Marine and estuarine water quality represents significant environmental issues within countries across the ASEAN region. Recognising the commonalities of the underpinning problems and solutions, and their management, member states have been making concerted effort to develop a harmonised framework of approach within ASEAN. The Hanoi Plan of Action (1999-2004) (HPA) called for the development of a framework to improve regional coordination for the integrated protection and management of coastal zones, development of a regional action plan for the protection of the marine environment from land-based and sea-based activities, and promote regional coordination to protect Marine Heritage Parks and Reserves.