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Nutrient Pollution

Nutrients, nitrogen and phosphorus, are necessary for healthy rivers, lakes, and estuaries—feeding the plants and animals that inhabit them. However, just as we can get unhealthy and sick from too much food, waterways receiving too much nutrient matter can become unhealthy and contribute to harmful algae blooms (HABs). Often, the excess nutrients are entering from man-made sources and activities through stormwater, wastewater and industrial runoff.


Various industries such as farming, ranching and phosphate mining can result in nutrient pollution entering downstream waterways if their wastewater and runoff is not adequately captured and treated on-site.


The fertilizers that enhance agricultural production can sometimes wash into agricultural canals that often discharge to downstream flowing waterways or waterbodies. Ranching livestock creates animal waste rich in nutrients. Phosphate mining extracts natural phosphorus, a component often used in fertilizer production.


Water running off parking lots, lawns and other surfaces in residential and commercial areas often finds its way into nearby canals, rivers, and eventually into lakes and estuaries. This is called stormwater runoff and can carry all the pollutants generated from human activities in those areas. Some of those activities, such as uncollected pet waste and fertilizers contain nutrient pollution.

Nutrient Pollution Sources diagram. Nitrogen and phosphorus come from a variety of diffuse sources including waste discharges, atmospheric emissions, agricultural inputs, and development.


Human wastewater can also be a source of nutrient pollution. Municipal wastewater plants that are not treating to advanced wastewater treatment standards, do not have enough power back-up or storage to hold excess wastewater during storm events, or do not have alternate wastewater disposal locations can discharge nutrient-rich wastewater into downstream waters.

Additionally, septic tanks placed too low such that they are in the groundwater table or near surface waters, or that are not properly maintained and functional, can leak nutrient-rich wastewater into surface waters or groundwater that flows to surface waters.

Nature’s Kidneys

At the same time we are adding man-made nutrient pollution to our waterways, we are also losing wetlands, seagrasses and oysters — our natural water storage and treatment areas.

Wetlands act as nature’s kidneys in uptaking nutrients, removing more than they generate. However, just as our kidneys can become overloaded and stop functioning well, wetlands can be overloaded from human pollution.

Oysters also naturally filter water, up to 50 gallons each per day!  We lose oysters from poor water management, we lose their kidney-like cleansing ability.

Seagrasses and other underwater plants uptake and utilize nutrients for their growth, providing habitat and cleaner water.  However, nutrient pollution and excessive algae growth can block the light they need to survive.

This is why it is so important we take additional measures to protect the wetlands, seagrasses and oysters we have, as well as create and restore additional ones wherever possible.

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