What are the effects of agricultural runoff on water quality?

Agricultural runoff negatively impacts water quality by introducing pollutants like pesticides, fertilisers, and animal waste into water bodies.

Agricultural runoff is a significant source of water pollution. When it rains, water washes over agricultural land, picking up fertilisers, pesticides, and animal waste. This mixture then flows into rivers, lakes, and groundwater, introducing high levels of nutrients and harmful chemicals.

The excessive nutrients, particularly nitrogen and phosphorus from fertilisers, can cause a rapid growth of algae in water bodies, a phenomenon known as eutrophication. These algal blooms block sunlight, preventing other aquatic plants from photosynthesising. When the algae die, they are decomposed by bacteria, which use up the oxygen in the water. This can lead to oxygen depletion, or hypoxia, which can kill fish and other aquatic organisms, leading to a decline in biodiversity.

Pesticides in the runoff can also be harmful. They can accumulate in the bodies of aquatic organisms, causing health problems and even death. Some pesticides can also be toxic to humans, posing a risk to communities that rely on these water sources for drinking or bathing.

Animal waste is another concern. It can introduce harmful bacteria and viruses into water bodies, posing a risk to both aquatic life and human health. In addition, the organic matter in the waste can also contribute to eutrophication.

In summary, agricultural runoff can have serious impacts on water quality. It can lead to eutrophication, harm aquatic life, and pose risks to human health. It's therefore crucial to manage agricultural practices to minimise these impacts.