Determining Eligibility and the Area of Potential Effects

Two determinations set the size of a project's preservation problem before anyone argues about effects. The first is which properties count as historic properties. The second is how far out the study boundary extends. Both are made early, both are made by the agency, and both are difficult to revisit once construction financing is committed.

Eligible counts the same as listed

Section 800.16(l) defines a historic property as any prehistoric or historic district, site, building, structure or object included in, or eligible for inclusion in, the National Register. The word eligible carries equal weight with included. A farmstead that no one has ever nominated, if it meets the criteria, is protected in the review exactly as a property listed for decades would be.

The definition also reaches further than buildings and sites. Properties of traditional religious and cultural importance to an Indian tribe or Native Hawaiian organization can meet the criteria and be treated as historic properties, even where nothing built stands on them. Identifying those places depends almost entirely on consultation, because the information that establishes significance is held by the community rather than in a public file. A survey conducted only by walking the ground and reading county records will not find them.

This is the answer to owners who assume that avoiding a nomination avoids federal attention, and to developers who check the Register database and conclude a site is clear. The database records listings. It does not record everything that would qualify, and it cannot record the properties nobody has yet evaluated.

How eligibility is decided in practice

Most eligibility questions never leave the state. The agency official applies the National Register criteria in consultation with the preservation officer and any Indian tribe or Native Hawaiian organization that attaches religious and cultural significance to the property. If the agency and the preservation officer agree, that consensus determination governs for the purpose of the undertaking.

A determination made for one undertaking does not settle the question forever, though as a practical matter it is treated as settled. Agencies and preservation officers rely on earlier determinations when the same property comes up again, and reopening one requires a reason: new information, a different boundary, or a claim of significance that was never evaluated. Sponsors should therefore assume that a prior finding of eligibility on a neighboring project will govern theirs unless they can show why it should not.

Disagreement changes the route. Where the agency and the preservation officer do not agree, or where the Advisory Council or the Secretary of the Interior so requests, the agency obtains a determination of eligibility from the Secretary under 36 CFR Part 63. That determination is made on documentation resembling a nomination, and it binds the federal review. It does not list the property, which is why the register and the set of properties treated as historic never fully coincide, a gap that also arises from owner objections described in the nomination process and the objection that blocks listing.

Drawing the area of potential effects

Section 800.16(d) defines the area of potential effects as the geographic area or areas within which an undertaking may directly or indirectly cause alterations in the character or use of historic properties, if any exist. Two features of the definition control everything that follows. The area is influenced by the scale and nature of the undertaking, and it may be different for different kinds of effects.

The area is not the same as the project site and it is not the same as a parcel boundary. It is defined by where effects may reach, which can be considerably larger than the land the sponsor controls and occasionally smaller than the parcel where only a corner is disturbed. Because the boundary determines what gets surveyed, it determines what gets found, and consulting parties scrutinize it for exactly that reason.

In practice agencies draw more than one boundary. A tight boundary covers ground disturbance: the footprint, staging areas, access roads, borrow and spoil sites, and utility connections. A wider boundary covers indirect effects such as changes to a viewshed, vibration, noise, traffic and induced development. A tall structure can have a direct effects area of an acre and a visual effects area measured in miles.

Phasing identification on corridors and large sites

Linear projects and large land areas cannot always be surveyed before an alignment is chosen. The regulation permits a phased process where alternatives are under consideration or where access to the whole area is not available. Identification and evaluation proceed as the design narrows, and the schedule for completing them is written into a programmatic agreement, an approach described in the consultation sequence and its agreement documents.

Phasing is a timing concession, not a substantive one. The work still has to be done, and doing it late means doing it with fewer options. Where phased survey later finds a significant site under a chosen alignment, the sponsor faces a redesign or the harder conversation described in adverse effect findings and the mitigation that follows. Where the site is archaeological and lies on federal or tribal land, a second statute applies independently, with its own permit requirement and its own penalties, set out in the rules governing archaeological resources on public land.