Oak Grove Hydroelectric Project
The Oak Grove Hydroelectric Project is a 44 megawatt hydroelectric plant operated by Portland General Electric on the Oak Grove Fork Clackamas River. Water for this project is held by three lakes, built between 1923 and 1956. The dam creates the impoundment Lake Harriet.History
In 1907, the Southern Pacific Company began to acquire water rights for the Oak Grove fork. These rights were transferred in 1911 to the Portland Railway, Light and Power Company, which later became PGE.
In 1923, the concrete diversion dam at Lake Harriet was completed. This lake holds with a surface area of. A pipeline goes downstream from Lake Harriet to the powerhouse. Power generation from the Oak Grove fork began in August 1924.
In 1953, Frog Lake was completed, adding of storage with of surface, which was later reduced to on in 1997. Finally, in 1956, the compacted-earth dam for Timothy Lake was completed, creating the largest lake in the system at and. The Oak Grove Powerhouse contains two Francis turbines.
