It was at lunchtime that SOS Alarm received the alarm about the oil spill.
Staff from NCC, who are working on site to renovate the old locks, met the rescue service on site.
- This is hydraulic oil that has come out of the river.
During the renovation work, there was a barge there with hydraulic cylinders on and oil leaked from there.
But these are not large quantities - we are not talking about thousands of liters, says Göran Andtbacka, head and staff resource for the rescue service in the Gothenburg region.
May affect sensitive salmon fishing
In addition, hydraulic oil is easier to work with than diesel oil in this context.
- It's grateful.
It is easier to get hold of the hydraulic oil, which does not flow out as much.
It is important to get as much of the oil in as quickly as possible, not least so that the sensitive salmon fishing a bit south of the locks is not disturbed.
At 3 pm on Tuesday afternoon, the decontamination work was still in progress.