Stream banks sustain at least $5 million in storm damages

Significant storms over the last two months have caused at least $5 million in damages to Tri-Valley stream banks, according to Zone 7 Water Agency representatives.

Bank failures have occurred at more than 40 sites, with the majority of damage happening along creeks and flood-control channels in the western portion of Zone 7’s service area, staff said at a Feb. 15 Board of Directors meeting. Damage has included channel bank slides, embankment washouts and toe erosion.

The worst of it is evident at three contiguous sites along the Alamo Canal beside Interstate 680 near West Las Positas Boulevard. There, Zone 7 staff stabilized the embankment with temporary vertical steel piping, cleared mud and debris, and placed plastic sheeting over the slide area to prevent further effects from rain.

“This stretch of trail contains other buried infrastructure and required additional protection to ensure that the infrastructure was protected,” Zone 7 general manager Jill Duerig said in an email Monday.

Other spots that have sustained serious damage include Arroyo Mocho in Pleasanton and South San Ramon Creek near Dublin High School, Duerig said.

The damage has also forced the closure of the Centennial and Arroyo Mocho trails in Pleasanton. It’s anticipated they will remain closed through summer, Duerig said, adding Zone 7 has been working with local cities and park departments as they assess the safety of trails.

The damage estimates are expected to rise, as more rain has fallen since the update at last month’s board meeting. More rain “could cause further damage at existing sites that warrant immediate action,” Duerig said.

“Zone 7 is monitoring sites that could impact public health and safety or infrastructure,” she added.

Staff said they will pursue all possible funding assistance for the permanent bank repairs. They have had meetings and field inspections with the state Office of Emergency Services and the Federal Emergency Management Agency, as they are collecting repair estimates and evaluating damage across the state.

Gov. Jerry Brown has declared a state of emergency for numerous counties, including Alameda, due to impacts from flooding, erosion and mudslides. Last month, President Donald Trump also approved a major disaster declaration for California counties including Alameda, freeing up federal funding for recovery efforts.