Eutrophication is a natural process in aquatic ecosystems that have a slow pace of water renewal: lakes, rivers, ponds and coastal bays. 

Excessive input of nutrients (nitrogen, phosphorus, trace elements, etc) leads to a proliferation of plant life, which then smothers the aquatic habitat.

Liquid effluents produced by domestic, industrial and agricultural activity will cause or accelerate eutrophication when they are heavily laden with nutrients:

• phosphorus, present in phosphates,
• nitrogen, present in ammonium and nitrates.