Final answer:
Agricultural activities affect surface water quality through runoff of nutrients, leading to eutrophication and dead zones. The use of pesticides and herbicides can also harm aquatic ecosystems. This is considered nonpoint source pollution, which poses a challenge for maintaining water quality.
Step-by-step explanation:
Agriculture activity most likely affects the surface water of an area through the runoff of fertilizers, pesticides, and soil. When it rains, these substances can be carried from fields into nearby streams, rivers, and lakes. This runoff can lead to eutrophication, which is the enrichment of water with nutrients, especially nitrogen and phosphorus from fertilizers. This can cause excessive growth of algae that deplete oxygen in the water, leading to dead zones where aquatic life cannot survive.
In addition to eutrophication, agriculture can contribute to water pollution through the use of pesticides and herbicides. These chemicals can end up in surface water bodies, damaging the ecosystem and potentially affecting human health through the water supply. Overuse of water for irrigation also affects water quality by reducing the natural cycle that maintains stable water availability, which is also known as water scarcity.
The pollution from agriculture activities is considered nonpoint source pollution because it comes from a broad area rather than a single, identifiable source. This type of pollution can be difficult to manage and control, making it a significant challenge for maintaining clean surface water near agricultural areas.