BOARD00035

• Board Meeting Date: 6/3/1982
• Description: CWCB Meeting
• Board Meetings - Doc Type: Meeting

Comparison of CWCB and FEMA Model Regulations

The following is a list of the major differences between the
proposed final revised model regulations and FEMA's model
regulations. This should help explain why the State of Colorado
should develop its own model regulations rather than simply
adopt FEMA's model regulations:

Hazard Area Concept vs. Floodway Concept

The revised model regulations offer two concepts for
dividing the floodplain: the hazard area concept and the
floodway concept. FEMA uses only the floodway concept. The
staff feels that there are many cases in Colorado (for instancj,
in steep-sloped mountain streams) where the floodway concept is
not appropriate. For these reasons, the model regulations offer
the choice of either of the two concepts.

In addition, the criterion for the floodway concept in the
CWCB revised model regulations is a O.5-foot rise in water
surface elevation. The FEMA criterion is 1.0-foot rise, a
criterion which the staff feels can encourage too much
encroachment in many of Colorado's floodplains. The Urban
Drainage and Flood Control District (Denver Metro area) and many
communities in Colorado presently use the more restrictive 0.5-
foot rise criterion.

Floodprone Areas

For communities with approximate floodplain delineations,
FEMA has separate model regulations in addition to their model
regulations for communities with detailed delineations. Besides
combining regulations into one document, a step intended to help
communities that have both detailed and approximate delineations,
the CWCB revised model regulations are tied directly to the CWCB
designation process. In addition, they require not only that the
100-year floodplain be identified, as FEMA requires, but they
also require that detailed information be generated so that the
floodplain can be divided according either to the hazard area
concept or to the floodway concept. This detailed identification
is not, however, required for most agricultural or recreational
uses in flood prone areas.

Exemption for Water Diversion or Storage Structures and
for Bridges

FEMA does not exe~pt from their definition of "obstructions"
diversion or storage structures for water supply or irrigation or
bridges. The staff feels that this ignores the importance of
water development facilities in Colorado and the large number of
bridges across streams in Colorado. Under FEMA's model

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