These are likely to be required through three RBMP cycles until 2027, in order to reach good status for surface water and groundwater. The Wiedau River, shared between Denmark and Germany and discharging into the Waddcn Sea, has been highly controlled by weirs and gates to protect it from tides and surges. During the last decade, a number of projects have been completed to make the weirs passable for migrating fish, and to return straightened and modified stretches of the river to its original meandering course. This requires transboundary agreements on the measures to be taken, political commitment to their enforcement, and sustained cooperation to monitor their effectiveness.