Westervelt Ecological Services
Sutter Basin 27 oct 09 003

Stream and Wetland Mitigation

Stream and Wetland Mitigation


Mitigation, a term that frequently occurs in the discussion of restoration, “refers to the restoration, creation, or enhancement of wetlands and streams to compensate for permitted losses” (Lewis, 1989).

Under Section 404 of the Clean Water Act, wetlands may be legally filled, but their loss must be compensated for by the restoration, creation, or enhancement of other wetlands. This strategy is known as “no net loss” of wetlands.

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Wetland Restoration

On the road to climate resilience, sustainability starts in our wetlands. At WES, we are working to conserve and restore the vital landscapes that remain, offsetting the impacts of development while fighting climate change.

Regulatory Agencies

In 1972, the legislature expanded upon the Federal Water Pollution Control Act of 1948, establishing the current Clean Water Act. Section 404 of the act regulates the dredge or fill material into wetlands, lakes, streams, rivers, estuaries, and certain other types of waters. With the goal of avoiding, minimizing, and compensating for the unavoidable loss of wetlands. The U.S. Army Corp of Engineers (USACE) and the Environmental Protection Agency (EPA) are responsible for the enforcement and on-site investigation of the act.

There are also numerous state regulations and agencies that provide additional protection for wetlands and streams.




The manipulation of the physical, chemical, or biological characteristics of a site with the goal of returning natural/historic functions to former or degraded wetland. For the purpose of tracking net gains in wetland acres, restoration is divided into:

  • Re-establishment: The re-creation of a former wetland resulting in a gain of wetland acres.
  • Rehabilitation: The re-creation of a former wetland that results in a gain in wetland function but does not result in a gain in wetland acres.


The creation of wetland functions resulting in a gain of wetland acres.


The improvement in wetland function(s)that does not result in a gain in wetland acres.


WES has completed numerous mitigation banks and projects across the nation that restore wetlands.