Lake restoration and biomanipulation

Norconsult is project leader and expertise regarding the restoration of Lake Vallentunasjön. The lake is 700 hectares, in recreation areas and near population centers.
Project name:
Lake restoration and biomanipulation
Client:
Vallentuna and Täby municipalities
Location:
Sweden
Time span:
2009-in progress
Key figures:
<p>Project cost: 200 000 Euro/year</p>

Lake Vallentunasjön has had a problem with muddy water due to eutrophication. After extensive investigations initially, a project of depletion of fish has been carried out, in order to reduce the number of cyprinids and favour the fish of prey. In this way the amount of phyto plankton decreases, which cause the muddying, and favour grazing animal plankton. The fishing was carried out with trawling and stake nets, and the cyprinids have become bio-gas.

Parallel to the depletion of fish, follow up measures are carried out where the sediment in the lake and water coming into the lake is monitored.

Profile picture of Björn Tengelin
Björn Tengelin
Uppdragsledare, Team Vattenbyggnad