It is what is known as a peat fire, which is decomposed soil that burns 12 to 15 feet underground, according the Steve Hill with the Contra Costa County Fire Protection District.
"(Peat fires) are tough to extinguish. But the appearance is right now, in fact, it has been extinguished," says Hill.
The Marsh Fire was ignited by a fire in a homeless encampment. It spread through 200 acres of marsh land along the waterfront in Pittsburg and Bay Point. The poor air quality prompted health advisories.
Hill says 200 million gallons of water were dumped on the fire. Fire crews tried to flooded the area for the past seven days.
"(It is) Impossible to get fire fighters out there because it is very dangerous conditions in the marshy area. And it wasn't in an area where we could get water on fire boats," explains Hill.
According to Hill, it's been a busy fire season. Fires have increased 20% since last year in the county.
"If we look back two years, that number is up about 50%. So, the indications are not good considering that we are not yet in what's typical the peak of fire weather," he says.
And as wildfires burn near Yosemite National Park, fire crews from the Bay Area have been called to assist. Fremont sent crews Saturday morning. Sonoma County sent a crew from five local fire districts on Saturday afternoon.
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"(They) most likely will be sent immediately right to the line. And probably have a pretty active fire fight throughout the night," says Chad Costa, the Assistant Fire Chief for the City of Petaluma.
His teams have a lot experience after battling the Glass and Tubbs wildfires, among others, which devastated parts of Sonoma County.
"We are all very happy to go help those (who) helped us. Let's hope they stay safe, and get a handle on this thing as quick as possible," says Costa.
Costa says despite the fires raging in Mariposa County, it's been a mild July in terms of weather, which helps fire fighters.
"We just haven't had a lot of red flag warnings. It has been fairly mild weather wise," he says.
Some of those previous massive summer fires burned tens of thousands of acres. Some were so strong, they even created their own weather system.
Costa says fire crews have more experience. And CAL Fire has more resources. That means fire crews can be more aggressive in getting ahead of fires.
But Costa warns that California's fire season isn't over yet.
"We have August and September and October, which can be really rough months for us. So, things can change quickly. Hopefully the weather keeps on our side as much it can, says Costa.
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