Pumped-storage plan raises fears for clear-water Pyhäjärvi

Energy company Koskienergia is seeking permission to build a pumped-storage plant at the Parantalankoski hydroelectric plant in Äänekoski, prompting concern among nearby residents about the water quality of Lake Pyhäjärvi, Yle reports.

The plan is to build a pumping station beside the existing plant. It would move water from Lake Kiimasjärvi, below the plant, back into Pyhäjärvi, above it. The company has applied to the Permit and Supervisory Authority for a water permit.

Pyhäjärvi has clear water and an excellent ecological status, while Kiimasjärvi’s ecological status is rated satisfactory. Several hundred holiday homes and some permanent residences are located on Pyhäjärvi’s shores.

Saara Pakkala, who lives with her family near the plant, said she was upset by the proposal. She and her spouse swim in the lake throughout the year, she said, and value its clean, clear water.

Koskienergia chief executive Hannu Ruotsalainen said the company needs the plant to provide balancing power for wind and solar generation. Water would be pumped into storage when electricity is cheap and used to generate electricity when prices are high. The project would not increase the plant’s total electricity output, but would allow it to generate power when supply is low.

Ruotsalainen said the company’s modelling indicates that the water pumped into Pyhäjärvi would be the same water previously released from the lake into the downstream water system. It would enter the lake’s surface layer, he said, limiting any effect on bottom sediment to a small area in the bay above the plant.

The Parantalankoski plant has operated since the 1960s. Koskienergia has also applied for permission to remove the existing regulation dam at Pyhäkoski, at the northern end of Pyhäjärvi, and replace it with a natural bottom sill. The change would make it possible to restore Pyhäkoski for migratory fish.

Ruotsalainen described the proposed plant as a significant investment for the company but did not give a cost estimate. Construction could begin in about two years if the necessary permits are granted.