Derby Dam is a diversion dam built from 1903 to 1905 on the Truckee River, located about 20 miles (32 km) east of Reno in Storey and Washoe counties in Nevada, United States. It diverts water into the that would otherwise enter Pyramid Lake. The canal feeds Lake Lahontan reservoir in the Carson River watershed, where it is used for irrigation. It was the first project of the newly organized U.S. Reclamation Service (known today as the U.S. Bureau of Reclamation), organized by the Reclamation Act of 1902.