Nutrients are pollutants of concern because they can lead to eutrophication.

Eutrophican is a term used to describe an excess of nutrients that can stimulate an explosive growth of algae or an algal bloom in surface water. This increase in algae will cause the water to become low in dissolved oxygen. Low dissolved oxygen and toxic algae blooms can lead to fish kills, toxic shellfish poisoning, and other public health issues. All of these affects combined can select for only certain species of fish that are low-oxygen tolerant species and decrease fish diversity.

Probable Causes

  • Sewage treatment plants
  • Septic tanks
  • Urban runoff
  • Agricultural runoff
  • Mississippi River diversions
  • Channelization of runoff directly into the estuary
  • Channel dredging and loss of wetlands resulting in reduced capacity of the estuary to filter out nutrients

Probable Impact

  • Algal blooms, floating masses of algae and noxious odors
  • Reduced recreational value of beaches and water bodies
  • Anoxic conditions resulting in fish kills
  • Changes in species composition and population
  • Decreases in wildlife populations with sport and commercial value
  • Reduced recreational and commercial value of wetlands and the estuaries