Statement (3) is incorrect. 'Eutrophication is an enrichment of water by nutrient salts that cause structural changes to the ecosystem such as – increased production of algae and aquatic plants, depletion of fish species, general deterioration of water quality and other effects that reduce and preclude use'. Eutrophication is a serious environmental problem since it results in the deterioration of water quality. Statements (1) and (2) are correct.