Stormwater

Sandwiched between the Olympic and Cascade mountain ranges, Puget Sound's urban areas receive up to 40 inches of rain each year. Historically, most of this water soaked into the ground or was taken up by plants. In forested areas in the Pacific Northwest, evergreen trees transport about 40% of rainfall back to the atmosphere through their needles. The remaining water filters through other plants and the soil. The ecosystem is driven by this water cycle, but over the past 100 years, human development has drastically altered this natural pattern.

Urban areas were originally designed to move stormwater quickly and efficiently downstream through a series of drains, pipes, and sewers. Flood prevention was the main reason for getting stormwater out of the city fast, but over the years municipalities have come to realize that speedy water removal is actually detrimental to the health of Puget Sound.

Without the filtering effect of plants and soil, surface runoff increases and stream flows become "flashier"—surges in runoff are more frequent and more intense. This means greater flooding, and more polluted water flowing into Puget Sound.

 

Source: "Stormwater fixes could cost billions"; Salish Sea Currents.

Stormwater flowing into catch basin carries contaminants to our waterways. Photo: Ben McLeod (CC BY-NC-SA 2.0) https://www.flickr.com/photos/benmcleod/420158390

OVERVIEW

Stormwater facts

Runoff from rain and melting snow is one of the leading causes of pollution in Puget Sound. Here are selected facts related to stormwater, its prevalence, how it affects the Puget Sound ecosystem, and its environmental and economic impacts.

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A returning Coho Salmon at the Suquamish Tribe's Grovers Creek Hatchery. Photos: K. King/USFWS (CC BY-NC 2.0)
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Stacked tires. Photo: Kool Cats Photography. https://flic.kr/p/ChFgxf (CC BY-NC 2.0)
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Close up of a stonefly larva on river rocks.
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Combining bugs and chemistry in Soos Creek stormwater study

Many creeks and waterbodies in Puget Sound may look pristine, but most face serious threats from stormwater pollution. A new study at Soos Creek shows how mud-dwelling bugs, traditional chemistry and digital "heatmaps" can be used to track stormwater impacts and identify the most polluted areas. Scientists and planners hope that this may one day lower the price tag on costly stormwater fixes. 

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Benthic invertebrates range in size from those easily seen with the naked eye to those that cannot be spotted without the use of a microscope. Photo: Christopher Dunagan
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Healthy stream, healthy bugs

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Alaska Airlines 737 taking off from Sea-Tac Airport with Mt Rainier and Central Terminal in background. Photo: Port of Seattle by Don Wilson
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Airport offers a glimpse at tightening stormwater regulations

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Raindrops on a cafe window.  Photo: Jim Culp (CC BY-NC-ND 2.0) https://www.flickr.com/photos/jimculp/7140363701
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Stormwater fixes could cost billions

Pollution from stormwater has been called one of the greatest threats to Puget Sound. How much will it cost to hold back the rain? A new EPA-funded study says the price could reach billions per year, a figure that dwarfs current state and federal allocations.

Chemical symbols for QPPD and QPPD-6 overlain on image of black car driving on wet road
1/30/2024

Lawsuits fly, as regulators come to grips with a toxic tire chemical

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Car wheel and tire next to a pothole puddle.
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Scientists worldwide are immersed in studies of a deadly tire chemical

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Photographing the 'Creek of Hope'

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Cover of 2022 Salish Sea toxics monitoring synthesis: A selection of research
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Smokestacks in sunlight. Photo: Joe Brusky (CC BY-NC 2.0 https://creativecommons.org/licenses/by-nc/2.0/)
1/14/2020

Air contaminants, such as mercury and PCBs, undermine the health of Puget Sound

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Cover of 2018 Salish Sea Toxics Monitoring Synthesis: A Selection of Research
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2018 Salish Sea toxics monitoring synthesis: A selection of research

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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
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A dying female coho salmon in the Lower Duwamish spotted by Puget Soundkeeper volunteers in October 2017. Photo: Kathy Peter
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English Sole (Parophrys vetulus) in Puget Sound. Photo: biodiversityguy https://biodiversityguy.smugmug.com/Underwater/Reference-List-Photos-of/i-3GgD5hB/A
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PCBs in fish remain steady while other toxics decline

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WDFW biologists sorting and measuring fish from PSEMP's index sites in the Duwamish River and near the Seattle Waterfront. Photo: WDFW
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Monitoring helps to reveal hidden dangers in the food web

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Puget Sound Marine Waters 2015 report cover
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2015 Puget Sound Marine Waters Overview

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Birch Bay. Photo by Jeff Rice
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Birch Bay characterization and watershed planning pilot – taking action

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Lower Duwamish Waterway dredging on Superfund site. Photo: Gary Dean Austin (CC BY-SA 2.0) https://www.flickr.com/photos/49648789@N08/17069420399/
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Puget Sound Fact Book report cover
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Stormwater flowing into catch basin carries contaminants to our waterways. Photo: Ben McLeod (CC BY-NC-SA 2.0) https://www.flickr.com/photos/benmcleod/420158390
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Regional monitoring of CECs in the Salish Sea

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CECs include pharmaceuticals and thousands of other commonly used chemical compounds. Photo courtesy of EPA.
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Contaminants of emerging concern in the Salish Sea

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Benthic macroinvertebrates are visible to the naked eye. Photo by Jo Wilhelm, courtesy King County.
6/25/2012

Featured resource: Puget Sound Stream Benthos

Puget Sound Stream Benthos is a data management project which monitors benthic invertebrates in streams and rivers in the Puget Sound region. The system is maintained and operated by King County and was the result of a joint effort between King, Pierce, and Snohomish Counties.