The mill is located on the left bank of the New Motława.
The mill was powered by water directed here from the Stone Lock.
The mill was constructed in case of a siege. During a siege, the enemy would cut off water supplied to the mills of Gdańsk by the Radunia canal to stop them. In such a case, the auxiliary mill would be still working because it used to be powered by water directed from the Stone Lock.
On the wall next to the lock gates, there is a stone slate on which the water levels were marked during the great flood of 1829. Water began to rise at night on 9th/10th April 1829. During the great flood about ¾ area of Gdańsk was flooded.
At present, the auxiliary mill of the 17th century is not used and it has been waiting for its revitalisation.