The mainstem Pacheco Creek is formed by the confluence of the North Fork Pacheco Creek and South Fork Pacheco Creek about west of Pacheco Pass. The creek generally follows Highway 152, passing from Santa Clara County to San Benito County, and continuing until it empties into San Felipe Lake, the source of the Pajaro River. The North Fork Pacheco Creek is a stream beginning in Henry W. Coe State Park at and receives the East Fork Pacheco Creek, at Chimney Rock before reaching Pacheco Reservoir, the latter just north of Highway 152 and the confluence of North and South Forks Pacheco Creek. The Mississippi Creek tributary of North Fork Pacheco Creek is has an impoundment (Mississippi Lake) above elevation, and sources on Bear Mountain on the northern side of Henry W. Coe State Park.