Lahontan Dam and reservoir are part of the Newlands Project, one of the first irrigation projects selected for construction following passage of the Reclamation Act of 1902. In 1905 it became the first project to deliver water from works constructed by the United States Government. The project diverts and stores water from the Truckee and Carson Rivers to irrigate lands near Fallon and to produce hydroelectric power. Drainage water from the irrigated lands flow into the Stillwater Wildlife Management Area, one of the finest waterfowl areas in Nevada.

The dam, completed in 1915, is 162 feet high, 1,700 feet long at the top, and contains 733,000 cubic yards of earth fill. The reservoir has a storage capacity of 274,000 acre-feet when full.

The reservoir was named after the Ancient Lake Lahontan which covered over 8,500 square miles of the western Great Basin during the last Ice Age. It's ancient shore terraces may be seen high on the mountains of the surrounding region.