Nutrient pollution

Nutrient pollution is caused by excess nitrogen and phosphorus in the air and water. Nitrogen and phosphorus are nutrients that are natural parts of aquatic ecosystems. Nitrogen is also the most abundant element in the air we breathe. Nitrogen and phosphorus support the growth of algae and aquatic plants, which provide food and habitat for fish, shellfish and smaller organisms that live in water. But when too much nitrogen and phosphorus enter the environment - usually from a wide range of human activities - the air and water can become polluted. Nutrient pollution has impacted many streams, rivers, lakes, bays and coastal waters for the past several decades, resulting in serious environmental and human health issues, and impacting the economy.

-- Source: U.S. Environmental Protection Agency

Puget Sound. Photo: S.N. Johnson-Roehr (CC BY-NC 2.0) https://www.flickr.com/photos/snjr22/4095840433

OVERVIEW

Water and nutrient circulation in Puget Sound

Complex physical processes such as hydrology, nutrient cycling, and sediment transport are linked to water circulation patterns in Puget Sound. 

RELATED ARTICLES

Report cover
1/20/2023

Eyes Over Puget Sound: A Decade in Review

The Washington State Department of Ecology has reached one hundred Eyes Over Puget Sound reports. Since 2011, Ecology has provided aerial observations and documented visible features at the surface of Puget Sound from a floatplane. This unique perspective from the air featured Puget Sound's natural beauty, its oceanographic complexity, and its ecological treasures. It also raised awareness of the challenges that the water body is facing today. Our image-rich documentation of known eutrophication indicators ranges from algal and Noctiluca blooms to macroalgae, jellyfish, and human stressors. It provides a visually captivating time-capsule of issues facing Puget Sound. The report is rich in educational and outreach material, inspired numerous news reports, and drew academic and public attention during the period of marine heat wave of the north Pacific, The Blob.

Eyes Over Puget Sound report cover
12/10/2022

Eyes Over Puget Sound: Surface Conditions Report - October 2022

The report comes after a third year of La Nina conditions. Weak upwelling off the coast and low river flows of major rivers meant less cold, nutrient-rich, upwelled water was being entrained into Puget Sound in late summer and fall. Water conditions in Puget Sound in October were generally expected while Willapa Bay and Grays Harbor were both unusually warm and salty. Smoky air restricted our flight to Southern Puget and Central Sound where we saw blooms in terminal bays as well as patches of jellyfish. Sediment in Commencement Bay and along shorelines in Totten Inlet was unusual for a dry fall. A healthy foodweb has at its base a balance of nutrients. Explore what we found over the period of two decades of monitoring.

View of Puget Sound with red-orange water near the shoreline and blue sky with clouds above land in the distant background.
12/5/2022

Understanding the causes of low oxygen in Puget Sound

How do excess nutrients trigger low oxygen conditions in Puget Sound and what do those conditions mean for the species that live here?

Microscopic view of diatoms in various shapes and sizes.
12/4/2022

Tiny plankton play a mighty role in the health of Puget Sound

Diverse communities of microscopic organisms called phytoplankton make up the base of the aquatic food web. In that role, they are an essential to the tiny animals that eat them, but phytoplankton are not dependent on others. Thanks to chlorophyl, these tiny organisms can generate their own energy from nutrients and sunlight. Despite their essential role to a great diversity of sea life in Puget Sound, phytoplankton can also contribute to low-oxygen conditions, and some can be harmful in other ways.

View of turbulent ocean water with rain clouds on the horizon and land to the north and south
11/21/2022

What drives Puget Sound's 'underwater Amazon'?

In a new series we are calling Ask a Scientist we interview local researchers to get their thoughts on some of the important but lesser-known scientific facts about the Puget Sound ecosystem. Today, we speak with University of Washington oceanographer Parker MacCready about Puget Sound’s “underwater Amazon” and why it has profound implications for Puget Sound science and policy. It all begins, he says, with the mixing of fresh and salt water and something called the estuarine exchange flow.

Maps generated from the Salish Sea Model showing surface layer transport in the Northwest Straits (left) and sea surface salinity (right). Images: Pacific Northwest National Laboratory
5/18/2021

The Salish Sea Model

The Salish Sea Model is a computer model used to predict spatial and temporal patterns related to water circulation in the Salish Sea. It was developed at the United States Department of Energy's Pacific Northwest National Laboratory with funding from the Environmental Protection Agency. It is housed at the University of Washington Center for Urban Waters which is affiliated with the Encyclopedia of Puget Sound.  

Locations of shellfish beds in the Salish Sea (left) compared to regions predicted by the Salish Sea Model to have high microplastic accumulation (right). Maps: PNNL
3/30/2020

Ecosystem models expand our understanding of the Salish Sea

Scientists are using computer models to address complex issues in the Salish Sea like the rise of harmful algal blooms and the movement of toxic PCBs. LiveOcean, Atlantis and the Salish Sea Model are three systems that are changing the game for ecologists and other researchers.

Predicted annual average Δ in surface temperature and salinity over (a) the entire Salish Sea domain, as well as (b) in the nearshore intertidal regions of the Snohomish River estuary (see Khangaonkar et al. 2019 for details).  Image courtesy of Journal of Geophysical Research: Oceans.
7/15/2019

Salish Sea Model looks at climate impacts on the nearshore

A 2019 paper in the Journal of Geophysical Research: Oceans outlines how the Salish Sea Model describes the impacts of climate change, sea level rise and nutrient loads on the region's nearshore environment.

Water drop image courtesy of Bureau of Ocean Energy and Management
12/4/2018

Ten things to understand about the Clean Water Act

The federal Clean Water Act of 1972 was designed as a logical step-by-step approach to clean up the nation's waterways. Most people acknowledge that the law has been effective in reducing pollution, but industrial and environment groups tend to be on opposite sides when discussing whether regulations and permits adequately protect water quality. These 10 elements of the Clean Water Act (CWA) focus on how the law applies to Puget Sound.

A milky, turquoise, phytoplankton bloom in Hood Canal visible from space. Natural color MODIS image from Landsat 8 acquired July 24, 2016. Photo: NASA Earth Observatory https://earthobservatory.nasa.gov/NaturalHazards/view.php?id=88454
3/6/2018

Does Puget Sound need a diet? Concerns grow over nutrients

As the region's population grows, scientists say we can expect to see increasing amounts of nitrogen and other elements flowing into Puget Sound. Known as “nutrients” these elements are naturally occurring and even necessary for life, but officials worry that nutrients from wastewater and other human sources are tipping the balance. That could mean big problems for fish and other marine life, gradually depleting the water of oxygen and altering the food web.

The Budd Inlet sewage treatment plant. Photo courtesy of LOTT Clean Water Alliance
3/6/2018

Sewage treatment plant in Olympia a leader in nitrogen removal

A regional sewage-treatment system in Thurston County has helped contain  low-oxygen problems in Budd Inlet as the population continues to grow. The system cleans up some of the effluent for replenishing groundwater supplies.

The rapid growth of a red-orange algae, Noctiluca scintillans, dramatically colors the waters of Puget Sound near Edmonds on May 16, 2013. Such algae blooms have been seen more frequently in recent years. Photo: Jeri Cusimano via WA Ecology (CC BY-NC 2.0) https://www.flickr.com/photos/ecologywa/8744775119
2/28/2018

Dead plankton leave clues to a food-web mystery

High amounts of elements such as nitrogen can cause blooms of phytoplankton that sometimes trigger perturbations throughout the food web. This occurs most often in the spring and summer after the long, dark, cloudy days of winter begin to fade.

A sharp boundary appears as sediment-laden freshwater is discharged from British Columbia's Fraser River into the Salish Sea. Fresh water, which is less dense than salt water, spreads in a shallow (approximately 1 m deep) plume at the sea surface. Photo: Ed McNichol, Ocean Networks Canada (CC BY-NC-SA 2.0) https://www.flickr.com/photos/oceannetworkscanada/8711686267
2/28/2018

Puget Sound circulation triggers low-oxygen conditions at different times and in different places

The amount of oxygen in the Salish Sea is dependent on water circulation which distributes chemical elements such as nitrogen through the system.

Image describing low oxygen "dead zones"; image courtesy of NOAA
2/26/2018

How the state assesses low oxygen in Puget Sound

Under the federal Clean Water Act, states are required to assess the quality of their surface waters and compile a list of polluted water bodies. The law mandates cleanup plans to address pollution and other water-quality problems. This article describes how this process works in Washington state for dissolved oxygen. 

Algal bloom. Photo: Eutrophication&Hypoxia (CC BY 2.0) https://www.flickr.com/photos/48722974@N07/5120831456
2/26/2016

Harmful algal blooms in Puget Sound

An algal bloom is a rapid increase or accumulation in the population of algae in a water system. While most are innocuous, there are a small number of algae species that produce harmful toxins to humans and animals.

Dead salmon. Photo: Boris Mann (CC BY-NC 2.0) https://www.flickr.com/photos/boris/3037705761
2/23/2016

Transfer of nutrients in the ecosystem

Decaying organic matter plays an important role in marine ecosystems. 

8/7/2015

A study of the nutrients in the main basin of Puget Sound

This study compared recent and historical data to determine the presence of any significant changes in nutrient and oxygen concentrations subsequent to METRO discharge, examined seasonal cycles in water properties, and examined the flux of nutrients within the study area.

6/7/2015

Dissolved oxygen and hypoxia in Puget Sound

Hypoxia, defined as dissolved oxygen (DO) concentrations less than 2 mg / L, has become widespread throughout estuaries and semi-enclosed seas throughout the world (Diaz 2001). 

Map of the Hood Canal Action Area; courtesy Puget Sound Partnership
9/19/2012

Review finds minimal evidence for human impacts on Hood Canal hypoxia

An independent review conducted by the Puget Sound Institute (PSI) is featured in findings by the Environmental Protection Agency and the Washington State Department of Ecology that there is currently “no compelling evidence” that humans are the cause for recent trends in declines in dissolved oxygen in Hood Canal.