Oulu hydro plant explains February’s massive water releases after rare system failure

Oulu Energy has submitted a report to the Finnish Energy Authority explaining the unusual water discharges from its Merikoski power plant in February that flooded parts of central Oulu, the company announced on Tuesday.

The incident began when all three turbines at the Merikoski hydroelectric station shut down three times within 15 hours on 15 February due to ice accumulation on regional power lines. Safety mechanisms triggered automatic shutdowns, diverting Oulujoki River water through spillway gates and causing sudden rises in water levels.

Floodwaters and broken ice surged into Ainolanpuisto park and Hupisaaret’s pedestrian paths, while the Tuira district saw water overflow onto a light-traffic route. Investigations later revealed one spillway gate failed to open fully due to ice blockage beneath the waterline.

Oulu Energy described the event as highly unusual, noting that while simultaneous turbine stoppages are anticipated in contingency plans, the rapid ice buildup on power lines created exceptional conditions. The company stressed that the spillway area remains strictly off-limits, as gates may open without warning during faults.