18 C.F.R. § 415.2
For the purposes of this part, except as otherwise required by the context:
Project means the same word as defined by section 1.2(g) of the Delaware River Basin Compact.
Floodway means the channel of the watercourse and those portions of the adjoining flood plains which are reasonably required to carry and discharge the regulatory flood. For this purpose the limit of the floodway shall be established by allowing not more than a one-foot rise of the water surface elevation of the regulatory flood as a result of encroachment. Wherever practical, equal conveyance reduction from each side of the flood plain shall be used. (See Figure 1.)
Flood fringe means that portion of the flood hazard area outside the floodway.
Flood hazard area means the area inundated by the regulatory flood.
Flood plain means the area adjoining the channel of a stream which has been or hereafter may be covered by flood water.
Floodproofing means any combination of structural and nonstructural additions, changes, or adjustments to properties and structures which reduce or eliminate flood damage to lands, water and sanitary facilities, structures, and contents of buildings.
Flood protection elevation means one foot above the elevation of the flood that has a one percent chance of occurring in any one year. (The 100-year flood).
Major tributary means the mainstem of the following streams:
Pennsylvania
Brandywine Creek, Brodhead Creek, Big Bushkill Creek, Lackawaxen, Lehigh, Schuylkill, Neshaminy.
Delaware
Brandywine Creek, Christina.
New York
East Branch, Mongaup, Neversink, West Branch.
New Jersey
Assunpink, Musconetcong, Paulins Kill, Rancocas, Pequest.
Official flood plain map means a map showing the flood plain area of a community prepared pursuant to the National Flood Insurance Act, or a map recognized by the Executive Director as meeting equivalent hydraulic or engineering criteria.
Regulatory flood means the flood which has a one percent chance of occurring in any one year. (The 100-year flood.)
Structure means any assembly of material above or below the surface of land or water, including but not limited to, buildings, dams, fills, levees, bulkheads, dikes, jetties, embankments, causeways, culverts, roads, railroads and bridges.
18 C.F.R. §415.2