Final answer:
People influence water quality through agricultural runoff and the disposal of industrial and domestic waste, which lead to eutrophication and the introduction of toxic substances into water bodies, affecting aquatic life and human health.
Step-by-step explanation:
Water quality can be affected by people in various ways. Two significant ways are through the introduction of agricultural runoff and the disposal of industrial and domestic waste. Runoff from farms, containing pesticides and fertilizers, leads to nutrient-rich water that promotes excessive algae growth, a phenomenon known as eutrophication. This disrupts the aquatic ecosystem and can create 'dead zones' where aquatic life cannot survive. Domestic and industrial waste, often discharged into water bodies either untreated or partially treated, can contain harmful chemicals, heavy metals, and other pollutants that contribute to poor water quality. These substances can have toxic effects on aquatic life and ultimately on human health when they enter the food chain. Furthermore, pollutants can degrade recreational water sources and drinking water supplies, making them unsafe for human use.
Addressing the issue of water pollution requires strict regulations on waste disposal and the implementation of sustainable agricultural practices to reduce the impact on water bodies. Awareness and education about the consequences of water pollution are also vital in promoting conservation and clean-up efforts, to maintain the health of both ecosystems and human populations.