---
kind: "section"
citation: "40 C.F.R. § 93.157"
title: "40"
number: "93.157"
heading: "Reevaluation of conformity."
url: "https://uscodex.org/cfr/40/93.157"
---

# §93.157. Reevaluation of conformity.

- (a) Once a conformity determination is completed by a Federal agency, that determination is not required to be re-evaluated if the agency has maintained a continuous program to implement the action; the determination has not lapsed as specified in [paragraph (b)](#b) of this section; or any modification to the action does not result in an increase in emissions above the levels specified in [§ 93.153(b)](/cfr/40/93.153.md?p=b). If a conformity determination is not required for the action at the time NEPA analysis is completed, the date of the finding of no significant impact (FONSI) for an Environmental Assessment, a record of decision (ROD) for an Environmental Impact Statement, or a categorical exclusion determination can be used as a substitute date for the conformity determination date.
- (b) The conformity status of a Federal action automatically lapses 5 years from the date a final conformity determination is reported under [§ 93.155](/cfr/40/93.155.md), unless the Federal action has been completed or a continuous program to implement the Federal action has commenced.
- (c) Ongoing Federal activities at a given site showing continuous progress are not new actions and do not require periodic re-determinations so long as such activities are within the scope of the final conformity determination reported under [§ 93.155](/cfr/40/93.155.md).
- (d) If the Federal agency originally determined through the applicability analysis that a conformity determination was not necessary because the emissions for the action were below the limits in [§ 93.153(b)](/cfr/40/93.153.md?p=b) and changes to the action would result in the total emissions from the action being above the limits in [§ 93.153(b)](/cfr/40/93.153.md?p=b), then the Federal agency must make a conformity determination.

## Notes

### Amendments

[75 FR 17276, Apr. 5, 2010]

### Source

Source: 58 FR 63253, Nov. 30, 1993, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Source

Source: 58 FR 62235, Nov. 24, 1993, unless otherwise noted.

### Amendments

[75 FR 17276, Apr. 5, 2010]