Elood defence management in Jakarta is a critical govemmental activity, since Jakarta is a low-lying delta metropolis. Its protection against flooding is cmcial for the continuing of economic activities. Despite the urgent need for action, the implementation of flood defences like the Eastem Flood Canal has been a lengthy and strenuous process. The first plans to construct the Canal date back to the early 1970s and gained support early during the policy design process but the actual constmction only started in 2003 after institutional and political changes. Earlier evaluations point to a lack of financial resources as a cause of delayed implementation. We have explored the causes beyond budgetary reasons, and have used Kingdon's streams model to stmcture the policy design and implementation process, and to analyze the co-evolution of politics (the political stream), policies (the solutions stream) and social-ecological context (the problem stream). We have paid due attention to the effects of decentralization and the realized political reforms. Our research has revealed three causes for the implementation delay: (a) the disconnection of pohtical and institutional developments for problems and solutions before 1998; (b) institutional misalignment between municipal and ministerial authorities; and (c) an absence of critical actors in the policy process despite their control of financial and administrative resources. Implementation was only feasible when political and institutional developments coincided.