Thermal pollution, sometimes called "thermal enrichment", is the degradation of water quality by any process that changes ambient water temperature. Thermal pollution is the rise or drop in the temperature of a natural body of water caused by human influence. Thermal pollution, unlike chemical pollution, results in a change in the physical properties of water. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Urban runoff—stormwater discharged to surface waters from rooftops, roads, and parking lots—and reservoirs can also be a source of thermal pollution. Thermal pollution can also be caused by the release of very cold water from the base of reservoirs into warmer rivers.
Lake Stechlin, Germany, received coolant discharge from the nuclear power plant Rheinsberg starting in the 1960s. The plant was operational for 24 years, closing in June 1990.
Cooling tower at Gustav Knepper Power Station, Dortmund, Germany
A bioretention cell for treating urban runoff in California
Potrero Generating Station discharged heated water into San Francisco Bay. The plant was closed in 2011.
Water pollution is the contamination of water bodies, usually as a result of human activities, that has a negative impact on their uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources: sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution is either surface water pollution or groundwater pollution. This form of pollution can lead to many problems, such as the degradation of aquatic ecosystems or spreading water-borne diseases when people use polluted water for drinking or irrigation. Another problem is that water pollution reduces the ecosystem services that the water resource would otherwise provide.
Poster to teach people in South Asia about human activities leading to the pollution of water sources
Bauxite residue is an industrial waste that is dangerously alkaline and can lead to water pollution if not managed appropriately (photo from Stade, Germany).
Muddy river polluted by sediment
Solid waste and plastics in the Lachine Canal, Canada