Grayson Creek is a stream in Contra Costa County in northern California that flows northeasterly 7.4 miles (11.9 km) from its origin in Briones Regional Park to Pacheco Slough four miles east of Martinez. Pacheco Slough, in turn, connects to Suisun Bay. The Grayson Creek subwatershed is part of the Walnut Creek watershed and includes the cities of Pleasant Hill and Pacheco, California.Murderer's (aka Murderous) Creek is also located in Pleasant Hill.