The 52 square-mile San Gregorio Watershed is the second largest drainage in coastal San Mateo County. The watershed abuts the Tunitas watershed to the North, the Pescadero/Butano watershed to the South and drains into San Gregorio Creek, which empties into the Pacific Ocean. Three small, unincorporated communities of La Honda, San Gregorio, and Skylonda are contained in the San Gregorio watershed. Parts of the San Gregorio State Beach and Sam Mc Donald County Park and numerous Open Space Preserves are located in the watershed. California State Highway 84 courses through the watershed from the eastern boundary at the western margin of the San Francisco Bay Area to the Pacific Ocean at California State Highway 1. With approximately 45 miles of blue line streams, San Gregorio is one of nine priority creeks slated by CDFG for coho reintroduction.