Few other cooling applications approach the large volumes of water required to condense low pressure steam at power stations. Many facilities, particularly electric power plants, use millions of gallons of water per day for cooling. Water cooling on this scale may alter natural water environments and create new environments. Thermal pollution of rivers, estuaries and coastal waters is a consideration when siting such plants. Water returned to aquatic environments at temperatures higher than the ambient receiving water modify aquatic habitat by increasing biochemical reaction rates and decreasing oxygen saturation capacity of the habitat. Temperature increases initially favor a population shift from species requiring the high-oxygen concentration of cold water to those enjoying advantages of increased metabolic rates in warm water.