Stormwater Monitoring
Why Monitor Stormwater?
The Salish Sea: Beauty & Challenges
The Puget Sound region, renowned for its breathtaking landscapes and diverse ecosystems, has experienced significant population growth over the past several decades. In 1960, the region’s population was approximately 1.5 million. By 2020, it had surged to around 4.3 million, and as of early 2024, the population reached approximately 4.48 million.
This rapid increase in residents has led to heightened environmental pressures, including increased pollution. As cities expand and development increases so does pollution, straining the health of local waterways and marine habitats. More people mean more vehicles on the road, greater land conversion for housing and businesses, and increased use of chemicals in daily life—all of which contribute to pollution.
Major sources of pollution include:
Vehicle emissions that release chemicals and heavy metals, which settle on roads and wash into storm drains during rainfall
Runoff from lawns, parks, and farms carrying fertilizers, pesticides, and herbicides into waterways
Urban development that replaces forests and wetlands with impervious surfaces, reducing natural filtration and increasing stormwater runoff
Wastewater and septic systems, which can introduce nutrients and bacteria into streams, lakes, and marine waters when not properly managed
Plastics and litter, which break down into microplastics that accumulate in the environment and harm aquatic life
These pollutants ultimately flow into the Salish Sea, degrading water quality, disrupting ecosystems, and threatening marine species that depend on clean water for survival.
Did you Know?
1.
Stormwater is the #1 source of pollution in Puget Sound, carrying oil, heavy metals, and bacteria into our waterways.
2.
Just one inch of rain over a city block can generate over 50,000 gallons of runoff - enough to fill a swimming pool!
3.
Most of our stormwater is not treated or 'cleaned up', It runs directly into our lakes, rivers and the Salish Sea.
4.
E. coli levels in stormwater can sometimes exceed safety standards, putting public health at risk and potentially closing shellfish beds.
While municipalities are required to implement stormwater pollution controls, there is no standardized, long-term monitoring to track whether these efforts are effectively reducing contaminants in runoff. Without reliable data, local governments and the public have limited insight into stormwater pollution trends, potential risks to water quality, and necessary management improvements.
Our Project Scope
This community-driven project demonstrates how residents can actively contribute to environmental protection and support local governments in managing stormwater pollution. The Salish Sea Stormwater Monitoring is a community science volunteer-led water quality monitoring program. The goal of our project is to improve both water quality and water policy through community monitoring and action.
Our teams conduct monthly community-based stormwater monitoring at 122 municipal outfalls in Region 1 and 2. We hope to be expanding into Region 3 some time in 2025.
Along with a visual check of each outfall, our trained volunteers collect data on E. coli, turbidity, conductivity, pH and dissolved oxygen, helping to identify hotspots and seasonal trends in stormwater quality. When a threshold exceedance is found, we share these results with the stormwater managers so that they can begin finding the source.
Our Partners
We’re proud to work alongside an incredible network of partners who share our commitment to protecting clean water and healthy communities. Their support—whether through funding, collaboration, or shared expertise—helps amplify our impact and makes our work possible. Together, we’re making a difference, one drop at a time.
Who We Are:
We’re a group of enthusiastic volunteers who live along the Salish Sea coastline and are working to protect it. We’re passionate about giving back and making a difference for our beloved region.
News Articles:
Interested in diving in deeper? Read our collection of stormwater monitoring related new articles to expland your knowledge!
Our Data:
Several tools help us see our stormwater data in context with our entire region. Take a look to learn more about the information we collect!
