Environmental Review Toolkit

Section 4(f) Tutorial

Avoidance & Minimization


This portion of the tutorial will acquaint you with the following concepts, which are fundamental to Section 4(f):

When you have finished, you should have a basic understanding of the following:

  • The terms avoidance, minimization and mitigation
  • The term feasible and prudent and its relationship to avoidance
  • The term least overall harm and its relationship to minimization
  • The following rules of thumb:
    • If an alternative would have only a de minimis impact, it may be selected without further evaluation under Section 4(f).
    • If an avoidance alternative is determined to be feasible and prudent, it must be selected.
    • If multiple alternatives under consideration use Section 4(f) property and no feasible and prudent avoidance alternative exists, the alternative that will cause the least overall harm must be selected.


Before an alternative involving the use of a Section 4(f) resource can be selected, avoidance alternatives and minimization measures must be considered. (For de minimis impacts, mitigation measures should be taken into account in making the determination.) Avoidance alternatives are those that totally avoid the use of Section 4(f) properties while meeting the defined project needs; minimization measures are efforts to minimize the impact of a project on a Section 4(f) property.

Minimization measures may include mitigation, which is compensation for Section 4(f) impacts that cannot be avoided. Mitigation may entail replacement of Section 4(f) property or facilities.