Reducing nutrients in Puget Sound

Excessive levels of nutrients from human sources are changing Puget Sound's water quality, adversely affecting the nation's second largest marine estuary. Excess nutrients, such as nitrogen and carbon, can lead to low dissolved oxygen, which impacts the health of aquatic life.

The Puget Sound Nutrient Source Reduction Project is a collaborative effort with Puget Sound stakeholders to find solutions for reducing human sources of excess nutrients. The Puget Sound Nutrient Forum is a public advisory group created to discuss, learn, and provide input as we explore solutions.

What are excess nutrients?

Nutrients, such as nitrogen and organic carbon, are an important part of a healthy marine ecosystem, but too much nitrogen results in excessive algal growth and puts the health of the Puget Sound off balance. This algal growth occurs because nutrients act like fertilizer for algae and aquatic plants. When these algae and plants die, their decomposition uses up oxygen that marine animals needs to survive.

Why are they a problem?

Too much nitrogen and carbon in Puget Sound can lead to low dissolved oxygen, especially in shallower areas and bays. Low dissolved oxygen causes stress on aquatic species. In addition to low levels of oxygen, other effects of excess nutrients include:

  • Acidification, which can prevent shellfish and other marine organisms from forming shells
  • Shifts in the number and types or organisms that live on the seafloor, resulting in changes in the food chain
  • Increases in nuisance macro-algae, which can impair the health of eelgrass and shellfish beds
  • Increases in harmful algal blooms and other nuisance species, such as jellyfish
  • Changes in food web dynamics

Where do they come from?

Natural processes and human sources contribute nutrients to Puget Sound. Nitrogen and other nutrients are also contributed to the Sound through ocean upwelling, which is when cold nutrient-rich water (which is also low in dissolved oxygen) moves from deep waters to surface waters. Nitrogen is also deposited by air into marine waters. 

Human sources of nutrients can lead to the excess or imbalance of nutrients in Puget Sound. Sources of excess nutrients include:
  • Wastewater, or "sewage", treatment plant discharges
  • Using too much fertilize, which enters waterways when it rains
  • Poor land management, especially with livestock
  • On-site septic systems

What is Ecology doing about it?

We are working collaboratively with Puget Sound stakeholders through the Puget Sound Nutrient Source Reduction Project and Puget Sound Nutrient Forum to find solutions for reducing excess nutrients.