March 17 (UPI) -- Workers found natural-occurring asbestos in the rocks and air near the damaged Oroville Dam spillway, the California Department of Water Resources said.
The agency, in a news release Thursday, said risk to workers and nearby communities in Oroville is minimal but it has increased dust-control operations and officials will monitor the air quality in the area.
Workers found the asbestos during recent air quality and sediment testing, the agency. They found the asbestos in limited areas near the construction zone.
Naturally occurring asbestos is in 42 of California's 58 counties, according to the Environmental Protection Agency. The state rock is the serpentine, which contains asbestos.
"From the outset, crews removing debris have used dust control measures; including wetting soil with water trucks and using wet drilling methods to minimize dust, and employing rumble strips on roads to reduce dirt collecting on heavy equipment," the agency said in a release. "Additional measures may include washing of trucks and tires, implementing the use of personal air monitors in key areas, and increased air sampling."
Bob McLaughlin, Butte County Air Quality Management District assistant air pollution control officer, said the area is being treated like a contaminated site.
"Absolutely any time there's potential for public exposure to asbestos it's a concern," he said to the Chico Enterprise-Record. "It's either there, or it isn't. If it's there, you do everything you can to minimize dust emissions. You have to assume it's everywhere [at the site]. ... You need to be very diligent and proactive in protecting public health."
Officials expect the damaged main spillway is expected to be used sometime Friday.
The spillway has been shut off since Feb. 27, when California Department of Water Resources officials began repairs and removed debris built up after massive water releases into the Feather River below the dam. Officals used a never-attempted emergency spillway to release water.
Crews had removed 1.24 million cubic-yards of material as of Thursday morning, according to the DWR. The pile was originally estimated at 1.7 million cubic-yards.
Officials temporarily evacuated some 180,000 people for two days in three counties amid fear of mass flooding if the emergency spillway gave way.