About Pyhajarvi Dam

Pyhäjärvi near Säkylä is one of the most important lakes in southwestern Finland, lying in the Satakunta region and draining via the Eurajoki river into the Gulf of Bothnia. Covering approximately 154 square kilometres, the lake was regulated from 1958 onwards to support water supply, flood control, and modest hydropower generation. The reservoir holds an estimated 250 million cubic metres. Pyhäjärvi is the primary raw water source for a significant part of southwestern Finland's municipal water supply network, including the cities of Turku, Pori, and Rauma collectively through the Lounais-Suomen Vesi water utility. The lake's relatively shallow depth and fertile catchment have historically made it vulnerable to eutrophication; intensive water quality monitoring and catchment management programmes have been in place since the 1980s. Pyhäjärvi is also celebrated for its vendace fishery, supporting a significant commercial harvest of Finland's beloved smoked vendace (muikku).