Functions & values of wetlands

This information was modified from Chapter 2 of At Home with Wetlands: A Landowner's Guide.

Wetlands perform many ecological functions. Knowledge and understanding about the complexities wetland ecosystems represent is still developing.

Wetland ecologists have already documented the following environmental benefits wetlands provide:

  • Water purification
  • Flood protection
  • Shoreline stabilization
  • Groundwater recharge and stream flow maintenance

Wetlands also provide habitat for fish and wildlife, including endangered species. Not all wetlands provide all of these benefits, and how your particular wetland works depends on its location and type.

Some of the values of wetlands are yours and yours alone. No one else can say what the open space means to you and your family. You determine the benefit to your quality of life and how you value a wetland's beauty.

Wetland benefits depend on health

As amazing as wetlands are and contribute to the environment, they do have their limits. A partially filled or otherwise damaged wetland can only partially meet its potential for flood control, shoreline stabilization, or groundwater recharge.

A degraded wetland can lose its capacity to remove excess sediments, nutrients, and other pollutants. It can also lose its habitat value for fish and wildlife. Wetlands may have tremendous capacities to provide environmental benefits but they are not indestructible. If people want wetlands to continue to perform their ecological functions then everyone must do their part to protect them.

Below is a summary of how wetlands perform their complicated functions, along with a brief explanation of how these functions support humans and other species.

More information on wetland functions and values

  • U.S. Environmental Protection Agency's web page: How do Wetlands Function and Why are they Valuable?
  • Chapter 2 of Wetlands in Washington State, Volume 1: A Synthesis of the Science presents information on wetlands in Washington and how they function. Section 2.3, Introduction and Background on Wetland Functions, describes the evolution of our understanding of wetland functions during the last few decades. It defines the term wetland functions and explains the difference between wetland functions and values.
  • The Washington State Wetland Rating System was designed to differentiate between wetlands based on their sensitivity to disturbance, their rarity, our ability to replace them, and the functions they provide. This rating system groups wetlands into four categories.
  • The Washington State Wetland Function Assessment Methods are a collection of assessments that provide a score for the degree to which wetlands perform up to 15 functions. However, these methods are not currently being used. Instead, the documents are provided only for historical reference regarding the scientific basis for the wetland rating system, the current tool for gathering general information on wetland functions.