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Saving Puget Sound

Puget Sound Nutrient Source Reduction Project

Puget Sound’s health is degrading due to increasing levels of nutrients that are adversely affecting water quality in the nation's second largest marine estuary.

Puget Sound is a vital part of our natural resource economy and a reason why many people move to the region. It is a source of food and recreation for many Washingtonians; and is part of our shared cultural history and regional identity. How much can it change and still be the Puget Sound we know and love?

Unhealthy nutrient levels in Puget Sound

Nutrients are fertilizer for plants and algae, but too much growth can be bad for a healthy, resilient marine ecosystem. When these plants and algae die, their decomposition uses oxygen that marine animals need to survive. Continually increasing levels of nitrogen and organic carbon (the primary nutrients of concern) in marine waters are fueling these changes.

Nutrients come from both natural processes and human sources. Global human activities also affect nutrients in the air and nutrients entering Puget Sound from the Pacific Ocean, which has a large influence on Puget Sound. We are finding that nutrients in Puget Sound are out of balance altering some of its fundamental physical, chemical, and biological functions. This has potential impacts to salmonids and forage fish species in sensitive nearshore areas, inlets, and bays where their early life stages could be impacted by poor water quality conditions.

More than a decade's worth of monitoring data and robust computer modeling indicate adverse changes in the Sound’s water quality and ecosystem. Recent analyses using the Salish Sea model indicates that the total impact from local human nutrient sources are decreasing dissolved oxygen levels by more than what our water quality standards allow for human impacts. We are using state-of-the-art computer modeling tools and water quality data to inform a collaborative process with regional stakeholders to develop and evaluate meaningful options that will reduce nutrients from local human sources.

We must work together to protect and restore Puget Sound so that it will be more resilient to the negative effects of climate change and human pressures.

Using science to understand the complexities of the Salish Sea

The Salish Sea Model was developed by the Pacific Northwest National Laboratory (PNNL) in collaboration with Ecology, and with grant funding from the U.S. Environmental Protection Agency (EPA), to be the primary tool to understand water quality changes in Puget Sound. We compare water quality monitoring data against the model predictions to ensure that the model is accurate and reflects reality. The model helps us evaluate things that affect marine water quality including:

  • water circulation
  • incoming ocean conditions
  • watershed inflow and quality
  • regional weather and climate
  • human sources of nutrients
  • other parameters of concern

You can read more about the Salish Sea model. There you will also find two new reports (published July 2017) on the latest updates to the Salish Sea model including sediment diagenesis and ocean acidification.

Human impact

Recent modeling of water quality conditions in Puget Sound allows us to see impacts of total human nutrient sources from natural and ocean sources (Mohamedali et al, 2011; Roberts et al, 2014). We are finding that discharges of nutrients from human sources are pushing Puget Sound past the tipping point of its capacity to absorb those nutrients without negative impacts.

There are over 4 million people currently living in the Puget Sound region, and the Washington Office of Financial Management estimates another 1.7 million people will move to the region by 2040. That additional number of people means there could be over a 40 percent increase of nutrients discharged to Puget Sound from humans over the next several decades.

Climate change will add pressure – especially during drought years

In addition to increasing pressures from population growth, climate change will make conditions worse. Regional climate change models and scientists predict predict more intense storms more often. They also see a future with warmer average temperatures each year, which will alter watershed streamflow patterns and timing of snowmelt from what we’ve seen historically. Warmer temperatures will also lead to more droughts.

When we experience drought years, streamflow from Puget Sound watersheds decreases. The timing and volume of water melting off mountain tops, flowing down rivers, entering the Sound, and interacting with ocean water controls circulation and flushing of the entire system. Droughts throw off that natural system and result in nutrients from humans concentrating in Puget Sound instead of flushing out to the ocean.

Climate change changes everything, and with much of the water in Puget Sound coming from the ocean, we have to take increasing ocean water temperatures into consideration as we plan to adapt. Temperatures from freshwater sources that feed Puget Sound are also increasing from the combination of climate change and land use impacts. These warmer water temperatures will lower the total amount of dissolved oxygen in water that fish and other marine organisms need to survive as well as increase productivity rates of unwanted organisms.

What are we doing about it?

Water quality is continually changing in response to these factors both over time and geographically. While the Salish Sea model covers both U.S. and Canadian waters, we will be focusing on Puget Sound and Washington nutrient sources with this project.

We are conducting an extended scoping phase throughout 2017 and into 2018 to figure out how this project can fit with other Puget Sound restoration activities and build collaborative partnerships with stakeholders and partners in the region. The next project phase will focus on working with those partners and stakeholders to develop meaningful, holistic solutions for nutrient reduction and water quality improvement.

We're hosting a workshop with multiple speakers to discuss Puget Sound impacts from nutrients. Join us July 19 to hear from experts in the field and participate in the discussion.

Please sign up for our listserv to receive updates on this work.


Dustin Bilhimer
Puget Sound Nutrient Source Reduction Project Manager
Email: dustin.bilhimer@ecy.wa.gov
Phone: 360-407-7143