The GEF Transboundary Waters Assessment Programme (TWAP) is a two year project, with the overall objective of producing the first truly global assessment of all transboundary waters within the five recognised categories, and at the same time formalise the network of partners to establish firm institutional basis on which to base future periodic global assessments of transboundary waters.

In the project UNEP will serve as the implementing agency and UNEP/DEWA will act as the primary executing agency coordinating the work of UNESCO‐IHP, ILEC, UNEP‐DHI and the IOC of UNESCO. These agencies will serve as the lead executing agencies for the assessment of: transboundary aquifers and SIDS groundwater; transboundary lakes and reservoirs; transboundary rivers; Large Marine Ecosystems and the Open Ocean respectively1. Each of these executing agencies will engage with a network of partners with responsibilities either of a thematic issue or geographic area together with an extensive network of data and information rich institutions and organisations.

Global environment objective of TWAP is to apply the agreed methodologies developed during the medium sized project to the conduct of a global assessment of the following water components:

• Transboundary Aquifers and SIDS Groundwater Systems
• Transboundary Lake Basins
• Transboundary River Basins
• Large Marine Ecosystem
• Open Ocean

The project aims to assist the GEF and other international organizations in improved priority setting for funding allocations by providing a baseline and priorities for intervention. It is anticipated that this baseline will serve to assist international funding agencies in tracking the impacts of their interventions in terms of changes in state of the aquatic environments under consideration.