Hilmo Hydro Power Station

General information about the Kymijoki River and Hilmo Power Station

In the past, the Kymijoki River was a border river between Sweden and Russia, and throughout history it has acted as a dividing line and a unifying stretch of water for the Kymenlaakso Region. The Kymijoki River is the largest river in southern Finland and it is popular thanks to its wealth of opportunities for fishing.

The Hilmo Power Station building stands by the Hilmonkoski rapids, nearly two kilometres south of Lake Kivijärvi, which is the only regulated lake in the system. The water from the lake flows along a 1.6 km long dug canal and finally through a pipeline fitted with a swelling tower to Hilmo Hydro Power Station. After the power station, water flows along another 0.5 km long canal to Lake Vuosjärvi further south.

Hilmo’s design discharge is small compared to the lake’s regulation volume, so the level in the lake typically varies only a few centimetres over 24 hours. 

Water can be spilled from Lake Kivijärvi via the Potmo dam, located about 10 kilometres from the power station. The dam has a fish ladder, which aims to re-establish migrating of fish in the rapid. A number of brown trout smolts are released into the water system each year to maintain the area’s good fishing opportunities.

Some renovations and modernisation measures have taken place over the years. The latest such project was implemented in 1999, when the turbine, generator and electrical equipment were renovated.

General information about hydro power in Finland

After World War Two, large-scale hydro power plant construction took place when the country’s rebuilding work and the paper and pulp industry required a great deal of energy. As Finland is a relatively flat country, hydro power makes a small contribution and now accounts for 16% of Finland’s total electricity generation.

The largest hydro power stations are located in rivers in north and north east Finland. About half the watercourses have been expanded for electricity generation. Unregulated rapids are protected, so extra capacity can be obtained by increasing the efficiency of the old power stations or from artificial lakes.