Restoration of Lake Hiidenvesi

Lake Hiidenvesi is located in southern Finland. The Lake is the second largest lake in the region, with surface area of 30,3 km² and catchment area of 935 km². The Lake has four large basins.  Further information on the four basins of the Lake. Lake Hiidenvesi is naturally turbid. 

Water quality of Lake Hiidenvesi is mainly satisfactory. However, abundant algal blooms are common. The fish population is skewed due to high removal of fish biomass during the past ten years. In some parts extensive vegetation is causing problems. 

The Lake receives a high amount of pollution from the catchment area. During 1996-2002 the Lake received 27 000 kg phosphorus and 471 000 kg nitrogen per year. The suspended load brought by River Vihtijoki and River Vanjoki, is approx. 5,5 million kg annually. The diffuse load is twice the Lake's pollution tolerance values.

The Lake is highly valuable for the locals for recreation and fishing. Over 1000 summer cottages are located on the shores. 

Lake Hiidenvesi restoration 2008-2011 project concentrates on managing the problems further upstream and across the entire catchment area. The plan is to decrease pollution load entering the Lake by making changes in cultivation methods and construction of wetlands. The project will also take part to the massive restioration project of Lake Vanjärvi, located just above Lake Hiidenvesi.

The Lake Hiidenvesi project's budget for 2008-2011 is 1 388 700 €. One fifth is budgeted for construction of wetlands and one fourth for restoration of Lake Vanjärvi.

University of Helsinki has done research in the area during the past ten years. For further information see the publication list.