The main sources of nutrient impairments are over-fertilized agricultural lands, as well as urban lawns and gardens. Other sources include livestock, pet waste, municipal wastewater systems. Farmers apply nutrients in the form of chemical fertilizers, manure, and sludge. When fertilizers exceed plant needs, are left out in the open, or are applied just before it rains, nutrients can wash into our waterways over land or seep into groundwater.
Many backyard fertilizers for gardens or lawns contain nutrients. Just like in a rural setting, excess fertilizer that is not taken up by plants can seep into groundwater sources or be carried by stormwater over land to streams and rivers. Most dishwashing detergents are another source of nutrients that can be tracked back to the home. Finally, high concentrations of nutrients are also found in human and pet waste, which all too often contaminate our waters via leaking sewer lines or neglected pet waste.
These increased nutrient concentrations cause nuisance or toxic algae blooms in waterbodies. These blooms can ruin swimming and boating opportunities, create foul taste and odor in drinking water, and kill fish and aquatic life by removing oxygen from the water. High concentrations of nutrients must be filtered from our drinking water, since they can cause methemoglobinemia, a potentially fatal disease in infants, also known as blue baby syndrome.