Wildfire preps underway to protect Marin County water supply
SAN RAFAEL -- Californians often hear about people taking steps to prepare their homes and businesses for fire season. The same is being done for Marin County's water supply.
"We're in a kind of hardwood, oak woodland forest type here, so crews are removing the small diameter Douglas firs that are encroaching in them," explained Shaun Horne, Watershed Resources Manager for Marin Municipal Water District. "Douglas fir can become fuel that moves a fire up into the canopy of the forest."
On this warm May afternoon, crews were working their way up a hillside, cutting through a set of problems that have been growing beneath Mount Tam for years.
"One being the spread of Sudden Oak Death, which we've had about 10,000 acres of our land impacted," Horne said. "We've got invasive species, primarily in the form of French Broom that's colonized about 1,500 acres. Then we see encroachment of Douglas fir in the absence of natural fire on the landscape."
"So this is a good contrast," said Carl Sanders, MMWD's Natural Resources Manager, pointing to a cleared field. "This is an area that we recently worked. We have an oak land, woodland here now, that should fire come through, is not gonna burn nearly as hot as if we look after the other side of the road, an area that hasn't seen fire since 1945."
When visitors make their way around the trails the before-and-after is quite obvious, and while the areas of work can seem random, they are very targeted.
"Downslope behind us we have one of our water treatment plants," Horne said. "And then on the other side to the south of us is one of our primary drinking water reservoirs."
The goal is to protect infrastructure, and prevent a fire so intense enough to damage the land itself.
"Post-fire, should you get storms and you don't have a vegetative cover, water quality issues," Sanders said of potential fire impact. "You'll get sediment that enters our reservoirs that increases our cost and ability to treat water."
So the idea is to mimic what fire would do to this land, and prepare it for that eventuality.
"Really, the purpose of the work is to try to influence the behavior of a fire, by breaking up the continuity of these lateral and horizontal fuels," Horne said.
This work is part of the program launched in 2019. It gets layered on top of all of the other work that is done out here throughout the year, like the maintenance on the fire breaks that protect communities here in Marin County. Add it all up, and crews can treat about 1,200 acres a year. The district itself is about 22,000 acres.