Marin County readies for winter storms

Winter storm preparations have begun across Marin County.

Efforts are underway by the county’s Department of Public Works to get ready for the seasonal onslaught of downed trees, landslides, road damage and flooding. The work includes removing sediment buildup from creek beds, replacing pump station equipment, conducting roadside storm drain work and checking and repairing levees.

The work, which launched in late spring, is expected to be wrapped up by mid-October.

“Plain and simple, our annual storm preparation work is a critical piece of flood prevention and public safety,” said Laine Hendricks, a county spokesperson. “Clearing debris and obstructions from creeks, storm drains, and culverts helps prevent flooding by ensuring that water can flow freely.”

Last year, Marin County weathered numerous powerful storms that rolled in off the Pacific Ocean. According to the Marin Municipal Water District, the Mount Tamalpais watershed received 62.23 inches of rain from July 1, 2023, through June 30. The year prior, it received 76.96 inches of rainfall. The average is 52.25 inches.

The two consecutive wet winters let to overflowing reservoirs. In February, Marin County had two “atmospheric river” storms back to back.

Tracy Clay, an engineer and manager of the Marin County Flood Control District, said the county is not expecting an unusually wet year. Based on the National Weather Service’s prediction for the upcoming rainy season, precipitation levels should be normal.

“However, we plan and prepare for intense storm seasons every year,” Clay said. “There can be severe atmospheric rivers in our area on any given year regardless of larger climatic patterns such as El Niño and La Niña.”

“Weather or climate models do not help us predict or plan for specific seasons though,” Clay said. “We prepare for every year as though it is a wet El Niño year.”

Marin County’s eight flood control districts include 37 miles of creek beds, over a mile of flood walls, more than 14 miles of levees, 45 permanent pumps along with seven portable pumps, and several stormwater basins.

Within the creeks, plants and trees are removed to increase water flow capacity. This summer, a few creeks — Rush Creek, Vineyard Creek and Fairfax Creek — are scheduled for sediment removal. According to Hannah Lee, a county water engineer, certain triggers sometimes alert the county to needed creek maintenance.

“For example, Vineyard Creek was designed to have a specific carrying capacity and was modeled to have a bridge under Center Road that has 6 feet of clearance between the creek bottom and the bottom of the bridge,” Lee said. “When there is less than 6 feet of clearance under the bridge it triggers sediment removal.”

Novato Creek requires at least 2 feet of clearance between the sediment level and the barrier across the width of the creek, and less than that necessitates maintenance. Public Works Director Rosemarie Gaglione said creek maintenance alone costs the flood district around $1 million a year.

Part of the winter storm prep includes pump station maintenance, specifically four pumps in Santa Venetia, two pumps in Richardson Bay, and two in Bel Aire and Strawberry. The work entails removing the pumps and cleaning the machines.

Hendricks said the pump station work, as well as the annual inspection of levees and tide gates, are important because managers need to be sure the structures can handle the increased water flow that comes with storms.

At home, residents should remove any dead leaves and yard waste from their property before the rainy season begins to prevent debris from clogging storm drains and gutters. All of the materials should be placed in the green waste bins.

Sweeping it into the street can cause flooding to the block or even the whole neighborhood, said Julian Kaelon, a public works spokesperson. Kaelon suggested assisting neighbors who might not be able to clean out their yards.

“While we can’t control everything about storm season, such as how severe the storms will be or where mudslides might happen, we can control how well we prepare,” Hendricks said. “Clearing obstructions from waterways and ensuring the integrity of our infrastructure can help us face fewer problems down the line.”