The WQBE Toolkit

Identifying how we can get the best water quality outcomes.

King County Department of Natural Resources and Parks

April 25, 2023

Aerial view of Meadowbrook bridge over the Snoqualmie River running through a forest with Mount Si in the background.

Using science to improve water quality in the Puget Sound

To ensure a healthy environment for all of us, King County wants to know how we can best improve our water quality. We want to use science to make sure that we have the biggest positive influence on the things we care about and that we make the most of the money we spend.

The WQBE models work together to help us plan.

What's included in the WQBE Toolkit?

We built multiple models that we can use to answer different questions, together or separately.

How can we protect the things we care about? The Causal Models connect predicted water quality improvements (i.e., pollutant loading reductions or types of pollutant pathways/source mitigation) with expected outcomes for people, salmon, and orca.

Where is the pollution coming from? The Watershed Model estimates how rain interacts with the landscape and the resulting flow and pollutant loads entering major King County water bodies.

What is the most effective way to prevent pollution from entering our water bodies? The SUSTAIN Stormwater Best Management Practice (BMP) Model estimates how well stormwater programs reduce pollutants and the volume of stormwater. These models also show us the best return for our investment.

Connecting actions to outcomes

Graphic of a flow chart symbolizing the Causal Models.

Using Causal Models to estimate the outcomes of our actions for people, salmon, and orca.

What are the Causal Models?

The Causal Models connect predicted water quality improvements (i.e., pollutant loading reductions or types of pollutant pathway/source mitigation) with expected outcomes for people, salmon, and orca.

We assembled detailed information about the threats to the things we want to protect. We also consider how these parts of the environment relate to each other.

Example schematic showing the pollutant section of the orca causal model.

The Causal Models look at six areas where water quality affects people and the environment. These are:

Algal toxins in King County lakes
Fecal contamination at swimming beaches
Shellfish harvest
Toxics in fish
Chinook salmon
Southern Resident orca

For details on each causal model click the StoryMap link below!

Evaluating water quality projects

for human and environmental health

https://storymaps.arcgis.com

01 / 06

What have the causal models taught us?

Algal toxins in King County lakes - Cities and parks close swimming beaches at our lakes if there is a high concentration of toxic algae. Too much of the nutrient phosphorus leads to a rapid increase of algae growth, known as algae blooms. Algae blooms can release toxins that are harmful to human and animal health. Understanding water quality conditions at each lake can help us prevent algae blooms from happening.

Click on the arrow to the right to see more.

Fecal contamination at swimming beaches - Cities and parks will also close swimming beaches if there is too much fecal contamination from human and animal poop in the water. Each beach has its own sources of contamination that we can address. Across all beaches, waterbirds and wildlife are the most likely sources of fecal bacteria. Other sources, such as failing septic systems, are also important, depending on location.

A lifeguard tower sitting just right beyond the shoreline of a swimming beach.

Shellfish harvest – Sometimes people are not allowed to harvest shellfish from the Puget Sound. This can happen for a variety of reasons. The problem we can most directly address through stormwater projects is fecal contamination from human and animal poop. Assessing conditions at each shellfish growing area can help us identify effective water quality improvement projects.

Close up of an oyster shell in the sand at the beach.

Toxics in fish - Fish can pick up toxic pollutants from their environment. If the amount of toxic pollutants is too great, it can make the fish unsafe for people to eat. There are several fish species in King County that are considered unsafe to eat. In many cases, we need big reductions in pollutants to reach safer levels of toxins in these fish.

Chinook salmon - Several populations of Chinook salmon travel throughout King County waterways during their life cycle. These salmon populations are much smaller than they used to be. Our water quality and habitat projects can help these fish by providing native plants or cool water. To be most effective, we need to target the places where fish spend their time during different times of year.

Southern Resident orcas - To help our Southern Resident orca population, King County will need to be part of a large-scale, regional effort. We need to increase the amount of Chinook salmon available for orcas to eat and decrease the toxic pollutants that accumulate in their food. Other important efforts include reducing noise and disturbance from boats. It will take more than King County’s actions to improve the chances of Southern Resident orca survival.

Where are pollutants coming from in King County?

Graphic showing rain from the mountains draining into a river symbolizing the Watershed Model.

How the Watershed Model helps us target our most polluted areas.

What is the Watershed Model?

The Watershed Model estimates how rainwater interacts with the landscape and the resulting flow and pollutants entering major King County water bodies. It does this by taking into consideration landscape features such as slope, soil type, and geology as well as meteorological data. Flow and contaminant loads are modeled for a 20-year period. The Watershed Model was developed using the Loading Simulation Program in C++ ( LSPC ).

What pollutants does the Watershed Model tell us about?

01 / 05

Metals - The Watershed Model includes two heavy metals: copper and zinc. Copper and zinc can get into stormwater through sources like cars and roofing materials. These metals can be harmful to fish and other aquatic animals.

Click on the arrow to the right to see more.

Large highway with city lights and headlights visible at night.

Nutrients - Nutrients can contribute to low oxygen conditions that are harmful to aquatic species in both fresh and salt water. WQBE measures two nutrients: total nitrogen and total phosphorus. Sources of nutrients in King County include leaking sewer lines, failing on-site sewage systems as well as fertilizers and animal waste.

Instructor teaching older children about water sampling.

Organic pollutants - Organic pollutants can be harmful to both aquatic species and human health. They can get into stormwater through sources such as car exhaust, flame retardants, and legacy contamination. WQBE measures four different organic pollutants: total polychlorinated biphenyls (PCBs), total polybrominated diphenyl ethers (PBDEs), total polycyclic aromatic hydrocarbons (PAHs), and bis-2-ethylhexyl phthalate (BEHP).

Aerial view of Bellevue, Washington with Mt. Rainier in the distance.

Total suspended solids - Total suspended solids (TSS) are often used as a surrogate for other contaminants because many are associated with particles in the water. High TSS levels can also harm fish habitat.

Bacteria - Fecal coliform is a bacterium that comes from fecal contamination, which is poop from people, pets, or wildlife getting into the water.

How can we cost-effectively clean our stormwater?

graphic showing a graph with an x and y axis symbolizing the SUSTAIN models.

Using SUSTAIN Stormwater BMP Modeling to characterize regional solutions.

What does SUSTAIN do?

SUSTAIN stands for System for Urban Stormwater Treatment and Analysis Integration. This model was originally developed for the U.S. Environmental Protection Agency in 2014. Over the years, modelers have continued to use and improve upon the modeling system. SUSTAIN Models identify water quality BMPs, that we are calling Actions, that cost-effectively reduce the amount of pollution in stormwater.

The WQBE team has used SUSTAIN to assess Actions grouped into three programs: Green Stormwater Infrastructure (GSI) Incentive, Roadway Stormwater Treatment, and Regional Stormwater Treatment (Regional Stormwater Parks).

For more information about model inputs and how they work, check out this FAQ about how WQBE is using SUSTAIN.

What did SUSTAIN teach us?

Regional Stormwater Parks are worth the investment - Regional Stormwater Parks slow the flow of rainwater and use soil media and plants to help remove pollutants. These parks can also provide green spaces and other community benefits. Our SUSTAIN results show us that regional stormwater parks are the most cost-effective Action for reducing stormwater pollutants across the watershed. It is important to note that we have not yet modeled stormwater parks that address a flow control goal.

Click on the arrow to the right to see more.

A water feature in a concrete planter that is part of a stormwater park.

Distributed stormwater infrastructure is also needed - The SUSTAIN results show us that our Roadway Stormwater Treatment program and GSI, like rain gardens, are not as effective at reducing pollutants as Regional Parks. However, these programs still provide benefit throughout the watershed. Indeed, these additional Actions are important for flow control and preventing pollutants from entering our streams and harming salmon.

Planting next to a roadway that help filter stormwater.

Model constraints are important for understanding results - Many of these stormwater programs require public participation. To build a Regional Park, we may need to purchase private property. Rain gardens require homeowners who are willing to maintain them. We estimated how many people we think will participate in these programs and included that in the model. If we run the model without these constraints, we see very different results, particularly in our GSI Incentive Program.

House using rain barrels to collect water for their garden.

Who are we working with?

A collection of images showing King County water quality projects and listing key partners in this work. — WQBE Toolkit development partners.

As part of the Clean Water Healthy Habitat Initiative, WQBE produces information and data for several different programs in King County.

Stormwater Investment Plan - SUSTAIN results helped inform science-based goals to support the Stormwater Investment Plan. This group continues to meet with stormwater practitioners around the region to discuss how to implement these goals.
Wastewater Treatment Division (WTD) - The Watershed Model allows King County to understand where nutrients and other pollutants are coming from throughout our watersheds. SUSTAIN modeling can also help identify cost-effective ways to manage stormwater before it encounters our combined sewer systems. The WQBE team is working closely with WTD so that our results can help King County improve water quality.
Stormwater Retrofit Prioritization - King County is deciding how and where to build stormwater infrastructure to improve water quality. The retrofit prioritization team is using WQBE pollutant loading data from the Watershed Model to help King County and our partners identify the most polluted areas.

How did we develop WQBE?

The King County WQBE team developed WQBE using the most up-to-date scientific methods and input from:

Experienced consultants with broad technical capabilities. These consultants provided their technical expertise from working on past projects and knowledge of relevant scientific studies.
Subject matter experts. Several parts of this project relied on direct input from indivudual researchers, academics, consultants, environemntal advocacy groups, and staff from governmental agencies. We thank these individuals for lending their expertise and knowledge to this work.
Other partner organizations. We used webinars, our website, and presentations at conferences and regional meetings to connect with environmental professionals across the region to gain broad input on modeling methods and how we communicate findings.

Timeline for the King County WQBE Toolkit. King County developed the models in 2019 through 2022. We are refining the models in 2023 and 2024. We will maintain the models from 2025 onward. — WQBE Toolkit development timeline.