Abstract: In Indonesia, the inter-regions cooperation between the adjacent regions of the cross-border government services, have to be formally performed if the services have cross-regions externalities; and the provision of the services will more efficient if managed together. Therefore, the cooperation utilization of the Springs of Senjoyo between the Regency of Semarang and the City of Salatiga, which has a cross-regions externalities, have to be performed in formal cooperation. However, as there is not any cooperation agreement between, the cooperation is only based on a tradition which is done for a long time ago. The purpose of the research discussed in this article is to examine how inter-regional collaboration strategies are used in the interaction of the parties involved in the management of water utilization of the Springs of Senjoyo, and what matters that influence it. The research used the grounded theory research method, in particular Straussian mainstream, as the method is suitable for the intends of the research. Based on the research findings, it can be concluded that the City Government of Salatiga uses functional assertive collaboration strategies in the region interaction, because utilizing resources from neighboring areas, to meet the water needs of the population in the region. Meanwhile, the Regency Government of Semarang uses a strategy of cooperative collaboration between functional areas, because the government gives permissions to neighboring areas to take advantage of the resources available in the region. The strategy is a proper solution to solve the problem that the interaction is not a formal cooperation agreement. Both the interaction regions for the interaction of long-standing and become a tradition.