In the area of Kozjansko Regional Park, the beavers have built dams along Buča and Ribnik water courses, which are, as a consequence, flooding the surrounding fields. The beavers built a dam of 2 m hight on Buča brook and there are three smaller consecutive dams along Ribnik brook.
In both instances, the agricultural fields are stretching close to the edge of the watercourses. To reduce the damage due to the beaver activity, it will be necessary to plant and allow to grow a wider belt of vegetation (willows, alders etc.) along agricultural fields. According to the current legislation (Water Act, article 14 and 37), it is necessary to retain a 5 m wide and unmanaged vegetation belt outside of settlements along 2nd order watercourses. When dealing with 1st order watercourses, the unmanaged vegetation belt along the banks needs to measure between 15 and 40 m outside of settlements. It is necessary to protect or plant dense woody shrubs and trees to stabilise the banks and to prevent erosion, as well as to keep the water clean and to create habitats for various animal and plant species.
We can prevent the overflow of water relatively easy, with inserting a drainage pipe into the beaver dam, the so called beaver-deceiver. A similar procedure was already carried out at Žerjavinski brook, near castle Otočec, which we already covered in our previous posts. The pipe going through the beaver dam needs to be installed with a cage, preferably on both ends or at least upstream, so that the beavers cannot clog the pipe. Because of the pressure difference, the water is flowing from above the dam, to the level below the dam. The pipe needs to allow the depth of water to stay above the dam at least at 80 cm depth, as this is the lowest average water depth the beaver still tolerates.
Unfortunately, sometimes people take things into their own hands and remove beaver dams or even beaver lodges. This action is illegal as beavers are European protected species (Habitat Directive and Bern Convention) as well as protected by the national legislation (Decree on protected wild animal species, article 10). The action of dam removal is also not long-term successful solution as beavers start to repair the dams as soon as they get damaged or removed.
We will install three beaver-deceivers into the dams along Buča and Ribnik brooks at Kozjansko Regional Park during a spell of nice weather, in second half of March. The chosen pipes will measure 25 cm in diameter and will be 6 m long. To ensure the sufficient length, we will install two 6 m long pipes one after the other. With regulating the height and angle of the low end of the pipe, we will also regulate the water flow through the pipe and the water depth above the beaver dam.
Described intervention is the second of its kind in Slovenia and we hope, that it will help towards better understanding and cohabitation between beavers and men.
