Box Canyon Dam, Gravity dam near Mount Shasta, California.

Box Canyon Dam is a gravity dam on the Upper Sacramento River in the eastern Trinity Mountains. It holds back water to create Lake Siskiyou, which sits surrounded by forested ridges and slopes.

In April 1959 California began funding feasibility studies for a dam in Box Canyon. The legislature authorized $2,800,000 for the project in 1963, after the Davis-Grunsky Act, and in 1965 Assembly Bill No. 251 granted $2,000,000 to the Siskiyou County Flood Control and Water Conservation District. The dam was completed in 1965 for flood control, and a powerhouse was installed that same year for hydroelectric power.

The Lake Siskiyou Trail circles the reservoir and crosses the dam on foot, linking the dam to the surrounding Shasta-Trinity National Forest. The Box Canyon Trail starts on the dam's north side and follows the Upper Sacramento River down the narrow canyon toward the town of Mount Shasta.

The lake is easy to reach from nearby towns and offers access to the water for fishing and boating from several points. Visitors should know that water levels change with the season, so the shoreline varies throughout the year.

The 1965 project also added a powerhouse for hydroelectric generation, so the structure serves both flood control and power production. The Lake Siskiyou Trail crosses the crest of the dam, letting walkers pass from one shore of the reservoir to the other.