Finnish regulator warns Tahkoluoto power line project likely to cause significant environmental harm

A proposed overhead power transmission line between Tahkoluoto and Ulvila will probably have extensive and substantial environmental impacts, Finland’s Permit and Supervision Authority (LVV) concluded in an assessment published this week.

The regulator’s evaluation found the 110-kilovolt line would likely affect residential conditions, cultural landscapes, bird populations, fish stocks, and protected areas—particularly at its starting and ending points, where ecologically sensitive habitats and species are present.

Two route options have been proposed through the Pori archipelago toward the mainland. The northern alternative follows the Saaristotie road corridor, where the authority warns of major impacts on the cultural landscape. The southern route, crossing Kolpanlahti bay alongside an existing Fortum line, would require 18 new pylons, significantly altering seabed conditions and water quality.

Social effects, including construction noise exceeding guideline levels near homes and persistent high-frequency hum from the lines, are also deemed substantial. Local residents have strongly opposed the overhead design, arguing it would ruin the area’s unique scenery.

While the LVV noted that underwater cabling could mitigate marine harm, Tahkoluoto Offshore has dismissed this as prohibitively expensive and difficult to maintain. The regulator’s opinion does not decide the project’s fate but must be included in the formal permit applications.