Big River (California)

Big River
Arroyo Grande
Big River, from the Big River Unit of Mendocino Headlands State Park
Location of the mouth in California
Location
CountryUnited States
StateCalifornia
RegionMendocino County
Physical characteristics
SourceImpassable Rocks
  location7 mi (11 km) south of Willits, California
  coordinates39°19′3″N 123°22′23″W / 39.31750°N 123.37306°W / 39.31750; -123.37306
MouthPacific Ocean
  location
Mendocino, California
  coordinates
39°18′8″N 123°47′41″W / 39.30222°N 123.79472°W / 39.30222; -123.79472
  elevation
0 ft (0 m)
Basin size181 sq mi (470 km2)

The Big River is a 41.7-mile-long (67.1 km) river in Mendocino County, California, that flows from the northern California Coast Range to the Pacific Ocean at Mendocino, Mendocino County, California. From the mouth, brackish waters extend 8 miles (13 km) upstream, forming the longest undeveloped estuary in the state.