Lake Sagsjön: restoration of a freshwater ecosystem near Gotenburg, Sweden

Little Grebe AA3 (Shay Connolly)

The restoration of the lake will be beneficial to species such as the Little Grebe © Shay Connolly

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 virtually suffocate the ecosystem.

As a result, the lake is increasingly overgrown with vegetation and while several decades ago the lake was known as a good breeding habitat for birds, most birds have disappeared today.

The objectives of this partnership project between Jehander (HeidelbergCement aggregate company in Sweden), Gothenburg Ornithological Society (member of SOF\BirdLife in Sweden) and the Municipality of Mölndal are the following:

  • Restore the quality of the lake habitats for breeding birds: more open water, meadows and lake shores suitable for feeding birds;
  • Reduce the nutrient load of the lake and improve the ecological status of its outflowing waters.
biomass  3

Biomass in Lake Sagsjön © Morgan Johansson

The principal 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.
biomass  2

Clearing the vegetation in Lake Sagsjön © Morgan Johansson

Here is a fresh update from Morgan Johansson who leads the project locally: “After a short vacation the work on lake Sagsjön was resumed. Last week three machines cut off and extracted large part of the emergent vegetation in the lake. A total of 90 machine hours were spent on this task.

The construction of the first and largest of the observation platforms is well underway.

Work to remove the shrubs and small trees is also underway and soon we will begin removing reeds along the shoreline with the help of an excavator.

Next step will be to restore the old jetties (for anglers) and place nest boxes and on the islands”.

platform 3

Construction of the wildlife observation platform © Morgan Johansson

The Municipality of Mölndal recognises 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 Important Bird Area, which will affect positively the bay and the birdlife that depends on it.

One thought on “Lake Sagsjön: restoration of a freshwater ecosystem near Gotenburg, Sweden

  1. Pingback: Restoration of Lake Sagsjön continues (in pictures) «

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