Section 106: Federal Review in California

Section 106 of the National Historic Preservation Act, codified at 54 U.S.C. 306108, requires a federal agency to consider how its actions affect historic properties before it approves them. It applies to any undertaking, which 36 CFR 800.16(y) defines as a project, activity, or program funded in whole or in part under the direct or indirect jurisdiction of a federal agency, carried out by or on behalf of a federal agency, carried out with federal financial assistance, or requiring a federal permit, license, or approval.

The practical test is whether federal money, federal land, or a federal permit touches your project. A Clean Water Act Section 404 permit, a federal loan guarantee, a right-of-way across BLM land, an FCC or FERC authorization, a Federal Highway Administration approval, HUD funding, and a Corps of Engineers permit all create that connection. A wholly private project on private land with only local permits does not, though California law may still apply.

No. Section 106 is procedural. It requires the agency to identify historic properties, assess effects, consult, and consider the outcome, and it does not require any particular result. An agency can lawfully approve a project that will destroy a historic property, provided it followed the process and considered comments by the Advisory Council.

Section 4(f) of the Department of Transportation Act works differently and is substantive. See what Section 4(f) is.

Because Section 106 is procedural, the risk it creates is procedural. Projects get delayed or enjoined because the record is thin, not because a resource was found.

There are four, and they run in order under 36 CFR 800.3 through 800.6.

• Initiate the process (800.3). The agency confirms the action is an undertaking with potential to affect historic properties, identifies the State or Tribal Historic Preservation Officer, and identifies consulting parties, including tribes.
• Identify historic properties (800.4). The agency defines the area of potential effects, makes a reasonable and good faith effort to identify historic properties within it, and evaluates whether they are eligible for the National Register.
• Assess adverse effects (800.5). The agency applies the criteria of adverse effect and reaches a finding.
• Resolve adverse effects (800.6). The agency consults to avoid, minimize, or mitigate, usually concluding in a Memorandum of Agreement.

If the agency and the SHPO cannot resolve an adverse effect, 36 CFR 800.7 sends the matter to the Advisory Council, which comments within 45 days.

The regulations set review clocks, not project schedules. The clocks that matter most:

• The SHPO or THPO has 30 days to respond to a request for review of a finding or determination. If it does not respond, the agency may proceed or consult with the Advisory Council instead (36 CFR 800.3(c)(4)).
• A finding of no historic properties affected becomes final if the SHPO or THPO does not object within 30 days (36 CFR 800.4(d)(1)).
• A finding of no adverse effect gets a 30-day SHPO or THPO review (36 CFR 800.5(c)). If the Advisory Council is asked for an opinion it responds within 15 days, extendable once by 15 days.
• The Advisory Council decides whether to join a resolution within 15 days of notice (36 CFR 800.6), and comments on a failure to resolve within 45 days (36 CFR 800.7).

Note what these clocks do not cover. Each of them attaches to a formal finding or determination submitted for review. Defining the area of potential effects, identifying and evaluating properties, and negotiating an agreement have no deadline at all, and on a project with an adverse effect they are usually where the time goes.

The area of potential effects, or APE, is the geographic area or areas within which an undertaking may directly or indirectly cause alterations in the character or use of historic properties (36 CFR 800.16(d)). It is not the project footprint, and it is not one shape. A project can have a small APE for direct ground disturbance and a much larger one for visual effects.

Getting the APE wrong is the most common reason a Section 106 submittal comes back. Draw it too small and the SHPO objects, draw it too large and you have paid for a survey you did not need.

Under 36 CFR 800.5(a)(1), an adverse effect exists when an undertaking may alter, directly or indirectly, any of the characteristics that qualify a historic property for the National Register in a manner that diminishes the integrity of its location, design, setting, materials, workmanship, feeling, or association. The provision reaches reasonably foreseeable effects that occur later in time, are farther removed in distance, or are cumulative.

The examples at 800.5(a)(2) include physical destruction or damage, alteration inconsistent with the Secretary of the Interior’s Standards, removal from the historic location, change to the character of the property’s use or to physical features in its setting, introduction of visual, atmospheric, or audible elements that diminish integrity, neglect that causes deterioration, and transfer or sale without adequate preservation restrictions.

They are different findings with different consequences. No historic properties affected means either that no historic properties are present in the area of potential effects or that none will be affected. No adverse effect means historic properties are present and will be affected, but not in a way that diminishes the qualities making them eligible.

The distinction matters beyond Section 106. A Section 4(f) de minimis impact finding for a historic site requires one of these two findings plus written SHPO or THPO concurrence (23 CFR 774.5(b)(1)). Once an adverse effect is found, the de minimis path closes.

No, and this is the most persistent misunderstanding in the field. Neither the National Historic Preservation Act nor the National Register criteria at 36 CFR 60.4 sets a 50-year eligibility threshold. The only 50-year reference in the criteria is Criteria Consideration G, which restricts properties younger than 50 years, allowing them only where they are of exceptional importance.

So fifty years is a floor for ordinary consideration, not a grant of eligibility. A property must still meet at least one of the four National Register criteria and retain integrity. A 1930s building with no significant association and heavy alteration is not eligible, and a 1985 building of exceptional importance can be.

For a federal undertaking, 36 CFR 800.13 governs post-review discoveries. If the agency has not planned for discoveries, it must notify the SHPO or THPO, any tribe or Native Hawaiian organization that might attach religious and cultural significance to the property, and the Advisory Council within 48 hours of the discovery. Those parties then have 48 hours to respond.

On tribal lands the agency must comply with tribal regulations and obtain the tribe’s concurrence on the proposed action (36 CFR 800.13(d)). Concurrence is a higher bar than consultation.

The better answer is to not be in this position. A discovery plan negotiated before ground disturbance converts a 48-hour scramble into a documented procedure, and it is the cheapest insurance in cultural resources compliance.

A Memorandum of Agreement resolves adverse effects for a specific undertaking. It records the mitigation the agency, the SHPO or THPO, and other signatories agreed to, and it must be filed with the Advisory Council before the agency approves the project (36 CFR 800.6).

A Programmatic Agreement covers a program or a class of undertakings rather than one project, under 36 CFR 800.14(b). Agencies use them where effects are similar and repetitive, where effects cannot be fully determined before approval, where the scope is regional or multi-state, or where non-federal parties hold major decision-making authority. If your project falls under an existing Programmatic Agreement, that document, not the standard four-step process, tells you what to do.

For California transportation work the relevant instrument is the Caltrans Section 106 Programmatic Agreement, which was replaced on December 6, 2024. See what changed in the Caltrans agreements.

Yes. 36 CFR 800.8(c) allows an agency to use its NEPA process to satisfy Section 106, provided it meets the standards in that section, including notifying the SHPO or THPO and the Advisory Council of its intent. That option remains available. The Council on Environmental Quality’s government-wide NEPA regulations came out of the Code of Federal Regulations by interim final rule effective April 11, 2025, adopted as a final rule effective January 8, 2026, but 36 CFR 800.8 contains no cross-references to them and was not affected.

One thing did change in practice. Section 800.8(c)(1)(iv) requires public involvement consistent with the agency’s published NEPA procedures, and most agencies rewrote those procedures in 2025 and 2026. What substitution requires procedurally now varies by agency, so check the specific agency’s current procedures rather than assuming a common baseline.

No. *Seven County Infrastructure Coalition v. Eagle County*, decided May 29, 2025, is a NEPA case. It held that courts owe agencies substantial deference on NEPA and that agencies need not analyze effects of separate projects or effects outside their regulatory authority, applying a “reasonably close causal relationship” test.

Section 106’s scope comes from 36 CFR Part 800, which the decision did not touch. Part 800 still reaches indirect effects and effects later in time, farther removed in distance, or cumulative. That means a federal agency can now produce a narrow NEPA effects analysis and still owe a broader Section 106 analysis on the same project. Anyone telling you *Seven County* shrank your cultural resources obligation is reading the case too broadly.

As of September 4, 2026, nothing has changed in the law. The Advisory Council on Historic Preservation voted 16 to 5, with 2 abstentions, on July 24, 2026, to advance a Notice of Proposed Rulemaking that would substantially rewrite 36 CFR Part 800. That notice is under interagency review at the Office of Management and Budget. It has not been published in the Federal Register, no comment period has opened, and there is no final rule.

Reporting on the draft describes several significant changes, including replacing the staged findings with a single agency-prepared report, narrowing the area of potential effects to direct effects, narrowing the definitions of historic property and undertaking, and allowing an agency to resolve adverse effects without SHPO or THPO agreement. The draft that circulated contains placeholders where the regulatory text should be, so the specifics are not settled even in draft form.

What this means for a project today: the current rules govern, and they govern until a final rule takes effect. If you are planning work that will run into 2027 or beyond, the more useful question is whether your agreement documents are written to survive a regulatory change. We are tracking the rulemaking and can tell you where your project sits.

There are, and their scope is contested. The national energy emergency declared in January 2025 was continued for a further year on January 12, 2026. The Advisory Council has issued guidance stating that agencies may use the expedited route at 36 CFR 800.12 with notification to the Council, SHPOs, THPOs, and tribes, and a seven-day comment period. The Department of the Interior adopted its own emergency Section 106 process in April 2025, tracking the energy resources named in the executive order: crude oil, natural gas, lease condensates, natural gas liquids, refined petroleum products, uranium, coal, biofuels, geothermal heat, the kinetic movement of flowing water, and critical minerals.

One caution worth understanding before you rely on it. Section 800.12(d) limits the emergency provisions to undertakings implemented within 30 days of the declaration unless the agency requests an extension. The Advisory Council has taken the position that the provisions run for the duration of the presidential declaration. That is the Council’s stated position rather than settled law, and no court has ruled on it. A project that relies on the expedited route inherits that uncertainty.