Air-quality officials are working with repair crews at California's damaged Oroville Dam spillway after the discovery of naturally occurring asbestos there.
The California Department of Water Resources said Thursday that authorities found the asbestos in what it said were limited areas at the site.
Work crews currently are removing tons of rocks, earth and other debris that washed to the base of the Oroville spillway last month after a large part of the spillway failed.
Asbestos can cause cancer. Rocks containing natural asbestos are common in California foothills and mountains.
State water officials say they are working with air-quality officials from Butte County to reduce dust at the site since it could contain asbestos. That includes washing down construction trucks and using wet drilling methods to minimize dust.