33 U.S.C. § 403 — Obstruction of navigable waters generally; wharves; piers, etc.; excavations and filling in

This section protects the nation's navigable waters from unauthorized obstruction, building, and alteration. It works in three parts.

First, it bans creating any obstruction to the navigable capacity of United States waters, unless Congress has specifically authorized it.

Second, it bans building or starting to build any wharf, pier, dolphin, boom, breakwater, bulkhead, jetty, or other structure in any port, roadstead, haven, harbor, canal, navigable river, or other U.S. water. This ban applies outside established harbor lines, or anywhere harbor lines haven't been set. The only way around the ban is to follow plans that the Chief of Engineers has recommended and the Secretary of the Army has authorized.

Third, it bans excavating, filling, or otherwise changing the course, location, condition, or capacity of any port, roadstead, haven, harbor, canal, lake, harbor of refuge, or the area enclosed by any breakwater, or the channel of any navigable U.S. water. As with building structures, this work is only allowed if the Chief of Engineers recommended it and the Secretary of the Army authorized it before the work began.