Guideline for the Development of Effective Water Sharing Agreements provides the basis for developing a complete, comprehensive, and well-integrated agreement for allocating and managing shared water resources. Effective water allocation and management requires planning and regulation by water basins, which often cross national, state, or tribal boundaries. The need to share these water resources inevitably breeds conflict, which can be best alleviated by an agreement among the different political organizations having jurisdiction over water allocation and water management. This Standard outlines a process to ensure that all pertinent factors are considered in the development of an agreement, so that the physical realities of the shared resources as well as the different political systems, cultures, and water use customs are accommodated. The Standard assesses the factors influenced by shared water use: correlating the geographical and political issues, inventorying the sources and uses of the water resource, analyzing the ecological impact of the transboundary use, and examining its effect on economic growth and quality of life of the various constituents. The Standard then presents alternatives for allocation of surface, underground, and atmospheric water among the parties, with special emphasis on extreme events (droughts and floods). Using a common format for drafting uniform state laws, Standard ASCE/EWRI 60-12 includes three model water sharing agreements: coordination and cooperation, limited purpose water sharing, and comprehensive water sharing. Each element of an agreement is provided in statutory language, followed by a commentary section that describes the purpose and scope of the provisions. Cross-references to other provisions are included, along with a list of interstate and international water sharing agreements that contain similar provisions. The provisions of this Standard are written in permissive language and offer users a series of options or instructions, but the Standard does not prescribe a specific course of action. Significant judgment is left to the drafters of the agreement.