Nutrient pollution 

Excessive Nutrients Harm the Bay

Nitrogen and phosphorus are nutrients that enter Narragansett Bay from wastewater treatment plants, septic systems, cesspools, and stormwater pollution. While nutrients are an essential part of the Narragansett Bay ecosystem, large amounts of nutrients can be "too much of a good thing."   

Here's why

Excessive nutrients cause algae to grow rapidly. The algae decomposes and uses a lot of oxygen in the process. This deprives fish and shellfish of the oxygen they need to live. These "low oxygen" or "hypoxic" events can cause fish kills. 

Nutrient pollution causes the clouding of Bay waters, robbing eelgrass of the sunlight it needs to grow. It also can create large mats of sea lettuce and phytoplanktin, which can cause diseases in fish, shellfish, and people.  

Large mats of seaweed can grow to several feet deep. When they wash up on shore, the stench of the decaying seaweed makes for unpleasant beaches. Waters under the thick algae mats are often very low in oxygen. 

Under certain conditions - such as when rains, winds, heat, tides, algae, sea lettuce, and nutrients combine - oxygen is literally taken out of the water. We may not have much control over the weather elements, but we can reduce nitrogen by upgrading wastewater treatment plants and septic systems, replacing cesspools with septic systems, and controlling stormwater pollution. Investments by homeowners, businesses, cities and towns, and state government are essential to managing the nutrients that enter Narragansett Bay.