FLOOD04031

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Subdivision Design in Flood Hazard Areas
• Date: 9/1/1997
• Prepared For: State of Colorado
• Prepared By: FEMA
• Floodplain - Doc Type: Educational/Technical/Reference Information

mitigate any impact on flood elevations. The most
important loss of storage in most watercourse situations is
the fill that occurs at elevations near where the peak flood
elevation "..ill occur. Offstream storage that occurs at the
time of peak runoff will be the most effective in attenuating
peak flow. The WRD therefore recommends that in-kind
replacement storage must be provided whenever fill is
allowed to be placed with the 100-year floodplain for most
watercourses. In-kind replacement is defined as excavating
at the same relative elevation (hydraulically equivalent) as
fill occurs. The impact of lost floodplain storage to flood
elevations "..rill vary from watercourse to watercourse
depending on several factors such as width of the
flood way, total instream and offstream storage, etc.

Policies
1. Fill \ViII not be allowed where the depth of the 100-year
flood is greater than two feet. Exceptions may be made on
a case-by-case basis for the follo\Ving:

a) Agricultural and Agricultural/Residential zoned parcels;
b) Minor tributary swales and areas where piped
drainage is required by County Improvement
standards;
c) Watercourse crossings.

2. There will be no net loss of storage within the 100-
year floodplain. In-kind replacement of lost storage
will be required. The following exceptions will be
allowed:
[exceptions (a) and (b) are specific place names of creeks in
Sacramento County and are not noted here]

c) Agricultural and Agricultural/Residential zoned
parcels of five acres or greater, on a case-by-case
basis;
d) Areas where piped drainage is required by the County
Improvement Standards.

Excerpts from the San Diego County, California,
Code of Regulatory Ordinances Relating to Flood Damage Prevention
(Ordmance No. 8334, December 7, 19Y3)

Sec. 811.102. Findings of Fact
a) The flood hazard areas of the County of San Diego are
subject to periodic inundation which results in loss of life
and property, health and safety hazards, disruption of
commerce and governmental services, extraordinary public
expenditures for flood protection and relief, and
impairment of the tax base, all of which adversely affect
the public health, safety and general welfare.

b) These flood losses are caused by the cumulative effect of
obstructions in areas of special flood hazards which
increase flood heights and velocities, and when
inadequately anchored, damage uses in other areas. Uses
that are inadequately flood proofed, elevated or
otherwise protected from flood damage also contribute
to the flood loss.

Sec. 811.103. Statement of Purpose
It is the purpose of this ordinance to promote the public
health, safety, and general welfare, and to minimize public
and private losses due to flood conditions in specific areas by
provisions designed:
a) to protect human life and health;

b) to minimize expenditure of public money for costly flood
control projects;

c) to minimize the need for rescue and relief efforts
associated ,....ith flooding and generally undertaken at the
expense of the general publicj

d) to minimize prolonged business interruptions;

e) to minimize damage to public facilities and utilities such as
water and gas mains, electric, telephone and sewer lines,
streets and bridges, located in areas of special flood
hazardj

f) to help maintain a stable tax base by providing for the
second use and development of areas of special flood
hazard so as to minimize future flood blight areas;

g) to ensure that potential buyers are notified that propet:ty is
in an area of special flood hazard; and

h) to ensure that those who occupy the areas of special flood
hazard assume responsibility for their actions.

Section 811.104. Methods of Reducing Flood Losses
In order to accomplish its purpose, this ordinance includes
methods and provisions for:
a) restricting or prohibiting uses which are dangerous to
health, safety, and property due to water or erosion
hazards, or which result in damming increases in erosion
or flood heights or velocities;
b) requiring that uses vulnerable to floods, including facilities
which serve such uses, be protected against flood damage
at the time of initial constructionj
c) controlling the alteration of natural flood plains, stream
channels, and natural protective barriers, which help
accommodate or channel flood waters;
d) controlling filling, grading, dredging, and other
development which may increase flood damage; and
e) preventing or regulating the construction of flood barriers
which will unnaturally divert flood waters or which may
increase flood hazards in other areas.

Sec. 811.401. Development Permit
A development permit shall be obtained before construction
or development begins within any area of special flood
hazards, established in section 811.302 [in San Diego County,
alluvial fans are the primary area of special flood hazard].
Application for a development permit may include but not be
limited to: plans in duplicate drav..'1l to scale showing the
nature, location, dimensions, and elevation of the area in
question; existing or proposed structures; fill storage of
materials, drainage facilities; and the location of the foregoing.
Specifically the following information is required.
a) Proposed elevation in relation to mean sea level of the
lowest floor (including basement) of all structures; in Zone
AO, elevation of the highest adjacent grade and proposed
elevation of lowest flood of all structuresj
b) Proposed elevation in relation to mean sea level to which
any structure will be floodproofed;
c) All appropriate certifications listed in Section 811.403 of
this ordinance;
d) Description of the extent to which any watercourse Mil be
altered or relocated as a result of proposed development; and

59