CHICO, Calif. - The North Complex Fire has burned a large portion of Lake Oroville's watershed. This could lead to hazardous water quality after winter rains run all of that sediment into the lake and the effects could last decades. However, how water quality could be affected by the fire is still largely unknown.
The North Complex Fire which burned in both Butte & Plumas counties destroyed many structures and vast swaths of forest. All of that ash & debris will likely run off into the rivers and into Lake Oroville. The main tributaries into Lake Oroville are the North, Middle and South Forks of the Feather River and the West Branch.
When the rain comes, a lot of what burned will run into these tributaries and deposit all of the sediment into Lake Oroville. The main focus before the rain comes will be erosion control and preventing as much sediment as possible from entering the lake.
A lot of what burned is organic matter and when it gets deposited into the lake, it will mean a large influx of nutrients.
"The nutrients are becoming more mobile because they've been burned and they are oxidized. As a result of this increased export in the water, nutrients are peaking in water and that becomes food for algae. And so, following a fire we will see an increase nitrogen export and an increase in algal blooms," said Associate Prof. Sandrine Matiasek, Environmental Sciences, Chico State.
If toxic, algal blooms could harm anyone directly exposed to it and harm the health of the environment and aquatic life.
Recreational use at Lake Oroville should be fine before rain arrives, but that could change this winter.
"As far as direct human impacts on swimming, I would say probably limited. As far as eating fish from Lake Oroville... unsure. It probably will take time for these toxic compounds to build up in fish tissue," said Matiasek.
Farmers & ranchers could also be impacted by water that is toxic.
Lake Oroville is also a part of the State Water Project which supplies drinking water to 25 million people in Southern California. The impacts could be wide-ranging if it becomes unsafe to drink.
Unfortunately, the impacts wildfires can have on water quality is still quite unknown and will require much more research.
A FULL INTERVIEW with Associate Prof. Sandrine Matiasek, Environmental Sciences, Chico State is also attached to this article.
It is about 13 minutes and she describes how wildfires can impact the watershed.