River Mill Hydroelectric Project

River Mill Hydroelectric Project
U.S. National Register of Historic Places
File:River Mill power plant and dam on the Clackamas River near Estacada, Oregon (3230119950).jpg River Mill dam c. 1911
Nearest city	Estacada, Oregon
Coordinates
Area	5 acres (2.0 ha)
Built	1911
Architect	Nils F. Ambursen, Puget Sound Bridge & Dredging Co.
Architectural style	Hydroelectric facility
NRHP reference No.	01000497
Added to NRHP	May 10, 2001

River Mill Hydroelectric Project, also known as River Mill Dam and Station M, is a hydroelectric dam and powerhouse in Clackamas County, Oregon, United States. It is just north of Estacada, Oregon, on the Clackamas River at river mile 23.5 (km 37.8). It received its name from being near a sawmill that was located along the river.

The dam has been in continuous production of hydroelectric power since 1911, when its construction was funded by the Portland Railway, Light and Power Company. It was one of four related projects on the Clackamas River: the Oak Grove Hydroelectric Project (developed 1923–56), the North Fork dam (1958), and the Faraday Dam (1907–10), all upstream (south) of River Mill. All but Faraday, demolished 2018, are still owned and operated by the successor company, Portland General Electric.

File:River Mill Dam Estacada Oregon.JPG

River Mill dam, view from east bank

The principal designer of the original Mill Run Dam was the Norwegian immigrant Nils F. Ambursen (1876–1958). Based in Boston, his Ambursen Hydraulic Construction Company designed over a hundred dams in the United States from 1903 through 1917. Ambursen's patented concrete-slab-and-buttress dam design was a significant advance in dam design of this era. River Mill is one of only three Ambursen-type dams built west of the Mississippi.

The project is listed on the National Register of Historic Places, and in the Oregon Historic Sites Database of the Oregon State Historic Preservation Office.

File:River mill dam governor test.png

Governor in River Mill dam.