Updated Saturday 10:45 a.m.: Both lanes have reopened, according to the Napa County Sheriff's Office.
The California Highway Patrol issued an advisory Friday night that motorists should avoid State Highway 128 and the Berryessa-Knoxville Road, 1/2 mile south of Capell Cove near Turtle Rock, due to a major rockslide.
The roads will be closed and traffic detoured on Saturday, according to CHP.
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