• Definition: The process where water bodies receive excess nutrients, particularly nitrogen and phosphorus, leading to increased algal growth.
• Example: Imagine a once clear lake near a farmland turning green due to an algal bloom, because of all the excess fertilizer from the farm entering the lake.
• Impact: The increased algae and plankton block light for underwater plants, which can eventually lead to oxygen starvation (anoxia) and the formation of "dead zones" in coastal areas near river mouths.

• Nitrogen compounds in water are problematic due to three reasons: they promote excessive algal growth, represent economic loss for farmers as lost fertilizer, and may affect human health (high nitrate levels in drinking water can cause methemoglobinemia or "blue baby syndrome").

Real-world example: Excess nitrogen in the water supply of Flint, Michigan, could have contributed to its water crisis in 2014-2015.

• Alter human activities producing pollution: For instance, using different types of fertilizers and detergents.
• Regulate and reduce pollutants at emission point: Sewage treatment plants can remove nitrates and phosphates from waste.

Restore water quality: This can be achieved by pumping mud from eutrophic lakes.

• For better understanding, picture a sewage treatment plant working like a big filter, cleaning up the water before it gets to your tap.

Several measures can help reduce nitrate loss. These include avoiding nitrogen fertilizers use during wet seasons, preferring autumn-sown crops, avoiding application of nitrogen near bodies of water or before heavy rain, using less nitrogen fertilizer after a dry year, avoiding ploughing up grass, and using barley straw bales which help prevent green algae growth.