The conservation of wetland acreage in the United States, wherever and whenever practicable, is a national policy objective. This had led to an increased awareness of the need for making wise land use decisions, especially when modification of the natural environment is anticipated. Federal agencies are required to avoid construction in wetlands whenever there is a practicable alternative. It is important, therefore, to understand the functions, values, and ecological interrelationships of wetland systems so that an appropriate mitigation plan can be developed. General wetland types and their basic functions and values are identified, and highway construction impacts, impact assessment, and mitigation and enhancement procedures are discussed. Special emphasis is given to the reconstruction of wetlands affected by highway construction.(Author)