What causes eutrophication?

The main causes of eutrophication are an increase in the concentration of nutrients to an ecosystem. Increased nutrient enrichment can arise from both point and non-point sources:

• Point source pollution: Pollution that comes from contaminants that enter a waterway from a single identifiable source such as stationary locations or fixed facilities. Examples are discharges from a sewage treatment plant or industrial plants and fish farms.
• Non-point source pollution: Pollution from widespread including human activities with no specific point of discharge or entry into receiving watercourses. Examples are leaching out of nitrogen compounds from fertilized agricultural lands and losses from atmospheric deposition.