Sponsored by the Fluids Committee of the Engineering Mechanics Division of ASCE. This report provides environmental engineers with a comprehensive survey of recent developments in the application of fluid mechanics theories to treat environmental problems. Chapters cover principles of fluid mechanics, as well as contemporary applications to environmental problems involving river, lake, coastal, and groundwater areas. Topics include: turbulent diffusion; mixing of a turbulent jet in crossflow -- the advected line puff; multi-phase plumes in uniform, stratified, and flowing environments; turbulent transport processes across natural streams; three-dimensional hydrodynamic and salinity transport modeling in estuaries; fluid flows and reactive chemical transport in variably saturated subsurface media; heat and mass transport in porous media; parameter identification of environmental systems; finite element analysis of stratified lake hydrodynamics; water quality modeling in reservoirs; and linear systems approach to river water quality analysis In addition to providing valuable information to practitioners, this book also serves as a text for an advanced undergraduate or introductory graduate level course.