The marine and hydrokinetic (MHK) Environmental Impacts Knowledge Management System (KMS) (dubbed "Tethys" after the mythical Greek titaness of the seas) supports the U.S. Department of Energy’s Wind and Water Power Program.

As industry, academia, and government seek to develop new renewable energy sources from moving water and offshore wind, potential environmental effects must be evaluated and measured to ensure that aquatic and avian animals, habitats and ecosystem functions are not adversely affected, nor that important coastal and ocean uses are displaced.

Tethys seeks to gather, organize and make available information on potential environmental effects of marine and hydrokinetic and offshore wind energy development. Datasets, supporting documents, and other media are housed within Tethys in support of the following programs:

Marine and Hydrokinetic (MHK) Energy Development: MHK development is moving forward in U.S. and international waters, with projects that include the following devices: Tidal turbines placed in coastal and estuarine areas; Riverine turbines in fast-moving rivers; Wave energy converters in open coastal areas with significant waves; Current turbines in the Gulf Stream; and Ocean Thermal Energy Converters in deep tropical waters.

Offshore Wind Development: The first offshore wind farms are under development in U.S. waters, while significant generation of offshore wind already contributes to electricity needs in Europe and Asia. Nearshore offshore wind turbines are drilled into the seabed on monopoles; deeper waters require jacketed or floating wind turbines.

Annex IV Collaborative Information Sharing: Under the auspices of the Ocean Energy Systems Implementing Agreement (OES-IA), Annex IV is a collaborative project to gather and share information on the environmental effects of ocean energy development (tidal, wave, and ocean current). The Annex IV effort will be used to improve the worldwide understanding of potential impacts of MHK development, develop effective monitoring programs, and collaboratively develop effective mitigation strategies. Annex IV information is currently being gathered from MHK project developers, utilities, and researchers from the OES-IA member nations and will be made available beginning in early 2013.