Circulation

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

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

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 Puget Sound Institute. 

An image from the LiveOcean model showing Salish Sea circulation patterns.
3/10/2021

Estuarine circulation, mixing, and residence times in the Salish Sea

A 2021 article in the journal JGR Oceans describes circulation and mixing in the Salish Sea. The findings are based on simulations produced by the LiveOcean computer model.

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.

A screenshot of tidal fluctuations in Puget Sound. Image courtesy of University of Washington Coastal Modeling Group
11/15/2018

Puget Sound tides

This article provides a general overview of tidal patterns in Puget Sound. 

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.

Map image of Puget Sound and surroundings. Courtesy of USGS.
2/6/2017

Puget Sound's physical environment

The Puget Sound ecosystem is shaped by its physical environment. This article looks at Puget Sound's geologic history as well as dynamic factors such as the flow of its rivers and currents.

Blue dye is used to illustrate currents in the Puget Sound Model at the UW School of Oceanography. Video screenshot: copyright Richard Strickland and Encyclopedia of Puget Sound
4/29/2014

Videos: The Puget Sound Model

The Puget Sound Model was designed and built by the University of Washington School of Oceanography in the early 1950s to simulate the tides and currents of Puget Sound. A series of videos produced by the Encyclopedia of Puget Sound describes its construction and operation.

The Puget Sound Model at the UW School of Oceanography
3/19/2014

The Puget Sound Model summary

The Puget Sound Model was designed and built in the early 1950s at the University of Washington School of Oceanography as a research and teaching tool for understanding Puget Sound circulation patterns. The following text was written by Puget Sound Model co-creator John H. Lincoln (1915-2001) and is provided courtesy of the University of Washington School of Oceanography. 

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7/9/2021

Eyes Over Puget Sound: Surface Conditions Report - June 17, 2021

Despite a La Niña, precipitation and rain have been lower since March, leaving only snow-fed rivers running high. Due to lower rainfall and warm summer temperatures the salinity of Puget Sound is now generally higher. Strong blooms and large patches of organic material and macro-algae are building up in many places and wash onto beaches. During very hot summer days, tidal mudflats and beaches can get really warm. Beach wrack can harbor increased bacteria numbers now. See SCUBA cleaning up at Redondo beach.

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7/9/2021

Eyes Over Puget Sound: Surface Conditions Report - April 1, 2021

After a wet winter/spring transition it has been noticeably drier, warmer and sunnier. River flows are near normal levels and in Puget Sound and coastal bays salinity is increasing above normal. The spring bloom is developing but not very pronounced, yet, Noctiluca is already visible in southern Hood Canal. Suspended sediment near rivers and creeks, failing bluffs, and shellfish activities are frequent. Capturing herring spawning from the plane is informative; pilots share their observations.

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3/22/2021

Eyes Over Puget Sound: Surface Conditions Report - March 11, 2021

We are in a weakening La Niña, coastal downwelling has lessened and we are getting out of a cold and wet stretch, hurray. In March, rivers have almost returned to normal and carry clear water. It’s a good time to go diving if you don’t mind cold water. The productive season has only started in some places and patches of jellyfish are visible. Have a look at this edition and marvel about the secrets of the dead, or mysterious sediment clouds and the oil sheen spotted near Lummi Bay.

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2/17/2021

Eyes Over Puget Sound: Surface Conditions Report - February 3, 2021

Rivers are flowing higher than normal since 2020. Winter weather has been warmer and wetter. In marine waters, temperatures have become too cool for Northern Pacific anchovies to tolerate in North Sound. From patches of jellyfish and snow geese, to sediment and early blooms, there is more happening in the winter than you might expect. Puget Sound has many species worth showcasing such as the heart crab – a shy critter that wears its heart on its shell.

Tidal marsh at the Nisqually National Wildlife Refuge in Puget Sound. Photo courtesy of USFWS.
12/14/2020

Types of estuaries in Puget Sound

An estuary is a place where saltwater from the ocean mixes with freshwater from rivers and streams. Technically, this defines all of Puget Sound, but scientists have identified several types of "sub-estuaries" within the water body. These include pocket estuaries (or embayments), tidally-influenced rivers and wetlands and other areas near the shoreline connected with freshwater sources. This summary provides descriptions of these estuaries from the Washington State Department of Natural Resources, the Puget Sound Nearshore Partnership and other sources.  

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10/9/2020

Eyes Over Puget Sound: Surface Conditions Report - September 28, 2020

A warm and dry summer ended with a smoky September due to massive wildfires that were followed by strong rain. As a consequence, muddy river plumes in Puget Sound are very visible, especially near the Nooksack River. During summer, many wonderful citizen contributions documented the large formation of organic material in Central Sound and helped us cover the gap in EOPS flight from April-September. By September when we started flying again, a few bays still had red-brown blooms. Nevertheless, schools of fish are abundant, and jellyfish are sparse, which is good news. Meet our new ocean acidification experts.

Map showing a marine heat wave known as "the blob" which spread across the northeastern Pacific Ocean from 2014 to 2016. Image: Joshua Stevens/NASA Earth Observatory, Data: Coral Reef Watch
7/24/2020

'The blob' revisited: Marine heat waves and the Salish Sea

Years after the appearance of the devastating marine heat wave known as "the blob," scientists are still working to understand how it has affected the Salish Sea. In some ways, they say, it is like the blob never left.

11/13/2019

2018 Puget Sound Marine Waters Overview

A new report from the Puget Sound Ecosystem Monitoring Program says climate change altered the base of Puget Sound's food web in 2018, diminishing microscopic phytoplankton necessary for marine life. Scientists also observed lower abundances of fish, seabirds, and marine mammals.

11/15/2018

LiveOcean: Pacific Northwest ocean and estuary forecasts

LiveOcean is a computer model simulating ocean water properties in Puget Sound and the Pacific Northwest. It is produced by the University of Washington Ocean Modeling Group and makes three-day forecasts of currents, temperature, salinity and many biogeochemical fields including harmful algal blooms.

A large river delta in Puget Sound. Photo courtesy of Puget Sound Nearshore Ecosystem Restoration Project
10/5/2018

The mosaic of deltas and other estuarine ecosystems in Puget Sound

The diversity and complexity of estuarine ecosystems is vital to the overall health of Puget Sound. This summary fact sheet focuses on the current state of estuarine ecosystems in Puget Sound—large river deltas, embayments, their interconnecting beaches, and rocky coasts—and the historical changes that have occurred since the development of the Puget Sound coastline. Additional emphasis is placed on the historical losses of tidal wetlands within these estuaries. 

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.

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. 

Puget Sound Marine Waters 2015 report cover
9/27/2016

2015 Puget Sound Marine Waters Overview

The Puget Sound Ecosystem Monitoring Program released its fifth annual Marine Waters Overview this week. The report provides an assessment of marine conditions for the year 2015 and includes updates on water quality as well as status reports for select plankton, seabirds, fish and marine mammals.

Puget Sound portion of a 1798 chart showing "part of the coast of N.W. America : with the tracks of His Majesty's sloop Discovery and armed tender Chatham / commanded by George Vancouver, Esqr. and prepared under his immediate inspection by Lieut. Joseph Baker." Credit: Library of Congress, Geography and Map Division.
9/18/2015

Puget Sound: a uniquely diverse and productive estuary

Puget Sound is the second largest estuary in the United States. Today, we understand that estuaries—where freshwater and saltwater merge—are among the most productive places for life to exist.

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). 

Tidal turbines like this one developed by OpenHydro, Ltd. will be installed in Puget Sound in mid 2015 as part of a demonstration project. Sustainable, large-scale development of tidal energy will require studying and learning from these early-stage projects. Image source: OpenHydro, Ltd./DCNS
3/25/2014

Tidal energy in Puget Sound

Scientists have identified the strong underwater currents of Puget Sound's Admiralty Inlet as a potential source of electricity for nearby utilities. The following article describes some of the basic principles and mechanisms of tidal energy.  

The float plane prepares to take off. Photo by Jeff Rice for the Encyclopedia of Puget Sound.
6/19/2013

About the Eyes Over Puget Sound monitoring program

Once a month, Washington State Department of Ecology marine scientists take to the air to obtain high-resolution aerial photo observations and gather water data at the agency's monitoring stations and via state ferry transects. This provides a visual picture of the health of Puget Sound, which they call Eyes Over Puget Sound or EOPS.

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.

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
3/30/2010

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.