Water pollution is bad as it poses a risk to public health and damages ecosystems. As a result, wildlife populations die out and people are at higher risk of diseases. It arises because of agricultural and human activities.
When water becomes polluted, it carries diseases and bacteria that pose a public health risk. Sometimes, this is because of polluted urban run off from sewers and drainpipes, or from animal feces entering the water system as a result of agricultural practices. One of the biggest threats is fecal coliforms. Although their presence in water systems does not always pose a public health risk, they do indicate that pathogenic organisms are there. In addition to polluting water, they may be consumed by shellfish, which means they enter the food system, too.
As well as posing a threat to people, water pollution damages local ecosystems. Eutrophication arises as a result of nutrient imbalances promoting algae blooms, which deprives local wildlife of the oxygen they need to thrive. In addition, an increase in salt in freshwater sources prevents local plants from thriving, further damaging nearby wildlife. Although eutrophication occurs naturally, humans exacerbate the problem by increasing the causative substances that enter water systems. In some areas, like San Francisco Bay, fish species are endangered as a result of water pollution.