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Avoiding & minimizing wetland impacts

As you design your project, use the information on this webpage to help you avoid and minimize impacts to wetlands. This will help you to demonstrate to the permitting agencies that you have applied mitigation sequencing. Avoiding and minimizing wetlands impacts may help save time and money on your project.

Requirements to avoid and minimize development impacts

Wetlands are protected by local, state, and federal laws. Applicants with development proposals that may adversely affect wetlands must apply mitigation sequencing before permitting agencies consider compensatory mitigation options. In Washington, permitting agencies require applicants to show that they have followed the mitigation sequence and worked first to avoid and minimize impacts to wetlands wherever practicable.

Mitigation sequencing includes:

  1. Avoiding the impact altogether by not taking a certain action or parts of an action.
  2. Minimizing impacts by limiting the degree or magnitude of the action and its implementation by using appropriate technology, or by taking affirmative steps to avoid or reduce impacts.
  3. Rectifying the impact by repairing, rehabilitating, or restoring the affected environment.
  4. Reducing or eliminating the impact over time through preservation and maintenance operations during the life of the action.
  5. Compensating for the impact by replacing, enhancing, or providing substitute resources or environments.
  6. Monitoring the impact and taking appropriate corrective measures.
State and federal laws require applicants to avoid and minimize impacts whenever reasonable through practicable alternatives. Under state rule, a practicable alternative is defined as an alternative that is:

"Available and capable of being done after taking into consideration cost, existing technology, and logistics in light of overall project purposes."

Avoiding and minimizing impacts becomes even more important when rare, high quality, or difficult to replace resources are involved.

Avoiding and minimizing impacts are site-specific

Permitting agencies consider many factors to determine when applicants have met the requirements for avoiding and minimizing impacts. There are three phases to this process:

  1. Project assessment: Assess your site and project.
  2. Avoidance: Avoid wetland impacts where practicable.
  3. Minimization: Minimize impacts to wetlands where impacts cannot be avoided.

Avoidance & minimization checklists

Use this avoidance & minimization checklist to show how your project has avoided and minimized wetland impacts. The checklist provides examples of how to accomplish avoidance and minimization during site analysis, project design, and construction.

Carefully considering the techniques and thoroughly documenting your efforts will help you prepare more complete applications, which facilitates faster review and decisions.
Project assessment

Project assessment is the process of investigating what natural resources, such as wetlands or streams, exist on your property and what kinds of protection are required by law. It’s important to understand what resources on your property might be subject to regulation so you can incorporate avoidance and minimization into your project design. It will also help you understand what must be compensated for if wetland impacts are unavoidable.

An individual project assessment begins by looking at the overall landscape setting, drainage basin, and existing natural and human-made features. Research should include databases for priority habitats (PHS maps), wetland inventory maps, fish use maps (Salmonscape), local critical areas maps, aerial maps, LIDAR, etc.

Have your site assessed for regulated resources

Following a complete examination of the available databases and mapping tools, the site must be thoroughly assessed for any and all regulated resources. Many sites contain unmapped streams or wetlands. Some may have threatened or endangered plants or animals that are not shown on any resource maps.

While mapping resources and previous studies provide important background information, they typically need to be supplemented with current site-specific information for permitting. Site-specific studies, such as wetland delineation and rating, are necessary to accurately characterize the resources on a site.

Avoidance Minimization