Pinole is a city in Contra Costa County, California, United States. The population was 18,390 at the 2010 census.
According to the United States Census Bureau, the city has a total area of 13.6 square miles (35 km2). 5.3 square miles (14 km2) of it is land, and 8.3 square miles (21 km2) of it (60.79%) is water.
The city of Pinole has habitat areas that support the endangered species Santa Cruz Tarweed on the California coastal prairie ecosystem. A colony of this rare plant was discovered during preparation of an Environmental Impact Report for a proposed shopping center on the east side of I-80 in the late 1980s. Subsequently a plan was developed by the city to conduct replanting of this tarweed on the slopes within the right-of-way of Interstate Highway 80. Also running through is Pinole Creek.