Bellevue Watershed Management Plan

Streams run parallel to our lives in Bellevue. Here, I-90 borders the Mercer Slough wetland towards downtown Bellevue. The slough is Lake Washington’s largest remaining wetland.

Stream health is one of the best ways to measure the health of the surrounding watershed. A healthy stream has clean water, habitat for fish and wildlife, and enough room to flow through our landscapes. If we work together, we can all support healthy streams.

Bellevue borders Lake Washington and Lake Sammamish, and has three small lakes – Phantom Lake, Larsen Lake, and Lake Bellevue. Over 800 acres (or 1,000 football fields) of wetlands in Bellevue help prevent stormwater runoff from causing floods or erosion. Our wetlands also provide habitat for fish and wildlife.

Stormwater from across the city eventually drains into local bodies of water, like Coal Creek or Lake Washington.

What do you think of when you think of a healthy stream?

Preserving and protecting streams in Bellevue is essential for maintaining a healthy, resilient ecosystem and ensuring the wellbeing of both the environment and the community.

When cities grow, it’s not as easy for rain to soak into the ground. Rain runs off roads, parking lots, and buildings, picking up pollutants on the way. These pollutants then flow into our streams and can be harmful to fish and wildlife.

Learn more about the flow of stormwater and what you can do to help keep it clean:

Bellevue’s streams support a wide variety of wildlife including salmon, eagles, minks, salamanders, beavers, herons, trout, and frogs. Healthy streams give these animals the food, shelter, and space they need to thrive.

Great Blue Herons search for native Peamouth Minnow in Kelsey Creek every spring.

We last heard from you in 2021 about what matters most when it comes to Bellevue’s streams. We learned that you value how important streams are to local ecosystems and the wildlife that live in and near streams. We also found that many of you use Bellevue’s streams to connect with and enjoy the beauty of nature close to home.

Bellevue community members of all ages enjoy exploring our streams. To ensure future generations can enjoy our streams, we need to act now to protect watershed health. Our team of scientists, planners, and engineers have been working on strategies to protect our watersheds. We studied stream health and used community input to help identify specific investments that could improve the health of Bellevue’s watersheds.

You may already see special gardens like this one around Bellevue. These gardens soak up water like a sponge and slow the flow of stormwater runoff.

The city is following the best available science to reduce pollutants and improve stream habitat for fish and wildlife. We would like your help to decide how to focus our efforts and resources over the next 20 years to benefit Bellevue’s watersheds and the community.

Bellevue’s landscape has changed a lot in the past 150 years, from forests and farmland to a busy city.

It’s not only our streams that are impacted by the city’s growth – Bellevue’s streams are connected through storm drains across the city that ultimately drain into Lake Sammamish, Lake Washington, and Puget Sound. When it rains, the rainwater hitting the roofs of buildings eventually ends up in these large bodies of water.

The Watershed Management Plan will help us make smart choices that protect stream health as our city continues to grow.

Before we start fixing up our “house”, we need to know what exactly needs fixing, and what tools we have in our toolbox. Each watershed in Bellevue is different and some streams are healthier than others. The project team is studying the health factors, or things that tell us if a watershed is healthy or unhealthy. Understanding the health factors of Bellevue’s watersheds will help us create tools to protect, improve, or maintain current conditions.

The health factors for Bellevue’s watersheds include:

Stormwater runoff from roofs, roads, and walkways.		Loss of floodplain or other natural surfaces that filter runoff and protect streambanks.
There are over 20,000 storm drains in Bellevue! Have you noticed the blue and white “Don’t Pollute, Drains to Stream” signs near Bellevue’s storm drains? These are an important reminder that what drains from our roads and walkways eventually ends up in our streams and lakes.		With fewer natural surfaces and floodplains to slow stormwater runoff, streambanks can become eroded. Bank erosion means that sediments, like dirt and rocks, wash into streams and can cause impacts to water quality and wildlife habitats.
Pollutant levels in streams, lakes, and wetlands.		Physical barriers to fish and wildlife, like culverts.
Pollutants like pesticides, E. coli or chemicals may not be visible to the naked eye, but they still harm our streams. Stream scientists test water quality to understand more about what is impacting the health of a stream.		This culvert under NE Eighth Street near 132nd Ave NE in Bellevue allows Kelsey Creek to flow under the road. Culverts like this one are often too shallow and require too big of a drop for fish to safely pass through.

Identifying these factors allows the team to decide which streams need help first and what kind of actions will be most useful for each watershed.

The Watershed Management Plan will recommend actions the city, our partners, and you can use to improve watershed health.

Projects, such as building a stormwater facility that filters rainwater runoff from streets before it gets to streams.		Programs, like planting and retaining more trees citywide to provide stormwater flow control.
Features that remove pollutants from stormwater can be added to new and existing buildings. This detention vault temporarily stores runoff underground and then slowly releases it to reduce the impacts of flooding.		Trees in the city support stream health by soaking up and holding stormwater before it reaches storm drains.
Maintenance, such as regular street cleaning to keep chemicals and trash from entering streams.		Policies or regulations, like changes in city code to encourage developers to include building features that clean runoff before it enters streams.
Street sweepers help keep our streams clean with a combination of water, brooms, and vacuums! As they drive along our streets, the big brooms on either side of the sweeper push garbage and other pollutants towards the back of the vehicle, where they are vacuumed up and disposed of.		These open bottom infiltration chambers collect stormwater runoff from storm drains and allow it to soak into the ground below.

What tools would you include in your stream health toolbox?

The choices that we make now can help keep our streams healthy for future generations. Improving stream health in Bellevue is a community effort, and we want your input throughout the process.

There are many ways to connect with the city during development of the plan.

• We welcome your questions, concerns, and comments by email at any time at watershedplan@bellevuewa.gov.
• Request a briefing from our project team for your community group or organization.
• Sign up for email updates to learn about plan progress and opportunities to share input.
• Share your questions, comments, and ideas in the comment boxes on this page.

Streams are a valuable part of our community. We want to find realistic solutions that encourage community members to care about and understand stream health. From increased recreational opportunities to reduced flooding, healthier streams create healthier communities.

We started by prioritizing stream investments based on scientific study and analysis. Next, we need to hear from you to help us decide how to make actions for stream health even better for the community.

We want to know:

• Which benefits of healthier streams matter most to you (such as less flooding, managing climate change or more opportunities for play or education)?
• What role do you want to play in improving stream health in your community?
• What have we missed? What else should we consider when developing the Plan?