Pacheco Reservoir is a man-made reservoir in the Diablo Range in California, U.S.A. The lake is formed by a dam on the north fork of Pacheco Creek, whose waters reach Monterey Bay by way of the Pajaro River. The Pacheco Pass Water District is currently responsible for operation and maintenance of the Pacheco Reservoir. Located north of State Route 152 in eastern Santa Clara County, the lake is about an hour's drive from downtown San Jose.