Europe and Central Asia

Restoration of Lake Sagsjön, a bird habitat in Gothenburg area - Sweden

 

Background

Lake Sagsjön borders Jehander’s hard rock quarry in Kållered. Storm waters flow from the quarry to the lake and bring with them large amounts of sediment that virually suffocate the ecosystem. As a result the lake is increasingly overgrown with vegetation. Several decades ago the lake was known as a good breeding habitat for several bird species, but today most birds have disappeared.

Location : The Lake Sagsjön borders Jehander’s quarry near Kållered, on the west coast of Sweden
Size : 50 ha
Mineral type : Crushed rock
Habitat(s) created: Euthrophic lake, reedbed and wet meadows, shallow waters.
Target species : Breeding great crested grebe, water rail, ducks and coot, fresh water fish and insects. Feeding osprey and sand martin.
Protected areas : Sandsjobacka, Bay of Kungsbackafjorden (IBA code SE045), Bay of Torslanda Viken (SE044).
Organisations : Gothenburg Ornithological Society (member of SOF\BirdLife Sweden), Sand&Grus AB Jehander (part of HeidelbergCement Northern Europe), Municipality of Mölndal.
 

Why is this project needed?

Lake Sagsjön is an ecological link connecting nearby nature protected areas Sandsjobacka and is an important part of the “green corridor” from here to Lindome river valley. Two IBAs are located a few kilometers away – the Bay of Kungsbackafjorden and the Bay of Torslanda Viken.
 

Project objectives

• Restore the quality of the lake habitats for breeding birds: more open water, meadows and lake shores as suitable habitats for breeing and feeding birds.
• Reduce the nutrient content of the lake and improve the ecological status of its outflowing waters.
 
The principle activities of the project include
• Clearing vegetation biomass from the lake shores and create open water.
• Installation of nesting islands and nest boxes for ducks and grebes.
• Create a natural nutrient trap to reduce sediment flow, using waterfringe vegetation.
• Improve access trails to the lake for bird watching and enjoyment of nature.
• Provide conditions for angling in some parts of the lake and keep other parts calm.
 

Public benefits

• The project aims to increase breeding bird populations but also to improve the area as feeding habitat for visiting birds such as Sand Martins, Peregines and Osprey.
• The Municipality of Mölndal recognised the positive contribution of the project to the community and provides important support to the project. Additional funding has been provided by the regional authorities, while the Swedish Forest Agency helps with some of the works.
• The improved ecological status of the lake waters will have positive effect beyond the borders of the site. The lake waters flow into the rivers Sagsjöbäcken and Kungsbacka to the Bay of Kungsbackafjorden, an IBA, and affect negatively the bay and the birdlife there.