Attachment 2 Agency CommentsCity of Tigard
REQUEST FOR COMMENTS
DATE: March 31, 2023
TO: Affected Agency
FROM: City of Tigard Planning Division
STAFF CONTACT: Agnes Lindor, Senior Planner
Phone: (503) 718-24 29 Email: AgnesL@tigard-or.gov
DCA2025-00001
-FEMA ESA Compliance Amendments -
PROPOSAL: The City is proposing development code and municipal code amendments to the Area of Special Flood
Hazard regulations. The amendments to the development code are necessary to incorporate regulatory changes required
by the Federal Emergency Management Agency (FEMA) as they relate to the Endangered Species Act (ESA). These
regulatory changes are required in order for the City of Tigard to continue participation in the National Flood Insurance
Program (NFIP). The proposed amendments include:
-Updates to Municipal Code Chapter 9.10 that add new definitions and no net loss standards; and
-Updates to Chapter 18.510, Sensitive Lands, to require a no net loss analysis with a sensitive lands review for
development within areas of special flood hazard.
LOCATION: Citywide. ZONE: All zones with Areas of Special Flood Hazard . APPLICABLE REVIEW
CRITERIA: Statewide Planning Goals 1 (Citizen Involvement), 2 (Land Use Planning), 7 (Areas subject to Natural
Hazards); METRO’s Urban Growth Management Functional Plan Titles 3, and 8; Comprehensive Plan Goals 1.1.2, 2.1.1,
2.1.2, 2.1.3, 2.1.11, 2.1.20, 7.1.4, 7.1.5, 7.1.7, 7.1.8, 7.1.9, 7.1.11, 7.1.14, and 11.1.1; and Tigard Development Code
Chapters 18.790, Text and Map Amendments.
From information supplied by various departments and agencies and from other information available to our staff, a report
and recommendation will be prepared and a decision will be rendered on the proposal in the near future. If you wish to
comment on this application, WE NEED YOUR COMMENTS BACK BY: MONDAY, APRIL 14, 2025. You may use
the space provided below or attach a separate letter to return your comments. If you are unable to respond by the above
date, please phone the staff contact noted above with your comments and confirm your comments in writing as soon as
possible. If you have any questions, contact the Tigard Planning Division, 13125 SW Hall Boulevard, Tigard, OR 97223.
PLEASE CHECK THE FOLLOWING ITEMS THAT APPLY:
We have reviewed the proposal and have no objections to it.
Please contact of our office.
Please refer to the enclosed letter.
Written comments provided below:
Name & Number of Person(s) Commenting:
X See body of email
Jevra Brown, Aquatic Resource Planner, Department of State Lands
Attachment 2
From: BROWN Jevra * DSL
Sent: Wednesday, April 9, 2025 3:07 PM
To: Agnes Lindor
Subject: RE: Request for Comments: DCA2025-00001 FEMA ESA Compliance
A achments: TigardRFCommentsFEMABiOp.pdf
Agnes & the City of Tigard,
Thank you for asking the Department of State Lands to review your proposed
changes to the City’s code. The proposed changes are in response to the Federal
Emergency Management Agency (FEMA) Na onal Flood Insurance Program (NFIP)
Biological Opinion (BiOp) Pre-Implementa on Compliance Measures (PICM). Many of my
comments are typographical rather than substan ve…😉 Other comments are not on
sec ons that are proposed for current changes, but are either ques ons on the intent of
the sec on, or areas where the city and the department may benefit from further
discussion. I did not review the Title 9 document because it is very FEMA centric &
mostly (en rely?) outside of DSL’s regulatory authority, that is, we regulated removal & fill
within wetlands and waters that may be within the floodplain, but separately from FEMA.
1) RE.: 18.510.020 A. 3. Wetlands that appear on the City of Tigard "Wetland and
Stream Corridors Map" but are not regulated by other agencies including the U.S. Army
Corps of Engineers and the Division of State Lands…” The Department of State Lands has
been a Department for about 20 years. Please update the name throughout the
document.
2) I assume the above noted paragraph is to bring wetlands into local regula on that are
not regulated either federally or by the state, while under B. 3? The city is delega ng
wetlands under the jurisdic on of the Corps, DSL, CWS, etc. to their regula ons?
Cau onary note: a wetland may be “jurisdic onal” under one or all of those agencies, but
for mul ple reasons an ac on may not require a permit from any of these agencies.
Would such a situa on be captured under A. 3.? Might the city want to adjust the
language? (See also 18.510.050 A. 8. And B. 1. B., although those may not fully cover
excep ons and are on a different topic.) What is the intent?
3) In 18.510.030 B. It seems a phrase, word or punctua on may be missing in this
sentence: “…the necessary permits for all "development" must comply include a CWS
service provider le er, which…”
4) In 18.510.030 E. 1. Please add the new Tigard River Terrace LWI, Pacific Habitat
Services, 2023.
5) In 18.510.030 E. 2. Please add at the end: “Delinea ons must be reviewed and
approved by the Department of State Lands.” This will provide another set of eyes to
Attachment 2
verify the delinea on findings and allow the administra ve boundary changes to the LWIs
under OAR 141-086-0230(5)
6) In 18.510.070 A. 2. h. “…and State of Oregon Land Board, Division of State Lands…”
The Land Board is the Department of State Lands’ Board and while DSL’s rules o en say
that the permits may be issued by or come under a decision of the board, it is typically
the DSL that issues removal-fill permits. The way this is wri en may be redundant, but
you may want to check with your legal counsel. The same language under 18.510.070 C.
7. and 18.510.070 D. 7. As for 18.510.070 D. 7. – or elsewhere – where in Tigard code is
ORS 227.350 (wetland land use no ce) encoded?
7) I may not be understanding the intent of 18.510.080. C. and perhaps there is a clearer
way to express this sec on? Is the following interpreta on correct? 18.510.080 A.
establishes that land form altera ons are prohibited within locally significant wetlands
(LSWs) except as outlined in 18.510.100, & B. sets the width of setbacks for vegetated
corridors. Is C. saying that if the land form altera on needs a permit from the agencies
listed then the land form altera on needs a permit from those agencies and does not
need to comply with sec on B. except for condi ons given in C. a. & b.?
8) If an LSW is the subject of a plan amendment as presented in 18.510.100, then DSL
should be part of that process. There isn’t me to flesh this out now, and it does not
appear that the city is proposing change to this chapter at this me. The department
would appreciate a discussion of coordina on surrounding LSWs. Further, change in LSW
determina on should not be allowed, or needs further review or remedia on, if
prohibited ac ons such as vegeta on removal or ground disturbance has occurred within
the wetland prior or during the request process.
9) There may be a difficulty with 18.510.110 Map Verifica on Process. Does the term
“significant habitat areas” include LSWs? The method to verify boundaries for wetlands is
to gain review and approval of a wetland delinea on by the Department of State Lands
(see the addi onal benefits in 5) above). However, delinea on requires property access
permission. It may not be possible in all cases to gain access permission to delineate all
wetlands within 150 feet of the property as required in 18.510.110. B. 1. a. iii. What is
city’s intent/needs here?
I would appreciate clarifica ons where I had ques ons about the intent of the
sec on being reviewed, when we can arrange that. Also looking forward to discussions
on other topics raised above as soon as we can find me… If you have any ques ons
about my comments for your current code update please do not hesitate to call or write.
Jevra Brown, Aquatic Resource Planner
Department of State Lands
Cell 503-580-3172 | Jevra.Brown@DSL.Oregon.gov
Checking for wetlands and waters? – Use the STATEWIDE WETLANDS INVENTORY
~SWI Update January 2025 – Layers Added!~
Attachment 2
You don't often get email from agnesl@tigard-or.gov. Learn why this is important
Our native turtles may not reproduce until they are 15 years old. Turtles living near even mildly
busy roads have a 10-20 % chance of dying each year.
Paraphrased from Of Time and Turtles
From: Agnes Lindor <agnesl@ gard-or.gov> Sent: Monday, March 31, 2025 9:18 AM To: Joe Wisniewski <joew@ gard-or.gov>; Mark VanDomelen <markv@ gard-or.gov>; Anna
Sla nsky <asla nsky@BeavertonOregon.gov>; bmar n@beavertonoregon.gov; Linda Tate
<cityofdurham@comcast.net>; Michael Weston <mweston@ci.king-city.or.us>; rsmith
<rsmith@ci.king-city.or.us>; keith.liden@gmail.com; ssiegel@ci.oswego.or.us;
skoper@tuala n.gov; landuseno fica ons@oregonmetro.gov; ODOT_R1_DevRev
<ODOT_R1_DevRev@odot.oregon.gov>; portlandpermits@usace.army.mil; Anthony Mills
<Anthony_Mills@washingtoncountyor.gov>; Jackie Humphreys
<HumphreysJ@CleanWaterServices.org>; LUComments <LUComments@cleanwaterservices.org>;
BROWN Jevra * DSL <Jevra.BROWN@dsl.oregon.gov> Subject: Request for Comments: DCA2025-00001 FEMA ESA Compliance
DCA2025-00001
- FEMA ESA Compliance Amendments -
PROPOSAL: The City is proposing development code and municipal code amendments to the Area
of Special Flood Hazard regulations. The amendments to the development code are necessary to
incorporate regulatory changes required by the Federal Emergency Management Agency (FEMA) as
they relate to the Endangered Species Act (ESA). These regulatory changes are required in order for
the City of Tigard to continue participation in the National Flood Insurance Program (NFIP). The
proposed amendments include:
Updates to Municipal Code Chapter 9.10 that add new definitions and no net loss
standards; and
Updates to Chapter 18.510, Sensitive Lands, to require a no net loss analysis with a
sensitive lands review for development within areas of special flood hazard.
LOCATION: Citywide. ZONE: All zones with Areas of Special Flood Hazard. APPLICABLE
REVIEW CRITERIA: Statewide Planning Goals 1 (Citizen Involvement), 2 (Land Use Planning), 7
(Areas subject to Natural Hazards); METRO’s Urban Growth Management Functional Plan Titles 3,
and 8; Comprehensive Plan Goals 1.1.2, 2.1.1, 2.1.2, 2.1.3, 2.1.11, 2.1.20, 7.1.4, 7.1.5, 7.1.7, 7.1.8, 7.1.9,
7.1.11, 7.1.14, and 11.1.1; and Tigard Development Code Chapters 18.790, Text and Map
Amendments.
From information supplied by various departments and agencies and from other information available to
our staff, a report and recommendation will be prepared and a decision will be rendered on the proposal
in the near future. If you wish to comment on this application, WE NEED YOUR COMMENTS
BACK BY: MONDAY, APRIL 14, 2025. You may use the space provided below or attach a separate
letter to return your comments. If you are unable to respond by the above date, please phone the staff
contact noted above with your comments and confirm your comments in writing as soon as possible. If
you have any questions, contact the Tigard Planning Division, 13125 SW Hall Boulevard, Tigard, OR
97223.
Attachment 2
Agnes Lindor | Senior Planner
City of Tigard | Community DevelopmentDirect: 503.718.242913125 SW Hall Boulevard, Tigard OR 97223 | tigard-or.gov
Thank you,
DISCLAIMER: E-mails sent or received by City of Tigard employees are subject to public record
laws. If requested, e-mail may be disclosed to another party unless exempt from disclosure under
Oregon Public Records Law. E-mails are retained by the City of Tigard in compliance with the
Oregon Administrative Rules “City General Records Retention Schedule.”
Attachment 2
City of Tigard Engineering Comments
1
Chapter 9.10
AREAS OF SPECIAL FLOOD HAZARD
9.10.010. Purpose.
9.10.020. Definitions.
9.10.030. Applicability.
9.10.040. General Provisions.
9.10.050. National Flood Insurance Program General Standards.
9.10.060. No Net Loss Standards.
9.10.0760. Violations.
§ 9.10.010. Purpose.
The purpose of this chapter is to promote public health, safety, and general welfare, and to minimize public
and private losses due to flooding in flood hazard areas by provisions designed to:
A. Protect human life and health;
B. Minimize expenditure of public money for costly flood control projects;
C. Preserve natural and beneficial floodplain functions;
CD. Minimize the need for rescue and relief efforts associated with flooding and generally undertaken at
the expense of the general public;
DE. Minimize prolonged business interruptions;
EF. 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 hazard;
FG. Help maintain a stable tax base by providing for the sound use and development of flood hazard areas
so as to minimize blight areas caused by flooding;
GH. Notify potential buyers that the property is in an area of special flood hazard;
HI. Notify those who occupy areas of special flood hazard that they assume responsibility for their
actions; and
IJ. Participate in and maintain eligibility for flood insurance and disaster relief.
9.10.020. Definitions.
Unless specifically defined below, words or phrases used in this chapter shall be interpreted so as to give
them the meaning they have in common usage. These definitions are only applicable to this chapter and
Tigard Community Development Code (TCDC) Chapter 18.510, Sensitive Lands.
"Appeal" means a request for a review of the interpretation of any provision of this chapter or a request for
a variance.
Commented [LB1]: We brought this up last time the
floodplain code was amended. Terminology. FEMA
currently refers to this as the Special Flood Hazard Area
(SFHA). We would recommend going through the TMC
and revising accordingly.
Attachment 2
City of Tigard Engineering Comments
2
"Area of shallow flooding" means a designated Zone AO, AH, AR/AO or AR/AH (or VO) on the city's
Flood Insurance Rate Map (FIRM) with a one percent or greater annual chance of flooding to an average
depth of one to three feet where a clearly defined channel does not exist, where the path of flooding is
unpredictable, and where velocity flow may be evident. Such flooding is characterized by ponding or sheet
flow.
"Area of special flood hazard" means the land in the floodplain within the city subject to a one percent or
greater chance of flooding in any given year. It is shown on the Flood Insurance Rate Map (FIRM) as Zone
A, AO, AH, A1-30, AE, A99, AR. "Special flood hazard area" is synonymous in meaning and definition
with the phrase "area of special flood hazard."
"Base flood" means a flood having a one percent chance of being equaled or exceeded in any given year.
"Base flood elevation (BFE)" means the elevation to which floodwater is anticipated to rise during the base
flood.
"Basement" means any area of the building having its floor subgrade (below ground level) on all sides.
"Critical facility" means a facility for which even a slight chance of flooding might be too great. Critical
facilities include, but are not limited to, schools; nursing homes; new and replacement bridges; hospitals;
police, fire, and emergency response in stallations; and installations that produce, use, or store hazardous
materials or hazardous waste.
"Development" means any man-made change to improved or unimproved real estate, including, but not
limited to, buildings or other structures, mining, dredging, filling, grading, paving, excavation or drilling
operations or storage of equipment or materials.
“Fill” means placement of any materials such as soil, gravel, crushed stone, or other materials that
change the elevation of the floodplain. Placement of fill is considered “development”.
“Fish accessible space” means the volumetric space available to fish to access.
“Fish egress-able space” mean the volumetric space available to fish to exit or leave from.
"Flood" or "flooding" means:
1. A general and temporary condition of partial or complete inundation of normally dry land areas
from:
a. The overflow of inland or tidal waters;
b. The unusual and rapid accumulation or runoff of surface waters from any source;
c. Mudslides (i.e., mudflows) which are proximately caused by flooding as defined in
subsection 1.b of this definition and are akin to a river of liquid and flowing mud on the
surfaces of normally dry land areas, as when earth is carried by a current of water and
deposited along the path of the current.
2. 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,
Commented [LB2]: To be “clear & objective”, need to
define what the “volumetric space” is, and what the
minimum should be (width and depth).
Attachment 2
City of Tigard Engineering Comments
3
accompanied by a severe storm, or by an unanticipated force of nature, such as flash flood or an
abnormal tidal surge, or by some similarly unusual and unforeseeable event which results in
flooding as defined in subsection 1.a of this definition.
Flood Elevation Study. See "Flood Insurance Study."
"Flood Insurance Rate Map (FIRM)" means the official map of the city, on which the Federal Insurance
Administrator has delineated both the special hazard areas and the risk premium zones applicable to the
city. A FIRM that has been made available digitally is called a Digital Flood Insurance Rate Map (DFIRM).
"Flood Insurance Study (FIS)" means an examination, evaluation and determination of flood hazards and,
if appropriate, corresponding water surface elevations, or an examination, evaluation and determination of
mudslide (i.e., mudflow) or flood-related erosion hazards.
"Flood proofing" means any combination of structural and nonstructural additions, changes, or adjustments
to structures which reduce or eliminate risk of flood damage to real estate or improved real property, water
and sanitary facilities, structures, and their contents.
“Floodplain functions” mean flood storage, water quality, and riparian vegetation conditions.
"Floodway" means the channel of a river or other watercourse and the adjacent land areas that must be
reserved in order to discharge the base flood without cumulatively increasing the water surface elevation
more than one foot. Also referred to as "regulatory floodway."
"Functionally dependent use" means 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,
and does not include long term storage or related manufacturing facilities.
“Green infrastructure” means the use of natural or human-made hydrologic features to manage water
and provide environmental and community benefits. Green infrastructure uses management approaches
and technologies that use, enhance, or mimic the natural hydrologic cycle processes of infiltration,
evapotranspiration, and reuse. At a large scale, it is an interconnected network of green space that
conserves natural systems and provides assorted benefits to human populations. At a local scale, it
manages stormwater by infiltrating it into the ground where it is generated using vegetation or porous
surfaces, or by capturing it for later reuse. Green infrastructure practices can be used to achieve no net
loss of pervious surface by creating infiltration of stormwater in an amount equal to or greater than the
infiltration lost by the placement of new impervious surface.
“Habitat restoration activities” mean activities with the sole purpose of restoring habitats that have only
temporary impacts and long-term benefits to habitat. Such projects cannot include ancillary structures
such as a storage shed for maintenance equipment, must demonstrate that no rise in the BFE would
occur as a result of the project, and obtain a CLOMR and LOMR, and have obtained any other required
permits (e.g., CWA Section 404 permit).
“Hazard trees” mean standing dead, dying, or diseased tree or ones with a structural defect that makes
it likely to fail in whole or in part and that present a potential hazard to a structure or as defined in Title
8, Urban Forestry.
"Highest adjacent grade" means the highest natural elevation of the ground surface prior to construction
next to the proposed walls of a structure.
Commented [LB3]: Two “ands” in sentence. Suggest
putting a comma before this “and”, and then removing
the “and”
Attachment 2
City of Tigard Engineering Comments
4
"Historic structure" means any structure that is:
1. Listed individually in the National Register of Historic Places (a listing maintained by the
Department of the Interior) or preliminarily determined by the Secretary of the Interior as meeting
the requirements for individual listing on the National Register;
2. Certified or preliminarily determined by the Secretary of the Interior as contributing to the
historical significance of a registered historic district or a district preliminarily determined by the
Secretary to qualify as a registered historic district;
3. Individually listed on a state inventory of historic places in states with historic preservation
programs which have been approved by the Secretary of the Interior; or
4. Individually listed on a City of Tigard Historic Resources list acknowledged by the Secretary of
the Interior.
“Hydraulically equivalent elevation” means a location (e.g., a site where no net loss standards are
implemented) that is approximately equivalent to another (e.g., the impacted site) relative to the same
100-year water surface elevation contour or base flood elevation. This may be estimated based on a point
that is along the same approximate line perpendicular to the direction of flow.
“Hydrologically connected” means the interconnection of groundwater and surface water such that they
constitute one water supply and use of either results in an impact to both.
“Impervious surface” means a surface that cannot be penetrated by water and thereby prevents
infiltration and increases the amount and rate of surface water runoff, leading to erosion of stream
banks, degradation of habitat, and increased sediment loads in streams. Such surfaces can accumulate
large amounts of pollutants that are then “flushed” into local water bodies during storms and can also
interfere with recharge of groundwater and the base flows to water bodies.
“Low impact development (LID)” means an approach to land development (or redevelopment) that works
with nature to manage stormwater as close to its source as possible. It employs principles such as
preserving and recreating natural landscape features and minimizing effective imperviousness to create
functional and appealing site drainage that treats stormwater as a resource rather than a waste product.
Low impact development refers to designing and implementing practices that can be employed at the site
level to control stormwater and help replicate the predevelopment hydrology of the site. Low impact
development helps achieve no net loss of pervious surface by infiltrating stormwater in an amount equal
to or 186 greater than the infiltration lost by the placement of new impervious surface. LID is a subset
of green infrastructure.
"Lowest floor" means the lowest floor of the lowest enclosed area (including basement). An unfinished or
flood 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 floor, provided that such enclosure is not built so
as to render the structure in violation of the applicable non-elevation design requirements of this chapter.
"Manufactured dwelling" means 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 attached to the
required utilities. The term "manufactured dwelling" does not include a "recreational vehicle" and is
synonymous with "manufactured home."
"Manufactured dwelling park or subdivision" means a parcel (or contiguous parcels) of land divided into
Commented [LB4]: Suggest deleting the word “level”
Commented [LB5]: What is the “186” for? Suggest
deleting it.
Attachment 2
City of Tigard Engineering Comments
5
two or more manufactured dwelling lots for rent or sale.
“Mean higher-high water” means the average of the higher-high water height of each tidal day 202
observed over the National Tidal Datum Epoch
"Mean sea level" means, for purposes of the National Flood Insurance Program, the National Geodetic
Vertical Datum (NGVD) of 1929 or other datum, to which base flood elevations shown on the city's Flood
Insurance Rate Map are referenced.
"New construction" means, for floodplain management purposes, structures for which the "start of
construction" commenced on or after the effective date of a floodplain management regulation adopted by
City of Tigard and includes any subsequent improvements to such structures.
“No net loss” means a standard where adverse impacts must be avoided or offset through adherence to
certain requirements so that there is no net change in the function from the existing condition when a
development application is submitted to the state, tribal, or local jurisdiction. The floodplain functions
of floodplain storage, water quality, and vegetation must be maintained.
“Offsite” means mitigation occurring outside of the project area.
“Onsite” means mitigation occurring within the project area.
“Ordinary High Water Mark” means the line on the shore established by the fluctuations of water and
indicated by physical characteristics such as a clear, natural line impressed on the bank; shelving;
changes in the character of soil; destruction of terrestrial vegetation; the presence of litter and debris;
or other appropriate means that consider the characteristics of the surrounding areas.
“Qualified Professional” means a person who has a minimum of a bachelor’s degree in wildlife or
fisheries habitat biology, or a related degree in a biological field from an accredited college or university
with a minimum of four years’ experience as a practicing fish or wildlife habitat biologist; or is listed on
the Oregon Department of Transportation’s official list of consultants qualified to provide Endangered
Species Act Documentation.
“Reach” means a section of a stream or river along which similar hydrologic conditions exist, such as
discharge, depth, area, and slope. It can also be the length of a stream or river (with varying conditions)
between major tributaries or two stream gages, or a length of river for which the characteristics are well
described by readings at a single stream gage.
"Recreational vehicle" means a vehicle which is:
1. Built on a single chassis;
2. 400 square feet or less when measured at the largest horizontal projection;
3. Designed to be self-propelled or permanently towable by a light duty truck; and
4. Designed primarily not for use as a permanent dwelling but as temporary living quarters for
recreational, camping, travel, or seasonal use.
“Riparian” means of, adjacent to, or living on, the bank of a river, lake, pond, or other water body.
Commented [LB6]: What is the “202” for? Suggest
deleting it.
Commented [LB7]: Note: this only applies to a
biologist, who should not be designing engineered
infrastructure. Suggested changing from “qualified
professional” to “qualified licensed engineer” in future
text which refers to detention/retention facility analysis
and design.
Attachment 2
City of Tigard Engineering Comments
6
“Riparian buffer zone (RBZ)” means the outer boundary of the riparian buffer zone is measured from
the ordinary high water line of a fresh waterbody (lake; pond; ephemeral, intermittent, or perennial
stream) or mean higher-high water line of a marine shoreline or tidally influenced river reach to 170
feet horizontally on each side of the stream or 170 feet inland from the MHHW. The riparian buffer
zone includes the area between these outer boundaries on each side of the stream, including the stream
channel. Where the RBZ is larger than the special flood hazard area, the no net loss standards shall only
apply to the area within the special flood hazard area.
“Riparian buffer zone fringe” means the area outside of the RBZ and floodway but still within the SFHA.
“Silviculture” means the art and science of controlling the establishment, growth, composition, health,
and quality of forests and woodlands.
Special Flood Hazard Area. See "Area of special flood hazard" for this definition.
"Start of construction" includes substantial improvement and means the date the building permit was issued,
provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement, or other
improvement was within 180 days from the date of the permit. The actual start means either the first
placement of permanent construction of a structure on a site, such as the pouring of slab or footings, the
installation of piles, the construction of columns, or any work beyond the stage of excavation; or the
placement of a manufactured dwelling on a foundation. Permanent construction does not include land
preparation, such as clearing, grading, and filling; nor does it include the installation of streets and/or
walkways; nor does it include excavation for a basement, footings, 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. For a substantial improvement,
the actual start of construction means the first alteration of any wall, ceiling, floor, or other structural part
of a building, whether or not that alteration affects the external dimensions of the building.
"Structure" means, for floodplain management purposes, a walled and roofed building, including a gas or
liquid storage tank, that is principally above ground, as well as a manufactured dwelling.
"Substantial damage" means damage of any origin sustained by a structure whereby the cost of restoring
the structure to its before damaged condition would equal or exceed 50% of the market value of the structure
before the damage occurred.
"Substantial improvement" means any reconstruction, rehabilitation, addition, or other improvement of a
structure, the cost of which equals or exceeds 50% of the market value of the structure before the "start of
construction" of the improvement. This term includes structures which have incurred "substantial damage,"
regardless of the actual repair work performed. The term does not, however, include either:
1. Any project for improvement of a structure to correct existing violations of state or local health,
sanitary, or safety code specifications which have been identified by the local code enforcement
official and which are the minimum necessary to assure safe living conditions; or
2. Any alteration of a "historic structure," provided that the alteration will not preclude the
structure's continued designation as a "historic structure."
“Undeveloped Space” means the volume of flood capacity and fish-accessible/egress-able habitat from
the existing ground to the Base Flood Elevation that is undeveloped. Any form of development including,
but not limited to, the addition of fill, structures, concrete structures (vaults or tanks), pilings, levees and
dikes, or any other development that reduces flood storage volume and fish accessible/egress-able habitat
Commented [LB8]: Suggest “as” in lieu of “is”
Attachment 2
City of Tigard Engineering Comments
7
must achieve no net loss.
"Violation" means the failure of a structure or other development to be fully compliant with the city's
floodplain management regulations. A structure or other development without the elevation certificate,
other certifications, or other evidence of compliance required in this chapter is presumed to be in violation
until such time as that documentation is provided.
9.10.030. Applicability.
A. All development within areas of special flood hazard is subject to the terms of this chapter and is
required to comply with its provisions and all other applicable regulations including, but not limited
to, TCDC Chapter 18.510, Sensitive Lands.
B. The areas of special flood hazard identified by FEMA in a scientific and engineering report entitled
"The Flood Insurance Study for Washington County, Oregon and Incorporated Areas effective
October 19, 2018" with accompanying Flood Insurance Map (FIRM Pan els: 41067C0529F,
41067C0533E, 41067C0534E, 41067C0541E through 41067C0544E, and 41067C0563E) is hereby
adopted by reference and declared to be a part of this chapter.
9.10.040. General Provisions.
A. Coordination with State of Oregon Specialty Codes. Pursuant to the requirement established in ORS
455 that the City of Tigard administers and enforces the State of Oregon Specialty Codes, the City of
Tigard does hereby acknowledge that the Oregon Specialty Codes contain certain provisions that
apply to the design and construction of buildings and structures located in areas of special flood
hazard. Therefore, this chapter is intended to be administered and enforced in conjunction with the
Oregon Specialty Codes.
B. Warning. 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 rare occasions. Flood heights may be increased by man-made or natural causes. This
chapter does not imply that land outside the areas of special flood hazards or uses permitted within
such areas will be free from flooding or flood damages.
C. Permit Review. The duties of the Floodplain Administrator, or their designee, shall include, but not be
limited to, review all development permits to determine that:
1. Determine that theThe permit requirements of this ordinance have been satisfied;
2. Determine that allAll other required local, state, and federal permits have been obtained and
approved;
3. Review all development permits to dDetermine if the proposed development is located in a
floodway.
a. If located in the floodway, assure that the floodway provisions are met;
b.4. Review all development permits to dDetermine if the proposed development is located in an
area where base flood elevation data is available either through the Flood Insurance Study or
from another authoritative source. If base flood elevation data is not available then ensure
compliance with the provisions of Section 9.10.050.J;and
Commented [LB9]: Need to include map amendments.
Suggest inserting here: ”and approved map
amendments”.
Commented [LB10]: This should be Item 4, as this
sentence does not pertain to the floodway.
Attachment 2
City of Tigard Engineering Comments
8
c.5. Provide to building officials the base flood elevation applicable to any building requiring a
development permit;
4. 6.Review all development permit applications to dDetermine if the proposed development qualifies
as a substantial improvement as defined by Section 9.10.020;
5.7. Review all development permits to dDetermine if the proposed development activity is a
watercourse alteration. If a watercourse alteration is proposed, ensure compliance with the
provisions in Section 9.10.050.C; and
6. 8.Review all development permits to dDetermine if the proposed development activity includes the
placement of fill or excavation; and.
7. Determine whether the proposed development activity complies with the no net loss standards
in Section 9.10.060.
D. Information to be Obtained and Maintained. The following information shall be obtained and
maintained and shall be made available for public inspection as needed:
1. Obtain, record, and maintain the actual elevation (in relation to mean sea level) of the lowest floor
(including basements) and all attendant utilities of all new or substantially improved structures
where base flood elevation data is provided through the Flood Insurance Study, Flood Insurance
Rate Map, or obtained in accordance with Section 9.10.050.J.
2. Obtain and record the elevation (in relation to mean sea level) of the natural grade of the building
site for a structure prior to the start of construction and the placement of any fill and ensure that
the requirements of Section 9.10.050.N are adhered to and all other required local, state, and
federal permits have been obtained and approved.
3. Upon placement of the lowest floor of a structure (including basement) but prior to further
vertical construction, obtain documentation, prepared and sealed by a professional licensed
surveyor or engineer, certifying the elevation (in relation to mean sea level) of the lowest floor
(including basement).
4. Where base flood elevation data are utilized, obtain record drawing certification of the elevation
(in relation to mean sea level) of the lowest floor (including basement) prepared and sealed by a
professional licensed surveyor or engineer, prior to the final inspection.
5. Maintain all elevation certificates submitted to the City of Tigard.
6. Obtain, record, and maintain the elevation (in relation to mean sea level) to which the structure
and all attendant utilities were floodproofed for all new or substantially improved floodproofed
structures where allowed under this chapter and where base flood elevation data is provided
through the FIS, FIRM, or obtained in accordance with Section 9.10.050.J.
7. Maintain all floodproofing certificates required under this chapter.
8. Record and maintain all variance actions, including justification for their issuance.
9. Obtain and maintain all hydrologic and hydraulic analyses performed as required under Section
Commented [LB11]: This should be Item 5, as it does
not necessarily apply only to floodways
Commented [LB12]: Correspondingly, these should be
items 5-8
Attachment 2
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9
9.10.050.N.
10. Record and maintain all substantial improvement and substantial damage calculations and
determinations as required under subsection H.
11. Documentation of how no net loss standards have been met (see Section 9.10.060).
1211. Maintain for public inspection all records pertaining to the provisions of this chapter.
E. City Boundary Alterations. The Floodplain Administrator shall notify the Federal Insurance
Administrator in writing whenever the boundaries of the city have been modified by annexation or the
city has otherwise assumed authority or no longer has authority to adopt and enforce floodplain
management regulations for a particular area, to ensure that all Flood Hazard Boundary Maps and
Flood Insurance Rate Maps accurately represent the city's boundaries. The notification will include a
copy of a map of the city suitable for reproduction, clearly delineating the new corporate limits or
new area for which the city has assumed or relinquished floodplain management regulatory authority.
F. Watercourse Alterations. The Floodplain Administrator shall notify adjacent communities, the
Department of Land Conservation and Development, and other appropriate state and federal agencies,
prior to any alteration or relocation of a watercourse, and submit evidence of such notification to the
Federal Insurance Administration. This notification shall be provided by the applicant to the Federal
Insurance Administration as a Letter of Map Revision along with either a proposed maintenance plan
to assure the flood carrying capacity within the altered or relocated portion of the watercourse is
maintained; or certification by a registered professional engineer that the project has been designed to
retain its flood carrying capacity without periodic maintenance. The applicant shall be required to
submit a Conditional Letter of Map Revision when required under subsection G to ensure compliance
with all applicable requirements in subsection G and Section 9.10.050.C.
G. Requirement to Submit New Technical Data. The city's base flood elevations may increase or
decrease resulting from physical changes affecting flooding conditions. As soon as practicable, but
not later than six months after the date such information becomes available, the city must notify the
Federal Insurance Administrator of the changes by submitting technical or scientific data in
accordance with Title 44 of the Code of Federal Regulations (CFR), Section 65.3. The city may
require the applicant to submit such data and review fees required for compliance with this section
through the applicable FEMA Letter of Map Change process. The Floodplain Administrator shall
require a Conditional Letter of Map Revision prior to the issuance of a floodplain development permit
for proposed floodway encroachments that increase the base flood elevation and proposed
development which increases the base flood elevation by more than one foot in areas where FEMA
has provided base flood elevations but no floodway. An applicant shall notify FEMA within six
months of project completion when an applicant has obtained a Conditional Letter of Map Revision
from FEMA. This notification to FEMA shall be provided as a Letter of Map Revision.
H. Substantial Improvement and Substantial Damage Assessments and Determinations. The Floodplain
Administrator shall:
1. Conduct substantial improvement (as defined in Section 9.10.020) reviews for all structural
development proposal applications and maintain a record of Substantial Improvement
calculations within permit files in accordance with subsection D.
2. Conduct substantial damage assessments when structures are damaged due to a natural hazard
event or other causes.
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2. Make substantial damage determinations whenever structures within the area of special flood
hazard (as established in Section 9.10.030.B) are damaged to the extent that the cost of restoring
the structure to its before damaged condition would equal or exceed 50% of the market value of
the structure before the damage occurred.
I. Floodplain Development Permit Required. A development permit shall be obtained before
construction or development begins within any area horizontally within the area of special flood
hazard established in Section 9.10.030.B. The development permit shall be required for all structures,
including manufactured dwellings, and for all other development, as defined in Section 9.10.020,
including fill and other development activities.
J. Application for Development Permit. Application for a development permit may be made on forms
furnished by the Floodplain Administrator and may include, but not be limited to, plans in duplicate
drawn to scale showing the nature, location, dimensions, and elevations 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:
1. In riverine flood zones, the proposed elevation (in relation to mean sea level), of the lowest floor
(including basement) and all attendant utilities of all new and substantially improved structures;
in accordance with the requirements of subsection D;
2. Proposed elevation in relation to mean sea level to which any nonresidential structure will be
floodproofed;
3. Certification by a registered professional engineer or architect licensed in the State of Oregon that
the floodproofing methods proposed for any nonresidential structure meet the floodproofing
criteria for nonresidential structures in Section 9.10.050.M.3;
4. Description of the extent to which any watercourse will be altered or relocated;
5. Base flood elevation data for subdivision proposals or other development when required by this
chapter;
6. Substantial improvement calculation for any improvement, addition, reconstruction, renovation,
or rehabilitation of an existing structure; and
7. The amount and location of any fill or excavation activities proposed.
K. Not Net Loss. Adherent to the NMFS 2016 Biological Opinion, mitigation is necessary to ensure a
no net loss in floodplain functions. FEMA’s 2024 Draft Oregon Implementation Plan identifies
proxies that provide measurable actions that can prevent the no net loss of the parent floodplain
functions. These proxies include undeveloped space, pervious surfaces, and trees to account for a
no net loss in respective floodplain functions of floodplain storage, water quality, and vegetation.
Mitigation of these proxies must be completed to ensure compliance with no net loss standards. No
net loss applies to the net change in floodplain functions as compared to existing conditions at the
time of proposed development and mitigation must be addressed to the floodplain function that is
receiving the detrimental impact. The standards described below apply to all special flood hazard
areas as defined in Section 19.10.020.
LK. Severability. This chapter and the various parts thereof are hereby declared to be severable. If any
Commented [LB13]: Should be “No”, not “Not”.
Commented [LB14]: The statement /goal is “no net
loss”. In this sentence, it should read .. “that can prevent
the net loss of the parent floodplain functions”; delete
the “no”
Attachment 2
City of Tigard Engineering Comments
11
section clause, sentence, or phrase of this chapter is held to be invalid or unconstitutional by any court
of competent jurisdiction, then said holding shall in no way effect the validity of the remaining
portions of this chapter.
ML. Abrogation. This chapter is not intended to repeal, abrogate, or impair any existing easements,
covenants, or deed restrictions. However, where this chapter and another provision, easement,
covenant, or deed restriction conflict or overlap, whichever imposes the more stringent restrictions
shall prevail.
9.10.050. National Flood Insurance Program General Standards.
In all areas of special flood hazard, the no net loss standards in Section 9.10.060 and the following
standards shall be adhered to:
A. All new construction and substantial improvements shall be constructed with materials and utility
equipment resistant to flood damage.
B. All new construction and substantial improvements shall be constructed using methods and practices
that minimize flood damage.
C. Alteration of Watercourses. The Floodplain Administrator shall require that the flood carrying
capacity within the altered or relocated portion of said watercourse is maintained and that
maintenance is provided within the altered or relocated portion of said watercourse to ensure that the
flood carrying capacity is not diminished. Compliance with Section 9.10.040.F and G.
D. Anchoring. All new construction and substantial improvements shall be anchored to prevent flotation,
collapse, or lateral movement of the structure resulting from hydrodynamic and hydrostatic loads,
including the effects of buoyancy. All manufactured dwellings shall be anchored in accordance with
subsection M.4.
E. Water Supply, Sanitary Sewer, and On-Site Waste Disposal Systems.
1. All new and replacement water supply systems shall be designed to minimize or eliminate
infiltration of flood waters into the system.
2. New and replacement sanitary sewage systems shall be designed to minimize or eliminate
infiltration of flood waters into the systems and discharge from the systems into flood waters.
3. On-site waste disposal systems shall be located to avoid impairment to them or contamination
from them during flooding consistent with Oregon Department of Environmental Quality
regulations.
F. Electrical, Mechanical, Plumbing, and Other Equipment. Electrical, heating, ventilating, air-
conditioning, plumbing, duct systems, and other equipment and service facilities shall be elevated at
or above the base flood level or shall be designed and installed to prevent water from entering or
accumulating within the components and to resist hydrostatic and hydrodynamic loads and stresses,
including the effects of buoyancy, during conditions of flooding. In addition, electrical, heating,
ventilating, air-conditioning, plumbing, duct systems, and other equipment and service facilities shall,
if replaced as part of a substantial improvement, meet all the requirements of this section.
G. Tanks. Underground tanks shall be anchored to prevent flotation, collapse and lateral movement
Attachment 2
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under conditions of the base flood. Above-ground tanks shall be installed at or above the base flood
level or shall be anchored to prevent flotation, collapse, and lateral movement under conditions of the
base flood.
H. Critical Facilities. Construction of new critical facilities must be, to the extent practicable, located
outside areas of special flood hazard.
1. Construction of new critical facilities, other than critical bridges, are allowed within areas of
special flood hazard if no feasible alternative site is available and the following applicable criteria
are met:
a. Critical facilities constructed within areas of special flood hazard must have the lowest floor
elevated three feet above base flood elevation or to the height of the 500 -year flood,
whichever is higher.
b. To the extent practicable, access to and from the critical facility should also be protected to
three feet above base flood elevation or to the height of the 500-year flood, whichever is
higher.
c. Floodproofing and sealing measures must be taken to ensure that toxic substances will not be
displaced by or released into floodwaters.
2. All new and replacement critical bridges must have the lowest extension of the bridge
superstructure elevated three feet above base flood elevation or to the height of the 500-year
flood, whichever is higher.
3. Where standard subsection H.2 cannot be met, an analysis of alternative bridge designs is
required by a registered professional civil engineer. The proposed encroachment will result in the
least impact to base flood levels in the area of special flood hazard of the practicable alternative
bridge designs — as demonstrated through hydrologic and hydraulic analyses performed in
accordance with standard engineering practice.
I. Subdivision Proposals.
1. All new subdivision proposals and other proposed new developments (including proposals for
manufactured dwelling parks and subdivisions) greater than 50 lots or five acres, whichever is the
lesser, shall include within such proposals, base flood elevation data.
2. All new subdivision proposals and other proposed new developments (including proposals for
manufactured dwelling parks and subdivisions) shall:
a. Be consistent with the need to minimize flood damage.;
b. Have public utilities and facilities such as sewer, gas, electrical, and water systems located
and constructed to minimize or eliminate flood damage.; and
c. Have adequate drainage provided to reduce exposure to flood hazards.
d. Comply with no net loss standards in Section 9.10.060.
J. Use of Other Base Flood Data. When base flood elevation data has not been provided in accordance
Attachment 2
City of Tigard Engineering Comments
13
with Section 9.10.030.B the local floodplain administrator shall obtain, review, and reasonably utilize
any base flood elevation data available from a federal, state, or other source, in order to administer
Section 9.10.050. All new subdivision proposals and other proposed new developments (including
proposals for manufactured dwelling parks and subdivisions) must meet the requirements of
subsection I. Base flood elevations shall be determined for development proposals that are five acres
or more in size or are 50 lots or more, whichever is lesser in any A Zone that does not have an
established base flood elevation. Development proposals located within a riverine unnumbered A
Zone shall be reasonably safe from flooding; the test of reasonableness includes use of historical data,
high water marks, FEMA provided base level engineering data, and photographs of past flooding, etc.
When no base flood elevation data is available, the elevation requirement for development proposals
within a riverine unnumbered A Zone is a minimum of two feet above the highest adjacent grade, to
be reasonably safe from flooding. Failure to elevate at least two feet above grade in these zones may
result in higher insurance rates.
K. Structures Located in Multiple or Partial Flood Zones. In coordination with the State of Oregon
Specialty Codes:
1. When a structure is located in multiple flood zones on the city's pertinent Flood Insurance Rate
Maps (FIRMs) the provisions for the more restrictive flood zone shall apply.
2. When a structure is partially located in an area of special flood hazard, the entire structure shall
meet the requirements for new construction and substantial improvements.
L. Specific Standards for Riverine (Including All Non-Coastal) Flood Zones. These specific standards
shall apply to all new construction and substantial improvements in addition to the general standards
contained in subsections A through K and the no net loss standards in Section 9.10.060.
1. Flood Openings. All new construction and substantial improvements with fully enclosed areas
below the lowest floor (excluding basements) are subject to the following requirements. Enclosed
areas below the base flood elevation, including crawl spaces shall:
a. Be designed to automatically equalize hydrostatic flood forces on walls by allowing for the
entry and exist of floodwaters;
b. Be used solely for parking, storage, or building access; and
c. Be certified by a registered professional engineer or architect or meet or exceed all of the
following minimum criteria:
i. A minimum of two openings,
ii. The total net area of non-engineered openings shall be not less than one square inch for
each square foot of enclosed area, where the enclosed area is measured on the exterior of
the enclosure walls,
iii. The bottom of all openings shall be no higher than one foot above grade,
iv. Openings may be equipped with screens, louvers, valves, or other coverings or devices
provided that they shall allow the automatic flow of floodwater into and out of the
enclosed areas and shall be accounted for in the determination of the net open area, and
Attachment 2
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14
v. All additional higher standards for flood openings in the State of Oregon Residential
Specialty Codes Section R322.2.2 shall be complied with when applicable.
2. Garages. Attached garages may be constructed with the garage floor slab below the base flood
elevation in riverine flood zones, if the following requirements are met:
a. If located within a floodway the proposed garage must comply with the requirements of
subsection N;
b. The floors are at or above grade on at least than one side;
c. The garage is used solely for parking, building access, and/or storage;
d. The garage is constructed with flood openings in compliance with subsection L.1 to equalize
hydrostatic flood forces on exterior walls by allowing for the automatic entry and exit of
floodwater;
e. The portions of the garage constructed below the base flood elevation are constructed with
materials resistant to flood damage;
f. The garage is constructed in compliance with the general standards subsections A through K;
and
g. The garage is constructed with electrical, and other service facilities located and installed so
as to prevent water from entering or accumulating within the components during conditions
of the base flood.
3. Detached Garages. Detached garages must be constructed in compliance with the standards for
appurtenant structures in subsection M.6 or nonresidential structures in subsection M.3 depending
on the square footage of the garage.
M. For Riverine (Non-Coastal) Areas of Special Flood Hazard with Base Flood Elevations. In addition to
the general standards in subsections A through K, the following specific standards shall apply in
riverine (non-coastal) areas of special flood hazard with base flood elevations: Zones A1-A30, AH,
and AE:
1. Before Regulatory Floodway. In areas where a regulatory floodway has not been designated, no
new construction, substantial improvement, or other development (including fill) shall be
permitted within Zones A1-30 and AE on the city's Flood Insurance Rate Map (FIRM), unless it
is demonstrated that the cumulative effect of the proposed development, when combined with all
other existing and anticipated development, will not increase the water surface elevation of the
base flood at any point within the city and will not result in the net loss of floor storage volume.
When determined that structural elevation is not possible and where the placement of fill
cannot meet the above standard, impacts to undeveloped space must adhere to the no net loss
standards in Section 9.10.060.
2. Residential Construction.
a. New construction, conversion to, and substantial improvement of any residential structure
shall have the lowest floor, including basement, elevated at one foot above the base flood
elevation.
Commented [LB15]: Should be “flood” not “floor”
Attachment 2
City of Tigard Engineering Comments
15
b. Enclosed areas below the lowest floor shall comply with the flood opening requirements in
subsection L.1.
3. Nonresidential Construction.
a. New construction, conversion to, and substantial improvement of, any commercial, industrial,
or other nonresidential structure shall have the lowest floor, including basement, elevated at
one foot above the base flood elevation. Or, together with attendant utility and sanitary
facilities:
i. Be floodproofed so that below the base flood level the structure is watertight with walls
substantially impermeable to the passage of water;
ii. Have structural components capable of resisting hydrostatic and hydrodynamic loads and
effects of buoyancy; and
iii. Be certified by a registered professional engineer or architect that the design and methods
of construction are in accordance with accepted standards of practice for meeting
provisions of this section based on their development or review of the structural design,
specifications and plans. Such certifications shall be provided to the Floodplain
Administrator as set forth Section 9.10.040.D.
b. Nonresidential structures that are elevated, not floodproofed, shall comply with the standards
for enclosed areas below the lowest floor in subsection L.1.
c. Applicants floodproofing nonresidential buildings shall be notified that flood insurance
premiums will be based on rates that are one foot below the floodproofed level (e.g., a
building floodproofed to the base flood level will be rated as one foot below.
4. Manufactured Dwellings.
a. Manufactured dwellings to be placed (new or replacement) or substantially improved that are
supported on solid foundation walls shall be constructed with flood openings that comply
with subsection L.1;
b. The bottom of the longitudinal chassis frame beam shall be at or above base flood elevation;
c. Manufactured dwellings to be placed (new or replacement) or substantially improved shall be
anchored to prevent flotation, collapse, and lateral movement during the base flood.
Anchoring methods may include, but are not limited to, use of over-the-top or frame ties to
ground anchors (Reference FEMA's "Manufactured Home Installation in Flood Hazard
Areas" guidebook for additional techniques); and
d. Electrical crossover connections shall be a minimum of 12 inches above base flood elevation
(BFE).
5. Recreational Vehicles. Recreational vehicles placed on sites are required to:
a. Be on the site for fewer than 180 consecutive days; and
Attachment 2
City of Tigard Engineering Comments
16
b. Be fully licensed and ready for highway use, on its wheels or jacking system, is attached to
the site only by quick disconnect type utilities and security devices, and has no permanently
attached additions; or
c. Meet the requirements of subsection M.4, including the anchoring and elevation requirements
for manufactured dwellings.
6. Appurtenant (Accessory) Structures. Relief from elevation or floodproofing requirements for
residential and nonresidential structures in Riverine (non-coastal) flood zones may be granted for
appurtenant structures that meet the following requirements:
a. Appurtenant structures located partially or entirely within the floodway must comply with
requirements for development within a floodway found in subsection N;
b. Appurtenant structures must only be used for parking, access, or storage and shall not be used
for human habitation;
c. Appurtenant structures on properties are limited to one-story structures less than 600 square
feet in A zones and must meet applicable setbacks from property lines;
d. The portions of the appurtenant structure located below the base flood elevation must be built
using flood resistant materials;
e. The appurtenant structure must be adequately anchored to prevent flotation, collapse, and
lateral movement of the structure resulting from hydrodynamic and hydrostatic loads,
including the effects of buoyancy, during conditions of the base flood;
f. The appurtenant structure must be designed and constructed to equalize hydrostatic flood
forces on exterior walls and comply with the requirements for flood openings in subsection
L.1;
g. Appurtenant structures shall be located and constructed to have low damage potential;
h. Appurtenant structures shall not be used to store toxic material, oil, or gasoline, or any
priority persistent pollutant identified by the Oregon Department of Environmental Quality
unless confined in a tank installed incompliance with subsection G; and
i. Appurtenant structures shall be constructed with electrical, mechanical, and other service
facilities located and installed so as to prevent water from entering or accumulating within the
components during conditions of the base flood.
N. Floodways. Located within the areas of special flood hazard established in Section 9.10.030.B are
areas designated as floodways. Because the floodway is an extremely hazardous area due to the
velocity of the floodwaters which carry debris, potential projectiles, and erosion potential, the
following provisions apply:
1. Prohibit encroachments, including fill, new construction, substantial improvements, and other
development within the adopted regulatory floodway unless:
a. Certification by a registered professional civil engineer is provided demonstrating through
hydrologic and hydraulic analyses performed in accordance with standard engineering
Attachment 2
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17
practice that the proposed encroachment shall not result in any increase in flood levels within
the city during the occurrence of the base flood discharge; or
b. A city may permit encroachments within the adopted regulatory floodway that would result in
an increase in base flood elevations, provided that a Cconditional Letter of Map Revision is
applied for and approvedapproval has been obtained by the Federal Insurance Administrator
through the Conditional Letter of Map Revision (CLOMR) application process, and the
requirements for such revision as all requirements established under Volume 44 of the Code
of Federal Regulations, Section 65.12 are fulfilled, and the encroachments comply with the
no net loss standards in Section 9.10.060.
2. If the requirements of subsection N.1 are satisfied, all new construction, substantial
improvements, and other development shall comply with all other applicable flood hazard
reduction provisions of Section 9.10.050.
O. Standards for Shallow Flooding Areas. Shallow flooding areas appear on FIRMs as AO Zones with
depth designations or as AH Zones with base flood elevations. For AO Zones the base flood depths
range from one to three feet above ground where a clearly defined channel does not exist, or where
the path of flooding is unpredictable and where velocity flow may be evident. Such flooding is
usually characterized as sheet flow. For both AO and AH Zones, adequate drainage paths are required
around structures on slopes to guide floodwaters around and away from proposed structures.
1. Standards for AH Zones. Development within AH Zones must comply with the standards in
subsections A through O.
2. Standards for AO Zones. In AO zones, the following provisions apply in addition to the
requirements in subsections A through K and O.
a. New construction, conversion to, and substantial improvement of residential structures and
manufactured dwellings within AO Zones shall have the lowest floor, including basement,
elevated above the highest grade adjacent to the building, at minimum to or above the depth
number specified on the Flood Insurance Rate Maps or at least two feet if no depth number is
specified. For manufactured dwellings the lowest floor is considered to be the bottom of the
longitudinal chassis frame beam.
b. New construction, conversion to, and substantial improvements of nonresidential structures
within AO Zones shall either:
i. Have the lowest floor (including basement) elevated above the highest adjacent grade of
the building site, at minimum to or above the depth number specified on the Flood
Insurance Rate Maps or at least two feet if no depth number is specified; or
ii. Together with attendant utility and sanitary facilities, be completely floodproofed to or
above the depth number specified on the Flood Insurance Rate Map or a minimum of two
feet above the highest adjacent grade if no depth number is specified, so that any space
below that level is watertight with walls substantially impermeable to the passage of
water and with structural components having the capability of resisting hydrostatic and
hydrodynamic loads and the effects of buoyancy. If this method is used , compliance shall
be certified by a registered professional engineer or architect as stated in subsection
M.3.a.iii.
Attachment 2
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c. Recreational vehicles placed on sites within AO Zones on the city's Flood Insurance Rate
Maps shall either:
i. Be on the site for fewer than 180 consecutive days; and
ii. Be fully licensed and ready for highway use, on its wheels or jacking system, is attached
to the site only by quick disconnect type utilities and security devices, and has no
permanently attached additions; or
iii. Meet the elevation requirements of subsection O.2.a, and the anchoring and other
requirements for manufactured dwellings of subsection M.4.
d. In AO Zones, new and substantially improved appurtenant structures must comply with the
standards in subsection M.6.
e. In AO zones, enclosed areas beneath elevated structures shall comply with the requirements
in subsection L.1.
9.10.060. Not Net Loss Standards.
A. General Provisions.
1. No net loss of the proxies for the floodplain functions is required for development in the special
flood hazard area that would reduce undeveloped space, increase impervious surface, or result
in a loss of trees that are 6-inches dbh or greater. No net loss can be achieved by first avoiding
negative effects to floodplain functions to the degree possible, then minimizing remaining effects,
then replacing and/or otherwise compensating for, offsetting, or rectifying the residual adverse
effects to the three floodplain functions.
2. Compliance with no net loss for undeveloped space or impervious surface is preferred to occur
prior to the loss of habitat function but, at a minimum, shall occur concurrent with the loss.
3. No net loss must be provided within, in order of preference: 1) the lot or parcel that floodplain
functions were removed from, 2) the same reach of the waterbody where the development is
proposed, or 3) the special flood hazard area within the same hydrologically connected area as
the proposed development. Table 9.10 presents the no net loss ratios, which increase based on
the preferences listed above.
B. Undeveloped space. Development proposals shall not reduce the fish-accessible and egress-able
habitat and flood storage volume created by undeveloped space within the special flood hazard
area. A development proposal with an activity that would impact undeveloped space shall achieve
no net loss of fish-accessible and egress-able space and flood storage volume. Lost undeveloped
space must be replaced with fish-accessible and egress-able compensatory volume based on the
ratio in Table 1; must be hydrologically connected to the waterbody that is the flooding source; and
designed so that there is no increase in velocity.
C. Impervious surfaces. Impervious surface mitigation shall be mitigated through any of the following
options:
1. Development proposals shall not result in a net increase in impervious surface area within the
special flood hazard area through the use of ratios prescribed in Table 1, or
Commented [LB16]: Recommend adding “without
suitable mitigation” after “greater”.
Commented [LB17]: This should be pervious , not
impervious…. No net loss of impervious surface? We can
easily accommodate “no net loss of impervious surface”,
by adding more impervious surfaces.
Commented [LB18]: Need to define what is “fish
accessible and egress-able space”, and what would
compensatory “fish accessible and egress-able space”
Attachment 2
City of Tigard Engineering Comments
19
2. Use low impact development or green infrastructure to infiltrate and treat stormwater produced
by the new impervious surface, as documented by a qualified professional, or
3. If prior methods are not feasible and documented by a qualified professional stormwater
retention is required to ensure no increase in peak volume or flow and to maximize infiltration,
and treatment is required to minimize pollutant loading. See Section 9.10.060.E.3 for
stormwater retention specifications.
D. Trees. Development proposals shall result in no net loss of trees 6-inches dbh or greater within the
special flood hazard area.
1. Trees of or exceeding 6-inches dbh that are removed from the RBZ, Floodway, or RBZ-fringe
must be replaced at the ratios in Table 1 and planted within the special flood hazard area.
2. Replacement trees must be native species that would occur naturally in the Level III ecoregion
of the impact area.
E. Stormwater Management. Any development proposal that cannot mitigate as specified in Sections
9.10.060.C.1 and 9.10.060.C.2 must include the following:
1. Water quality (pollution reduction) treatment for post-construction stormwater runoff from any
net increase in impervious area; and
2. Water quantity treatment (retention or detention facilities) unless the outfall discharges into the
ocean.
3. Retention and detention facilities must:
a. Limit discharge to match the pre-development peak discharge rate (i.e., the discharge rate
of the site based on its natural groundcover and grade before any development occurred)
for the 10-year peak flow using a continuous simulation for flows between 50 percent of
the 2-year event and the 10-year flow event (annual series).
b. Treat stormwater to remove sediment and pollutants from impervious surfaces such that at
least 80 percent of the suspended solids are removed from the stormwater prior to
discharging to the receiving water body.
c. Be designed to not entrap fish.
d. Be certified by a qualified professional.
4. Detention facilities must be designed by a qualified professional and drain to the source of
flooding.
5. Stormwater treatment practices for multi-parcel facilities, including subdivisions, shall have an
enforceable operation and maintenance agreement to ensure the system functions as designed.
This agreement will include:
a. Access to stormwater treatment facilities at the site by the City of Tigard for the purpose of
inspection and repair.
Commented [LB19]: Delete “professional” (which by
definition refers to a biologist, and insert “registered
professional engineer” (should not need “civil”, as a
geotechnical engineer can do this as well.
Commented [LB20]: Same as above: strike
“professional” and insert “registered professional
engineer”; need a comma after “engineer”.
Commented [LB21]: Where is “Level III ecoregion” or
any ecoregion defined? Clear and objective.
Commented [LB22]: Need reference to city Urban
Forestry Manual for replacement tree sizes and numbers.
Commented [LB23]: Again retention/detention facilities
need to be designed by an engineer: suggest adding
”qualified professional for fish passage and entrapment
concerns, and by a qualified registered professional
engineer for hydrology and retention/detention facility
design.
Commented [LB24]: Need to add item e. “ e. Meet
city, ACOE, and CWS design standards, as applicable”.
ACOE is listed to meet SLOPES requirements.
Commented [LB25]: Add the word “Paved”. City
requires paved access to all LIDA facilities. This can be
“grasscrete” or other pervious paved surface.
Commented [LB26]: Strike “city of Tigard” and insert
“city and CWS personnel”
Attachment 2
City of Tigard Engineering Comments
20
b. A legally binding document specifying the parties responsible for the proper maintenance of
the stormwater treatment facilities. The agreement will be recorded and bind subsequent
purchasers and sellers even if they were not party to the original agreement.
c. For stormwater controls that include vegetation and/or soil permeability, the operation and
maintenance manual must include maintenance of these elements to maintain the
functionality of the feature.
d. The responsible party for the operation and maintenance of the stormwater facility shall have
the operation and maintenance manual on site and available at all times. Records of the
maintenance and repairs shall be retained and made available for inspection by the City of
Tigard for five years.
F. Exempt Activities. The following activities are not subject to the no net loss standards; however, they
may not be exempt from floodplain development permit requirements.
1. Normal maintenance of structures, such as re-roofing and replacing siding, provided there is no
change in the footprint or expansion of the roof of the structure.
2. Normal street, sidewalk, and road maintenance, including filling potholes, repaving, and
installing signs and traffic signals, that does not alter contours, use, or alter culverts and is less
than six inches above grade. Activities exempt do not include expansion of paved areas;
3. Routine maintenance of landscaping that does not involve grading, excavation, or filling;
4. Routine agricultural practices such as tilling, plowing, harvesting, soil amendments, and ditch
cleaning that does not alter the ditch configuration provided the spoils are removed from special
flood hazard area or tilled into fields as a soil amendment;
5. Routine silviculture practices (harvesting of trees), including hazardous fuels reduction and
hazard tree removal as long as root balls are left in place;
6. Removal of noxious weeds and hazard trees, and replacement of non-native vegetation with
native vegetation;
7. Normal maintenance of above ground utilities and facilities, such as replacing downed power
lines and utility poles provided there is no net change in footprint;
8. Normal maintenance of a levee or other flood control facility prescribed in the operations and
maintenance plan for the levee or flood control facility. Normal maintenance does not include
repair from flood damage, expansion of the prism, expansion of the face or toe or addition of
protection on the face or toe with rock armor.
9. Habitat restoration activities.
10. Pre-emptive removal of documented susceptible trees to manage the spread of invasive species.
11. Projects that are covered under separate consultations under Section 4(d), 7, or 10 of the
Endangered Species Act (ESA).
G. Riparian Buffer Zone (RBZ).
Commented [LB27]: Should just be “city”, not “City of
Tigard”
Attachment 2
City of Tigard Engineering Comments
21
1. The Riparian Buffer Zone is measured from the ordinary high-water line of a fresh waterbody
(lake; pond; ephemeral, intermittent, or perennial stream) or mean higher-high water of a
marine shoreline or tidally influenced river reach to 170 feet horizontally on each side of the
stream or inland of the MHHW. The riparian buffer zone includes the area between these outer
boundaries on each side of the stream, including the stream channel.
2. Functionally dependent uses are only subject to the no net loss standards in Section 6.1 for
development in the RBZ. Ancillary features that are associated with but do not directly impact
the functionally dependent use in the RBZ (including manufacturing support facilities and
restrooms) are subject to the beneficial gain standard in addition to no net loss standards.
3. Any other use of the RBZ requires a greater offset to achieve no net loss of floodplain functions,
on top of the no net loss standards described above, through the beneficial gain standard.
4. Under FEMA’s beneficial gain standard, an area within the same reach of the project and
equivalent to 5% of the total project area within the RBZ shall be planted with native herbaceous,
shrub and tree vegetation.
Table 9.10 No Net Loss Standards
Basic Mitigate
Ratios
Undeveloped
Space (ft3)
Impervious
Surface (ft2)
Trees
(6”<dbh≤20”)
Trees
(20”<dbh≤39”)
Trees
(39”<dbh)
RBZ and Floodway 2:1 1:1 3:1 5:1 6:1
RBZ-Fringe 1.5:1 1:1 2:1 4:1 5:1
Mitigation Multipliers:
Mitigation onsite
to Mitigation
offsite, same reach
100% 100% 100% 100% 100%
Mitigation onsite
to Mitigation
offsite, different
reach, same
watershed (5th
field)
200% 200% 200% 200% 200%
Notes:
1. Mitigation multipliers of 100% result in the required mitigation occurring at the same value described
by the ratios above, while multipliers of 200% result in the required mitigation being doubled.
a. For example, if a development would create 1,000 square feet of new impervious surface, then
1,000 square feet of new pervious surface would need to be created. However, if only 500 square
feet can be created within the same reach, the remaining 500 square feet created within a
different reach would need to be double the required amount because of the 200 percent
multiplier. In other words, another 1,000 square feet of pervious surface would need to be created
at the location in the different reach, in addition to the 500 square feet created within the same
reach.
9.10.0760. Violations.
No structure or land shall hereafter be constructed, located, extended, converted, or altered without full
compliance with the terms of this chapter and other applicable regulations, including, but not limited to,
TCDC Chapter 18.510, Sensitive Lands. Violations of the provisions of this chapter by failure to comply
with any of its requirements (including violations of conditions and safeguards established in connection
Commented [LB28]: What is the “5th field”. Either
define or delete.
Attachment 2
City of Tigard Engineering Comments
22
with conditions) shall constitute a Class 1 civil infraction, processed according to the procedures in the
civil infractions ordinance, set out in TMC Chapter 1.16. Each violation of a separate provision of this
chapter shall constitute a separate infraction, and each day that a violation of this chapter is committed or
permitted to continue shall constitute a separate infraction. A finding of a violation of this chapter shall
not relieve the responsible party of the duty to abate the violation. The penalties imposed by this section
are in addition and not in lieu of any remedies available to the city. If a provision of this chapter is
violated by a firm or corporation, the officer or officers, or person or persons responsible for the violation
shall be subject to the penalties imposed by this chapter. Nothing contained herein shall prevent the City
of Tigard from taking such other lawful action as is necessary to prevent or remedy any violation.
Attachment 2
City of Tigard Engineering Comments
1
Chapter 18.510
Sensitive Lands
18.510.010 Purpose.
18.510.020 Applicability.
18.510.030 AdministrativeGeneral Provisions.
18.510.040 Reserved.Review Process.
18.510.050 General Provisions for Wetlands.Review Type Determination
18.510.060 Approval Period and Extensions.Reserved.
18.510.070 Sensitive Lands Applications.Approval Criteria
18.510.080 Special Provisions within Locally Significant Wetlands and Along the Tualatin River,
Fanno Creek, Ball Creek, and the South Fork of Ash Creek.
18.510.090 Density Transfer and Reductions.
18.510.100 Plan Amendment Option.
18.510.110 Significant Habitat Areas Map Verification Procedures.
18.510.010. Purpose.
A. Maintain integrity of rivers, streams, and creeks. Sensitive land regulations in this chapter are
intended to maintain the integrity of the rivers, streams, and creeks in Tigard by minimizing erosion,
promoting bank stability, maintaining and enhancing water quality and fish and wildlife habitats, and
preserving scenic quality and recreation potential.
B. Implement comprehensive plan and floodplain management program. The regulations of this chapter
apply to all areas of special flood hazard within the City of Tigard. These regulations are intended to
implement the comprehensive plan and the city's floodplain management program as required by the
Federal Emergency Management Agency (FEMA) through the National Flood Insurance Program, to
help to preserve sensitive land areas from encroaching use, and to maintain the October 19, 2018,
zero-foot rise floodway elevation. All development within the areas of special flood hazard are
subject to the terms of this ordinance and required to comply with its provisions and all other
applicable regulations including Tigard Municipal (TMC) Chapter 9.10.
C. Implement Clean Water Service (CWS) design and construction standards. The regulations of this
chapter are intended to protect the beneficial uses of water within the Tualatin River Basin in
compliance with the CWS "Design and Construction Standards."
D. Implement the Metro Urban Growth Management Functional Plan. The regulations of this chapter are
intended to protect the beneficial water uses and functions and values of resources within water
quality and flood management areas and to implement the performance standards of the Metro Urban
Growth Management Functional Plan.
E. Implement Statewide Planning Goal 5 (Natural Resources). The regulations in this chapter are
intended to address the requirements of Statewide Planning Goal 5 (Natural Resources) and the safe
harbor provisions of the Goal 5 administrative rule pertaining to wetland and riparian corridors.
F. Protect public health, safety, and welfare. Sensitive land areas are designated as such to protect the
public health, safety, and welfare of the community through the regulation of these sensitive land
Attachment 2
City of Tigard Engineering Comments
2
areas.
G. Location. Sensitive lands are lands potentially unsuitable for development because of their location
within:
1. The areas of special flood hazard or 1996 flood inundation line, whichever is greater;
2. Natural drainageways;
3. Wetland areas that are regulated by the other agencies including the U.S. Army Corps of
Engineers and the Division of State Lands, or are designated as significant wetland on the City of
Tigard "Wetland and Stream Corridors Map";
4. Steep slopes of 25% or greater and unstable ground;
5. Significant fish and wildlife habitat areas designated on the City of Tigard "Significant Habitat
Areas Map"; and
6. Significant tree groves as shown on the "City of Tigard Significant Tree Grove Map." (Ord. 17-22
§2; Ord. 18-21 §2; Ord. 20-01 §1; Ord. 23-09, 12/12/2023)
18.510.020. Applicability.
A. The standards and procedures in this chapter apply to the following sensitive lands within the City
of Tigard:
1. The area of special flood hazard or 1996 flood inundation line, whichever is greater;
2. Drainageways;
3. Wetlands that appear on the City of Tigard "Wetland and Stream Corridors Map" as either:
a. Locally significant, or
b. Non-significant and not subject to regulatory authority of other agencies including the
U.S. Army Corps of Engineers and the Department of State Lands.
4. Steep slopes, for the purposes of this chapter, are slopes 25% or greater;
5. Significant fish and wildlife habitat areas designated on the City of Tigard "Significant
Habitat Areas Map"; and
6. Significant tree groves as shown on the "City of Tigard Significant Tree Grove Map."
B. The following sensitive lands are defined as sensitive lands for the purposes of this title and Title 8
Urban Forestry, but are not regulated by this chapter:
1. Significant fish and wildlife habitat areas designated on the City of Tigard "Significant
Habitat Areas Map"; and
Attachment 2
City of Tigard Engineering Comments
3
2. Significant tree groves as shown on the "City of Tigard Significant Tree Grove Map."
3. Wetlands that meet the jurisdictional requirements and subject to regulatory authority of the
U.S. Army Corps of Engineers, Department of State Lands, CWS, or other federal, state, or
regional agencies. The city will require that all necessary approvals from other agencies are
obtained.
18.510.030. General Provisions
A. Approval required. An applicant proposing development within sensitive lands, as defined in this
chapter, must obtain approval in certain situations. Depending on the nature and intensity of the
proposed activity within sensitive lands, either a Type I or Type II review is required, as provided in
Section 18.510.050. The approval criteria for different types of sensitive lands are provided in
Section 18.510.070.
B. Interagency coordination. All necessary approvals must be obtained from all federal, state, or local
governmental agencies, where applicable. All development applications must include a service
provider letter from Clean Water Services.
C. Other uses. Except as explicitly authorized by other provisions of this chapter, all other uses are
prohibited within sensitive lands.
D. Nonconforming uses. A use established prior to the effective date of this title, which would be
prohibited by this chapter or that would be subject to the limitations and controls imposed by this
chapter, shall be considered a nonconforming use. Nonconforming uses shall be subject to the
provisions of Chapter 18.50, Nonconforming Circumstances.
E. Wetlands.
1. Wetland regulations apply to those areas classified as significant on the City of Tigard
"Wetland and Streams Corridors Map," and to a vegetated corridor ranging from 25 to 200
feet wide, measured horizontally, from the defined boundaries of the wetland, as provided in
"Table 3.1, Vegetated Corridor Widths," and "Appendix C, Natural Resource Assessments,"
of the CWS "Design and Construction Standards." Wetland locations may include but are not
limited to those areas identified as wetlands in "Wetland Inventory and Assessment for the City
of Tigard, Oregon," prepared by Fishman Environmental Services, December 1994; “West
Bull Mountain Area Local Wetland Inventory” prepared by Pacific Habitat Services, Inc., July
2012; and River Terrace and West Planning Areas of Tigard Local Wetland Inventory”
prepared by Pacific Habitat Services, Inc., March 2023.
2. Precise boundaries may vary from those shown on wetland maps; specific delineation of wetland
boundaries may be necessary. Wetland delineation will be done by qualified professionals at the
applicant's expense. Delineations must be reviewed and approved by the Department of State
Lands.
18.510.040. Review Process
A sensitive lands review is required for all development within sensitive lands unless the development is
allowed without review, as provided in Subsection 18.510.050.A. Review type determinations are
provided in Section 18.510.050. Sensitive lands reviews are processed as follows:
Commented [LB1]: Does CWS have jurisdictional
authority over Wetlands? I thought only DSL and ACOE
have jurisdiction.
Attachment 2
City of Tigard Engineering Comments
4
A. Area of special flood hazard. A sensitive land review for development within the area of special flood
hazard is processed through a Type I or II procedure as provided in 18.710.050 and 18.710.060,
respectively.
B. Drainageways. A sensitive land review for development within drainageways is processed through a
Type I or II procedure as provided in 18.710.050 and 18.710.060, respectively.
C. Steep slopes. A sensitive land review for development within steep slopes is processed through a Type
I or II procedure as provided in 18.710.050 and 18.710.060, respectively.
D. Wetlands. A sensitive land review for development within wetlands is processed through a Type II
procedure as provided in 18.710.060.
18.510.020. Applicability.
18.510.050. Review Type Determination
A. CWS stormwater connection permit. All proposed development must obtain a stormwater connection
permit from CWS in compliance with its design and construction standards.
BA. Allowed uses with no approval No review required. Except as provided below and by Subsections
18.510.020.D, F, and G of this section, the The following uses and activities are allowed uses without
review within drainageways, and steep slopes that are 25 percent or greater, and unstable ground
when the use does not involve paving. For the purposes of this chapter, the word "structure" excludes:
children's play equipment, picnic tables, sand boxes, grills, basketball hoops, and similar recreational
equipment.
1. Accessory uses such as lawns, gardens, or play areas; except in a water quality sensitive area or
vegetated corridor, as defined in the CWS "Design and Construction Standards" or the Statewide
Goal 5 vegetated corridor established for the Tualatin River, as defined in Section 18.510.080.
2. Farm uses conducted without locating a structure within the sensitive land area; except in a water
quality sensitive area or vegetative corridor, as defined in CWS "Design and Construction
Standards" or the Statewide Goal 5 vegetated corridor established for the Tualatin River, as
defined in Section 18.510.080.
3. Community recreation uses, excluding structures; except in a water quality sensitive area or
vegetated corridor, as defined in the CWS "Design and Construction Standards" or the Statewide
Goal 5 vegetated corridor established for the Tualatin River, as defined in Section 18.510.080.
4. Public and private conservation areas for water, soil, open space, forest, and wildlife resources.
5. Removal of poison oak, tansy ragwort, blackberry, English ivy, or other noxious vegetation.
6. Maintenance of floodway excluding re-channeling; except in a water quality sensitive area or
vegetated corridor, as defined in the CWS "Design and Construction Standards" or the Statewide
Goal 5 vegetated corridor established for the Tualatin River, as defined in Section 18.510.080.
76. Fences; except in a water quality sensitive area or vegetated corridor, as defined in the CSW
"Design and Construction Standards"; or the Statewide Goal 5 vegetated corridor established for
the Tualatin River, as defined in Section 18.510.080.
Attachment 2
City of Tigard Engineering Comments
5
87. Accessory structures that are less than 120200 square feet in size; except in a water quality
sensitive area or vegetated corridor, as defined in the CSW "Design and Construction Standards";
or the Statewide Goal 5 vegetated corridor established for the Tualatin River, as defined in
Section 18.510.080.
98. Land form alterations involving up to 10 cubic yards of material; except in a water quality
sensitive area or vegetated corridor, as defined in the CSW "Design and Construction Standards";
or the Statewide Goal 5 vegetated corridor established for the Tualatin River, as defined in
Section 18.510.080.
C. Exemptions. When performed under the direction of the city, the following are exempt from the
provisions of this section:
9. The following are exempt from the provisions of this section when performed under the
direction of the city:
1a. Responses to public emergencies, including emergency repairs to public facilities.;
2b. Stream and wetlands restoration and enhancement programs, except in the areas of special
flood hazard when meeting the definition of development in TMC Section 9.10.020.;
3c. Non-native vegetation removal.;
4d. Planting of native plant species.; and
5e. Routine maintenance or replacement of existing public facilities projects, except in the areas
of special flood hazard when meeting the definition of development in TMC Section
9.10.020.
D. Jurisdictional wetlands. Landform alterations or developments that are only within wetland areas that
meet the jurisdictional requirements and permit criteria of the U.S. Army Corps of Engineers, Division of
State Lands, CWS, or other federal, state, or regional agencies, and are not designated as significant
wetlands on the City of Tigard "Wetland and Streams Corridors Map," do not require a sensitive lands
review. The city will require that all necessary approvals from other agencies are obtained. All other
applicable city requirements must be met, including sensitive land reviews for areas within the areas of
special flood hazard, slopes of 25% or greater or unstable ground, drainageways, and wetlands that are
not under state or federal jurisdiction.
EB. AdministrativeType I sensitive lands review.
1. AdministrativeA Type I sensitive lands reviews within the drainageways, and steep slopes that
are 25% or greater, and unstable ground are processed through a Type I procedure, as provided in
Section 18.710.050, is required for the following actions:
a. The repair, reconstruction, or improvement of an existing structure or utility, the cost of
which is less than 50% of the market value of the structure prior to the improvement or the
damage requiring reconstruction.;
b. Minimal gGround disturbance or landform alteration involving 10 to 50 cubic yards of
material.; and
Attachment 2
City of Tigard Engineering Comments
6
c. Building permits for accessory structures that are 120200 to 528 square feet in size.
2. AdministrativeA Type I sensitive lands reviews within the areas of special flood hazard are
processed through a Type I procedure, as provided in Section 18.710.050,is required for the
following actions:
a. Determination that the proposed development or any land form alteration is located
entirely outside the area of special flood hazard.Within the areas of special flood hazard but
outside the floodway (floodway fringe):
i. The construction of accessory structures up to 528 square feet in size; and
ii. Any landform alteration involving up to 50 cubic yards of material.
b. Stream and wetland restoration and enhancement programs, including work in the floodway,
when performed under the direction of the city.
3. The approval authority will approve, approve with conditions, or deny a sensitive land review
application using the standards and approval criteria Sections 18.510.040, 18.510.050030,
18.510.070, and 18.510.080.
FC. Sensitive lands approvals issued by the directorType II sensitive lands reviews.
1. A Type II Ssensitive land reviews within drainageways, steep slopes that are 25% or greater or
unstable ground, and wetlands areas that are not regulated by other local, state, or federal
agencies are processed through a Type II procedure, as provided in Section 18.710.060,is
required for the following actions:
a. Ground disturbance or land form alterations involving more than 50 cubic yards of material.;
b. Repair, reconstruction, or improvement of an existing structure or utility, the cost of which
equals or exceeds 50% of the market value of the structure prior to the improvement or the
damage requiring reconstruction.;
c. Residential and nonresidential structures intended for human habitation.;and
d. Accessory structures that are greater than 528 square feet in size.
2. A Type II sensitive lands review within the area of special flood hazard is required for the
following actions:
a. Ground disturbance or landform alterations in the area of special flood hazard, including
the floodway.
b. Repair, reconstruction, or improvement of an existing structure or utility, the cost of which
equals or exceeds 50% of the market value of the structure prior to the improvement or the
damage requiring reconstruction provided no development occurs in the floodway.
23. The approval authority will approve, approve with conditions, or deny a sensitive lands review
application using the standards and approval criteria provided in Sections 18.510.030,
18.510.070, and 18.510.080.
Attachment 2
City of Tigard Engineering Comments
7
G. Sensitive lands approvals issued by the hearings officer.
1. Sensitive land reviews within areas of special flood hazard are processed through a Type III-HO
procedure, as provided in Section 18.710.080, for the following actions:
a. Ground disturbance or landform alterations in all floodway areas;
b. Ground disturbance or landform alterations in floodway fringe locations involving more than
50 cubic yards of material;
c. Repair, reconstruction, or improvement of an existing structure or utility, the cost of which
equals or exceeds 50% of the market value of the structure prior to the improvement or the
damage requiring reconstruction provided no development occurs in the floodway;
d. Structures intended for human habitation; and
e. Accessory structures that are greater than 528 square feet in size, outside of floodway areas.
2. The approval authority will approve, approve with conditions, or deny a sensitive lands review
application using the approval criteria provided in Section 18.510.070.
H. Other uses. Except as explicitly authorized by other provisions of this chapter, all other uses are
prohibited on sensitive land areas.
I. Nonconforming uses. A use established prior to the effective date of this title, which would be
prohibited by this chapter or that would be subject to the limitations and controls imposed by this
chapter, shall be considered a nonconforming use. Nonconforming uses shall be subject to the
provisions of Chapter 18.50, Nonconforming Circumstances. (Ord. 17-22 §2; Ord. 18-21 §2; Ord. 18-
23 §2; Ord. 20-01 §1; Ord. 22-06 §2; Ord. 23-09, 12/12/2023)
18.510.030. Administrative Provisions.
A. Interagency coordination. The approval authority will review all applications for a sensitive lands
review to determine that all necessary approvals be obtained from those federal, state, or local
governmental agencies, from which prior approval is also required.
As provided in CWS "Design and Construction Standards," the necessary permits for all "development"
must comply include a CWS service provider letter, which specifies the conditions and requirements
necessary, if any, for an applicant to comply with CWS water quality protection standards and for the
agency to issue a stormwater connection permit.
B. Applicable standards and criteria. The approval authority will apply the standards and criteria
provided in this chapter when reviewing an application for a sensitive lands review. (Ord. 17-22 §2;
Ord. 18-21 §2; Ord. 18-23 §2; Ord. 23-09, 12/12/2023)
18.510.040. Reserved.
18.510.050. General Provisions for Wetlands.
A. Code compliance requirements. Wetland regulations apply to those areas classified as significant on
Attachment 2
City of Tigard Engineering Comments
8
the City of Tigard "Wetland and Streams Corridors Map," and to a vegetated corridor ranging from
25 to 200 feet wide, measured horizontally, from the defined boundaries of the wetland, as provided
in "Table 3.1, Vegetated Corridor Widths," and "Appendix C, Natural Resource Assessments," of the
CWS "Design and Construction Standards." Wetland locations may include but are not limited to
those areas identified as wetlands in "Wetland Inventory and Assessment for the City of Tigard,
Oregon," Fishman Environmental Services, 1994.
B. Delineation of wetland boundaries. Precise boundaries may vary from those shown on wetland maps;
specific delineation of wetland boundaries may be necessary. Wetland delineation will be done by
qualified professionals at the applicant's expense. (Ord. 17-22 §2; Ord. 18-21 §2)
18.510.060. Approval Period and Extensions.Reserved
Expirations and extensions of approvals are provided in Subsection 18.20.050.G. (Ord. 17-22 §2; Ord. 18-
21 §2; Ord. 18-23 §2; Ord. 18-28 §1; Ord. 22-06 §2)
18.510.070. Sensitive Lands Applications.Approval Criteria.
A. Approval required. An applicant, who wishes to develop within a sensitive area, as defined in this
chapter, must obtain approval in certain situations. Depending on the nature and intensity of the
proposed activity within a sensitive area, either a Type II or Type III review is required, as provided
in Subsections 18.510.020.F and G. The approval criteria for different types of sensitive areas are
provided in Subsections 18.510.070.B–E.
BA. Within the areasArea of special flood hazard. The approval authority will approve or approve with
conditions an application for sensitive lands review on properties that contain any within the areas of
special flood hazard when all of the following either the clear and objective criteria or the
alternative criteria are met:
1. Clear and objective criteria. The proposed development or land form alteration is located
entirely outside of the area of special flood hazard.
2. Alternative criteria. The proposed development or land form alteration is located within the
area of special flood hazard and complies with all of the following criteria:
1. Compliance with all of the applicable requirements of this title and TMC Chapter 9.10 ;
2a. Land form alterations must preserve or enhance the areas of special flood hazard storage
function and maintenance of the zero -foot rise floodway must not result in any
encroachments, including fill, new construction, substantial improvements and other
development unless certified by a registered professional engineer that the encroachment will
not result in any increase in flood levels during the base flood discharge;. a. If in the
floodway and no-rise requirement is met, the development will comply with all applicable
flood hazard reduction provisions.
3. Land form alterations or developments within the areas of special flood hazard are allowed
only in areas designated as commercial, industrial, or parks and recreation on the
comprehensive plan land use map, except that alterations or developments associated with
community services uses, utilities, or public support facilities are allowed on residentially
zoned properties subject to applicable zoning standards;
b. An assessment, prepared and certified by a qualified professional, must demonstrate that
Attachment 2
City of Tigard Engineering Comments
9
the proposed land form alteration or development results in no net loss of the following
floodplain functions: floodplain storage, water quality, and vegetation. The assessment
must include a mitigation plan, if applicable. The assessment must comply with all no net
loss standards in in TMC Section 9.10.060.
4c. Where a land form alteration or development is allowed to occur within the areas of special
flood hazard it will not result in any increase in the water surface elevation of the 100 -year
flood.;
5d. The land form alteration or development plan includes a pedestrian or bicycle pathway in
compliance with the adopted Transportation System Plan or Greenways Trail System Master
Plan, unless the construction of said pathway is deemed as untimely.;
6e. Pedestrian or bicycle pathway projects within the areas of special flood hazard must include a
wildlife habitat assessment that shows the proposed alignment minimizes impacts to
significant wildlife habitat while balancing the community's recreation and environmental
educational goals.;
7f. The necessary U.S. Army Corps of Engineers and State of Oregon Land Board,
DivisionDepartment of State Lands, and CWS permits and approvals must be obtained.; and
8g. Where land form alterations or development are allowed within and adjacent to the areas of
special flood hazard, the city will require the consideration of dedication of sufficient open
land area within and adjacent to the areas of special flood hazard in compliance with the
comprehensive plan. This area must include portions of a suitable elevation for the
construction of a pedestrian or bicycle pathway within the areas of special flood hazard in
compliance with the adopted Transportation System Plan or Greenways Trail System Master
Plan.
CB. With sSteep slopes. The approval authority will approve or approve with conditions an application for
a sensitive lands review onwithin steep slopes of 25% or greater or unstable ground when all of the
following criteria are met:
1. Compliance with all of the applicable requirements of this title;
21. The extent and nature of the proposed land form alteration or development will not create site
disturbances to an extent greater than that required for the use.;
32. The proposed land form alteration or development will not result in erosion, stream
sedimentation, ground instability, or other adverse on-site and off-site effects or hazards to life or
property.;
43. The structures are appropriately sited and designed to ensure structural stability and proper
drainage of foundation and crawl space areas for development with any of the following soil
conditions: wet or high water table; high shrink-swell capability; compressible or organic; and
shallow depth-to -bedrock.; and
54. Where natural vegetation has been removed due to land form alteration or development, the areas
not covered by structures or impervious surfaces will be replanted to prevent erosion in
compliance with CWS "Design and Construction Standards".
Attachment 2
City of Tigard Engineering Comments
10
DC. Within dDrainageways. The approval authority will approve or approve with conditions an
application for a sensitive lands review within drainageways when all of the following criteria are
met:
1. Compliance with all of the applicable requirements of this title;
21. The extent and nature of the proposed land form alteration or development will not create site
disturbances to an extent greater than that required for the use.;
32. The proposed land form alteration or development will not result in erosion, stream
sedimentation, ground instability, or other adverse on-site and off-site effects or hazards to life or
property.;
43. The water flow capacity of the drainageway is not decreased.;
54. Where natural vegetation has been removed due to land form alteration or development, the areas
not covered by structures or impervious surfaces will be replanted to prevent erosion in
compliance with CWS "Design and Construction Standards".;
65. The drainageway will be replaced by a public facility of adequate size to accommodate maximum
flow in compliance with Clean Water Services requirements and the city's adopted stormwater
master plan.;
76. The necessary U.S. Army Corps of Engineers and State of Oregon Land Board,
DivisionDepartment of State Lands, and CWS approvals must be obtained.;
87. Where land form alterations or development are allowed within and adjacent to the areas of
special flood hazard, the city will require the consideration of dedication of sufficient open land
area within and adjacent to the areas of special flood hazard in compliance with the
comprehensive plan. This area will include portions of a suitable elevation for the construction of
a pedestrian or bicycle pathway within the areas of special flood hazard in compliance with the
adopted pedestrian bicycle pathway plan.
ED.Within wWetlands. The approval authority will approve or approve with conditions an application for
a sensitive lands review within wetlands when all of the following criteria are met:
1. Compliance with all of the applicable requirements of this title;
21. The proposed land form alteration or development is not located within a locally significant
wetland or its associated vegetative corridor neither on wetland in an area designated as
significant wetland on the comprehensive plan areas of special flood hazard and wetland map nor
is within the vegetative corridor as provided in "Table 3.1 Vegetative Corridor Widths" and
"Appendix C: Natural Resources Assessments" of the CWS "Design and Construction
Standards," for such a wetland.;
32. The extent and nature of the proposed land form alteration or development will not create site
disturbances to an extent greater than the minimum required for the use.;
43. Any encroachment or change in on-site or off-site drainage that would adversely impact wetland
characteristics have been mitigated.;
Commented [LB2]: WE typically don’t want to increase
the flow capacity either as this may impact downgradient
properties that might have a “bottleneck” and the
flooding risk on these downgradient properties.. Suggest
adding text: If flow capacity is increased within the
drainageway, analysis by a qualified licensed engineer
must be performed to indicate there is no
demonstratable increase in flooding risk to downgradient
properties.
Attachment 2
City of Tigard Engineering Comments
11
54. Where natural vegetation has been removed due to land form alteration or development, erosion
control provisions of the Surface Water Management program of Washington County must be
met and areas not covered by structures or impervious surfaces will be replanted in like or similar
species in compliance with CWS "Design and Construction Standards".;
65. All other sensitive lands requirements of this chapter have been met.;
76. The necessary U.S. Army Corps of Engineers and State of Oregon Land Board,
DivisionDepartment of State Lands, and CWS approvals must be obtained.;
87. Physical limitations and natural hazards, areas of special flood hazard and wetlands, natural areas,
and parks, recreation and open space policies of the comprehensive plan have been met.
18.510.080. Special Provisions within Locally Significant Wetlands and Along the Tualatin River,
Fanno Creek, Ball Creek, and the South Fork of Ash Creek.
A. In order to address the requirements of Statewide Planning Goal 5 (Natural Resources) and the safe
harbor provisions of the Goal 5 administrative rule (OAR 666-023-0030) pertaining to wetlands, all
wetlands classified as significant on the City of Tigard "Wetlands and Streams Corridors Map" are
protected. No land form alterations or developments are allowed within or partially within a
significant wetland, except as allowed or approved in compliance with Section 18.510.100.
B. In order to address the requirements of Statewide Planning Goal 5 (Natural Resources) and the safe
harbor provisions of the Goal 5 administrative rule (OAR 660-023-0030) pertaining to riparian
corridors, a standard setback distance or vegetated corridor area, measured horizontally from and
parallel to the top of the bank, is established for the Tualatin River, Fanno Creek, Ball Creek, and the
South Fork of Ash Creek.
1. The standard width for "good condition" vegetated corridors along the Tualatin River is 75 feet,
unless wider in compliance with CWS "Design and Construction Standards," or modified in
compliance with Section 18.510.100. If all or part of a locally significant wetland (a wetland
identified as significant on the City of Tigard "Wetlands and Streams Corridors Map") is located
within the 75-foot setback area, the vegetated corridor is measured from the upland edge of the
associated wetland.
2. The standard width for "good condition" vegetated corridors along Fanno Creek, Ball Creek, and
the South Fork of Ash Creek is 50 feet, unless wider in compliance with CWS "Design and
Construction Standards," or modified in compliance with Section 18.510.100. If all or part of a
locally significant wetland (a wetland identified as significant on the City of Tigard "Wetlands
and Streams Corridors Map") is located within the 50-foot setback area, the vegetated corridor is
measured from the upland edge of the associated wetland.
3. The minimum width for "marginal or degraded condition" vegetated corridors along the Tualatin
River, Fanno Creek, Ball Creek, and the South Fork of Ash Creek is 50 percent of the standard
width, unless wider in compliance with CWS "Design and Construction Standards," or modified
in compliance with Section 18.510.100.
4. The determination of corridor condition is based on the natural resource assessment guidelines as
provided in the CWS "Design and Construction Standards."
5. The standard setback distance or vegetated corridor area applies to all development proposed on
Commented [LB3]: Again, does CWS have jurisdictional
authority in wetlands?
Attachment 2
City of Tigard Engineering Comments
12
property located within or partially within the vegetated corridors, except as allowed below:
a. Roads, pedestrian or bike paths crossing the vegetated corridor from one side to the other in
order to provide access to the sensitive area or across the sensitive area, as approved by the
city in compliance with Section 18.510.070 and by CWS "Design and Construction
Standards";
b. Utility or service provider infrastructure construction (i.e. storm, sanitary sewer, water,
phone, gas, cable, etc.), if approved by the city and CWS;
c. A pedestrian or bike path, not exceeding 10 feet in width and in compliance with the CWS
"Design and Construction Standards";
d. Grading for the purpose of enhancing the vegetated corridor, as approved by the city and
CWS;
e. Measures to remove or abate hazards, nuisances, or fire and life safety violations, as approved
by the regulating jurisdiction;
f. Enhancement of the vegetated corridor for water quality or quantity benefits, fish, or wildlife
habitat, as approved by the city and CWS;
g. Measures to repair, maintain, alter, remove, add to, or replace existing structures, roadways,
driveways, utilities, accessory uses, or other developments provided they are in compliance
with city and CWS regulations, and do not encroach further into the vegetated corridor or
sensitive area than allowed by the CWS "Design and Construction Standards."
C. Land form alterations or developments located within or partially within the Goal 5 safeharbor
setback or vegetated corridor areas established for the Tualatin River, Fanno Creek, Ball Creek,
and the South Fork of Ash Creek that meet the jurisdictional requirements and permit criteria of
the CWS, U.S. Army Corps of Engineers, Department of State Lands, or other federal, state, or
regional agencies, are not subject to this subsection B, except where the:
a. Land form alterations or developments are located within or partially within a good condition
vegetated corridor, as provided in Paragraphs 18.510.080.B.1 and 2;
b. Land form alterations or developments are located within or partially within the minimum
width area established for marginal or a degraded condition vegetated corridor, as provided in
Paragraph 18.510.080.B.3.
These exceptions reflect instances of the greater protection of riparian corridors provided by the safe
harbor provisions of the Goal 5 administrative rule.
18.510.090. Density Transfer and Reductions.
A. Density transfer. Required residential density for apartments, rowhouses, and small form residential
development may be transferred from sensitive lands using the following methods:
1. The units per acre calculated by subtracting land areas listed in Subparagraphs 18.40.020.A.1–3
from the gross acres may be transferred to the remaining buildable land areas subject to the
following limitations:
Attachment 2
City of Tigard Engineering Comments
13
a. The number of units that can be transferred is limited to the number of units that would have
been allowed on 25% of the unbuildable area if not for these regulations; and
b. The total number of units per site does not exceed 125% of the maximum number of units per
gross acre allowed.
2. Units per acre calculated by subtracting land areas listed in Paragraph 18.40.020.A.4 from the
gross acres may be transferred to the remaining buildable land areas on land zoned RES-D and
RES-E subject to the following limitations:
a. The number of units that can be transferred is limited to the number of units that would have
been allowed on the wetland area, if not for these regulations;
b. The total number of units per site does not exceed the maximum number of units per gross
acre allowed.
B. Density reduction. The minimum number of residential units required in a development may be
reduced if necessary to ensure that impacts on habitat areas are minimized. The amount of
reduction in the minimum density is calculated by subtracting the square footage of inventoried
significant habitat that is permanently protected from the total square footage used to calculate the
minimum density requirement. The approval authority may impose any reasonable condition
necessary to mitigate identified impacts resulting from development on otherwise unbuildable
land.
The approval authority will approve, approve with conditions, or deny the density reduction
provided that the proposal will directly result in the protection of significant habitat areas through
placement in a non-buildable tract or protected with a restrictive easement.
18.510.100. Plan Amendment Option.
A. Comprehensive plan amendment. Any owner of property affected by the Goal 5 safeharbor (1)
protection of significant wetlands or (2) vegetated areas established for the Tualatin River, Fanno
Creek, Ball Creek, and the South Fork of Ash Creek may apply for a comprehensive plan amendment
as provided in Chapter 18.790, Text and Map Amendments. This amendment must be based on a
specific development proposal. The effect of the amendment would be to remove Goal 5 protection
from the property, but not to remove the requirements related to the CWS Stormwater Connection
Permit, which must be addressed separately through an alternatives analysis, as described in Section
3.02.5 of the CWS "Design and Construction Standards." The applicant must demonstrate that such
an amendment is justified by either of the following:
B. ESEE analysis. The applicant may prepare an environmental, social, economic and energy (ESEE)
consequences analysis prepared in compliance with OAR 660-23-040.
1. The analysis must consider the ESEE consequences of allowing the proposed conflicting use,
considering both the impacts on the specific resource site and the comparison with other
comparable sites within the Tigard Planning Area;
2. The ESEE analysis must demonstrate to the satisfaction of the city council that the adverse
economic consequences of not allowing the conflicting use are sufficient to justify the loss, or
partial loss, of the resource;
Attachment 2
City of Tigard Engineering Comments
14
3. In particular, ESEE analysis must demonstrate why the use cannot be located on buildable land,
consistent with the provisions of this chapter, and that there are no other sites within the Tigard
Planning Area that can meet the specific needs of the proposed use;
4. The ESEE analysis must be prepared by a team consisting of a wildlife biologist or wetlands
ecologist and a land use planner or land use attorney, all of whom are qualified in their respective
fields and experienced in the preparation of Goal 5 ESEE analysis;
5. If the application is approved, then the ESEE analysis must be incorporated by reference into the
Tigard Comprehensive Plan, and the "Tigard Wetland and Stream Corridor Map" be amended to
remove the site from the inventory.
C. Demonstration of change. In this case, the applicant must demonstrate that the sensitive area site no
longer meets the applicable significance threshold defined by the Goal 5 administrative rule, relative
to other comparable resources within the Tigard Planning Area.
1. Significance thresholds are described and applied in the addendum to the City of Tigard Local
Wetlands Inventory adopted by reference as part of this chapter.
2. To approve this claim, the city council must find that the decline in identified resource values did
not result from a violation of this title.
18.510.110. Significant Habitat Areas Map Verification Procedures.
A. Applicants who concur that the significant habitat areas map is accurate must submit the following
information to serve as the basis for verifying the boundaries of inventoried habitat areas:
1. Submission requirements.
a. A detailed property description;
b. A scale map of the property showing the locations of significant habitat areas, any existing
built area, wetlands or water bodies, Clean Water Services' vegetated corridor, the areas of
special flood hazard, the 1996 flood inundation line, and contour line s (two-foot intervals for
slope less than 15% and 10-foot intervals for slopes 15% or greater); and
c. A current aerial photograph of the property.
2. The approval authority's decision will be based on consideration of submitted information, site
visit information, and other factual information. Should the applicant disagree with the
determination on the location of significant habitat areas on the property, the precise boundaries
must be verified by the applicant in compliance with the detailed delineation methodology
outlined in Subsection 18.510.110.B.
B. Applicants who believe that the map is inaccurate must submit a detailed delineation conducted by a
qualified professional in compliance with the following methodology to verify the precise boundaries
of the inventoried habitat areas by means of a Type II procedure.
1. Verifying boundaries of inventoried riparian habitat. Locating habitat and determining its riparian
habitat class is a 4-step process:
Attachment 2
City of Tigard Engineering Comments
15
a. Locate the water feature that is the basis for identifying riparian habitat.
i. Locate the top of bank of all streams, rivers, and open water within 200 feet of the
property.
ii. Locate the areas of special flood hazard or 1996 flood inundation line, whichever is
greater, within 100 feet of the property.
iii. Locate all wetlands within 150 feet of the property. Identified wetlands on the property
must be further delineated consistent with methods currently accepted by the Oregon
DivisionDepartment of State Lands and the U.S. Army Corps of Engineers.
b. Identify the vegetative cover status of all areas on the property that are within 200 feet of the
top of bank of streams, rivers, and open water, are wetlands or are within 150 feet of
wetlands, and are flood areas and within 100 feet of flood areas.
i. Vegetative cover status must be as identified on the metro vegetative cover map.
ii. The vegetative cover status of a property may be adjusted only if (a) the property was
developed prior to the time the regional program was approved; or (b) an error was made
at the time the vegetative cover status was determined. To assert the latter type of error,
applicants must submit an analysis of the vegetative cover on their property using
summer 2002 aerial photographs and the following definition of vegetative cover types in
Table 18.510.1.
Table 18.510.1
Definitions of Vegetative Cover Types
Type Definition
Low structure
vegetation or open
soils
Areas that are part of a contiguous area 1 acre or larger of grass,
meadow, croplands, or areas of open soils located within 300 feet
of a surface stream (low structure vegetation areas may include
areas of shrub vegetation less than 1 acre in size if they are
contiguous with areas of grass, meadow, croplands, orchards,
Christmas tree farms, holly farms, or areas of open soils located
within 300 feet of a surface stream and together form an area of 1
acre in size or larger).
Woody vegetation
Areas that are part of a contiguous area 1 acre or larger of shrub
or open or scattered forest canopy (less than 60 percent crown
closure) located within 300 feet of a surface stream.
Forest canopy
Areas that are part of a contiguous grove of trees 1 acre or larger
in area with approximately 60 percent or greater crown closure,
irrespective of whether the entire grove is within 200 feet of the
relevant water feature.
c. Determine whether the degree that the land slope upward from all streams, rivers, and open
water within 200 feet of the property is greater than or less than 25 percent (using the
vegetated corridor measurement methodology as provided in Clean Water Services Design
and Construction Standards; and
d. Identify the riparian habitat classes applicable to all areas on the property using Table
Attachment 2
City of Tigard Engineering Comments
16
18.510.2 and Table 18.510.3.
Table 18.510.2
Method for Locating Boundaries of Class I and II Riparian Areas
Distance in
feet from
water feature
Development/Vegetation Status[1]
Developed
areas not
providing
vegetative
cover
Low structure
vegetation or
open soils
Woody
vegetation
(shrub and
scattered forest
canopy)
Forest canopy
(closed to open
forest canopy)
Surface streams
0-50 Class II Class I Class I Class I
50-100 Class II [2] Class I Class I
100-150
Class II [2]
if slope > 25
percent
Class II [2]
if slope > 25
percent
Class II [2]
150-200
Class II [2]
if slope > 25
percent
Class II [2]
if slope > 25
percent
Class II [2]
if slope > 25
percent
Wetlands (Wetland feature itself is a Class I Riparian Area)
0-100 Class II [2] Class I Class I
100-150 Class II [2]
Flood Areas (Undeveloped portion of flood area is a Class I Riparian Area)
0-100 Class II [2] Class II [2]
Notes:
[1]
The vegetative cover type assigned to any particular area was based on 2
factors: the type of vegetation observed in aerial photographs and the size of
the overall contiguous area of vegetative cover to which a particular piece of
vegetation belonged. As an example of how the categories were assigned, in
order to qualify as a "forest canopy" the forested area had to be part of a larger
patch of forest land at least 1 acre in size.
[2]
Areas that have been identified as habitats of concern, as designated on the
Metro Habitats of Concern Map, will be treated as Class I riparian habitat
areas in all cases, subject to the provision of additional information that
establishes that they do not meet the criteria used to identity habitats of
concern as described in Metro's Technical Report for Fish and Wildlife.
Examples of habitats of concern include: Oregon white oak woodlands,
bottomland hardwood forests, wetlands, native grasslands, riverine islands or
deltas, and important wildlife migration corridors.
Attachment 2
City of Tigard Engineering Comments
17
Table 18.510.3
Tualatin Basin "Limit" Decision [1]
Resource
Category
Conflicting Use Category
High Intensity
Urban Other Urban
Future Urban
(2002 and
2004
additions)
Non-Urban
(outside UGB)
Class I & II
Riparian inside
vegetated
corridor
Moderately
Limit Strictly Limit Strictly Limit N/A
Class I & II
Riparian
outside
vegetated
corridor
Moderately
Limit
Moderately
Limit
Moderately
Limit
Moderately
Limit
All other
Resource Areas Lightly Limit Lightly Limit Lightly Limit Lightly Limit
Inner Impact
Area Lightly Limit Lightly Limit Lightly Limit Lightly Limit
Outer Impact
Area Lightly Limit Lightly Limit Lightly Limit Lightly Limit
Notes:
[1] Vegetated corridor standards are applied consistently throughout the District; in
HIU areas they supersede the "limit" decision.
2. Verifying boundaries of inventoried upland habitat was identified based on the existence of
contiguous patches of forest canopy, with limited canopy openings. The "forest canopy"
designation is made based on analysis of aerial photographs as part of determining the vegetative
cover status of land within the region. Upland habitat is as identified on the Significant Habitat
Areas Map unless corrected as provided in this subsection.
a. The only allowed corrections to the vegetative cover status of a property area as follows:
i. To correct errors made when the vegetative status of an area was determined based on
analysis of the aerial photographs used to inventory the habitat. The perimeter of an area
delineated as "forest canopy" on the Metro Vegetative Cover Map may be adjusted to
more precisely indicate the dripline of the trees within the canopied area provided that no
areas providing greater than 60 percent canopy crown closure are de-classified from the
"forest canopy" designation. To assert such errors, applicants must submit an analysis of
the vegetative habitat cover on their property using the aerial photographs that were used
to inventory the habitat and the definitions of the different vegetative cover types
provided in Table 18.510.1; and
ii. To remove tree orchards and Christmas tree farms from inventoried habitat; provided,
Attachment 2
City of Tigard Engineering Comments
18
however, that Christmas tree farms where the trees were planted prior to 1975 and have
not been harvested for sale as Christmas trees may not be removed from the habitat
inventory.
b. If the vegetative cover status of any area identified as upland habitat is corrected in
compliance with Subparagraph 18.510.110.B.2.a to change the status of an area originally
identified as "forest canopy," then such area will not be considered upland habitat unless it
remains part of a forest canopy opening less than 1 acre in area completely surrounded by an
area of contiguous forest canopy.
Attachment 2