If Stettin was Polish, then "in view of the fact that the supply of water is found between the Oder and the Lausitzer Neisse, if the Oder's tributaries were controlled by someone else the river could be blocked."[32] Soviet forces had initially expelled Polish administrators who tried to seize control of Stettin in May and June, and the city was governed by a German communist-appointed mayor, under the surveillance of the Soviet occupiers, until 5 July 1945.[33]