Temperature pollution

Temperature plays an important role for the health of water bodies and affects in-stream plant and animal species:

• Salmon and other aquatic species need cool water to survive and maintain healthy populations.

• Warm water is more likely to have algal blooms which can suffocate fish, contaminate shellfish, and be unsafe for human use, leading to closures. 

• As climate change progresses, it is vital to support the resilience of our waterbodies to better cope with more extreme weather conditions and threats from increased temperatures. 

What increases temperature in streams?

A leading cause of increased water temperatures throughout the state is loss of trees, shrubs, and other plants along streams and rivers. These areas, called riparian buffers, provide shade that help regulate temperature and keep water cool. Buffers also help filter out pollutants, reduce erosion, and can help minimize the impacts from flooding. Streamside vegetation can be impacted by many things, including development, cultivation, and livestock access to the area.

What is our role?

Provide recommendations to protect water quality

We work with interest groups and partner agencies to develop Best management practices (BMPs) to address nonpoint sources of temperature pollution. We published a Clean Water Guidance chapter on Riparian Areas and Management with our 2022 Nonpoint Plan. Read our guidance focus sheet to learn more. 

Provide funding to implement solutions

We provide technical and financial assistance to local partners and landowners to help get water quality solutions on the ground. Our funding programs support streamside vegetation that help waterways meet water quality standards. We're piloting new incentive programs and exploring new opportunities with our partners to keep water clean and cool. 

Work with partners

We work with other agencies and local partners across the state to regulate water quality and implement practices that support healthy water temperature. For example, we collaborate with Washington State Department of Natural Resources to help ensure that forestry activities are protective of water quality, including temperature. We also partner with Conservation Districts and provide funding for programs. Finally we work directly with landowners and nonprofits to support agricultral practices that protect cool water. 

What can you do to help keep streams cool?

Protecting and restoring streamside vegetation provides multiple benefits to us and our environment!

Do you own land?

If you have a streamside habitat already in place, it is important to protect it. If there are streams or other waterways on your property that don't have adjacent trees or other vegetation, we recommend adding native trees and shrubs to the area. Our local nonpoint field staff and funding programs are here to help you plant streamside vegetation!  

Don’t own land?

You can still help! Attend a local volunteer event to plant trees next to streams in your community, or install a local rain garden, which can help increase groundwater flow to streams during the dry summer months.