Oroville followed the present Oroville Dam Boulevard (County Route B2) to the present location of the Oroville Dam, and then ran north and northeast alongside the North Fork Feather River along a route now covered by Lake Oroville. It left to the north on Dark Canyon Road, meeting the present alignment at Jarbo Gap. Since the old road would be flooded, a $14.8 million new alignment, much of it four lanes, was built around the west side; the Western Pacific Railroad was also relocated to a nearby alignment. The double-decker West Branch Bridge over the West Branch Feather River northwest of the dam, carrying the highway above the rail line, was dedicated on August 15, 1962. Three portions of SR 70 have been upgraded to freeways: north of SR 99 to Berry and Kempton Roads in the early 2010s; south from Marysville to the State Route 65 split in the mid-1950s, extended farther south in the late 1960s and late 2000s; and around downtown Oroville, built in the early 1960s. In 2004, SR 70 was upgraded to a four-lane expressway between Feather River Boulevard north of the Bear River and the Yuba/Sutter county line to the freeway portion south of McGowan Parkway. A freeway interchange was constructed in 2008 at Plumas Lake Boulevard for access to the Plumas Lake development previously served at an uncontrolled intersection with Plumas Arboga Road. The removal of this intersection effectively upgraded the expressway portion to freeway south to the Feather River Boulevard intersection. In the early 2010s, the last two-lane segment of SR 70 south of Marysville was expanded to a four-lane expressway, with a freeway section bypassing the small town of East Nicolaus to the west. In 2015, the interchange with Feather River Boulevard in Plumas Lake was opened to traffic, eliminating the last signalized intersection between Sacramento (with SR 99) and Marysville. Future Between Marysville and Oroville, SR 70 is being widened to a four-lane expressway, with a center left-turn lane and eight foot wide shoulders on each side. The project is estimated to be complete by 2024 with the portions between SR 162 and East Gridley Road already complete. Major intersections See also References External links California @ AARoads - California 70 California Highway Conditions: SR 70 California Highways: SR 70 070 070 State Route 070 State Route 070 State Route 070 State Route 070 State Route 070 U.S. Route 40