The Flemish coastal region has two major key challenges: coastal flood risk and risk of drought. As an answer to the first challenge, a new phase of land reclamation on sea is proposed, fitting into its historical path dependence. This, however, will aggravate the second challenge, and contradict the principles of integrated water resources management (IWRM). The two challenges take place on two different governance frontiers of land and water governance, but have a growing mutual influence. It is argued that the coastal spatial governance regarding these two challenges suffers from a lock-in.