SR 149 was relocated onto a new two-lane alignment in the mid-1970s, leaving behind Openshaw Road. Caltrans began studies for interchanges at each end in September 1992. The California Transportation Commission approved funding for four-laning SR 149 in April 1994 and the two interchanges in May 1996, with construction to begin in 1998 and cost $47 million. Due to state budget problems and the need to study environmental impacts, the project was repeatedly pushed back; these impacts and inflation had more than doubled the cost to $120 million in 2004. In particular, an endangered species of meadowfoam was discovered on the south embankment, forcing a redesign. Construction began in September 2005 on a new freshwater marsh near the State Route 70 intersection to replace beaver ponds in the path of the highway, and it was completed in March 2006.