A property that has been determined eligible for listing in the state or federal register by the State historic Preservation Officer (SHPO) is then subject to an “Assessment of Impact/Effect” of the proposed action. The words “Impact” and “Effect” are used interchangeably, “Impact” is used specific to state level reviews (GEPA/State Stewardship) and “effect” for federal level reviews (Section 106), The Assessment of Impact/Effect weighs the proposed scope of work against the historic significance and integrity of the resource(s) and assesses the impact/effect of the action on character-defining features and historic materials.
Historic resource studies are useful in providing the type of information required to submit an Assessment of Effect form, and can reduce the review period by reducing SHPO requests for additional Information.
As part of the SHPO submittal process, a narrative including a discussion of avoidance and minimization measures/alternatives should be provided. The narrative should discuss alternatives explored to avoid potential adverse impact/effect and, if unavoidable, to minimize the adverse impact/effect. Backup documentation including alternate designs, budgets, etc. should be included where necessary.
There are four types of impacts/effects:
- No Impact/Effect – The proposed action does not affect any historic resources.
- No Significant Impact/Effect – The proposed action has a minor, but insignificant, effect that is recognized but does not require mitigation.
- Conditional No Significant Impact/Effect – The proposed action has a minor effect that is recognized and can be readily avoided with recommendations provided by SHPO.
- Significant Impact/Effect – The reposed action is deemed to have a significant adverse effect to the historic resources. The action will require some type of mitigation (Standard Operating Procedure 13).
Return to: HPMP Standard Operating Procedures