the effects of thermal pollution as they progress from the source. Rivers present a unique problem with thermal pollution. As water temperatures are elevated upstream, power plants downstream receive warmer waters. Evidence of this effect has been seen along the Mississippi River, as power plants are forced to use warmer waters as their coolants. This reduces the efficiency of the plants and forces the plants to use more water and produce more thermal pollution. See also Water cooling Water pollution References Aquatic ecology Environmental impact of the energy industry Water pollution Cooling technology