Riparian Zones

Unit 3: Riparian Zones

Riparian Zones: Think outside the banks.

Essential question: 

How do riparian zones prevent pollution and protect water quality? What other ecosystem services do riparian zones provide and why are they so important?

Learning objective: 

After completing this exercise the student will be able to:

 1. Describe the characteristics of a riparian zone. 

 2. State the importance of riparian zones to people, wildlife, and the Columbia River.

Next Generation Science Standards:

NGSS Disciplinary Core Ideas (Grades 6-8)

  • MS-ESS2 Earth’s Systems
  • MS-ESS3 Earth and Human Activity
  • MS-LS1 From Molecules to Organisms: Structures and Processes
  • MS-LS2 Ecosystems: Interactions, Energy, and Dynamics


Riparian zones are the areas of land bordering streams and rivers. They mark the transition area between aquatic (water) and terrestrial (land) systems. You might picture them as the ribbon of green along a stream or river. Riparian plants depend on the saturated soils and flooding patterns associated with the aquatic systems. When you think of the entire Columbia River watershed, riparian zones actually cover a very small area, but they are extremely important.

When riparian areas are intact and filled with trees, shrubs, grasses, and/or other vegetation, they act as buffers, protecting the river from the adverse effects of adjacent and nearby land use. Healthy riparian zones can capture and filter sediment, excess nutrients, and pollution from surface runoff. They can provide temperature regulation through shading to keep water cool. Plant roots hold the sponge-like soils in place providing bank stability and preventing erosion, and those soils can soak up and store excess water to reduce flooding during high flows and then release it slowly during periods of low flow. Riparian zones also offer habitat for a diverse community of plants and animals and provide critical inputs for the aquatic food web in the form of leaves, and other organic materials that drop from the vegetation into the water.

Intact and healthy riparian zones are critical to the health of the Columbia River and the people and wildlife that depend on the river. Unfortunately, the value of riparian zones is often overlooked. When people destroy or harm riparian zones, scientists observe far-reaching impacts including compromised water quality and habitat loss.   . 

Worldwide riparian zones are among some of the most altered and degraded ecosystems. People might clear riparian vegetation for agriculture, industrial activities, construction, or transportation, leaving the river exposed to excess runoff, nutrients, sediment and pollution. Here in the Pacific Northwest, scientists have named riparian zone degradation as one of the contributing factors to the decline in freshwater habitat for salmon, and current salmon recovery efforts involve riparian zone protections and management practices.1

By restoring degraded riparian areas we can work to bring back some important riparian-zone functions that keep the river clean, cool, and healthy. 

Columbia Riverkeeper is working with local students and community members on a three-acre riparian restoration project at the Hood River waterfront called the Nichols Natural Area. Our vision is to engage, educate, and inspire the diverse communities of the Columbia River Gorge to turn a former industrial site into vibrant, healthy riverfront habitat. We hope you’ll visit the site and see for yourself how it is transforming and learn how restoring riparian habitat will help to prevent pollution and protect water quality in the Columbia River.


  • Biofiltration – a pollution control filtration process where the filter consists of porous material (e.g., sand or gravel) which is colonized by microbial communities that capture and biologically degrade (breakdown) pollutants.
  • Ecosystem Services – the benefits people obtain from an ecosystem
  • Ecotone – a region of transition between two biological communities, often containing characteristics of both communities and may contain species not found in either of the overlapping communities
  • Riparian Buffer – the natural vegetation from the edge of the stream or river bank out through the riparian zone. Riparian buffers are the most valuable protection a stream system has against outside influences.
  • Water Quality – the degree to which water is clean, and whether it is suitable for various uses such as drinking, allowing plants to grow, or for fish to live in, etc.

Link to all Pollution Prevention Vocabulary Terms

Riparian Zone Activities

Explore hands-on and thought-provoking activities

Additional Resources:

This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement RB 01J73501 to Columbia Riverkeeper. The contents of this website subpage do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does the EPA endorse trade names or recommend the use of commercial products mentioned in this document.