A dam is typically used to convert tidal energy into electricity by forcing the water through turbines that activate a generator. Wave energy converters can be classified in terms of their location: fixed to the seabed, generally in shallow water; floating offshore in deep water; or tethered in intermediate depths. The extraction of kinetic energy from river and ocean currents or tides will reduce water velocities in the vicinity of the project. Hazardous materials associated with the operation and maintenance of hydrokinetic energy devices and associated support compounds would include the fuel for boats, vessels, and barges, and lubricants and hydraulic fluids contained in the wave or tidal energy devices. Vessels used for maintenance of hydrokinetic energy devices and components could contribute small amounts of fuel or oil to the ocean or river through bilge discharges or leaks. The presence of a wave or tidal turbine energy farm could cause some marine mammals to avoid the area.