6.030 De:nitions.

Unless speciLcally deLned below, words or phrases used in this Ordinance shall be interpreted so as to give them

the meaning they have in common usage and to give this ordinance the most reasonable application.

A. Alter. In the context of this Article and the changing of a riverine or drainage channel, shall mean any activity

which decreases, increases, or otherwise causes changes to the carrying capacity of said riverine or drainage

channel.

B. Appeal. A request for a review of the Floodplain Administrator’s interpretation of any provision of this

ordinance or a request for a variance.

C. Area of Shallow Flooding. A designated AO, AH, or VO zone on the Flood Insurance Rate Map (FIRM). The base

Mood depths range from one to three feet; a clearly deLned channel does not exist; the path of Mooding is

unpredictable and indeterminate; and, velocity Mow may be evident.

D. Area of Special Flood Hazard. The land in the Mood plain within a community subject to a one percent or

greater chance of Mooding in any given year.

E. Base Flood. The Mood having a one percent chance of being equaled or exceeded in any given year (also called

the “100 year Mood”).

F. Basement. Any area of the building having its Moor subgrade, i.e., below ground, level on all sides.

G. Breakaway Walls. Any type of wall, whether solid or lattice, and whether constructed on concrete, masonry,

wood, metal, plastic or any other suitable building material which is not part of the structural support of the

building and which is designed to break away under abnormally high tides or wave action without causing any

damage to the structural integrity of the building on which they are used or any buildings to which they might be

carried by Mood waters. A breakaway wall shall have a safe design loading resistance of not less than ten and no

more than twenty pounds per square foot. Use of breakaway walls must be certiLed by a registered engineer or

architect and shall meet the following conditions:

1. Breakaway wall collapse shall result from a water load less than that which would occur during the base

Mood; and

2. The elevated portion of the building shall not incur any structural damage due to the eOects of wind and

water loads acting simultaneously in the event of the base Mood.

The Petaluma Implementing Zoning Ordinance is current through Ordinance 2907, passed September 8, 2025.

Ch. 6 Floodway and Flood Plain Districts | Petaluma Implementing Zoning Ordinance Page 4 of 15

H. Coastal High Hazard Area. The area subject to high velocity waters, including coastal and tidal inundation or

tsunamis. The area is designated on a Flood Insurance Rate Map (FIRM) as Zone V1-V30, VE or V.

I. Development. Any man-made change to improved or unimproved real estate including, but not limited to,

buildings or other structures, mining, dredging, Llling, grading, excavation, drilling operations, permanent storage

of equipment and materials (i.e., lumber yards, junk yards, vehicle storage yards, etc.), excluding the improvement

or maintenance of public roads.

J. Development Permit. A zoning permit, grading permit or building permit or any other permit, certiLcate, or

license pertaining to the erection, construction, reconstruction, moving, conversion, alteration, or addition to any

building or structure and the use of any land, building or premise, per the procedure set forth in Section 6.070(B).

K. Flood or Flooding. A general and temporary condition of partial or complete inundation of normally dry land

areas from: (1) the overMow of inland or tidal waters; (2) the unusual and rapid accumulation or runoO of surface

waters from any source; and/or (3) the collapse or subsidence of land along the shore of a lake or other body of

water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical

levels or suddenly caused by an unusually high water level in a natural body of water, accompanied by a severe

storm, or by an unanticipated force of nature, such as Mash Mood or an abnormal tidal surge, or by some similarly

unusual and unforeseeable event which results in Mooding as deLned in this deLnition.

L. Flood Boundary and Floodway Map. The oNcial map on which the Federal Emergency Management Agency or

Federal insurance Administration has delineated both the areas of Mood hazard and the Moodway.

M. Flood Insurance Rate Map (FIRM). An oNcial map of the City of Petaluma or Sonoma County, on which the

Federal Insurance Administration has delineated both the areas of special Mood hazards and the risk premium

zones applicable to the community.

N. Flood Insurance Study. The oNcial report provided by the Federal Insurance Administration. The report

contains Mood proLles, as well as the Flood Boundary-Floodway Map, the Flood Insurance Rate Maps, and the

water surface elevation of the base Mood.

O. Floodplain or Flood-prone Area. Any land area susceptible to being inundated by water from any source (see

deLnition of Mooding).

P. Floodplain Management. The operation of an overall program of corrective and preventive measures for

reducing Mood damage, including but not limited to emergency preparedness plans, Mood control works, and

Moodplain management regulations.

Q. Floodplain Management Regulations. Zoning ordinances, subdivision regulations, building codes, health

regulations, special purpose ordinances (such as Moodplain ordinance, grading ordinance and erosion control

ordinance), and other applications of police power. The term describes such state or local regulations in any

combination thereof, which provide standards for the purpose of Mood damage prevention and reduction.

R. Floodproofed. Watertight with walls substantially impermeable to the passage of water and with structural

components having the capability of resisting hydrostatic and hydrodynamic loads and eOects of buoyancy.

The Petaluma Implementing Zoning Ordinance is current through Ordinance 2907, passed September 8, 2025.

Ch. 6 Floodway and Flood Plain Districts | Petaluma Implementing Zoning Ordinance Page 5 of 15

S. Floodproo4ng. Any combination of structural and nonstructural additions, changes, or adjustments to

structures which reduce or eliminate Mood damage to real estate or improved real property, water and sanitary

facilities, structures and their contents.

T. Floodway. Also referred to as regulatory Moodway. The channel of a river or other watercourse and the

adjacent land areas that must be reserved in order to discharge the base Mood without cumulatively increasing the

water surface elevation more than one (1) foot.

U. Functionally Dependent Use. A use which cannot perform its intended purpose unless it is located or carried

out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the

loading and unloading of cargo or passengers, and ship building and ship repair facilities, but does not include

long-term storage or related manufacturing facilities.

V. Habitable Floor. Any Moor usable for living purposes, which includes working, sleeping, eating, cooking or

recreation, or a combination thereof. A Moor used only for storage purposes is not a “habitable Moor”.

W. Highest Adjacent Grade. The highest natural elevation of the ground surface prior to construction next to the

proposed walls of a structure.

X. Lowest Floor. The lowest Moor of the lowest enclosed area (including basement). An unLnished or Mood

resistant enclosure, usable solely for parking of vehicles, building access or storage in an area other than a

basement area is not considered a building’s lowest Moor; provided that such enclosure is not built so as to render

the structure in violation of the applicable non-elevation design requirements of this ordinance.

Y. Manufactured Home. A structure, transportable in one or more sections, which is built on a permanent chassis

and is designed for use with or without a permanent foundation when connected to the required utilities. For

Moodplain management purposes, the term “manufactured home” also includes park trailers, travel trailers and

other similar vehicles placed on a site for greater than 180 consecutive days.

Z. Manufactured Home Park or Subdivision. A parcel (or contiguous parcels) of land divided into two or more

manufactured home lots for sale or rent.

AA. Mean Sea Level. For purposes of the National Flood Insurance Program, the National Geodetic Vertical Datum

(NGVD) of 1929 or other datum, to which base Mood elevations shown on a community’s Flood Insurance Rate

Map are referenced.

BB. New Construction. Structures for which the “start of construction” commenced on or after the eOective date of

this Ordinance.

CC. No Net Fill. Any material brought on to a project site within a Mood plain area that would displace Mood

waters. All Lll shall be oOset by the removal of a like amount of material. This material may be removed from a

portion of the project site; or it may be removed from a site in the immediate area where the removal of

compensating material from the oO-site location can be determined, to the satisfaction of the City Engineer and

the Sonoma County Water Agency, to result in a reasonable equivalence of hydrology and hydraulics to the

The Petaluma Implementing Zoning Ordinance is current through Ordinance 2907, passed September 8, 2025.

Ch. 6 Floodway and Flood Plain Districts | Petaluma Implementing Zoning Ordinance Page 6 of 15

situation before the development. For purposes of compliance, one or more individual parcels or an entire reach

may demonstrate a “zero net Lll” balance.

DD. Petaluma River Basin. All signiLcant Mooding sources aOecting the City of Petaluma including the Petaluma

River, Washington Creek, Lynch Creek, Willow Brook, Thompson Creek, Kelly Creek, Adobe Creek, Capri Creek,

Corona Creek, and several minor tributaries thereto.

EE. Person. An individual or his agent, Lrm, partnership, association or corporation, or agent of the

aforementioned groups, or this state or its agencies or political subdivisions.

FF. Regulatory Floodway. The channel of a river or other watercourse and the adjacent land areas that must be

reserved in order to discharge the base Mood without cumulatively increasing the water surface elevation more

than one foot.

GG. Remedy a Violation. To bring the structure or other development into compliance with State or local

Moodplain management regulations, or, if this is not possible, to reduce the impacts of its noncompliance to a level

acceptable to the City. Ways that impacts may be reduced include protecting the structure or other aOected

development from Mood damages, implementing the enforcement provisions of the ordinance or otherwise

deterring future similar violations, or reducing Federal Lnancial exposure with regard to the structure or other

development.

HH. Riverine. Relating to, formed by, or resembling a river (including tributaries), stream, brook, etc.

II. Special Flood Hazard Area (SFHA). An area having special Mood or Mood-related erosion hazards, and shown on

an FHBM or FIRM as Zone A, AO, A1-30, AE, A99, AH, V0, V1-V30, VE or V.

JJ. Start of Construction. Includes substantial improvements, rehabilitations, additions and reconstructions, and

means the date the building permit was issued, provided the actual start of construction, repair, reconstruction,

placement, or other improvement was within 180 days of the permit date. The actual start means either the Lrst

placement of permanent construction of a structure on a site, such as the pouring of a slab or footings, the

installation of piles, the construction of columns, or any work beyond the stage of excavation; or placement of a

manufactured home on foundation. Permanent construction does not include land preparation, such as clearing,

grading and Llling; nor does it include the installation of streets and/or sidewalks; nor does it include excavation

for a basement, footing, piers, or foundations or the erection of temporary forms; nor does it include the

installation on the property of accessory buildings, such as garages or sheds not occupied as dwelling units or not

part of the main structure.

KK. Structure. A walled and/or roofed building, including a gas or liquid storage tank, that is principally above

ground, as well as a manufactured home.

LL. Substantial Improvement. Any repair, reconstruction, rehabilitation, addition or improvement of a structure,

the cost of which exceeds 50 percent of the market value of the structure, not inclusive of the land value, before

the start of construction of the improvement either (1) before the improvement or repair is started; or (2) if the

structure has been damaged and is being restored, before the damage occurred. For the purposes of this

deLnition, “substantial improvement” is considered to occur when the Lrst alteration of any wall, ceiling, Moor, or

The Petaluma Implementing Zoning Ordinance is current through Ordinance 2907, passed September 8, 2025.

Ch. 6 Floodway and Flood Plain Districts | Petaluma Implementing Zoning Ordinance Page 7 of 15

other structural part of the building commences, whether or not that alteration aOects the external dimension of

the structure. The term does not, however, (1) include any project for the improvement of a structure to comply

with existing state or local health, sanitary, or safety code speciLcations which are solely necessary to assure safe

living conditions; or (2) any alteration of a structure listed on the National Register of Historic Places or a State of

City Inventory of Historic Places provided that the alteration will not preclude the structure’s continued

designation as a historic structure.

MM. Variance. A grant of relief from the requirements of this ordinance which permits construction in a manner

that would otherwise be prohibited by this ordinance.

NN. Violation. The failure of a structure or other development to be fully compliant with the community’s

Moodplain management regulations. A structure or other development without the elevation certiLcate, other

certiLcations, or other evidence of compliance required in this ordinance is presumed to be in violation until such

time as that documentation is provided.