33 CFR § 329.13 - Geographic limits: Shifting boundaries.

---
identifier: "/us/cfr/t33/s329.13"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "33 CFR § 329.13 - Geographic limits: Shifting boundaries."
title_number: 33
title_name: "Navigation and Navigable Waters"
section_number: "329.13"
section_name: "Geographic limits: Shifting boundaries."
chapter_name: "CORPS OF ENGINEERS, DEPARTMENT OF THE ARMY, DEPARTMENT OF DEFENSE"
part_number: "329"
part_name: "DEFINITION OF NAVIGABLE WATERS OF THE UNITED STATES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "33 U.S.C. 401"
regulatory_source: "51 FR 41251, Nov. 13, 1986, unless otherwise noted."
cfr_part: "329"
---


# 329.13 Geographic limits: Shifting boundaries.

Permanent changes of the shoreline configuration result in similar alterations of the boundaries of the navigable waters of the United States. Thus, gradual changes which are due to natural causes and are perceptible only over some period of time constitute changes in the bed of a waterbody which also change the shoreline boundaries of the navigable waters of the United States. However, an area will remain “navigable in law,” even though no longer covered with water, whenever the change has occurred suddenly, or was caused by artificial forces intended to produce that change. For example, shifting sand bars within a river or estuary remain part of the navigable water of the United States, regardless that they may be dry at a particular point in time.