Record autumn rain raises Oulu River levels in central Oulu

The Oulu River catchment is experiencing its wettest autumn in more than 60 years, with water levels high enough to flow through and around power plants from Lake Oulujärvi to the Bothnian Bay, Yle reports.

Fortum is releasing water from Lake Oulujärvi under an exceptional permit and has permission for similar releases at its power plants along the Oulu River. The releases are needed because of the unusually large volume of water and to lower regulated water levels before winter and freezing.

Fortum says rainfall in the region since August has exceeded any total recorded during more than 60 years of monitoring. The company has warned residents and cottage owners near the shore about the unusually high water levels. River flows have at times been record-high for the season, and some jetties have been submerged, said Mikael Heikkilä, who oversees Fortum’s regulation of the Oulu River catchment.

Water from Fortum’s 11 hydropower plants in North Ostrobothnia and Kainuu is flowing towards Oulu in greater-than-usual volumes. At the city’s Merikoski power plant, operated by Oulu Energy, the dam and flood gates have been used for bypass releases for two months. The plant is already running at full capacity, but all the gates are now in use because more water is arriving than it can handle, project manager Samuli Korpela said.

The releases have raised water levels below the dam, including in Ainola Park, where water has reached some pathways and risen higher than usual in the park and the dam channel. Although no heavy rain is forecast in the coming days, Heikkilä said the situation could continue for weeks because natural lakes in the region remain unusually high.