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Nitrogen in the Puget Sound Ecosystem

The Puget Sound ecosystem is experiencing many stresses, one of which is nitrogen pollution.

High nitrogen contributes to low dissolved oxygen

Too much nitrogen can decrease dissolved oxygen levels in Puget Sound. There are many areas in Puget Sound with very low levels of dissolved oxygen. Just like humans need oxygen to breathe, plants and animals also need oxygen dissolved in the water to breathe.

What is Nitrogen?

Nitrogen is a nutrient that is present in the natural environment that many marine plants and animals need to survive. People contribute nitrogen to the environment that is above the levels present naturally, because nitrogen is present in human wastewater and in fertilizers used on lawns and in agriculture. Some of the nitrogen from human activities eventually enters Puget Sound via rivers and outfalls.

See below for more information on what we are learning about nitrogen and its effects on dissolved oxygen in Puget Sound and the rest of the Salish Sea.

Sources and Pathways Where does nitrogen come from, and how does nitrogen enter Puget Sound?

Effects What effects can we see in Puget Sound as a result of nitrogen pollution?

Fate and Transport What happens to nitrogen once it enters Puget Sound?

Marine Trends Are the levels of nitrogen measured within Puget Sound changing over time?

Watershed Trends Are the levels of nitrogen entering Puget Sound changing over time?

Monitoring What kinds of nitrogen data and information are we collecting?

Other factors contribute to low oxygen

Nitrogen is one of many factors that influence dissolved oxygen levels in Puget Sound. Other factors include but are not limited to: circulation, the influence of the Pacific Ocean, temperature, salinity, etc.

Notice: The development of this webpage has been funded wholly or in part by a National Estuary Program grant.
This project has been funded wholly or in part of the US EPA under assistance agreement EPA Grant Agreement No. PC-00J20101. Catalog of Domestic Assistance Number 66.456 – National Estuary Program (Tasks 1 and 11) to Department of Ecology. The contents of this webpage do not necessarily reflect the views and policies of the EPA, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.