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Ämmäkoski is one of the three hydroelectric power plants in Kajaani. It is located on the Kajaani River that flows through the city center. Ämmäkoski is located right below Koivukoski I-II. The ruins of the medieval Kajaani Castle sit between the two power plants.

Ämmä Koivukoski I-II & Koivukoski III


Historically Kajaani´s industry located along the Kajaani River and Petäisenniska area and the power plants originally were to produce power for Kajaani´s industry.[1]

Ämmäkoski, designed by Architect Onni Tarjanne, was constructed in 1917. The power house has an in-situ concrete frame and plastered brick cladding. Ämmäkoski was renovated in 1940, when Architect Eino Pitkänen designed an extention for the building. At the same time the plant was re-styled in line with the principles of functionalism. A third turbine was also added and today the power plant produces 4.9 MW of electricity.[2]  

Ämmäkoski is located right in the city centre, an unusual feature for hydropower plants in the Oulujoki region. The city´s business district was built according to functionalist planning principles during the economic boom of 40s and 50s by Architect Eino Pitkänen.[3]

[1] Veli-Pekka Huhmo. Oulujoen vesistön voimalaitosarkkitehtuuri. Oulu: Humanpolis Oy, 2017, 84

[1] Ibid, 85

[2] Karoliina Kikuchi, 2020


Technical information

Owner: Kainuun Voima Oy (Kainuu Power Company) 

Finished: 1917, the extention and renovation in 1940. 

Designers: Onni Tarjanne, architect, the extention and renovation by Eino Pitkänen, architect 

Capacity: 4.9 MW, head 6.5 m  

Power house: In-situ concrete frameplastered brick cladding

Special featuresLocated downtown Kajaani. The power house has been re-styled according to functionalist planning principles. 

Protection status: Classified as RKY (Nationally significant built cultural environment – RKY 2009: Hydropower plants on the River Oulujoki and Sotkamo Route).[4] 

[4] Veli-Pekka Huhmo. Oulujoen vesistön voimalaitosarkkitehtuuri. Oulu: Humanpolis Oy, 2017, 85


Residential area

Ämmänkoski has no residential area.



All pictures below are part of the power plant's history. All images are copyrighted. You may use the images for personal use but the images may not be used in commercial contexts or printed matter without our permission. Click on the pictures to enlarge them.

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