Flooding problems mount on coast

The situation was complicated when a tree fell over the northbound lane of Highway 1 in Montara shortly after daybreak. Cal Fire reported that obstruction was almost cleared by 8:45 a.m. By 9:30 a.m., the county reported that Highway 84 and Old La Honda Road were also closed due to downed trees in the Santa Cruz Mountains.

By midmorning, Pacifica Police reported that northbound lanes of Highway 35 at Sharp Park Road were closed due to flooding.

Heavy rain pummeled parts of the Bay Area, including the Coastside. Saturday morning's rains were part of a wave of wet weather that was due to continue at least into the afternoon on Saturday. Forecasters are calling for a break in the rain on Sunday before more wet weather next week.

By 1 p.m., Half Moon Bay meteorologist Jan Null was reporting on social media that Saturday was the second-wettest 24-hour period on record in San Francisco, where 4.78 inches of rain had fallen in a day.

Earlier in the day the National Weather Service had issued a Flood Warning, meaning flooding was occurring in parts of the region. It expired at 11 a.m., however a Flood Watch remains in effect until 10 p.m. tonight, meaning residents should be aware that flooding is possible as showers continue. A wind advisory expired at 10 a.m. today.

Regardless of the official warnings, flooding was widespread and ongoing into the afternoon. Cal Fire said it helped evacuate people near the intersection of Oak Street and Pilarcitos Avenue in Half Moon Bay shortly after noon. The fire agency said no one was injured at the scene. Cal Fire and Coastisde Fire Protection District personnel also responded to a house in El Granada that was damaged from a mudslide and a flooded garage in Miramar. 

Half Moon Bay Mayor Debbie Ruddock said flooding from Pilarcitos Creek backed up into the Sewer Authority Mid-coastside plant and for a time threatened operations.

“Pilarcitos Creek got blocked for a time by brush and started flooding SAM plant,” she wrote in an email to the Review. “As water got higher and faster it pushed through to the inlet and flood waters receded somewhat. We came very close to disaster.”

SAM General Manager Kishen Prathivadi said the influx forced SAM staff to temporarily shut off the Montara and Portola pump stations, but not before some untreated wastewater overflowed from the tanks. The Portola station by El Granada’s Burnham Strip overflowed into Surfer’s Beach and was shut off for nearly two hours. A tank in Montara, which has nearly 450,000 gallons of wet weather storage, exceeded its capacity as well.

Roads were underwater across the region. Notably, Highway 101 was closed in both directions at Oyster Point, where high tide and rain flooded the entire road.