Experiences with DSS in ecologically based water management in the province of Friesland, The Netherlands

General rules and measures from 1970 onwards have resulted in a distinct improvement of surface water quality (mainly related to oxygen conditions), after a long period of severe water pollution in The Netherlands. However, because of intensification of uses of our environment, with often contradicting interests, severe environmental problems became more visible, such as eutrophication, acidification, desiccation, fragmentation, and recently also effects of climate change. Restoration and rehabilitation measures started around 1990 in the province of Friesland, related to functions of water systems. A limited number of projects in nature reserves have been realised, triggered by governmental subsidies and from the principle, first come, first served. However, nowadays a more well-considered setting of priorities is needed. In this paper, two examples will be presented of methods used by setting priorities (in time) between areas, and three examples by making choices between measures within a limited area. One of these pilots is a cost-effectiveness study, showing an approach needed according to the EU Water Framework Directive. Some specifically developed, decision support systems (DSS) are presented, while the cost-effectiveness system uses (inter)national developed frames. It is concluded that there is neither a clear policy in using DSS in regional water management, nor a set of standardised instruments for preparing weighted decisions for wetland restoration. Research and development of simple, easily applicable DSS for regional water management is urgently needed.