty part of the wa­ter sup­ply for the city of Santa Cruz that feeds from the San Lorenzo River. The city’s wa­ter­shed com­pli­ance man­ager Chris Berry doesn’t be­lieve it will knock out wa­ter de­liv­ery for res­i­dents, but he’s pre­pared for the worst.

Of­fi­cials will err on the side of cau­tion in is­su­ing evac­u­a­tions, but might re­assess as the win­ter goes on.

“That’s re­ally to pre­vent the sce­nario where you have evac­u­a­tion fa­tigue, be­cause then you get lower and lower com­pli­ance,” said Drew Coe, with Cal Fire’s wa­ter­shed pro­tec­tion pro­gram.

The worry that res­i­dents won’t heed warn­ings is a real one. In the Mon­tecito mud­slides, only 28% of res­i­dents evac­u­ated for the mud­slide warn­ing com­pared to 75% of res­i­dents who left for the fire, county of­fi­cials said.

In the Santa Cruz Moun­tains, the fire wors­ened no­to­ri­ously spotty cell phone and in­ter­net ser­vice, which will make it more dif­fi­cult to get the word out. The Sher­iff’s Depart­ment will push out re­verse 911 calls and CodeRed alerts to emails and cell phones, and send deputies doortodoor, spokes­woman Ash­ley Keehn said.

Su­per­vi­sor Ryan Coon­erty said the county is work­ing on set­ting up evac­u­a­tion cen­ters and a ho­tel book­ing pro­gram for evac­uees. Cal Fire may also need to in­stall tem­po­rary refuges on high ground ver­sus evac­u­at­ing en­tire ar­eas, Larkin said. Ma­hood said that if res­i­dents can’t evac­u­ate, they can walk up­hill at least 20 feet above the creek’s el­e­va­tion to be safer.

“It’s bet­ter to ed­u­cate peo­ple so they can take care of them­selves,” she said.

Most moun­tain res­i­dents are not naive to the risk. Last week, Boul­der Creek Com­mu­nity Church, which backs up to a steep, burned hill, in­stalled six 20foot, 4ton con­crete bar­ri­ers to lessen the im­pact of a mud­slide, Pas­tor Adam Miller said.

Farther north, pro­fes­sional con­trac­tor Alex Palo­mar bumped along Jami­son Creek Road in a bright or­ange pickup truck head­ing to his 50acre prop­erty. The fire in­cin­er­ated the home he shared with his part­ner in a clus­ter of red­woods and burned the two hill­sides flank­ing it. To get to the home’s foun­da­tion, Palo­mar has to cross a dirt road over a creek that dur­ing win­ter can swell up to 5 feet.

“This creek, if you get a land­slide into here, it’s go­ing to back up and then wash out roads and de­stroy ev­ery­thing,” Palo­mar said. “There’s noth­ing you can do to fix this.”

Still, he’s try­ing to pro­tect the home’s foun­da­tion so he can re­build. He bought 400 feet of wat­tle, a straw prod­uct tied with mesh, that he will stake into the ground around the foun­da­tion, and a gi­ant roll of black sta­bi­liza­tion fab­ric that he planned to lay over the road, then cover with gravel, to keep it from wash­ing out.

Af­ter a pan­demic and a wild­fire, ex­hausted res­i­dents worry mud­slides will be the third strike of 2020.

“I’m hop­ing it’s not that bad, but it’s got the po­ten­tial,” Palo­mar said. “I just don’t trust this year.”

Mal­lory Moench is a San Fran­cisco Chron­i­cle staff writer. Email: mal­lory. moench@ sfchron­i­cle. com Twit­ter: @ mal­lo­ry­moench

Pho­tos by Noah Berger / Spe­cial to The Chron­i­cle

Above: Alex Palo­mar, whose home burned in the CZU Light­ning Com­plex wild­fires, ex­am­ines wat­tle, a straw and mesh prod­uct that he hopes will pre­vent mud­slides at his Boul­der Creek prop­erty. Top: Houses in Boul­der Creek be­low a hill­side scorched in the fires.

Pho­tos by Noah Berger / Spe­cial to The Chron­i­cle

Mud­slides are seen as in­creas­ingly likely af­ter wild­fires stripped hill­sides bare in ar­eas near John­nie’s Su­per Mar­ket in Boul­der Creek ( Santa Cruz County).

Alex Palo­mar, who lost his home in Boul­der Creek to the CZU Light­ning Com­plex, hauls wat­tle, wo­ven sta­bi­liza­tion fab­ric, he’ll use to pro­tect his prop­erty from mud­slides dur­ing win­ter rains.

0 0 10 5 CREEKRD. BEAR

SANTA CRUZ

John Blan­chard / The Chron­i­cle

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