This year's lashing from winter storms has left more than 80 roads in Ventura County badly damaged, with estimates that it will cost more than $10 million to repair them.
Officials from the county Public Works Agency said the damage has closed three major roads.
Landslides have shut down a 3.3-mile section of Balcom Canyon Road between Bradley Road and South Mountain Road.
A 200-foot section of the road dropped 40 feet into the canyon because of slides, officials said.
There are also numerous smaller landslides along the roadway, guaranteeing that the road will be closed indefinitely while engineers figure out how to repair it.
South Mountain Road will also be closed between Lemon Road and two miles west of Balcom Canyon Road.
It is expected to cost more than $3 million to repair the road, which has sections that are washed out completely and some that are still covered by mud and dirt.
It could take four to six months to complete the work, officials said.
Flooding along the Ventura River washed away a 150-foot section of Santa Ana Road between Casitas Vista Road and Santa Ana Boulevard, officials said.
Crews will have to repair the road, as well as the rock and river embankments that were washed away during the flooding.
Repairs will cost about $1 million and could take until the end of April.