Harriet Lake, located in Clackamas County, Oregon, is a privately owned reservoir primarily used for hydroelectric power generation. Constructed in 1923, this arch dam stands at 68 feet tall and spans 186 feet in length, with a storage capacity of 400 acre-feet. The lake covers an area of 22 acres and is fed by the Oak Grove River, with a maximum discharge rate of 11,200 cubic feet per second.

Despite its age, Harriet Lake boasts a low hazard potential and a moderate risk assessment rating. While the condition assessment is not currently available, the dam is inspected annually by the Federal Energy Regulatory Commission to ensure its safety and compliance with regulations. The spillway, with a width of 134 feet, is uncontrolled, adding to the recreational opportunities and potential for downstream water management.

Although privately owned, Harriet Lake offers not only hydroelectric power but also recreational opportunities for visitors. With its scenic location and historical significance, this dam serves as a vital resource in the region's water management infrastructure while providing a picturesque backdrop for those who visit.