The Effects: Human and Animal Health

Excess nutrients and harmful algal blooms (HABs) create toxins and other chemical compounds in water that can be dangerous to people, pets and livestock that are exposed to them.

Direct Exposure to Toxic Algae

People who drink, accidentally swallow or swim in water affected by a HAB can experience serious health problems including:

• Rashes
• Stomach or liver illness
• Respiratory problems
• Neurological effects

Nitrates in Well Water

Nitrate, a compound found in fertilizer, can enter drinking water in agricultural areas served by wells. A 2010 report on nutrients in ground and surface water by the U.S. Geological Survey found that nitrates were too high in 64 percent of shallow monitoring wells in agricultural and urban areas.

Infants are more susceptible to the health effects posed by nitrates, which can be serious and sometimes fatal.

Byproducts of Drinking Water Treatment

When nutrient pollution leads to the formation of toxic algae blooms in rivers, lakes and reservoirs that serve as sources of drinking water, the toxins can enter drinking water treatment plants. Disinfectants used to treat pathogens in drinking water react with the algal toxins, creating harmful chemical byproducts called dioxins. These byproducts have been linked to serious health risks, including reproductive and developmental problems.