FLOODPLAIN MANAGEMENT
Sections:
20.50.010 Statutory authority.
20.50.020 Statement of fact.
20.50.030 Purpose.
20.50.040 Intent.
20.50.050 Designation of county floodplain administrator.
20.50.060 Applicability.
20.50.070 Interpretation.
20.50.080 Warning and disclaimer of liability.
20.50.090 Development permit required.
20.50.100 Permit application.
20.50.110 Duties and responsibilities of the county floodplain administrator.
20.50.120 Standards for construction.
20.50.130 Variances.
20.50.140 Letter of map amendment (LOMA).
20.50.010 Statutory authority.
Pursuant to NRS 278.020, 244A.057, the county adopts the following floodplain
management regulations. (Ord. 763, 1996)
20.50.020 Statement of fact.
A. Portions of Douglas County are subject to periodic inundation by flood
waters which may result 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 uses that are inadequately elevated,
flood-proofed, or protected from flood damage. The cumulative effect of obstructions
in flood-prone areas increases flood heights and velocities which also contribute
to the flood loss. (Ord. 763, 1996)
20.50.030 Purpose.
It is the purpose of this chapter to promote the public health, safety,
and general welfare, and to minimize public and private losses due to flooding
in specific areas through the implementation of provisions designed to:
A. Protect human life and health;
B. Minimize expenditure of public money for costly flood control projects;
C. Minimize the need for rescue and relief efforts associated with flooding
which are usually at the expense of the general public;
D. Minimize prolonged business interruptions;
E. Minimize damage to public facilities and utilities such as water and
gas mains, electric, telephone and sewer lines, and streets and bridges located
in areas of special flood hazards;
F. Help maintain a stable tax base by providing for the sound use and development
of areas of special flood hazard so as to minimize property devaluation resulting
from flood damage and events;
G. Ensure potential buyers are notified that property is located in areas
of special flood hazards;
H. Ensure those who occupy the areas of special flood hazards assume responsibility
for their actions; and
I. Maintain qualifying standards for participation in the National Flood
Insurance Program. (Ord. 763, 1996; Ord. 472, 1987; Ord. D331, 1980; Ord. 158,
1956)
20.50.040 Intent.
The intent of this chapter is to incorporate development standards which
further the purpose as follows:
A. Restrict or prohibit uses which are dangerous to health, safety, and
property due to water or erosion hazards, or which result in damaging increases
in erosion, flood heights or velocities;
B. Require that uses vulnerable to floods, including facilities which serve
such uses, be protected against flood damage at the time of initial construction;
C. Control the alteration of natural floodplains, alluvial fans, stream
channels, and natural protective barriers, which help accommodate or channel
flood waters;
D. Control filling, grading, dredging, and other development which may
increase flood damage; and
E. Prevent or regulate the construction of flood barriers which will unnaturally
divert flood waters or which may increase flood hazards in other areas. (Ord.
763, 1996)
20.50.050 Designation of county floodplain
administrator.
The director is appointed county floodplain administrator and is responsible
for administration and implementation of this chapter. For the purposes of
this chapter the county floodplain administrator will simply be referred to
as “administrator”. (Ord. 801, 1997; Ord. 763, 1996; Ord. 472, 1987; Ord. 331,
1980)
20.50.060 Applicability.
A. This ordinance shall apply to all properties within the county which
are located within a FEMA designated special flood hazard zone and X-shaded
flood zone. For the purposes of this chapter, the areas of special flood hazard
or X-shaded flood zone identified by the Federal Insurance Administration (FIA)
of the Federal Emergency Management Agency (FEMA) in the Flood Insurance Study
(FIS) and accompanying Flood Insurance Rate Maps (FIRM) and Flood Boundary and
Floodway Maps (FBFM), dated September 30, 1992 and April 4, 1994, and all subsequent
amendments and or revisions are adopted by reference and declared to be a part
of the ordinance. The FIS and attendant mapping is the minimum area of applicability
of this ordinance and may be supplemented by studies for other areas which allow
implementation of this ordinance and which are recommended to the board by the
administrator. The FIS, FIRM’s and FBFM’s are on file with the community development
department.
B. No structure or land shall be constructed, located, extended, converted,
or altered without full compliance with the terms of this chapter and other
applicable regulations. A violation of the regulations is a criminal misdemeanor.
The board may take any lawful action to prevent or remedy any violation. (Ord.
801, 1997; Ord. 763, 1996; Ord. 472, 1987; Ord. 331, 1980)
20.50.070 Interpretation.
The interpretation and application of the provisions of this chapter shall
be the responsibility of the administrator and are:
A. Considered as minimum requirements; and
B. Deemed to neither limit nor repeal any other powers granted under state
statutes. (Ord. 763, 1996)
20.50.080 Warning and disclaimer of liability.
The degree of flood protection required by this chapter is considered reasonable
for regulatory purposes and is based on scientific and engineering considerations.
Larger floods can and will occur on occasion. Flood depths or heights may be
increased by man-made or natural causes. This ordinance does not imply that
land outside the areas of special flood hazards and the X-shaded zones or uses
permitted within such areas will be free from flooding or flood damages. This
ordinance shall not create liability on the part of the county, any officer
or employee, the state, or the Federal Insurance Administration, Federal Emergency
Management Agency, for any flood damages that result from reliance on this ordinance
or any lawful administrative decision. (Ord. 801, 1997; Ord. 763, 1996)
20.50.090 Development permit required.
A development permit is required for all construction and other development
to be undertaken in areas of special flood hazard and X-shaded zones in the
county. Applications for a permit shall be made on forms furnished by the county
and may include plans in duplicate, drawn to scale, showing the nature, location,
dimensions, and elevation of the area in question, existing or proposed structures,
fill, storage of materials and drainage facilities. (Ord. 763, 1996)
20.50.100 Permit application.
A. Where the property is located in a designated special flood hazard area,
the applicant shall provide at least the following information, where applicable:
1. For residential purposes, evidence that the parcel was in existence
prior to the adoption of this title, lawfully established pursuant to section
20.664.095, or the parcel contains a minimum 19 net acres. For any project
otherwise proposing parcels less than 19 acres in size, evidence that the area
within the special flood hazard area is retained in a natural state (no fencing
or improvements within parcel), held in common or single ownership with an overlying
drainage easement and the responsibility of a property owner’s association for
maintenance.
2. The proposed elevation in relation to mean sea level, of the
lowest floor, including the basement, of all residential and non-residential
structures whether new or substantially improved to be located in Zones A, A1-A30,
AE, and AH, if base flood elevations data are available.
3. The proposed elevation in relation to mean sea level, of the
lowest floor, including the basement, and the elevation of the highest adjacent
grade of all residential and non-residential structures whether new or substantially
improved to be located in Zone AO.
4. The proposed elevation in relation to mean sea level, to which
any new or substantially improved non-residential structure will be flood-proofed.
5. A certificate from a registered professional engineer or architect
in the state of Nevada stating that utility flood-proofing will meet the criteria
in subsection 20.50.120.G, standards for utilities.
6. A certificate from a registered professional engineer or architect
in the state of Nevada stating that any non-residential flood-proofed structures
will meet the criteria in subsection 20.50.120.E, non-residential flood-proofing
requirements.
7. A description of the extent to which any watercourse will be
altered or relocated as a result of the proposed development. Computations
by a registered professional engineer in the state of Nevada must be submitted
that demonstrate that the altered or relocated segment will provide equal or
more capacity than the original stream segment. The applicant must submit any
maps, computations or other material required by FEMA to the administrator for
submittal to FEMA to revise the documents enumerated in section 20.50.060, when
notified by the administrator, and must pay any fees or other costs assessed
by FEMA for this purpose. The applicant must also provide assurances that the
conveyance capacity of the altered or relocated stream segment will be maintained.
8. In certain circumstances the administrator will require a technical
analysis, by a professional engineer licensed in the state of Nevada, showing
that the proposed development located in the special flood hazard area will
not cause physical damage to any other property.
9. When there is no base flood elevation data available for Zone
A from any source, the base flood elevation data will be provided by the permit
applicant, and performed by a Nevada state licensed engineer.
10. A map produced by a professional engineer, licensed in the state
of Nevada, which clearly shows the limits of the special flood hazard area as
determined from the adopted FIRM, site topography, base flood elevation and
other best available information.
11. When required by the administrator, the applicant shall be required
to apply to FEMA for a conditional letter of map revision (CLOMR) and subsequent
letter of map revision (LOMR) in order that a finding can be made regarding
the impacts from proposed development.
B. Where the property is located in the X-shaded flood zone or other flood-prone
areas, as determined by the administrator, the applicant shall provide at least
the following information:
1. The proposed elevation above predeveloped adjacent grade of the
lowest floor (including basement) of all residential and non-residential structures
whether new or substantially improved.
2. The proposed elevation above predeveloped adjacent grade to which
any new or substantially improved non-residential structure will be flood-proofed.
3. In certain circumstances the administrator will require a technical
analysis, by a professional engineer licensed in the state of Nevada, showing
that the proposed development located in the X-shaded flood zone or flood-prone
area will not cause physical damage to any other property.
Additional information may be required on the permit application forms.
(Ord. 1129, 2005; Ord. 984, 2001; Ord. 801, 1997; Ord. 763, 1996; Ord. 567,
1992; Ord. 472, 1987; Ord. 331, 1980)
20.50.110 Duties and responsibilities of the
county floodplain administrator.
Duties and responsibilities of the administrator shall include, but not
be limited to the following:
A. Permit application review. A development permit will not be issued
for parcels within the special flood hazard zone or the X-shaded flood zone
until the administrator has certified that:
1. The application is complete and is consistent with the provisions
and standards of this chapter.
2. Ensure all other required state and federal permits have been
issued.
3. For residential purposes within the special flood hazard zone,
evidence that the parcel was in existence prior to the adoption of this title
or the parcel contains a minimum 19 net acres.
B. Use of other flood data.
1. When a development permit is required, the administrator shall
examine the project site in order to determine whether or not it is located
in a special flood hazard area based on current adopted FIRM’s and best available
information. When determining critical elevations for the development permit,
including but not limited to lowest floor, reference level and grading elevations,
the applicant shall use the greater or higher base flood elevation from either
the adopted FIRM or best available information.
C. Alteration of watercourses within FEMA designated flood zones. Prior
to the issuance of a permit for any alteration or relocation of a watercourse
the administrator must:
1. Verify that the applicant has notified all affected property
owners and communities, Nevada’s National Flood Insurance Program Coordinator,
Nevada Division of Water Resources and Federal Emergency Management Agency.
2. Determine that the permit holder has provided for maintenance
within the altered or relocated portion of the watercourse, based on information
provided by the applicant and other best available information, so that the
flood carrying capacity is not diminished.
D. Inspections. The administrator shall make periodic inspections throughout
the period of construction in order to monitor compliance with the requirements
of the floodplain development permit or any variance provisions.
E. Stop work orders. The administrator shall issue, or cause to be issued,
a stop work for any floodplain development not in compliance with the provisions
of this chapter or conditions of the development permit and all development
proceeding without a valid development permit.
F. Retaining floodplain development documentation. The administrator shall
obtain, retain for public inspection, and have available for the National Flood
Insurance Program or the Federal Emergency Management representative the following:
1. Floodplain development permits and certificates of compliance;
2. Certification for lowest floor elevation;
3. Certification for elevation or flood-proofing of nonresidential
structures;
4. Certification of elevation required as a part of division of
land;
5. Certification for floodway encroachments;
6. Variances issued pursuant to this chapter; and
7. Notices required for alteration of watercourses.
G. Map determinations. The administrator will make map interpretations
where needed, as to the location of the boundaries of the areas of special flood
hazard and where there appears to be a conflict between a mapped boundary and
actual field conditions. The applicant may be required to provide documentation
to assist the administrator in making the determination.
H. Appeals. Appeals of the decision of the administrator shall be made
in accordance with chapter 20.28 of this code. (Ord. 801, 1997; Ord. 763, 1996)
20.50.120 Standards for construction.
In all special flood hazard areas, the following standards apply:
A. Anchoring.
1. All new construction and substantial improvements shall be adequately
anchored to prevent flotation, collapse or lateral movement of the structure
resulting from hydrodynamic and hydrostatic loads, including the effects of
buoyancy.
2. All manufactured homes shall meet the required anchoring standards.
B. Construction materials and methods. All new construction and substantial
improvements shall be constructed:
1. With materials and utility equipment resistant to flood damage;
2. Design methods and practices that minimize flood damage;
3. To ensure electrical, heating, ventilation, plumbing, air conditioning
equipment and other service facilities are designed or located so as to prevent
water from entering or accumulating within the components during flooding;
4. Within flood zones AH or AO, with adequate drainage conveyance
structures to convey flood waters around and away from proposed structures.
C. Elevation requirements for lowest floor. Residential construction,
including the placement of manufactured housing units, new or substantial improvements,
shall have the lowest floor, including basement, as follows:
1. In zone AO, elevated above the predeveloped highest adjacent
grade to a height at least one foot above the depth number specified in feet
on the FIRM.
2. In zone A, elevated at least one foot above the base flood elevations
as determined by a Nevada state licensed engineer.
3. In zones AH, elevated at least one foot above the base flood
elevation as specified on the FIRM.
4. In zone AE, elevated at least one foot above the base flood elevation
as specified on the FIRM and determined by a Nevada State licensed engineer.
5. In all other zones, including X-Shaded and flood-prone areas,
elevated at least one foot above the base flood elevation or predeveloped highest
adjacent grade, whichever is greater, or as determined by the administrator.
D. Lowest floor certification requirements. Lowest floor certification
shall eomply with FEMA elevation certificate and instructions.
E. Non-residential flood-proofing requirements. Non-residential construction
shall either be elevated to conform with paragraph C, above, or together with
attendant utility and sanitary facilities as follows:
1. Shall be flood-proofed below the elevation so that the structure
is watertight with walls substantially impermeable to the passage of water;
and
2. Shall have the structural components capable of resisting hydrostatic
and hydrodynamic loads and effects of buoyancy; and
3. Shall be certified by a licensed professional engineer or architect
that the standards are satisfied. The certification shall be provided to the
administrator.
F. Requirements for areas below the lowest floor. All new construction
and substantial improvements within a special flood hazard area with fully enclosed
areas below the lowest floor (excluding basements) that are usable solely for
parking of vehicles, building access or storage, and which are subject to flooding,
shall be designed to automatically equalize hydrostatic flood forces on exterior
walls by allowing for the entry and exit of flood waters. Designs for meeting
this requirement must either be certified by a licensed professional engineer
or architect or meet or exceed the following minimum criteria:
1. Must have a minimum of two openings having a total net area of
not less than one square inch for every square foot of enclosed area subject
to flooding; and
2. The bottom of all such openings shall be no higher than one foot
above the lowest adjacent finished grade. The lowest adjacent finish grade includes
areas within the building crawl-space.
3. Openings may be equipped with louvers, valves, screens or other
coverings or devices provided they permit the automatic entry and exit of flood
waters.
G. Standards for utilities.
1. All new and replacement water supply systems shall be designed
to prevent infiltration and intermingling of flood waters.
2. All new and replacement sanitary sewage systems shall be designed
to prevent infiltration and intermingling of flood waters. Sanitary sewer and
storm drainage systems for buildings that have openings below the base flood
elevation shall be provided with automatic back-flow valves or other automatic
back-flow devices that are installed in each discharge line passing through
a building’s exterior wall.
3.On-site individual sewage disposal systems shall be designed,
constructed and located to avoid impairment to their functioning and to reduce
potential contamination during flood events.
H. Standards for divisions of land.
1. All tentative parcel and subdivision maps shall identify the
flood hazard area and the elevation of the base flood.
2. All tentative maps and grading plans are to provide the elevation
of proposed structures or building pads.
3. All tentative subdivision and parcel map proposals shall be designed
to minimize impacts to the floodplain, floodway as well as on- and off-site
flood damage.
4. All tentative subdivision and parcel map proposals shall design
and construct public utilities and facilities such as sewer, gas, electrical
and water systems to minimize flood damage.
5. Detailed hydrologic and hydraulic analyses required as part of
a map application must include analysis that demonstrates that the developed
project will not increase the base flood elevation by more than one foot at
any point within the community.
I. Standards for critical structures. Critical structures, as defined
in Appendix A of this title, are not permitted to be constructed within
a special flood hazard area, unless:
1. All alternative locations in flood zone X have been considered
and rejected.
2. All alternative locations in flood zone X-shaded have been considered
and rejected.
If the administrator determines the only practical alternative location for
the development of a new or substantially improved critical structure is in
a special flood hazard area, he shall give public notice of the decision and
reasons for the elimination of all alternative locations.
J. Special standards for manufactured homes.
1. All manufactured homes that are placed or substantially improved,
within zones A, AH, AE on the community’s Flood Insurance Rate Map shall be
elevated one foot on a permanent foundation so that the lowest floor will be
elevated to or above the base flood elevation and be securely anchored to an
adequately anchored foundation system to resist flotation, collapse and lateral
movement. Methods of anchoring may include, but are not to be limited to, use
of over-the-top or frame ties to ground anchors. This requirement is in addition
to applicable state and local anchoring requirements for resisting wind forces.
2. All manufactured homes to be placed or substantially improved
on sites in an existing manufactured home park or subdivision within zones A,
AH, and AE on the community’s Flood Insurance Rate Map are not subject to the
provisions of subparagraph 1, above, provided that:
a. The lowest floor of the manufactured home is at least one-foot
above the base flood elevation; or
b. The manufactured home chassis is supported by reinforced
piers or other foundation elements of at least equivalent strength that are
no less than 36 inches in height above grade and be securely anchored to an
adequately anchored foundation system to resist flotation, collapse, and lateral
movement.
K. Floodways. Designated floodways are located within the special flood
hazard areas. Since the floodway is an extremely hazardous area due to the
velocity of flood waters which carry debris, potential projectiles, and erosion
potential, the following provisions apply:
1. Encroachment will be prohibited, including fill, new construction,
substantial improvements, storage of equipment or supplies, and any other development
within the adopted regulatory floodway; unless it has been demonstrated through
hydrologic and hydraulic analyses, performed in accordance with standard engineering
practice that the proposed encroachment would not result in any increase in
flood levels within the community during the occurrence of the base flood discharge,
and FEMA has issued a Conditional Letter of Map Revision.
2. If subparagraph 1, above, has been satisfied, all proposed new
development and substantial improvements will comply with all other applicable
flood hazard reduction provisions of this chapter.
L. Alluvial fan areas.
1. All permit applications will be reviewed to determine if the
proposed development is located within an alluvial fan area and determine its
relation to designated flood zones.
2.The reviewing process will determine if the proposed site and
improvements, and adjacent or other affected properties, will be reasonably
safe from erosion, sediment deposition or flood hazards. Factors to be considered
in making this determination include but are not limited to the following:
a. Type and quality of soils;
b. Evidence of ground water or surface water problems;
c. Depth and quality of any fill;
d. The overall slope of the site; and
e. Location and character of conveyance facilities and structures
both up and downstream.
f. Impacts to conveyance capacities of existing drainages
and stormwater flow routes.
3. When a proposed development is located in an alluvial fan area,
the following shall be the minimum requirements:
a. A site investigation and further review shall be made
by persons qualified in geology and soils engineering;
b. The proposed grading, excavations, new construction, and
substantial improvements shall be adequately designed and protected against
erosion and flood damages both on- and off-site;
c. The proposed grading, excavations, new construction and
substantial improvements shall not aggravate the existing hazard by creating
either on-site or off-site disturbances; and
d. Drainage, planting, watering, and maintenance shall not
endanger ground or slope stability. (Ord. 984, 2001; Ord. 801, 1997; Ord. 763,
1996; Ord. 567, 1992; Ord. 472, 1987; Ord. 331, 1980)
A.
Nature of variances. A variance may be granted for a parcel of property with
physical characteristics so unusual that complying with the requirements of
this chapter would create an exceptional hardship to the applicant or the surrounding
property owners. The characteristics must be unique to the property and not
be shared by adjacent parcels. The unique characteristic must pertain to the
land itself, not to the structure, its inhabitants, or the property owners.
B. It is the duty of the planning commission and board to help protect
its citizens from flooding. This need is so compelling and the implications
of the cost of insuring a structure built below flood level are so serious that
variances from the flood elevation or from other requirements in the flood ordinance
are quite rare. The long term goal of preventing and reducing flood loss and
damage can only be met if variances are strictly limited.
C. Hearing board. In evaluating requests for variances, the board shall
consider all technical evaluations, all relevant factors, standards specified
in other chapters of this title, and determine that the request will not result
in:
1. Materials being swept onto other lands and injuring others;
2. Increased danger to life and property due to flooding or erosion
damage;
3. Increased susceptibility of the proposed facility and its contents
of flood damage and the effect of such damage on the existing individual owner
and future owners of the properly;
4. Reduction of services by the proposed facility to the community;
5. Incompatible use between existing development and anticipated
development;
6. An inconsistency with the master plan and floodplain management
program for the county and specific community;
7. Inadequate emergency access to the property in time of flood;
8. An increase in expected heights, velocity, duration, rate of
rise, and sediment transport of the flood waters expected at the site; and
9. Increased cost to the county and other agencies providing governmental
services during and after flood conditions, including maintenance and repair
of public utilities and facilities such as sewer, gas, electrical, and water
system, and streets and bridges.
D. General provisions.
1. Variances may be issued for new construction, substantial improvements,
and other proposed new development to be erected on a lot contiguous to or surrounded
by lots with existing structures constructed below the base flood level, provided
that the procedures of this chapter have been fully considered and complied
with.
2. Variances may be issued for the repair or rehabilitation of “historic
structures,” upon a determination that the proposed repair or rehabilitation
will not preclude the structure’s continued designation as an historic structure
and the variance is the minimum necessary to preserve the historic character
and design of the structure.
3. Variances shall not be issued within any mapped regulatory floodway
if any increase in flood levels during the base flood discharge would result.
4. Variances shall only be approved upon a determination that the
variance is the “minimum necessary” considering the flood hazard, to afford
relief. “Minimum necessary” means to afford relief with a minimum of deviation
from the requirements of this ordinance. For example, in the case of variances
to an elevation requirement, this means the board need not grant permission
for the applicant to build at grade, or even to the proposed elevation, but
only to that elevation which the board believes will provide relief and preserve
the integrity of the property.
5. In granting a variance, the board may attach such conditions
as it deems necessary to further the purposes of this chapter.
E. Required findings. In approving a request for a variance, the board
must make written findings of fact regarding the following:
1. A showing of good and sufficient cause;
2. A determination that failure to grant the variance would result
in exceptional hardship to the applicant;
3. A determination that the granting of a variance will not result
in increased flood heights, additional threats to public safety, or extraordinary
public expense, create a nuisance, cause fraud or victimization of the public,
or conflict with existing local laws or ordinances; and
4. That the applicant has signed a disclosure statement indicating
the he or she understands that:
a. The issuance of a variance to construct a structure below
the base flood level will result in increased premium rates for flood insurance;
and
b. Such construction below the base flood level increases
risks to life and property.
c. A copy the disclosure will be filed and recorded by the
county recorder in a manner so that it appears as an exception on the title
of the affected parcel of land. (Ord. 763, 1996)
20.50.140
Letter of map amendment (LOMA).
A. The following administrative procedures are provided to have the Federal
Insurance Administrator review information from an owner or lessee of property
who believes his property has been inadvertently included in a special flood
hazard area. These procedures shall not apply when there has been any alteration
of topography since the effective date of the first FIRM or FHBM showing the
property within an area of special flood hazard. The scientific or technical
information submission may include, but is not limited to the following:
1. An actual copy of the recorded map bearing the seal of the county
recorder, including recording information;
2. A topographical map showing:
a. Ground elevation contours in relation to the NVGD;
b. The total area of the property in question;
c. The location of the structure or structures located on
the property in question;
d. The elevation of the lowest adjacent grade to a structure
or structures; and
e. An indication of the curvilinear line which represents
the area subject to inundation by a base flood. The curvilinear line should
be based upon information provided by an appropriate authoritative source, such
as a federal agency, department of water resources, a county water control district,
the county engineer, a Federal Emergency Management Agency Flood Insurance Study,
or a determination by a licensed professional engineer;
3. A copy of the FHBM or FIRM indicating the location of the property
in question;
4. A certification by a registered professional engineer or licensed
land surveyor that the lowest grade adjacent to the structure is above the base
flood elevation; and
5. The completion of the appropriate forms in the FEMA’s Packet,
Amendments and Revisions To National Flood Insurance Program Maps. (Ord. 801,
1998; Ord. 763, 1996; Ord. 472, 1987; Ord. 331, 1980)
