In the wake of late-winter Napa rains, a landslide has resumed in a Browns Valley neighborhood two years after crumbling banks cracked driveways and led residents to sandbag homes against flooding.
The Napa County Flood Control and Water Conservation District reports that stream banks are slowly slipping along two stretches of Browns Valley Creek, in an area where storms in early 2017 put at least three homes at risk. The problem areas are near a culvert in the 1100 block of McCormick Lane and behind Browns Valley Market just east, according to operations manager Rick Thomasser.
This area is a short distance downstream from bank erosion that closed a lane of Browns Valley Road, west of Buhman Avenue, in February.
The renewed ground shifts have meant renewed anxiety for Leigh Ann Harmon, whose patio skirts the edge of Browns Valley Creek. With wintertime rainfall has arrived water levels as high as 10.11 feet on Feb. 16, only two feet below the flood stage, and with it a scouring of stream banks that has chipped away closer to the backyard of the house she and her husband built a decade ago.
“We’ve packed our ready-to-go bags and our cat carrier five times,” she said last Thursday outside the home on McCormick Lane, where the creek skirts the property in about a 100-degree arc – and the slope begins less than 55 feet from the house.
Beyond a wire-fence gate was a slope that has grown ever more vertical after three rainy seasons; farther on was a tangle of shrubs, woodland and toppled trees dangling mere inches above the bubbling creek, about a 20-foot drop below Harmon’s yard.
The effects of heavy rains was even more dramatic on the bank opposite Harmon’s home, where the landslide had exposed a sheer wall of brown soil where a few roots dangled from the edge of the turf remaining on top. A solitary orange pole remained planted in the ground – one of two, she said, that once held the gate to a back driveway toward the nearby Loyal Order of Moose lodge before the pathway buckled in 2017. (The lodge remains reachable by a footbridge that spans the creek from a back parking lot of Browns Valley Market on Browns Valley Road.)
The instability began in February, 2017, with a wrinkle in an uphill driveway at the south end of McCormick Lane, which branches from Browns Valley Road. Over several days, the driveway shifted and cracked, a hillside tree toppled and some concrete hill footings buckled.
Neighbors filled about 1,000 sandbags ahead of a storm, amid worries that the slide could cause area flooding or cause trees to fall onto homes, officials said.
With the hill forming a toe in the stream, how to permanently stabilize the ground – particularly with homes and other buildings so close to the waterway – remains as much a problem as it did two years ago, according to Thomasser of the flood control district.
“It’s a challenging situation because the hill is so steep and ends in the creek, but there’s nothing you can do at the toe of a (hill) short of a massive wall,” he said. “Sometimes these slides need to run their course, but the issue is you’re in a developed neighborhood, it’s private property, and it’s technically challenging.”
According to Harmon, county flood control district workers have visited her property several times, usually to cut away fallen tree limbs and branches that could cause water backups and higher stream levels unless they were removed.
A city code enforcement officer visited the site last week and notified the county flood control district for possible work on the slide, which includes areas both inside and outside city limits, according to Planning Manager Erin Morris.
City public works officials said during the 2017 slide they would respond to a slide severe enough to affect Browns Valley Creek, but doubted the erosion could be entirely stopped.
While Harmon’s house is not under immediate threat, she and her husband remain wary that further slides and debris eventually may block the creek completely, leaving the yard and first floor vulnerable to flooding. After two more trees fell across the creek while they were on vacation in mid-February, the couple had about 200 Santa Barbara sedges planted on their side of the stream bank in March, in hopes that the roots will grow and anchor the soil over the next three years.
“I don’t know when the other trees will come down, but they will,” she said.