Effluent
Effluent is an outflowing of water from a natural body of water, or from a man-made structure.
Effluent in the man-made sense is generally considered to be Pollution, such as the outflow from a Sewage treatment facility or the discharge from industrial works.
In the context of a Nuclear power plant or Nuclear processes such as creating Plutonium at the Hanford Site, effluent refers to the cooling water that is discharged from a Nuclear reactor that may or may not be radioactive. This water is generally not physically contaminated, but is usually warmer than the body of water it discharges into.