Rivers and Harbors Act - Section 10
Section 10 of the Rivers and Harbors Act (33 U.S.C. 401 et seq.) requires authorization from the U.S. Army Corps of Engineers for the construction of any structure in or over any navigable waters of the United States, the excavation and dredging or deposition of material, or any obstruction or alteration to a navigable water. Work outside the limits of navigable waters may require a Section 10 permit if the structure or work affects the course, location, condition, or capacity of the water body.
Navigable waters of the U.S. are those subject to the ebb and flow of the tide shoreward to the mean high water mark and are used, or have been used in the past, to transport interstate or foreign commerce. This includes coastal and inland waters, lakes, rivers and streams that are navigable, and the territorial seas.
There is some overlap between Section 10 of the Rivers and Harbors Act and Section 404 of the Clean Water Act. Permits for activities requiring approval under both Section 10 of the Rivers and Harbors Act and Section 404 of the Clean Water Act are processed simultaneously by the U.S. Army Corps of Engineers.
For more information, see: https://www.epa.gov/cwa-404/section-10-rivers-and-harbors-appropriation-act-1899