§42-235.4
Standards for Floodplains Without Established Base Flood Elevations. 
Within the Special Flood Hazard Areas designated as Approximate Zone A and established in §42-233.2 (Basis for
Establishing the Special Flood Hazard Areas), where no BFE data has been provided by FEMA, the following
provisions, in addition to §42-235.1 (General Standards), shall apply:
A.
No encroachments, including fill, new construction, substantial improvements or new development shall be
permitted within a distance of 20 feet from each side of the stream measured from the top of the bank or
five (5) times the width of the stream, whichever is greater, unless certification with supporting technical
data by a registered professional engineer is provided demonstrating that such encroachments shall not
result in any increase in flood levels during the occurrence of the base flood discharge. 
B.
The BFE used in determining the Regulatory Flood Protection Elevation shall be determined based on one
(1) of the following criteria set in priority order:
(1)
When BFE data is available from other sources, such as Federal, State or other, all new
construction and substantial improvements within such areas shall also comply with all applicable
provisions of this subpart and shall be elevated or flood proofed in accordance with standards in
this §42-235.1 (General Standards) and §42-235.2 (Specific Standards).
(2)
When floodway or non-encroachment area data are available from a Federal, State, or other
source, all new construction and substantial improvements within floodway and non-encroachment
areas shall also comply with the requirements of §42-235.2 (Specific Standards) and §42-235.6
(Floodways and Non-Encroachment Areas).
(3)
When a subdivision, manufactured home park or other development proposal is greater than five
(5) acres or has more than 50 lots/manufactured home sites/spaces, BFE data shall be provided.
Such BFE data shall be adopted by reference in accordance with §42-233.2 (Basis for Establishing
the Special Flood Hazard Areas).
(4)
When BFE data is not available from a Federal, State, or other source as outlined above, the
reference level shall be elevated or flood proofed to or above the Regulatory Flood Protection
Elevation as defined in Article XIV (Definitions).