Power plant shutdown leaves trout river nearly dry

A power plant’s maintenance shutdown left the Viinikanjoki river in Parkano, Finland, almost completely dry for two days, raising concerns among anglers about its valuable trout population, Yle reports.

The water flow was stopped on September 7 and 8 during the trout protection season. Water levels have since returned to normal.

Timo Ojalainen, chairman of the Parkano sport fishing association, said he had never seen the river’s bed exposed in the 60 years he has lived beside it. The river, known for its strong trout population, dried up almost completely in places, including the popular Kairokoski fishing spot.

Ojalainen questioned why the flow was stopped during the trout protection season, which began on September 1.

According to a survey conducted in 2016, the trout in the Viinikanjoki descend from the river’s original population and reproduce naturally. The sport fishing association says this attracts anglers from across Finland and from abroad. The conservation value of one trout living in the Viinikanjoki is estimated at 2,440 euros.

No dead fish have so far been observed in the river, according to the association.

Riverbed organisms may have been destroyed

Jarmo Pautamo, an entrepreneur who has studied natural waters and restored rapids for decades, estimates that the organisms living on the riverbed have been completely destroyed in some places.

These organisms include caddisfly larvae and other small creatures that fish eat. Pautamo said the fish’s food supply would be significantly reduced and that the ecosystem might not recover until next summer.

He also said fish forced to flee the dried-up rapids may have moved into deeper pools, where they are more vulnerable to predators.

Authorities investigate the shutdown

The Permit and Supervisory Agency is investigating whether the Käenkoski power plant acted in accordance with its permit when it stopped the flow in the Viinikanjoki.

The plant’s water permit dates from 1965. Anne Polso, a group manager responsible for water legislation supervision at the agency, said its conditions still apply.

The permit requires the operator to ensure that water supply below Käenkoski is not prevented and that changes to the flow do not cause damage or harm.

The operator must notify the agency if it deviates from the permitted operation. The Käenkoski power plant did not report the flow shutdown to the authorities.

Polso said permit holders should contact the agency in advance, particularly when a flow interruption is planned. Such notification allows the agency to assess whether the maintenance work complies with the permit and whether its timing and implementation are appropriate.

A water management expert at the Centre for Economic Development assessed that the local effects of the incident could be serious. A fishing biologist, however, said the timing of the interruption was not the worst possible.

The power plant said it had not intended to let the river dry out completely and had taken measures in advance to prevent that from happening.