NHPA Section 106 Process Map
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NHPA Section 106 Process Map
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NEPA-NHPA coordination is one of the key sources of Section 106 process friction. Section 106 consultation chronically drifts late in the NEPA process, despite regulations requiring concurrent review. The mismatch is structural. Meaningful identification requires a defined project footprint (a fixed Area of Potential Effect). But NEPA requires evaluating multiple alternatives before a route is chosen. Conducting identification across all alternatives would overwhelm SHPOs and THPOs and conflicts with tribes' reluctance to disclose sacred sites speculatively. ACHP's coordination requirements lack enforcement, and NHPA does not compel agencies to select the alternative that best avoids historic effects. This weakens the incentive for early consultation. NATHPO describes the resulting pattern as a "bifurcated process" that places tribes in a reactive posture after designs have advanced.
The §106 and NEPA processes often run in parallel for the same federal project. Section 800.8 allows agencies to use the NEPA process to satisfy §106 under specific conditions, and not for every type of NEPA review. The diagram below shows the three NEPA pathways and how each one interacts with §106.
Plain-language definitions of the core terms used throughout the Section 106 process. Each entry cites the corresponding subsection of 36 C.F.R. §800.16.
| Undertaking§800.16(y) | Any project, activity, or program that a federal agency funds (even partly), carries out, or approves. This includes projects that a private company runs if the company needs a federal permit, license, or financial assistance. If the federal government has any hand in a project, that project is an "undertaking" and Section 106 applies. |
| Historic Property§800.16(l) | Any district, site, building, structure, or object — prehistoric or historic — that is listed on the National Register of Historic Places or that qualifies for listing. A property does not have to be officially listed to count; if it meets the National Register criteria, the agency must treat it as a historic property. This includes places of traditional religious and cultural importance to tribes or Native Hawaiian organizations, as long as those places meet the National Register criteria. |
| Effect§800.16(i) | Any change to a historic property that alters the qualities making that property worthy of the National Register. An "effect" can be physical (like demolition or construction damage), visual (like a new building blocking a historic viewshed), or environmental (like noise or pollution that changes the property's character). |
| Area of Potential Effects (APE)§800.16(d) | The boundary the agency draws around every area where a project could change historic properties — directly or indirectly. The agency must consider all types of effects: physical ground disturbance, visual changes, noise, and atmospheric impacts. A single project can have different APEs for different types of effects — for example, a wider boundary for visual impacts than for physical construction. |
| Consultation§800.16(f) | The back-and-forth process where the agency asks for, listens to, and seriously considers the views of other parties involved in the Section 106 review — and, where possible, works toward agreement. Consultation is not just sending a letter and waiting; the agency must genuinely engage. When tribes are involved, the agency must conduct government-to-government consultation, recognizing tribes as sovereign nations. |
| Memorandum of Agreement (MOA)§800.16(o) | A legally binding agreement that spells out exactly what the agency will do to avoid, reduce, or offset adverse effects on historic properties from a specific project. The agency, the SHPO or THPO, and (if participating) the Council all sign the MOA. Once signed, the MOA governs the project and all of the project's parts, and the agency must file a copy with the Council. |
| Programmatic Agreement (PA)§800.16(t) | A legally binding agreement that covers an entire agency program, a complex project, or a group of related projects — unlike an MOA, which covers just one project. Compliance with the PA satisfies Section 106 for every individual project the agreement covers, until the PA reaches its expiration date or one of the signatories terminates the agreement. |
| Foreclosure§800.16(j) | When an agency takes an action — like starting construction or committing funds — that makes it impossible for the Council's comments to matter anymore, because the agency can no longer meaningfully change course. The law prohibits foreclosure. The agency must complete the Section 106 review before spending federal money or issuing a license, not after. |
| Comment§800.16(e) | The formal, written findings and recommendations that the Advisory Council on Historic Preservation sends to the head of a federal agency under Section 106. Formal comments carry more weight than the Council's advisory opinions earlier in the process — the head of the agency must personally consider formal comments before making a final decision. |
| SHPO§800.16(v) | State Historic Preservation Officer — the official each state appoints to run the state's historic preservation program. The SHPO is the agency's primary partner in the Section 106 review for most projects. The SHPO reviews the agency's findings, concurs or objects, and signs any Memorandum of Agreement. |
| THPO§800.16(w) | Tribal Historic Preservation Officer — a tribal official who has formally taken over the SHPO's Section 106 responsibilities for projects on that tribe's lands. When a THPO is in place, the agency works with the THPO instead of (or alongside) the SHPO for projects on or affecting tribal lands. |
| National Historic Landmark (NHL)§800.16(p) | A historic property that the Secretary of the Interior has designated as one of the nation's most significant historic places. When a project would adversely affect a National Historic Landmark, the stakes go up: the Advisory Council on Historic Preservation must participate in the consultation, and the agency must notify the Secretary of the Interior. |
Natural Gas Act §§3, 7 · 18 CFR §§157.21, 380.14, 2.1c, 385.2201 · 36 CFR §§800.2(a)(3), 800.14(c) · ACHP Exemption, 67 FR 16364 (2002)
Project sponsors do much of the front-end cultural resources work for FERC, including records research, field investigations, and Resource Report 4 filings. Resource Report 4 is the portion of a FERC application that identifies cultural and historic resources along a proposed project and explains how the applicant will satisfy Section 106. But FERC remains legally responsible for Section 106 findings and determinations. Applicant assistance is best understood as a capacity tool, not a transfer of federal responsibility.
18 CFR §380.14, §380.12(f) · 36 CFR §800.2(a)(3) · FERC Cultural Resources Guidelines (2017)
FERC authorizes sponsors to begin outreach, but it does not delegate government-to-government Tribal consultation. FERC recognizes a trust responsibility to federally recognized Tribes and consults with Tribes and Alaska Native Claims Settlement Act Corporations through its broader statutory responsibilities, including but not limited to Section 106. If a Tribe does not want to coordinate with the project sponsor, FERC consults directly.
18 CFR §2.1c · FERC, Revised Policy Statement on Consultation with Indian Tribes, 84 FR 56940 (2019) · FERC Cultural Resources Guidelines (2017)
FERC's process depends on early cultural resource identification, but full surveys may be limited before a certificate is issued because sponsors generally need landowner permission, state-law access, or other authorization. This means Section 106 information can be uneven early in the proceeding, especially for long linear projects crossing many parcels.
Natural Gas Act §7 · FERC Cultural Resources Guidelines (2017)
FERC's quasi-judicial structure limits private, off-the-record communications in contested proceedings. Staff can discuss procedural environmental review issues and coordinate with agencies. But they must avoid communications that go to the merits of a contested case. This makes FERC different from land-management agencies that can consult more freely throughout project development. In practice, FERC may not engage with tribes once an application has been filed, a source of tension.
18 CFR §385.2201 (incl. §385.2201(e)) · FERC Cultural Resources Guidelines (2017)
The ACHP has exempted federal agencies from considering effects on historic natural gas pipelines themselves. The exemption does not eliminate Section 106 review for other historic properties affected by a pipeline project, does not apply on tribal land, and includes a documentation condition for certain abandonments.
ACHP, Exemption Regarding Historic Natural Gas Pipelines, 67 FR 16364 (Apr. 5, 2002) · 36 CFR §800.14(c)
33 CFR Part 325, Appendix C · Clean Water Act §404 · Rivers & Harbors Act §10
In plain terms
USACE does not run the standard Section 106 process. It follows its own rulebook — Appendix C, the Corps' alternative Section 106 compliance regulations — built around the Corps permit process. The central move is that the Corps limits its historic-property review to the "permit area" (the water it regulates, plus closely tied uplands), rather than the broader area a project might affect. For linear projects like pipelines, long stretches of the pipeline fall out of the Corps' review area. The chart shows how a permit application moves through that review. The primary point of friction in the historic property review process is around Clean Water Act Section 404 permits, though Appendix C also covers permits under Rivers and Harbors Act Section 10.
⚠ Structural vulnerability
The Corps' approach to Section 106 compliance has been politically and legally contentious. ACHP declared Appendix C "inconsistent" with §106 regulations because it altered the scope of analysis and curtailed consultation rights. The Corps' "permit area" approach attaches §106 review only to small federal handles (e.g., water crossings) within much larger oil pipeline corridors, leaving most of the corridor outside §106. The Dakota Access Pipeline (1,168 miles; only ~37 miles under federal authority) is the paradigmatic case. By the time courts heard the §106 claims, construction was complete.
Nationwide Programmatic Agreement · 36 CFR §800.14(b) · Federal Land Policy and Management Act of 1976
In plain terms
Section 106 normally requires a federal agency to check with a state's historic-preservation office, case by case, before it does anything that might affect a historic site. For projects on public lands, BLM maintains a Programmatic Agreement, a standing deal among the BLM, the national Advisory Council, and the state preservation officers, that lets the BLM handle most of those reviews in-house. In exchange, BLM adheres to an agreed set of rules. The chart below shows when the BLM may use the streamlined Programmatic Agreement, and when it must fall back to the normal process.