Rapids churn Wheels turn Shafts turn Electric current
 
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Since the 1850s, the lower rapids was dammed by wooden dams to divert the current to the channels and flumes. There were floodgates at the upper ends of the flumes. During times of low water the factories stopped - neither did the turbines work during floods. Continuous disputes concerning the use of the water were everyday life for the factories.
Wooden dams were built into Tammerkoski rapids early on. They were not to block the entire rapids, as the "King's channel" was supposed to run freely in the middle of the rapids. At the upstream falls Finlayson diverted the water to the driving wheels through channels and wooden flumes. Frenckell paper mill operated the same way at the middle falls.
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The situation became easier in the 1890s when the factories were allowed to dam the entire rapids with wooden needle dams. The needle dam at the upper falls is seldom opened. The opening takes place through lifting up the planks one by one. A roller dam was built at the central falls in 1933; it is possible to let the water stream underneath it when there is a need to do so. Above the dam there is a basin, from which the water is diverted to the turbines. The dam structures of the lower falls power station were built jointly by the factories and finished in 1938.

Cross-section from needle dam.
 Rapids churn   wheels turn  shafts turn
Electric current
 Power from the rapids