Thermal pollution is the harmful release of heat from power plants and industries into water bodies, degrading water quality and changing temperature. It has both anthropogenic sources like nuclear power plants, coal plants, and industrial effluents, and natural sources like geothermal vents and hot springs. The impacts of thermal pollution include reduced dissolved oxygen, increased toxicity, disturbances to biological activities and reproduction, and changes to metabolic rates and mortality rates of marine life. Control measures include building plants away from rivers, using cooling ponds, dispersing heated water, and establishing spray or cooling towers.