Preliminary survey in connection with mussel farming
In connection with the plan to offer Kaldbaksfjørður for mussel farming, the Food and Veterinary Authority asked Firum to describe the currents and water exchange in the fjord.
The results showed that the seawater flowing through the fjord was very uniform. There was also little difference between the water inside the mouth of the fjord and outside it.
The water exchange in Kaldbaksfjørður is primarily driven by a two‑layer estuarine circulation, where freshwater flows outward in the upper layer and seawater from outside is drawn inward in the lower layer. During the summer, there is less precipitation, and the water exchange was reduced. At that time, a three‑layer stratification was observed in the fjord with an isolated bottom layer.
Microbial studies indicated that the main source of pollution was runoff from land rather than sewage pipes. This was most likely pollution from livestock farming and manuring on land, which was washed into the fjord during rainfall.
The greatest risk of long‑term pollution occurs in the summer, if there is first heavy freshwater runoff and then a dry period.
