[Code of Federal Regulations]
[Title 28, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 28CFR63.4]

[Page 155-156]
 
                    TITLE 28--JUDICIAL ADMINISTRATION
 
              CHAPTER I--DEPARTMENT OF JUSTICE (Continued)
 
PART 63--FLOODPLAIN MANAGEMENT AND WETLAND PROTECTION PROCEDURES--Table of Contents
 
Sec. 63.4  Definitions.

    Throughout this part, the following basic definitions shall apply:
    (a) Action--any Federal activity including:
    (1) Acquiring, managing and disposing of Federal lands and 
facilities;
    (2) Providing federally undertaken, financed, or assisted 
construction and improvements; and
    (3) Conducting Federal activities and program affecting land use, 
including but not limited to water and related land resources planning, 
regulating, and licensing activities.
    (b) Agency-- an executive department, a government corporation, or 
an independent establishment and includes the military departments.
    (c) Base flood-- that flood which has a one percent chance of 
occurrence in any given year (also known as a 100-year flood). (This 
term is used in the National Flood Insurance Program (NFIP) to indicate 
the minimum level of flooding to be used by a community in its 
floodplain management regulations.)
    (d) Base floodplain-- the 100-year floodplain (one percent chance 
floodplain). Also see definition of floodplain.
    (e) Channel-- a natural or artificial watercourse of perceptible 
extent, with a definite bed and banks to confine and conduct 
continuously or periodically flowing water.
    (f) Critical action--any activity for which even a slight chance of 
flooding would be too great.
    (g) Facility-- any man-made or man-placed item other than a 
structure.
    (h) Flood or flooding-- a general and temporary condition of partial 
or complete inundation of normally dry land areas from the overflow of 
inland and/or tidal waters, and/or the usual and rapid accumulation or 
runoff of surface waters from any source.
    (i) Flood fringe-- that portion of the floodplain outside of the 
regulatory

[[Page 156]]

floodway (often referred to as ``floodway fringe'').
    (j) Floodplain-- the lowland and relatively flat areas adjoining 
inland and coastal waters including floodprone areas of offshore 
islands, including at a minimum, that area subject to a one percent or 
greater chance of flooding in any given year. The base floodplain shall 
be used to designate the 100-year floodplain (one percent chance 
floodplain). The critical action floodplain is defined as the 500-year 
floodplain (0.2 percent chance floodplain).
    (k) Floodproofing-- the modification of individual structures and 
facilities, their sites, and their contents to protect against 
structural failure, to keep water out or to reduce effects of water 
entry.
    (l) Minimize-- to reduce to the smallest possible amount or degree.
    (m) One percent chance flood-- the flood having one chance in 100 of 
being exceeded in any one-year period (a large flood). The likelihood of 
exceeding this magnitude increases in a time period longer than one 
year. For example, there are two chances in three of a larger flood 
exceeding the one percent chance flood in a 100-year period.
    (n) Practicable-- capable of being done within existing constraints. 
The test of what is practicable depends upon the situation and includes 
consideration of the pertinent factors, such as environment, cost or 
technology.
    (o) Preserve-- to prevent modification to the natural floodplain 
environment or to maintain it as closely as possible to its natural 
state.
    (p) Regulatory floodway-- the area regulated by Federal, State or 
local requirements; the channel of a river or other watercourse and the 
adjacent land areas that must be reserved in an open manner, i.e., 
unconfined or unobstructed either horizontally or vertically, to provide 
for the discharge of the base flood so the cumulative increase in water 
surface elevation is no more than a designated amount (not to exceed one 
foot as set by the NFIP).
    (q) Restore-- to re-establish a setting or environment in which the 
natural functions of the floodplain can again operate.
    (r) Structures-- walled or roofed buildings, including mobile homes 
and gas or liquid storage tanks that are primarily above ground (as set 
by the NFIP).
    (s) Wetlands--``those areas that are inundated by surface or ground 
water with a frequency sufficient to support and under normal 
circumstances does or would support a prevalence of vegetative or 
aquatic life that requires saturated or seasonally saturated soil 
conditions for growth and reproduction. Wetlands generally include 
swamps, marshes, bogs, and similar areas such as sloughs, potholes, wet 
meadows, river overflows, mud flats, and natural ponds'' (as defined in 
Executive Order 11990 (Protection of Wetlands)).