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6500 SW Macadam Avenue,Suite 200
Portland,OR97239 700 NE Multnomah St, Portland, OR 97232
Phone:503.244.7005
Fax:503.244.9095
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Frontispiece. City of Lake Oswego drainage basins addressed in TMDLs
I hereby certify that the information contained in this document is true, accurate, and complete to the best
of my knowledge and belief.
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Scott Lazenby, City Manager Date
City of Lake Oswego
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Lake Oswego TMDL Implementation Plan 2019-2023
TABLE OF CONTENTS
SECTION 1 INTRODUCTION AND BACKGROUND 1
1.1 TMDL Background 1
1.2 Implementation Plan Overview 2
1.3 Implementation Plan Applicability 5
SECTION 2 STRATEGIES FOR POINT SOURCES 5
2.1 Management Strategies to Address WLAs 6
2.2 Timeline and Schedule 7
2.3 Monitoring 7
2.3.1 Implementation Monitoring 7
2.3.2 Effectiveness Monitoring 8
SECTION 3 STRATEGIES FOR NONPOINT SOURCES (LOAD ALLOCATIONS) 9
3.1 TMDL Load Allocations for Temperature 10
3.2 Analysis of Current Shade Conditions in Riparian Areas 13
3.3 Management Strategies to Address Load Allocations 13
3.3.1 Riparian Area Management—Preserve Existing Forest Canopy 14
3.3.2 Riparian Area Management—Increase Existing Shade and Riparian Habitat Quality 21
3.3.3 Design Standards for New Development and Redevelopment 22
3.3.4 Public Awareness and Education 23
3.3.5 Environmental Monitoring 23
3.4 Timeline and Schedule 23
3.5 Monitoring and Reporting 23
SECTION 4 COMPLIANCE WITH LAND USE REQUIREMENTS 24
SECTION 5 ADDITIONAL REQUIREMENTS 25
5.1 Funding 25
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5.2 Legal Authority 25
5.3 Cold Water Refugia 26
5.4 Public Involvement 26
SECTION 6 REFERENCES 27
Appendix A: Key Definitions
Appendix B: SWMP Implementation Activities
Appendix C: Effective Shade Modeling Methods
Appendix D: Summary of Title 3/Title 13 Requirements
Appendix E:Temperature Management Strategies
List of Figures
Figure 1. Sediment and bacteria reduction as a function of width in riparian buffers and VFS 8
Figure 2. Ecoregions and associated effective shade curves applicable to the City of Lake Oswego....12
Figure 3. Lake Oswego 2013-2014 canopy cover 14
Figure 4. Sensitive Lands program buffers for streams (LOC 50.07.004) 16
Figure 5. Sensitive Lands program buffers for streams with steep slopes (LOC 50.07.004) 17
Figure 6. Sensitive Lands program buffers for culverts (LOC 50.07.004) 18
Figure 7. Effective shade for current total and protected riparian canopy vs.TMDL shade targets 20
Figure 8. Example of artwork for"The River Starts Here" Campaign 23
List of Tables
Table 1.TMDL Summary for Lake Oswego TMDL Implementation Plan 3
Table 2. Protected Riparian Buffers in Lake Oswego 19
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List of Abbreviations
BMP Best Management Practice
City City of Lake Oswego
CWA Clean Water Act
CWR Cold Water Refugia
DEQ Oregon Department of Environmental Quality
DMA Designated Management Agency
DO Dissolved Oxygen
LA Load Allocation
LID Low Impact Development
LiDAR Light Detection And Ranging
LOC Lake Oswego Code
MS4 Municipal Separate Storm Sewer System
NPDES National Pollutant Discharge Elimination System
SWMP Stormwater Management Program
TMDL Total Maximum Daily Load
USB Urban Services Boundary
USEPA United States Environmental Protection Agency
VFS Vegetated Filter Strip
WLA Waste Load Allocation
WQMP Water Quality Management Plan
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SECTION 1 INTRODUCTION AND BACKGROUND
The City of Lake Oswego is located in northwestern Clackamas County and situated between the Willamette
River on the east, I-5 on the west,the City of Portland on the north, and both the rural Stafford Triangle and
the City of West Linn on the south. In the center of the City is Oswego Lake. While Oswego Lake was
originally a natural lake with an outlet to the Willamette River, an inlet from the Tualatin River and a dam to
raise the lake's elevation at the natural outlet were constructed to fuel the late 19t"-century iron mining and
smelting industries which helped to create the City. For surface water management purposes,the City is
divided into five primary watersheds (see the frontispiece):
• Tualatin River including Fanno Creek's tributaries within the City's jurisdiction (Ball Creek and Carter
Creek). Ball Creek and Carter Creek receive discharges from streams and the stormwater system on
the west side of the City;
• Oswego Lake which receives discharges from streams and the stormwater system encompassing
most of the City's jurisdiction and which discharges to the Willamette River via Oswego Creek.The
Lake can receive inflow from the Tualatin River if the canal headgates are opened which occurred in
the past but no longer happens;
• Springbrook Creek which is a tributary to Oswego Lake and which drains the central northern
section of the City;
• Tryon Creek which receives discharges from streams and the City's stormwater system on the
northeastern side of the City. It discharges to the Willamette River; and
• Willamette River which receives discharges from streams and the City's stormwater system from the
City's east side.
The Federal Clean Water Act (CWA) of 1977 gave authorization to the U.S. Environmental Protection Agency
(USEPA)to restore and maintain water quality in all water bodies within the U.S. In response to the CWA,
the USEPA designated certain state agencies, including the Oregon Department of Environmental Quality
[DEQ],to develop water quality standards, perform water quality monitoring to understand current
conditions, determine sources of pollution, and develop total maximum daily loads (TMDLs)to improve
water quality and restore the beneficial uses of surface waters. When a water body does not to meet water
quality standards, it is placed on USEPA's 303(d) list as an impaired water body, and TMDLs are developed
by DEQ to ensure beneficial uses of the water body.
1.1 TMDL BACKGROUND
A TMDL specifies the maximum amount of a pollutant that a water body can receive and still meet water
quality standards. A TMDL allocates pollutant loadings among point and nonpoint sources, background
levels, reserves for future growth, and a margin of safety. Point sources are typically defined as those
sources that enter surface waters through a pipe or defined conveyance system (i.e., municipal and
industrial stormwater and/or wastewater). Waste load allocations (WLAs) are provided in the TMDL for
point sources. Nonpoint sources are typically defined as those sources that enter surface water through
diffuse methods (e.g., surface runoff from agricultural and forested lands). Load allocations are provided in
the TMDL for nonpoint sources. With respect to the City of Lake Oswego (City),the DEQ has set TMDLs for
water bodies located in the Willamette River Basin and Tualatin River Basin. For the City,this includes all
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tributaries to Springbrook Creek and Oswego Lake, as well as direct or tributary discharges to the lower
Willamette River and the Tualatin River.
Any agency or municipality that has legal authority over activities or areas that are sources of a TMDL
pollutant for that watershed of concern is known as a Designated Management Agency(DMA).The DMA is
required to comply with the state's anti-degradation policy(Oregon Administrative Rules [OAR] 340-041-
0004), which requires that decisions affecting water quality prevent "unnecessary further degradation", and
to accommodate growth and development by increased water quality "treatment and control". After a
TMDL is approved for a watershed, a TMDL Implementation plan (Plan) is created by the DMA whose
jurisdiction is part of that watershed; it describes strategies that the DMA will implement to address the
TMDL. WLAs are addressed through the National Pollutant Discharge Elimination System (NPDES)for
Municipal Separate Storm Sewer System MS4 permit when a DMA is a permitted agency.
A comprehensive list of the City's TMDL history, dates, parameters, water bodies, and implementation plans
is provided in Table 1.TMDL parameters sometimes overlap between watersheds, and past implementation
plans and compliance requirements have been on different schedules for these TMDLs.To streamline the
implementation of the agreed-upon strategies, DEQ has agreed that the City's TMDL Implementation Plans
for the Lower Willamette River and the Tualatin Rover could be merged into one comprehensive document.
1.2 IMPLEMENTATION PLAN OVERVIEW
DEQ issued a 2007 TMDL Implementation Plan Guidance'document in conjunction with the issuance of the
Willamette River TMDL.The State requirements for a TMDL Implementation Plan are:
Oregon Administrative Rule (OAR)340-042-0080(41
Persons, including DMAs other than the Oregon Department of Forestry or the Oregon Department
of Agriculture, identified in a Water Quality Management Plan (WQMP) as responsible for
developing and revising sector-specific or source-specific implementation plans must:
(a) Prepare an implementation plan and submit the plan to the Department for review and
approval according to the schedule specified in the WQMP.The implementation plan must:
(A) Identify the management strategies the DMA or other responsible person will use to
achieve load allocations and reduce pollutant loading;
(B) Provide a timeline for implementing management strategies and a schedule for
completing measurable milestones;
(C) Provide for performance monitoring with a plan for periodic review and revision of
the implementation plan;
I http://www.deq.state.or.us/wq/tmdls/docs/imp'/07wg004tmdlimplplan.pdf
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Table 1.TMDL Summary for Lake Oswego TMDL Implementation Plan
Lake Oswego TMDL 5-Year
Timeframe TMDL Water Body(by basin)a Issuance Parameter Implementation Plan Plan Review
Date approval and
Date
Update
--
Lower Willamette River Basin: all • Bacteria 2008-Mercury
perennial streams and fish-bearing • Mercury update(temperature
intermittent streams, including: • Temperature(target pollutant is solar radiation; and bacteria had
• Springbrook Creek subbasin 2006 surrogate measure is effective shade) already been 2009 2014
• Oswego Lake/Oswego Creek addressed in the
• Tryon Creek Tualatin River TMDL
• Lower Willamette River Implementation Plan)
Tualatin River Basin: all perennial • pH
streams, including: 1988 • Chlorophyll a(target pollutant is phosphorus)
1988 to • Tualatin River • Dissolved oxygen (DO) (target pollutant is total
2014 • Carter Creek(Fanno Creek suspended solids)
tributary) Update of previous parameters and added the following:
• Ball Creek(Fanno Creek 2001 • Temperature(target pollutant is solar radiation; 2003
tributary) surrogate measure is effective shade))
• Oswego Lake(for • Bacteria
phosphorus only)
Update of the following:
2012 2015 2019
• Chlorophyll a(target pollutant is phosphorus)
• DO(target pollutant is total suspended solids)
• Lower Willamette River • Bacteria
Basin as listed above • Mercury
2014 to • Tualatin River Basin as listed 2006 • Temperature(target pollutant is solar radiation; 2015
2019 above 2012 surrogate measure is effective shade)) 2015 (conditional) 2019
• pH 2016(final)
• Chlorophyll a(target pollutant is phosphorus)
• DO(target pollutant is total suspended solids)
a See Appendix A for related definitions.
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(D)To the extent required by ORS 197.180 and OAR chapter 340, division 18,
provide evidence of compliance with applicable statewide land use requirements;
and
(E) Provide any other analyses or information specified in the WQMP.
(b) Implement and revise the plan as needed.
OAR 340-042-0080(51
For sources subject to permit requirements in ORS 4686.050,wasteload allocations and other
management strategies will be incorporated into permit requirements.
It should be emphasized that, under the first requirement above,this Plan is associated with strategies to
achieve load allocations which are associated with nonpoint sources. Wasteload allocations are associated
with point sources and are covered under the City's NPDES MS4 Phase I permit.
The Plan consists of five sections:
1) Section 1 is the introduction and background of the TMDL program and the watersheds which are
under the City's jurisdiction.
2) Section 2 addresses OAR 340-042-0080(5). It is a summary of the strategies in the City's NPDES MS4
permit that are related to WLAs for bacteria, mercury, pH, chlorophyll a and dissolved oxygen and
which provide compliance with the TMDLs.
3) Section 3 addresses OAR 340-042-0080(4)(a)(A), (B), and (C)) for temperature load allocations.
4) Section 4 addresses OAR 340-042-0080(4)(a)(D) and contains an evaluation of the Plan's
conformance with the City's land use goals and comprehensive plan.
5) Section 5 addresses OAR 340-042-0080(4)(a)(E), related to additional items identified in DEQ's
WQMP for the Lower Willamette River and Tualatin River that the DMA.These items include:
a) Analyze funding to determine what additional resources are necessary to develop, implement,
and maintain the management strategies;
b) Include citations and brief descriptions of legal authority used to carry out the management
strategies;
c) Address cold water refugia (CWR); and
d) Determine how to ensure public involvement including a public review and comment schedule.
Originally, the TMDL Plan was scheduled to undergo a 5-yr review in 2019, however in the Spring of 2018,
DEQ advised the City that it would like a 5-yr review and updated Plan by November 2018 in order to
complete a comprehensive review of the entire Willamette Basin.The City agreed to the accelerated
schedule and this Plan is a result of that effort.The City's MS4 permit,which is used to attain the WLAs for
bacteria, mercury, ph, chlorophyll a and dissolved oxygen, is currently on administrative extension.The
stormwater management plan associated with the City's MS4 permit (see Table B-1) has not been updated
due to the extension, however the City has proposed changes to Table B-1 in the Plan such as removing
milestones that have already been completed.The City may propose additional changes to Table B-1, after
the MS-4 permit has been renewed,through the adaptive management channel.
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1.3 IMPLEMENTATION PLAN APPLICABILITY
DEQ's TMDL documents apply to perennial and,for temperature, fish-bearing intermittent streams within
the City limits. Using the Clean Water Act's definition, perennial streams2 flow year-round during years of
normal precipitation (EPA, 2011;Appendix A). Intermittent streams are those which do not flow year-round
but have some of their flow is due to groundwater discharge rather than flowing only when runoff occurs in
a catchment area (see Appendix A).
The Oregon Department of Fish and Wildlife (ODFW) currently publishes fish distribution maps for
salmonids, Pacific lamprey, and sturgeon (see OAR 340-041-028(4) Figures 340(A) and 340(B)). Until the
ODFW determines that intermittent streams within the City are not fish-bearing, the City will consider all
streams mapped within its jurisdiction as being subject to the WLAs and TMDLs associated with the
Willamette River and the Tualatin River.
SECTION 2 STRATEGIES FOR POINT SOURCES
TMDLs specify the maximum amount of a pollutant that a water body can receive while maintaining water-
quality standards. It allocates pollutant loadings among point and nonpoint sources, background levels, and
reserves for future growth with a margin of safety. Wasteload allocations (WLAs) are provided for point
sources such as municipal stormwater outfalls which are covered under a NPDES MS4 permit.
The DEQ approved a NPDES MS4 Phase I permit for Clackamas County. As a co-permittee of the Clackamas
County permit,the City has implemented a stormwater program which complies with many of the
requirements of a TMDL Implementation Plan.The City's streams were included in its NPDES MS4 permit
which means that stormwater discharges, normally be considered to be nonpoint sources discharges, are
considered point sources and subject to WLAs.Therefore, the City does not have nonpoint sources of
bacteria, mercury, pH, chlorophyll a, and dissolved oxygen (DO)that would be subject to load allocations
under a TMDL Implementation Plan.The management strategies discussed in this section apply to all
sources of bacteria, mercury, pH, chlorophyll a, and DO as covered under the City's NPDES MS4 permit.
Section 2 provides a discussion of the City's strategies, schedules, and monitoring activities to address
bacteria, mercury, pH, chlorophyll a, and DO under the NPDES MS4 permit.
WLAs for temperature are not covered under the NPDES MS4 permit because our marine climate,
characterized by mild rainy winters and hot dry summers, results in very little to no stormwater when
temperatures spike in the Willamette River and its tributaries. Strategies for managing stream temperatures
are discussed in Section 3.
2 Absent site-specific investigation,DEQ assumes that all streams shown on USGS 7.5 minute quadrangles are perennial stream
features.
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2.1 MANAGEMENT STRATEGIES TO ADDRESS WLAs
By complying with its NPDES MS4 permit,the City should meet its TMDL requirements for the Willamette
River and the Tualatin River for all parameters except temperature.The City complies with its NPDES MS4
permit through implementation of its Stormwater Management Plan (SWMP) which is available on the City's
website3.The SWMP, approved by DEQ in 2012, contains best management practices (BMPs)that address
specific permit requirements and which can be used to meet TMDL requirements (see Appendix B).The
City's NPDES MS4 reports, submitted to DEQ by November 1 of each year, summarize progress with respect
to the implementation of the SWMP's BMPs and are on the City website.
The City proposes that those SWMP BMPs which address TMDLs include activities that target pollution
prevention, erosion control, illicit discharges, and stormwater management. Pollution-prevention BMPs
have a direct correlation to water quality improvements and are used to educate City residents about
reducing pollutants by picking up pet waste and limiting the use of fertilizers and pesticides.Through its
illicit discharge and ESC programs,the City reduces sediment and other pollutants which affect phosphorus,
mercury, and dissolved oxygen in its streams.
Implementation of the City's 2016 stormwater management manual has resulted in a reduction of
stormwater volume and velocity caused by development. Stormwater must be managed onsite to the
maximum extent possible and green infrastructure is encouraged for all development.The Community
Development Code limits vegetation removal adjacent to receiving waters and directs new development
away from designated Sensitive Lands (see Section 3.2).
The City's SWMP is a living document with BMP changes possible through DEQ-approved adaptive
management.The BMPs in Appendix B represent the City's current SWMP but have been revised to remove
completed milestones and incorporate additional methods the City is using to comply with its permit. A new
SWMP is expected when the MS4 permit is renewed, however the current MS4 permit is on administrative
extension as of April 1, 2017 and it is uncertain when the permit will be renewed by DEQ.
The City's NPDES MS4 permit requires a pollutant load reduction evaluation and development of TMDL
benchmarks to show progress toward meeting TMDL WLAs. Pollutant load reduction benchmarks for
bacteria, phosphorus, and total suspended sediment (as a surrogate for DO) with respect to Willamette
River and Tualatin River WLAs were included in the City's permit renewal application submitted to DEQ in
2008. Mercury is a phased TMDL with monitoring requirements in the current MS4 permit that are intended
to support DEQ's development of WLAs for the second phase. Development of pollutant load reduction
benchmarks for mercury will apply when DEQ develops WLAs for mercury.As a condition of its MS4 permit,
the City submitted its TMDL pollutant load reduction and WLA attainment assessment in 2015 and these
assessments are available on the City's website.
3The City's SWMP and recent Annual Reports can be found at http://www.ci.oswego.or.us/publicworks/stormwater-permits-plans-
and-reports. The website also provides a link to the City's MS4 permit.
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Riparian buffers, which are the primary BMP used by the City to provide the effective shade necessary to
meet the temperature TMDL, are important for reducing WLA pollutant loads to streams. For this reason,
they lead in DEQ's Recommended List of Key Strategies for TMDL Implementation (DEQ, 2013;Appendix A).
However, it is difficult to quantify the effectiveness of riparian buffers in the reduction of pollutant loading
due to limited data on existing ground cover in Lake Oswego.
Figure 1 presents the results of the pollutant load reduction function used in the Soil and Water Assessment
Tool (SWAT) model which is one of the USEPA BASINS family of models designed for TMDL development as
well as a meta-analysis of multiple studies by Liu et al. (2008).The EPA Riparian buffers in the Liu et al. meta-
analysis are mixed forest and shrubland.The SWAT model assumes that a bacteria and sediment pollutant
reduction of 100%can be achieved by 30-feet wide vegetated filter strips (VFS).The meta-analysis of Liu et
al. suggests that 30-foot buffers remove most but not all sediment and that erosion is a natural process for
native riparian vegetation.
In one of the more robust assessments of the effectiveness of riparian forests as BMPs, Stewart et al. (2006)
clearly demonstrated the effectiveness of riparian forest buffers for pollutant removal in their study of six
small watersheds in suburban Baltimore with varying proportions of forest within 100 feet of headwaters
and small streams.An increased forest canopy was associated with lower runoff coefficients, lower peak
stormflows, and 72% higher baseflows without differences in total annual water yield. Higher forest cover
was also associated with reduced annual loads of total solids, biological oxygen demand,total Kjeldahl
nitrogen,total phosphorus, lead, zinc, and fecal coliform resulting from reduced stormwater volume and
pollutants in baseflow, stormwater, or combined flows. In steep forested areas, buffers are readily accepted
as a means of reducing sediment from adjacent hillslopes to streams (see MacDonald and Ritland 1989).
2.2 TIMELINE AND SCHEDULE
Appendix B includes measurable goals and tracking measures for each BMP and represent the schedule for
implementing TMDL management strategies for bacteria, mercury, pH, chlorophyll a, and DO.These goals
may change through adaptive management or as a result of new or revised requirements in the MS4 permit
renewal.
2.3 MONITORING
There are two types of monitoring required by the City's NPDES MS4 permit. Implementation monitoring is
defined as tracking BMP implementation and ensuring that BMP measurable goals are met.The second
type, effectiveness monitoring, is the analysis and evaluation of stormwater and in-stream pollutant
concentrations.
2.3.1 Implementation Monitoring
In its annual NPDES MS4 report,the City summarizes the implementation activities for BMPs in its SWMP.
Each BMP has defined measurable goals and tracking measures (see Appendix B).
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100% -41 4
90% ♦
p 80% ♦ ♦
70% ♦
° 60%
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0 10 20 30 40 50 60 70 80 90
Vegetated Buffer Width (ft)
VFS/Fecal Coliform-SWAT —VFS/Sediment-SWAT
—VFS/Sediment(Liu et al.) • Native Riparian/Sediment(Liu et al.)
Figure 1. Sediment and bacteria reduction as a function of width in riparian buffers and VFS
(Sources:Moore et al.1998,Parajuli et al.2008,and Liu et al.2008.)
2.3.2 Effectiveness Monitoring
Since 1997, the City has been conducting effectiveness monitoring in the form of monthly ambient water
quality monitoring of 6 to 7 streams and wet-weather(stormwater) monitoring at 2 sites. Environmental
monitoring activities comply with the requirements of the NPDES MS4 permit.
Collected samples are analyzed for various parameters as required by the MS4 permit, e.g., bacteria,total
phosphorus, pH, DO,temperature, and volatile solids.The City was also required by the MS4 permit to
collect stormwater samples in 2014 for total and dissolved mercury and to conduct macro-invertebrate
sampling once per permit cycle.The last macro-invertebrate sampling occurred in the Fall of 2018.
Results from environmental monitoring efforts are included in the NPDES MS4 reports submitted to DEQ by
November 1st each year. A trend analysis of the data, required by the MS4 permit, was submitted to DEQ in
2015 and is available on the City's website.
The City does not monitor water quality within Oswego Lake.The following excerpt from the City's June 26,
2015 draft Healthy Ecosystems Chapter of the City's Comprehensive Plan explains the roles of the City and
the Lake Oswego Corporation in managing water quality in Oswego Lake:
Water quality in the City is primarily monitored by two entities: the City and the(Lake Oswego)
Corporation. The City monitors tributary streams, while the Lake(Oswego) Corporation alone
monitors water quality within Oswego Lake. Their primary goal is to obtain data to support
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management of the lake water quality. The Corporation has ongoing programs to maintain and
improve the Lake's water quality. It has an aquatic vegetation inspection and control program, a
water quality management program and monitors activities on the Lake on a regular basis. Since
1994, when the last Comprehensive Plan was adopted, the Lake Corporation replaced the dam at the
outlet to Oswego Creek, and the City replaced the sewer interceptor line that traverses the lake.
The Corporation has commissioned studies of the Lake to address problems caused by high
phosphate levels, macrophytes and sediments. It prepares a Water Quality Management Plan each
year to preserve the beneficial uses of the Lake. The plan includes preventive actions, water
treatments, sediment removal and continuous sampling. . . .
In addition to City development regulations, Oswego Lake is subject to State and Federal regulations.
The perimeter of the Lake is in the 100-year flood plain regulated by Federal Emergency
Management Agency(FEMA). The State considers the waters of Oswego Lake to be "waters of the
State,"and subject to certain water quality regulations under the Federal Clean Water Act(CWA),
administered by the DEQ. In 1988, the DEQ found that the Tualatin River basin and Oswego Lake
Basin did not meet Federal and State quality standards and determined them to be "water quality
limited"because of higher than allowable levels of phosphorus and other pollutants. More recently,
the Willamette River has been added to this list of streams/rivers that are subject to Total Maximum
Daily Load(TMDL)requirements. The Lake's characterization arises from the condition of its
tributaries and other sources of inflow.
SECTION 3 STRATEGIES FOR NONPOINT SOURCES
(LOAD ALLOCATIONS)
Elevated water temperature is a common problem in many tributaries in the Willamette Valley and has
resulted in temperature TMDLs for the Tualatin River and lower Willamette River basins to protect and
improve the water quality of the watershed. Salmonids require cool and well-oxygenated water to survive.
Water temperatures in excess of water quality standards make streams unsuitable for cold-water fish and
other cold-water aquatic species resulting in a variety of effects on many salmon and trout species ranging
from decreased spawning success to death (USEPA 2003).
For optimum health,juvenile and adult salmon require streams that are 13°to 18°C (55°to 64°F); warmer
water may not adversely affect salmonids if the spike in temperature is brief and there is abundant food.
Cold water is required for spawning and genetic abnormalities or mortality of salmonid eggs can occur
above 11°C (52°F) (Washington State Department of Ecology 2000).The maximum temperature that
salmonids can tolerate varies with species, life-stage (e.g.,fry,fingerling, or adult), prior acclimation, oxygen
availability, duration of warmer temperature, and the presence of pollutants, however it has been found
that temperatures in the range of 23°to 25°C (73°to 77°F) are lethal to salmon and steelhead.
The City's commitment to stabilizing stream temperatures is reflected in its continued designation as a Tree
City USA by the Arbor Day Foundation, its investment in public open space, and its municipal code regulating
sensitive lands and tree removal and replacement.The City provides workshops and technical assistance
each year to residents and developers that focus on habitat conservation and sound urban forestry
practices. In addition,the City partners with the Backyard Habitat Certification Program to increase native
vegetation and educate participants on urban forestry practices.
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Section 3.1 provides a summary of the load allocations and DEQ's shade curves for the Willamette and
Tualatin TMDLs. Section 3.2 presents an analysis of current shade conditions with respect to the load
allocations. Section 3.3 provides a summary of the City's current management strategies to address the load
allocations. Section 3.4 outlines the timeline and schedule for implementation and Section 3.5 summarizes
proposed monitoring and reporting.
3.1 TMDL LOAD ALLOCATIONS FOR TEMPERATURE
Several factors contribute to elevated in-stream temperatures such as changes in watershed processes and
channel morphology, climate, geographic location, riparian vegetation, dams, reservoirs, and point sources
such as industrial wastewater(DEQ 2006). DEQ determined that solar radiation from disturbed or removed
riparian vegetation is the largest contributor to elevated temperature in small streams without a known
point source discharge and it uses effective shade as a surrogate measure for addressing temperature
TMDLs.
Effective shade is determined through the use of shade curves on a region-specific basis.The shade curves,
along with stream orientation and width, provide a target for percent effective shade and corresponding
solar radiation loading (DEQ 2006).The effective shade target is interpreted by DEQ to represent the effect
of historically prevalent riparian vegetation, referred to as "system potential", coupled with natural
topography in blocking solar radiation loads. Shade is more effective at maintaining cold water
temperatures on narrow streams than wide streams because canopy cover in the riparian zone of a narrow
stream will cover a larger percentage of the stream's surface. Because of this correlation, DEQ has
determined that the most effective method for managing stream temperature in the mainstems of the
Willamette River and Tualatin River is by increasing shade on their tributaries. Since most tributaries to the
Willamette River within the City boundaries are 20 feet wide or less, canopy cover in riparian areas is
expected to be the most effective strategy for stabilizing or reducing stream temperatures.4
The City of Gresham conducted a study with Pacific Habitat Services on the benefits of effective shade on
streams (Majidi 2007).The study evaluated the amount of solar radiation blocked by riparian stream buffers
of various stream widths and aspects. It also assessed the benefit of vegetative cover on one streambank vs
both streambanks based on aspect.The study found that vegetative cover is most beneficial within 50 feet
of a stream for perennial creeks averaging 20 feet in width or less which comprises most of the streams in
the City's jurisdiction. Larger watercourses, such as the Tualatin River, Willamette River, and Oswego Lake
receive less effective shade benefit from riparian vegetation due to their width.
DEQ(2001, 2006) estimated effective shade targets required to meet temperature load allocations using
shade curves for 15 different geomorphic units/ecoregions (see Figure 2). Ecoregions within the City's
'The City's TMDL Implementation Plan assumes that shading Oswego Lake,while having a localized effect, would not be an effective
strategy for overall temperature reduction.Protecting vegetation around Oswego Lake is encouraged during development review
to reduce pollutant loading. The City's municipal code requires a 25-foot lakefront setback(LOC 50.04.003.7)which limits
development but does not require riparian protection. LOC Chapter 55(Tree Code)discourages removal of significant trees and
requires mitigation planting when removal is not avoidable.
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Lake Oswego TMDL Implementation Plan 2019-2023
jurisdiction include Prairie Terraces (Figure 5.71 in DEQ 2006) and the Willamette Foothills (Figure 5.72 in
DEQ 2006). By knowing the width of the channel and its compass orientation,these curves provide the
"amount of percent effective shade that each geomorphic unit tree composition provides to the stream
based on the stream's channel width and stream aspect from north" (DEQ 2006).
The effective shade targets determined by DEQ are intended to represent shade conditions that are the
climax vegetation of a particular site and it assumes that the best vegetation for a specific site will maximize
the stream's water quality.A system's maximum potential represents a close equivalent to the vegetative
conditions (though not necessarily plant species and distribution) experienced by early settlers before
substantial land clearing.
Land cover thought to be present in 1851 has been reconstructed through historical records by Christy et al.
(2011) and maintained in GIS. Using these data, the distribution of forest coverage was calculated for
riparian areas in the lower Willamette Basin (DEQ 2006),the Tualatin Basin (DEQ 2001, 2012), and the City
of Lake Oswego as follows:
1) Lower Willamette Watershed
a) 77.5% Forested (closed forests and woodland)
b) 22.5% Un-forested or Thinly Forested (savannah, shrubland, prairie, wetland)
2) Tualatin Watershed
a) 86.6% Forested
b) 13.4% Un-Forested or Thinly Forested
3) Lake Oswego Watershed
a) 94.2% Forested
b) 5.8% Un-Forested or Thinly Forested
The shade curve data was used to estimate the effective shade target for the City. Because the City has
limited data on channel widths, even with recent high resolution LiDAR data, streams were divided into
width classes ranging from 5 to 20 feet. Either actual channel width or a stream class of 30 feet was used for
streams more than 20 feet wide depending on how well channel banks were defined in the topographic
model (see Appendix C).5
The City calculated the effective shade target using data shown in these figures, coupled with data on
measures or estimated stream width and orientation.The calculations were made at nearly 8,400 nodes
spaced 25-feet apart for all streams mapped within the City's urban services boundary(USB).
5 The City has commissioned multiple stream surveys from the Lake Oswego Physical Resource Inventory in 1975 to the effort by
Fishman Environmental Services in 1991(Galen et al.1992).Limited updates have been completed,using the same methods,by
Fishman Environmental Services in 2003 and by SWC4 in 2007. These surveys were focused on inventorying upland and riparian
vegetation and wildlife;they did not include systematic collection of stream channel physical attributes.
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Lake Oswego TMDL Implementation Plan 2019-2023
r
/ ..
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9".. _____________ Prairie 6e 5 : Willamette .�,
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/0%._____.__r____1__w____a__1.__.__.__ 576 109E ___.. �_- 11.___ 576
i
0% 642 0% 602
0 0 RR R 3 2 o R g E F. a * R 8 8 'S 2 LE. 2 P a to
Channel Width(meters) Channel Width(meters}
Figure 2. Ecoregions and associated effective shade curves applicable to the City of Lake Oswego
(Source:DEQ 2006)
The average city-wide effective shade target was calculated to be 91.6%with target shade targets in the
following watersheds within the City's jurisdiction:
1) Tualatin River 91.8%
2) Springbrook Creek 90.1%
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Lake Oswego TMDL Implementation Plan 2019-2023
3) Oswego Lake 92.2%
4) Tryon Creek 91.3%
5) Willamette River 92.8%
3.2 ANALYSIS OF CURRENT SHADE CONDITIONS IN RIPARIAN AREAS
In 2009,the City mapped its forest canopy cover using 2007 multispectral images which showed that the
City had a canopy coverage of approximately 75% in riparian areas. Forest canopy mapping was a key
element of the City's first report on its urban forest(City of Lake Oswego 2009).The City's canopy cover and
riparian features were updated using 2014 LiDAR data (see Figure 3).As LiDAR data is updated and made
available,the City will be able to revisit its canopy coverage.
The City modeled the effective shade for its current canopy cover,within 150 feet of channel centerlines,
using the 2014 LiDAR data and DEQ's HeatSource program (see Appendix C). Specifically,the City:
1) updated the location of stream channels based on the topographic expression in the LiDAR bare
earth data;
2) developed a tree canopy map using LiDAR data that removed buildings, utility poles,vehicles, and
low(less than 4 feet high)vegetation (see Figure 3); and
3) revised the City's sensitive lands riparian overlay districts (LOC 50.07.004) based on the updated and
more accurate stream locations and existing City code standards, resulting in some properties with
riparian habitat being newly designated as sensitive lands.
The HeatSource program showed an average effective shade of 87.9%within the City and 150 feet of stream
centerlines. Specifically,the model calculated the following effective shade for watersheds within the City:
1) Tualatin River 81.3%
2) Springbrook Creek 89.9%
3) Oswego Lake 86.6%
4) Tryon Creek 93.1%
5) Willamette River 87.0%
Effective shade targets were exceeded in the Tryon Creek watershed and essentially met in the Springbrook
Creek watershed. Substantial canopy cover is shown for each of these watershed in Figure 3. The largest gap
between current effective shade and the TMDL effective shade target—nearly 10% —was found in the
Tualatin watershed.
3.3 MANAGEMENT STRATEGIES TO ADDRESS LOAD ALLOCATIONS
The City's 2003 Tualatin TMDL Implementation plan contained the original strategies used by the City for
reducing thermal loading to its streams. In its current Plan,the City will address temperature through
preservation and enhancement of its riparian habitat, modification of its stormwater design manual and
municipal code, education of the public, and continued environmental monitoring.
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Lake Oswego TMDL Implementation Plan 2019-2023
n
r
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fir% ' ' tk 4 r o,::,....1. .f.. ....,,,,,p___,&,..-$,- 4...,....1.4„. _ . 1,,,,,... ..„.„.„4:,.:211._ _,3 ," Y` • r `", , „,_,• �''`k�.e. ,.
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,... _ 'A,',?!..,':7s:AV 1 . ' :#
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Figure 3. Lake Oswego 2013-2014 canopy cover
3.3.1 Riparian Area Management— Preserve Existing Forest Canopy
The TMDLs for the Tualatin River and Willamette River define shade as the surrogate for thermal load
allocations; canopy cover of streams can be very effective for stabilizing and reducing temperatures in
higher order streams such as headwaters and small perennial streams. As determined in Section 3.2, a
majority of the City's riparian habitat is shaded. Therefore preservation of the existing coverage is a primary
component of the City's thermal strategy.
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The municipal tree code (LOC 55.02 and 55.08) is used to preserve canopy cover by protecting trees during
development and by regulating tree removal.' In addition,the City uses the Willamette Greenway Overlay
(LOC 50.05.009)to provide some vegetative protection along the Willamette River and a small portion of
streams within the City's jurisdiction benefit from protections enforced by other entities (see Table 2).The
Tryon Creek watershed is partially protected through constraints placed by the Oregon State Department of
Parks and Recreation and the Tualatin River watershed is partially protected by the City of Portland, City of
West Linn, Clackamas County and Water Environment Services.
To evaluate whether stream miles are already protected through its municipal codes,the City mapped its
stream segments and assumed that a stream segment was protected if there was at least 10 ft of buffer
beyond the buffer measurement point (see Figures 4 and Table C-1 in Appendix C). With the assistance of
other jurisdictions and the City's protective programs and municipal code, an average of 87%of the City's
riparian areas are protected from disturbance (see Table 2).The Willamette River and Oswego Lake showed
the lowest protection, however temperature management using shade for these larger waters has been
shown to be minimal (see Section 3.1). At 93.5%,the Tryon Creek watershed afforded the greatest
protectiveness of its stream buffers.
To implement statewide land-use planning goals, Metro created Title 3 and Title 13 in its Urban Growth
Management Plan to address development in riparian corridors.Title 3 prohibits new development within
specified established buffers and requires mitigation for unavoidable new development.Title 13 establishes
protected areas, called habitat conservation areas, for upland and riparian wildlife. Since preserving and
restoring shade are important strategies for addressing temperature,jurisdictions complying with Title 3
and/or Title 13 are addressing temperature loads (see Appendix D).
Vtroaun Corridor liamderr n oeywrdwho:of worm'
Stream Corrado;
Cemrructan + + 30'-50' Cen a struclie
Mahacir 10' tad Riparian 1reF_ I i Protected RI jda Area Ser6aek!a'
r x f
20' Wide Stream Corridor
No wetlands,culverts,or slopes greater than 251.
Class I RP district illustrated here;Class II receives 25'-SO'
protected area.See LOC 50.05.010.6.13iii for allowed reductions.
6 The Tree Code is not a land use regulation,unless the tree removal is in conjunction with a minor or major(land use)development
permit. The criteria for Type II Tree Permits(tree removal associated with construction/development)require avoidance impacts
associated with surface water runoff and erosion.
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r' 1� i
qr
:Cr W. stream Corridor I
consl ruction dndtectad 3fl'd9'Proi,eted l:oRslr'41Ltton
Setback ter Rrparlen Area Riparian Area Setback I0'
.r
1 (''..—alt.}.L.—__
rtrIV..
condor anunaory _ ._1
rr fop or vhenrrl
Stream Corridor > 20' Wide
No wetlands,culverts,or slopes greater than 25%.
Class I RP district illustrated here;Claus II receives 25'-50'
protected area.See LOC 50.05.010.5.biii for allowed reduction B.
Stream Corridor
10,
1
Construction 3e'-50'Protected men 3e'-50'Protected Construction
Seebeck le' 1 Riparian Area r'Oedend I Luse Ripykrlaq Arel Se tbock_70'
Streams with Associated Wetlands
Stream corridor boundary remains at least 10'gram the stream centerline
on both sides. Wetland boundaries are delineated according to the
1987 Corps of Engineers Manual.
Class I RP district illustrated here;Class II receives 25'-50'
protected area.See LOC 50.05.010.E.biii for allowed reductions.
Figure 4. Sensitive Lands program buffers for streams (LOC 50.07.004)
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Lake Oswego TMDL Implementation Plan 2019-2023
Conslrucboitviii
r ,�.r
�yq'r-�' 3O'39' i Crrcutrncuon
Soltwe r ID. dipdoan s i ifigoilsonvol maths.*Ira
I Stream Corridor f
A .
li
r t Land it
a t. 4-
i g 91
Streams with Steep Slopes or Ravines
y�•+ 3kfc.
� Ir' I Stvep elepea die'etillidt to in greater
than 25- measured as rise+run.
y
Class I RP district illustrated here;Class II receives 25'-50'
protected area.See LOC 50.05.O1O.E.biii for allowed reductions.
Maximum RP district and construction setback width capped at
ZOO'from edge of ordinary high water line.
Stream Corridor
Comae-ruction 30'-eo'Pror I ' 30'-50'Protected Construction
Setback 10' Riparian et giurU
back t0'
Lri
i i
i
L� I .
Fist Land - - rI A
'IF--in.rtir a*M m.r rom•
dao existing stops.' , l .tl0r le MSS,*cernd4r.
w I
I
The rleodp*.rn w.*.vans*.net
�Og.of n1.Hr.am currlHo-r
Streams with Topographic Variations
!legal fill is not treated as stream corridor boundary;
refer to the first page of this appendix.
Class I RP district illustrated here;Class II receives 25'-SO'
protected area.See LOC 50.DS.tiD.t.biii for allowed reductions.
Maximum RP district and construction setback width capped at
200'from edge of ordinary high water line.
Figure 5. Sensitive Lands program buffers for streams with steep slopes (LOC 50.07.004)
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Lake Oswego TMDL Implementation Plan 2019-2023
- ir
Protected riparian area extends - - rrt
acresn road where stream cofltinnes _
1.111
�2
Zs'-30'Protected r. _ IN w1
''' Riparian k111
-2 --I 'mote Ctre
_ — Ripa�r)(
�iarn Ar¢a _ g;LIEtri
LL-
!
~l 0- --,--7,1 - 7
Protected riparian area arcs
around culvert opening.
Protected Riparian Areas on Culverts
Class I RP district illustrated here; Class II receives 25'-50'
protected area. See LOC 56.65.616.6.biii for allowed reductions.
= ---------- _.... 1 .= ti
,w
r7 s
--Tap al bank 4!cYlwrl # * '6of cam.calnaur as # R i
6-.0 in abpr iti T it
r
lu
iv_--•exlwrt
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li
J/}+ Bram&IM alepr _
; + I x19n9 IRT� _
a 1•
IV r
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<,
_•� • . ____ ,A
Top of Bank of Culvert- Ravine or Steep Slope
Figure 6. Sensitive Lands program buffers for culverts(LOC 50.07.004)
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Lake Oswego TMDL Implementation Plan 2019-2023
Table 2. Protected Riparian Buffers in Lake Oswego
Stream Miles Protected Stream
Stream Miles Protected by Buffers Protected
Mapped Protected by Other by RP and 50%of
stream Lake Oswego Jurisdictions Total% RC Districts
Watershed (mi) (mi) (mi) Protected (acres)
Oswego Lake(excluding Springbrook Creek) 4.77 3.73 0 78.2% 88.58
Springbrook Creek Sub-Basin 5.73 4.92 0 85.9% 104.56
Tualatin River 7.18 5.77 0.58 88.4% 112.72
Willamette River excluding Tryon Creek 6.76 4.90 0.78 84.0% 121.84
Tryon Creek Subbasin 9.10 7.32 1.19 93.5% 200.14
City-wide 33.53 26.64 2.55 87.1% 627.85
Consisting of RP Districts plus 50%of the RC District
The City implements Metro's Title 3 and 13 requirements through its Sensitive Lands Overlay (LOC
50.05.010); primarily the Resource Protection (RP) and Resource Conservation (RC) districts.The resource
protection districts allow for very limited disturbance of riparian habitat; the resource conservation districts
create an additional buffer for habitat preservation on public and private open space tracts by limiting
disturbance to 20%with the assumption that the protected area will be the portion closest to the stream.
The City also implements Title 13 with a Habitat Benefit Areas (HBA) designation which is a voluntary,
incentive-based program for private properties with upland habitat. Current stream buffer requirements
and related protection measures are shown in Figures 4 through 6 and described in LOC 50.05.010.7
The City modeled the effective shade based on protected canopy as well as the current canopy. For
modeling purposes,the riparian buffers in other jurisdictions were assumed to be protected through Title 3
and provide localized shade to City streams:
1) West Linn protections on Arbor Creek(jurisdictional boundary)
2) Protections by City of Portland and adjacent unincorporated Multnomah County in the vicinity of
TCSNA or PCC Sylvania (Multnomah County gave land use planning authority to Portland in this area)
3) Protections by Clackamas County on riparian lands under Metro Title 3 (areas within the USB only)
Effective shade was modeled for each watershed as well as City-wide.Tryon Creek and Springbrook Creek
show the greatest ability to meet TMDL allocations (see Figure 7). Overall,the City-wide effective shade
(91.6%) is within reach of the City's TMDL load allocations for temperature.
7 City code was changed in 2015(Ordinance 2687) to widen riparian buffers for some RP districts from 25ft-30ft to Soft. The
widening occurred where RC districts were removed.from private properties containing upland habitat. to maintain substantial
compliance with Metro Titles 3 and 13.
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Most of the effective shade under the current sensitive lands code is associated with the RP overlays.The
Title 13-protected component of effective shade ranges from 0.4%of the total in the Tryon Creek basin to
4.6%of the total in the Tualatin River basin. Some limited development occurs on parcels with sensitive
lands overlays and mitigation is required for any loss of riparian canopy from private development. In
general, mitigation must be completed on the parcel where vegetation was removed.
Some riparian canopy losses occur naturally as a result of stream channel erosion. Other small losses are
allowed to occur without mitigation such as hazardous tree removal or removal due to routine repair or
replacement of City infrastructure;the City provides from these projects whenever possible.
AVERAGE % EFFECTIVE SHADE IN LAKE OSWEGO
BASINS
•2014 Forest Canopy Conditions(Protected and Unprotected)
•Existing Protected Riparian Buffers: RP+50%RC(and Other Jurisdiction Buffers)
•TMDL Load Allocation
Ncc, W
nj -1 N m O
�p Ol O Ol O Olco •
O Qj 01 cl
00 0l n O
00 N m 00 co N
N
00
O co tip 00
N
N
OSWEGO LAKE SPRINGBROOK TUALATIN WILLAMETTE TRYON CREEK CITY-WIDE
(N = 1181) CREEK RIVER (N=1777) RIVER (N=1686) (N=2253) (N=8312)
(N=1423)
Figure 7. Effective shade for current total and protected riparian canopy vs.TMDL shade targets8
8 Values at the top of each bar provide the average percent effective shade in the indicated subbasin. "N="reflects the number of
nodes at which effective shade was modeled with HeatSource and used to calculate the basin average effective shade value.
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Lake Oswego TMDL Implementation Plan 2019-2023
3.3.2 Riparian Area Management- Increase Existing Shade and Riparian Habitat
Quality
In addition to preserving existing shade,the City enhances riparian buffers through the following efforts9:
1) Habitat Enhancement Program, administered by the Parks Department with support from
Engineering;
2) Parks master planning;
3) Support of the Backyard Habitat Certification program; and
4) In-kind support for neighborhood and grass-roots efforts.
Habitat Enhancement Program (HEP)
The City's Habitat Enhancement Program, created in the FY14-15, is a riparian enhancement activity with
annual funding of$250,000 per year.The HEP has been included in every budget since its inception and is
also in the 6-year budget forecast presented to the City Council and other members of the budget
committee. City Council has stated its intent to continue to fund this program. Funds are split between
upland and riparian areas and between private and public properties with a focus on invasive plant removal
and revegetation with native shrubs and trees.
The funds, used on public lands and private open space, is expected to either increase planting of new
native vegetation that can provide shade or improve the diversity and accelerate the ecological succession
of existing forested areas. Forests within the City typically consist of mature hardwoods that recolonized
logged areas at the end of the 19th century and are nearing the end of their lifespan. In these areas,the HEP
funds are used to replace the aging hardwoods with conifers which provide a year-round shade and
stormwater benefit or increasing the complexity of the canopy by planting a variety of trees and shrubs to
increase rain interception and infiltration capacity of the soil.
Prioritization of future expenditures for the program will consider the new effective shade modeling results,
hydromodification effects, and public education efforts.
Park Master Planning
The City's Parks Department is actively engaged in implementing the Luscher Farms Park Master Plan which
considered stream restoration and riparian revegetation opportunities for the Wilson Creek headwaters
within the area.The Parks Department has also completed master plans for the Woodmont and Iron
Mountain Parks, both of which include wetland enhancement projects. These park improvements are in the
City's six-year capital improvement program.
9 These activities have not yet been evaluated for how well they accomplish the goal of increasing effective shade. The City will track
these activities,any changes to existing programs,and any new programs or initiatives developed prior to July 1,2016,in order to
evaluate each program's effectiveness for their short,intermediate,and long-term effectiveness to meet shade targets and to
provide reasonable assurance that the programs can be maintained in the long term.Modifications to these programs,and the
expected outcomes of the modifications, will be proposed in the 2019 TMDL Implementation Plan.
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Lake Oswego TMDL Implementation Plan 2019-2023
In order to ensure that riparian habitat protection is an integral part of the upcoming master plans, Parks
staff is coordinating the acquisition of baseline data and delineation of resources with the City's engineering
staff who will also serve on the technical advisory committees set up for the planning efforts at each park. In
this role, City staff will be able to provide guidance for design requirements, construction approaches, and
subsequent park stewardship by staff and volunteer groups.
Backyard Habitat Certification
The City partners with the Audubon Society of Portland, Friends of Tryon Creek, and the Columbia Land
Trust in the Backyard Habitat Program.Though not specific to riparian areas, certified yards can be expected
to provide more diverse and healthier vegetation to support the City's water-quality goals.
Participants receive technical assistance for planning and maintaining their landscape and cost incentives for
using native plant materials. After the initial project is completed, a participant can have their area certified
through adding elements of education, invasive species removal, native habitat revegetation, stormwater
management, pesticide reduction, and wildlife stewardship. Sites are inspected every three years to
maintain certification.The program is popular in the City with sites located in single-family home areas,
multi-family residential areas, school properties, and in institutional areas.
Urban Forest Management, Neighborhood Planning and Technical Assistance Support
The City maintains a robust urban forestry program which is designed to support the Parks Department in
managing public open space lands, the City's Tree City USA designation by the Arbor Day foundation, and
interested private landowners including those with larger lots. Recent amendments to the City's tree code
provide a holistic approach to managing urban forests while allowing residents to remove trees located
outside of sensitive lands districts.
Staff regularly provide assistance with neighborhood planning efforts which include a strong surface water
component.The City also has a small grant program to support public land enhancement and has included
preservation and enhancement of riparian properties in its grant process. The grant program can provide
funding for projects earlier than the City's operational priorities resulting in additional riparian restoration.
Staff provide technical assistance when requested to property owners and the watershed councils.
3.3.3 Design Standards for New Development and Redevelopment
Although shade is the surrogate measure defined by DEQ to address the temperature TMDL,
implementation of the City's stormwater management manual (SWMM) and stormwater municipal code
(LOC 38)will help stabilize and reduce stream temperatures, increase stream baseflows, and reduce
stormwater volumes and velocities through increased infiltration and requirements for onsite stormwater
management.
As development occurs, increases in impervious areas reduce infiltration and summer baseflows. Summer
stream temperatures are moderated by the inflow of colder groundwater in the summer. By requiring BMPs
that infiltrate stormwater in the winter,the volume of groundwater recharging the streams in the summer
increases and encourages improved riparian conditions.
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Lake Oswego TMDL Implementation Plan 2019-2023
The City's NPDES MS4 permit required an update of the City's stormwater management ii" ''
manual by 2014 which prioritized low-impact development planning principles and theit ire
4/1
construction of green infrastructure. Revisions to the SWMM and the City's stormwater
municipal code were adopted in 2016 and the City continues to monitor their
implementation, resolve inconsistencies, and determine improvements.As shown in the THE
FY16-17 and FY17-18 MS4 reports,the updated SWMM requirements have resulted in a RIVER
large portion of impervious area being mitigated with infiltration and green RI'VE R
infrastructure. STARTS
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3.3.4 Public Awareness and Education
A number of public education efforts and campaigns are implemented in conjunction
with the City's NPDES MS4 permit. As part of the City's Plan it will promote messages
educating the public about choices that can decrease the loading of TMDL parameters.
Currently the City leverages its public education funds through membership in several
regional groups with a stormwater focus such as the Regional Coalition, KOIN-TV PSAs,
and TBPAC. For example,the "River Starts Here" campaign by the Regional Coalition for
Clean Rivers and Streams (Figure 8 and back cover) is flexible enough to promote a range
of behaviors aimed at reducing pollutant loads. In addition, staff in the City's Urban
Forestry and Water Conservation programs provide workshops and technical assistanceAki -
for riparian enhancements and native plant selections.
3.3.5 Environmental Monitoring
The City conducts environmental monitoring in accordance with its NPDES MS4 permit.
Water-quality samples are collected monthly at 6 streams and at 2 sites during 3 wet Figure 8. Example of
weather events per year. Collected samples are analyzed for various parameters with artwork for"The
stream temperatures collected in the field. Results are summarized in the annual NPDES River Starts Here"
MS4 report. In addition, the City has 2 continuous monitoring stations for recording campaign
water levels and other field parameters. The City will continue collecting stream
temperature measurements as part of its environmental sampling effort.
3.4 TIMELINE AND SCHEDULE
TMDL Implementation Plans are effective for 5 years after approval by DEQ placing the next update for this
plan in 2024. Appendix E summarizes the City's proposed management strategies, measurable goals, and
annual tracking measures.
3.5 MONITORING AND REPORTING
The DEQTMDL Plan Implementation Guidance requires a DMA to submit two types of reports to DEQ on a
regular basis: 1) a progress report; and 2) an implementation plan update.The progress report is submitted
annually to DEQ and summarizes the City's activities towards implementing measurable goals and tracking
measures during the previous year (see Appendix E).To consolidate reporting requirements, DEQ allows the
annual TMDL report to be submitted with the annual NPDES MS4 report which is due November 1. Both
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Lake Oswego TMDL Implementation Plan 2019-2023
reports cover activities completed during the previous fiscal year(July 1 to June 30).The City may propose
minor changes to the measurable goals or tracking measures as part of its adaptive management during
submittal of its annual report on November 1.
The City is required to update its Plan and submit proposed changes to the DEQ every 5 years. During the
implementation plan update, the City evaluates the current Plan's effectiveness towards reaching its goals
and may propose major changes to the Plan with the limitation that the change must be as protective or
more protective of water quality.The current Plan will be in effect from 2019 to 2023; the next update will
be due November 1, 2023 when the City will propose changes to its Plan for 2024 to 2028.
SECTION 4 COMPLIANCE WITH LAND USE REQUIREMENTS
OAR 340-042-0080(3)(a)(D) requires TMDL Implementation Plans to include evidence of compliance with
applicable statewide land use requirements.According to DEQ TMDL Implementation Plan Guidance, DMAs
may demonstrate compliance by:
1) Identifying applicable acknowledged local comprehensive plan provisions and land use regulations
2) Explaining how the implementation plan is consistent with these local planning requirements or
what steps will be taken to make the local planning requirements consistent with the
implementation plan.
The City's 2014 Comprehensive Plan addresses water quality in general but does not address temperature or
other specific TMDL parameters. Specifically,the "Community Health and Public Safety" chapter addresses
water resource quality pursuant to Statewide Goal 6.The City's plan for Goal 6 states, in part, that the City
will:
1) "Educate and involve the community in opportunities to protect, restore, and enhance water
quality...through voluntary efforts to restore streams and riparian areas;"
2) "Strive to improve the water quality of Oswego Lake and the Willamette and Tualatin Rivers by
working with appropriate government agencies, Lake Oswego Corporation, and the community to
implement water quality programs and projects;" and
3) "Develop incentives for low-impact development..."
In addition,the Comprehensive Plan states that the City will protect, enhance, and restore wetlands and
stream corridors in order to comply with Goal 5.
The Comprehensive Plan is implemented primarily by the City's Community Development Code (CDC) which
governs land use.The CDC sections that implement Comprehensive Plan policies relating to Goals 5 and 6
include the Greenway Management Overlay District (LOC 50.05.009),the Sensitive Lands Overlay District
(LOC 50.05.010), Hillside Protection (LOC 50.06.006), Flood Management Area (LOC 50.05.011), Erosion
Control (LOC 52), and Stormwater Management (LOC 38.25).
Measures in the City's Plan focus on maintaining and, where possible, increasing effective shade through
preservation and enhancement of forest canopy in riparian zones.The City's municipal Code supports these
efforts in the following ways:
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1) The Greenway Management Overlay District applies special setbacks and standards to development
located within 150 feet of the Willamette River margin at ordinary low water. It requires that
development in this area protect water quality to ensure this aim is achieved.
2) The Sensitive Lands Overlay District restricts development in wetlands and stream corridors and
requires vegetated buffers (see Figure 4).These vegetated areas filter runoff and prevent erosion
thereby reducing potential bacteria, mercury, and phosphorous loads and increasing dissolved
oxygen.
3) The Storm water Management Code and SWMM, which implement the MS4 permit requirements,
require new development to maximize on-site infiltration, provide water quality treatment for
stormwater leaving a site, and maintain pre-development runoff rates.These efforts promote
infiltration which increases summer baseflows and stabilizes stream temperatures; reduce the
volume of stormwater released into streams; and reduce stream velocities during a storm event.
4) The Erosion Control Code favors retention of existing vegetation as an erosion control measure and
requires erosion control permits for any activities within 50 feet of a watercourse or wetland. It
reduces total suspended solids and potential mercury and phosphorous loads from leaving the site.
5) The Hillside Protection Code requires that development activities minimize soil disturbance and
vegetation removal on sloped properties which reduces erosion and promotes shade canopy. Land
disturbance or development is limited on undisturbed slopes of 25% percent or greater thereby
reducing erosion,total suspended solids, and potential mercury and phosphorous loads.
6) The Flood Management Area Code limits development in the floodplain thereby reducing potential
discharges of pollutants in the event of a flood.
SECTION 5 ADDITIONAL REQUIREMENTS
The fifth component of TMDL Implementation Plans required by OAR 340-042-0080 is "any other analyses
or information as specified in the WQMP."The WQMP for the Willamette Basin TMDL requires a fiscal
analysis, a summary of legal authority, and an analysis of cold water refugia (CWR) for DMAs below river
mile 50 of the Willamette River.
5.1 FUNDING
The City currently charges a surface water management utility fee to pay for implementation of the BMPs in
its MS4 permit.The fee is based on the average impervious surface area of a single family residential
property (3,030 sq ft)which is called an equivalent service unit(ESU).All single family residential properties
are charged for a single ESU whereas non-single family residential properties are charged for the amount of
impervious surface ESUs on the property.The City also collects system development charges (SDCs)when a
building permit is issued for new construction or when an existing development connects to a public
stormwater line.The City provides a summary of the stormwater expenditures in its annual MS4 report.
5.2 LEGAL AUTHORITY
The City municipal code prohibits illicit discharges and contains standards for erosion control and post-
construction stormwater management; and the City's SWMM implements the municipal code.These
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Lake Oswego TMDL Implementation Plan 2019-2023
requirements implement the BMPs outlined in the City's NPDES MS4 permit and provide authority for
actions described in this Plan to address bacteria, mercury, phosphorus, and suspended sediment(DO
surrogate).
The annual reports required by the City's NPDES MS4 permit are submitted to DEQ and include a
demonstration of continued legal authority to implement the programs outlined in the SWMP. In addition,
the City implements the requirements of Metro Title 3 and Title 13 through the Sensitive Lands Overlay in
the City's development code.These code provisions provide authority to implement management strategies
proposed by the City to address the TMDL parameters within its jurisdiction.
5.3 COLD WATER REFUGIA
The Willamette River WQMP requires that TMDL Implementation Plans for DMAs located below river mile 50
analyze,identify, protect,and enhance areas of cold water refugia (CWR). CWR are areas within a stream
system that are cooler than the ambient stream temperature and which can provide critical habitat for
salmonids. CWR are associated with different aspects of stream morphology including side channels,
alcoves, lateral seeps, and floodplain springs and brooks (Ebersole 2003).The City partnered with other
DMAs in the lower Willamette and the USGS to determine areas of existing and potential CWR. Preliminary
data show that the Willamette River is well-mixed with little temperature stratification and that the best
sources of CWR are tributaries to the Willamette River. When the USGS report is officially published, the City
will identify areas and potential projects to enhance the CWRs identified by the USGS.
5.4 PUBLIC INVOLVEMENT
The City addresses public involvement for management strategies described in Section 2 in conjunction with
its NPDES MS4 permit requirements. After approval by the DEQ,the City will post the Plan on its website.
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SECTION 6 REFERENCES
Bartholow,J.M. and J.A. Henriksen. 2006.Assessment of Factors Limiting Klamath River Fall Chinook
Salmon Production Potential Using Historical Flows and Temperatures. USGS Open-File Report
2006-1249. 111 p.
Christy,J.A., E.R.Alverson, M.P. Dougherty, S.C. Kolar, C.W. Alton, S.M. Hawes, L.Ashkenas& P. Minear.
2011. GLO historical vegetation of the Willamette Valley, Oregon, 1851-1910.ArcMap shapefile,
Version 2011_04. Oregon Biodiversity Information Center, Portland State University.
City of Lake Oswego. 2009. Lake Oswego's State of the Urban Forest Report. Lake Oswego Planning
Division, Urban and Community Forestry. 50 p.
City of Lake Oswego. 2013. Luscher Area Master Plan. Council Revised Draft. 25 July. Prepared by MIG,
Portland, Oregon.
City of Lake Oswego. 2014. Lake Oswego Code. Chapter 38: Surface Water Management, Chapter 50:
Community Development Standards, Chapter 52: Erosion Control; Chapter 55:Tree Planting.
City of Lake Oswego. 2014. Comprehensive Plan. Lake Oswego, Oregon.
City of Lake Oswego. 2015. City website. http://www.ci.oswego.or.us/
Cole, M. 2014. Clackamas County NPDES MS4 Co-Permittees 2013 Coordinated Macroinvertebrate
Assessment. Final Report. Prepared by Cole Ecological for the City of Gladstone, City of Lake
Oswego, City of Milwaukie, City of Oregon City, City of West Linn, and City of Wilsonville.
February.
DEQ(Oregon Department of Environmental Quality). 2001.Tualatin River TMDL, Chapter 4.
DEQ(Oregon Department of Environmental Quality). 2006. Willamette Basin TMDL, Chapter 5.
DEQ(Oregon Department of Environmental Quality). 2013.TMDL Implementation Plan Guidance: Fifth
Year Review Report Template for City and County Designated Management Agencies. April. 24 p.
Ebersole,J.L.,W.J. Liss, and C.A. Frissell. 2003. Cold Water Patches--Warm Streams: Physicochemical
characteristics and the Influence of Shading.Journal of the American Water Resources Association
(JAWRA) 39(2):355-368.
Galen, C.,J. Buchanan and P. Fishman. 1992. City of Lake Oswego Inventory of Natural Resources.
Prepared by Fishman Environmental Services, Portland, Oregon,for the City of Lake Oswego.
April.
Liu, X. X Zhang, M Zhang. Factors Influencing Efficacy of Vegetated Buffers on Sediment Trapping.
Journal of Environmental Quality, 2008. dl.sciencesocieties.org
MacDonald,A.; and K.W. Ritland. 1989. Sediment dynamics in Type 4 and 5 waters: A review and
synthesis.TFW-012-89-002. Olympia, WA.Timber Fish and Wildlife. 86p.
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Lake Oswego TMDL Implementation Plan 2019-2023
Majidi, K. 2007.Volume III: Gresham's Temperature TMDL Implementation Plan, Natural Resources
Program Watershed Management Division, Department of Environmental Services, City of
Gresham, Oregon.
McIntosh, B. and H.W. Li. 1998. Klamath Basin Pilot Project: Coldwater Refugia Study and Videography.
U.S. Department of Commerce, National Technical Information Service. Springfield,Virginia.
Metro. 1998.Title 3 Model Ordinance. Portland, Oregon.
Metro. 2005.Title 13 Model Ordinance. Portland, Oregon.
Moore,J.A.,J. Smyth, S. Baker,J.R. Miner. 1998. Evaluating coliform concentrations in runoff from
various animal waste management systems. Special Report 817.Agricultural Experiment Station,
Oregon State University, Corvallis, OR.
Nadeau,T-L. 2011. Streamflow Duration Assessment Method for Oregon, U.S. Environmental Protection
Agency, Region 10, Document No. EPA 910-R-11-002.
Parajuli, P.B., K.R. Mankin, P.L. Barnes. 2008.Applicability of targeting vegetative filter strips to abate
fecal bacteria and sediment yield using SWAT.Agricultural Water Management v. 95, p. 1189-
1200.
Steward, S., E. Gemmill, and N. Pentz. 2006. An Evaluation of the Functions and Effectiveness of Urban
Riparian Forest Buffers. Water Environment Research Federation Report 99-WSM-4. Prepared by
Baltimore County Department of Environmental Protection. 285 p.
Van Staveren,J. 2007. Gresham's Response to Temperature TMDLs. Presentation made at the Clean
Water Act&TMDLs Conference.January 26, 2007. Portland, Oregon.
Washington State Department of Ecology. 2000. FOCUS: Effects of Elevated Water Temperatures on
Salmonids. Focus Publication Number 00-10-046. Olympia, Washington.
Willamette Partnership. 2014. Protocol for Quantifying Thermal Benefits of Riparian Shade.
http://willametter artnership.org/wr-content/uploads/2015/02/Shade-a-lator-v8.0.5-8.0.8-
Protocol-2014-03-20.r df.
URS Corporation. 2008. City of Lake Oswego NPDES MS4 Permit Renewal Application. Portland, Oregon.
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Appendix A: Key Definitions
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Appendix A
Key Definitions
The following definitions provide guidance that is used to define the extent of streams covered by the TMDLs
and water quality standards within the City of Lake Oswego as well as other features requiring activities
needed to implement the TMDLs.
"Cold Water Refugia"
OAR 340-041-0002(10) (Department of Environmental Quality; Water Quality Standards)
"Cold Water Refugia" means those portions of a water body where or times during the diel (24-hr)
temperature cycle when the water temperature is at least 2 degrees Celsius colder than the daily maximum
temperature of the adjacent well-mixed flow of the water body.
"Ditch"
OAR 141-085-0510(28)(Department of State Lands)
"Ditch" means a manmade water conveyance channel. Channels that are manipulated streams are not
considered ditches.
"Fish Distribution"
Current (not exhaustive) maps are available from ODFW here:
https://nrimp.dfw.state.or.us/nrimp/default.aspx?pn=fishdistdata
Note—these maps do not include the local distribution of most resident(native or non-native)fish. No
systematic fish surveys have been conducted by ODFW or others within Lake Oswego.
"Intermittent Stream"
OAR 141-085-0510(046) (Department of State Lands)
"Intermittent Stream" means any stream which flows during a portion of every year and which provides
spawning, rearing, or food-producing areas for food and game fish.
USGS Water Supply Pacer 1541-A (Langbein, WB and Iseri, KT, 1972)
"Intermittent Stream" means a stream which flows only at certain times of the year when it receives water
from springs or from some surface source such as melting snow in mountainous areas.
US Environmental Protection Agency(Nadeau, 2011)
Intermittent Stream is a channel that contains water for only part of the year,typically during winter and
spring when the streambed may be below the water table and/or when snowmelt from surrounding uplands
provides sustained flow.The channel may or may not be well-defined.The flow may vary greatly with
stormwater runoff.An intermittent stream may lack the biological and hydrological characteristics commonly
associated with the continuous conveyance of water.
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"Riparian Area"
OAR 690-300-0010(44) (Oregon Water Resources Department)
"Riparian Area" means a zone of transition from an aquatic ecosystem to a terrestrial ecosystem, dependent
upon surface or subsurface water that reveals through the zone's existing or potential soil-vegetation complex,
the influence of such surface or subsurface water. A riparian area may be located adjacent to a lake, reservoir,
estuary, pothole, spring, bog, wet meadow, or ephemeral, intermittent or perennial stream.
"Stream/Perennial Stream/Stream Origin"
US Environmental Protection Agency(Nadeau, 2011)
A stream can be described as a channel containing flowing surface water including:
• Stormwater—increased streamflow resulting from the relatively rapid runoff of precipitation from the
land as interflow(rapid, unsaturated, subsurface flow), overland flow, or saturated flow from surface
water tables close to the stream; or
• Baseflow—flow resulting from groundwater entering the stream or sustained melt water from glaciers
and snowmelt (observed during long gaps between rainfall events); or
• A combination of both stormwater and baseflow; AND
• Contributions of discharge from upstream tributaries as stormwater or baseflow, if present.'
Perennial Streams have continuous flow during a year of normal [precipitation], often with the streambed
located below the water table for most of the year. Groundwater supplies the baseflow for perennial streams,
but flow is also supplemented by stormwater and snowmelt. A perennial stream exhibits the typical biological,
hydrological, and physical characteristics commonly associated with the continuous conveyance of water
Normal Precipitation is defined as the 30-year average, provided by the National Oceanographic and
Atmospheric Administration National Climatic Data Center, computed at the end of each decade.These data
are available as annual and monthly averages.
Water Table is the elevation of the saturated zone below which all interconnected voids are filled with water
and at which the pressure is atmospheric, commonly identified as the top of the local or regional groundwater
aquifer.
Stream Origin is the point where flow first appears on the land surface with enough force to disturb the
substrate creating a lasting sign of flow. Stream origins are often wetlands, springs, seeps or headcuts.
"Tributary"
USGS Water Supply Paper 1541-A (Langbein, WB and Iseri, KT, 1972)
A river or stream flowing into a larger river, stream, or lake.
"Waters of the State"
OAR 340-041-0002(72) (DEQ; Water Quality Standards)
"Waters of the State" means lakes, bays, ponds, impounding reservoirs, streams, creeks, estuaries, marshes,
inlets, canals,the Pacific Ocean within the territorial limits of the State of Oregon, and all other bodies of
surface or underground waters, natural or artificial, inland or coastal,fresh or salt, public or private (except
1 Does not include ditches.See definition above.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix A
those private waters that do not combine or effect a junction with natural surface or underground waters)that
are wholly or partially within or bordering the state or within its jurisdiction.
OAR 141-090-0020(33) (Department of State Lands)
"Waters of this state" means all natural waterways, all tidal and nontidal bays, intermittent streams,
constantly flowing streams, lakes,wetlands,that portion of the Pacific Ocean that is in the boundaries of this
state, all other navigable and nonnavigable bodies of water in this state and those portions of the ocean shore,
as defined in ORS 390.605. (ORS 196.800(14) and OAR 141-085-0010 and 141-085-0015).
33 CFR§328.3(a)(3);40 CFR§ 122.2.
"Waters of the United States" as all other waters such as intrastate lakes, rivers, streams (including
intermittent streams), mudflats, sandflats,wetlands, sloughs, prairie potholes, wet meadows, playa lakes, or
natural ponds,the use, degradation or destruction of which could affect interstate or foreign commerce
including any such waters: which are or could be used by interstate or foreign travelers for recreational or
other purposes; from which fish or shellfish are or could be taken and sold in interstate or foreign commerce;
or which are used or could be used for industrial purposes by industries in interstate commerce.
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Appendix B: SWMP Implementation Activities
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix B
Table B-1. Lake Oswego (City) Implementation Activities
Phosphorus Mercury Responsible
BMP Activity Bacteria (pH and and TVS Measurable goals covered by the MS4 permit Annual tracking measures
chlorophyll(a)) (DO)? Department
Implement the Illicit 1) Conduct dry weather field screening at 10%of major public outfalls annually. 1)Track the number of inspected outfalls.
ILL1 Discharge Elimination • • • Engineering 2) Conduct follow-up investigations for outfalls with discharges and take enforcement 2) Describe results of investigations.
actions as necessary 3) Report on updates to the IDDE Plan.
Program
Additional commitment: Update the IDDE Plan by November 1, 2021.
ILL2 Implement the Spill 0 0 • Engineering, Public 1) Respond to all spills reported to the City 1) Report the number of spills each year responded to by staff,the affected
Response Program Works, and Fire watershed,and any follow-up activities.
1) Annually review and update the list of industrial dischargers and potential high 1) Report the number of identified industrial dischargers and potential high
Screen Existing and New pollutant source facilities to the City's MS4 system. pollutant source facilities.
IND1 Industrial Facilities 0 • • Engineering 2) Notify the industrial facility and DEQ when facilities are identified that are subject to 2)Track the number of industrial facilities requiring DEQ 1200-Z permits.
an industrial stormwater permit(1200-Z).
Inspect Facilities with 1) Annually inspect 20%of the facilities required to obtain a DEQ 1200-Z permit. 1) Report on the number and inspection results of facilities required to obtain
IND2 Potential for Hazardous or 0 • • Engineering a DEQ 1200-Z permit
Toxic Pollutant Discharges
Implement the Erosion 1) Implement the ESC manual 1) Report the number of erosion and sediment control permits issued.
and Sediment Control 2) Provide wet-weather construction requirements with ESC permits. 2) Report any changes to the wet weather requirements
EC1 0 • • Engineering
(ESC) Manual and 3) Additional commitment: Update,as necessary,the municipal ESC code. 3) Report any changes to the adopted ESC manual and municipal code
Municipal Ordinance
1) Conduct initial, intermediate, and final site inspections for sites with an ESC permit. 1) Report the number of initial, intermediate, and final ESC inspections.
Conduct ESC Inspections 2) Conduct additional inspections for potentially problematic sites. 2) Report the number of sites requiring more than three inspections
EC2 and Enforcement 0 • • Engineering 3) Implement an escalating enforcement matrix. 3) Report number of enforcement actions, including warnings,written by the
City.
1) Use media outlets(social media, newsletters, etc.)to educate citizens about the 1)Summarize the media outlets used,frequency,and the primary
Provide Public Education effects of fertilizers, herbicides,and pesticides on water quality,general watershed stormwater messaging conducted by the City
and Outreach Materials information, proper disposal practices, and options for reporting spills and water 2)Track the number of catch basins marked.
PE1 Regarding Stormwater 0 0 0 Engineering quality problems 3)Summarize the media outlets used,audience reached (if known),and the
Management 2) Conduct catch basin marking. primary messages conducted by local and regional groups
3) Partner with regional and local groups,such as watershed councils and the Regional
Coalition of Clean Rivers and Streams,to reinforce stormwater messages.
Provide Educational 1) Promote the annual Erosion Control and Stormwater Summit hosted by the City of 1) Report on promotion efforts by the City.
PE2 Opportunities for O • O Engineering Keizer.
Construction Site
Operators
Conduct Staff Training for 1) Require staff and contractors to obtain and maintain pesticide applicator certification 1) Report on the number of staff and contractors who have an ODA
PE3 Pest Management 0 • • Parks and Recreation from the Oregon Department of Agriculture. applicator license.
Conduct Spill Response 1) Provide spill response training to appropriate city staff annually. 1) Report the number of employees receiving training.
PE4 Training for Staff O O 0 Public Works, Fire
Provide Stormwater or 1) Provide opportunities for stormwater or water quality training to staff annually. 1) Report the number of employees attending training and the training
Engineering, Public 2) Coordinate with other Clackamas County co-permittees regarding regional water subject
PE5 Water Quality Training for 0 0 0 Works qualityefforts. 2) Report the number of co-permittee meetings and anyjoint projects
Staff p p g p
related to stormwater management or water quality.
Review Development 1) Review development applications for compliance with the City's stormwater management 1) Report the number of development applications required to provide
DEV1 Applications • • • Engineering manual and regulations. stormwater management.
Key to pollutant symbols: A full circle(•)indicates the BMP is expected to address the parameter.An empty circle(0)indicates the BMP may be expected to address the parameter.A blank cell indicates that the effect of the BMP is unknown at this time.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix B
1 able B-1. Lake Oswe:o Cit Im s lementation Ac •
Phosphorus Mercury Responsible
BMP Activity Bacteria (pH and and TVS Measurable goals covered by the MS4 permit Annual tracking measures
chlorophyll(a)) (DO)? Department
Review and Update 1) Review and update,as necessary,the City's SWMM and municipal code language by June 1) Report on updates to the stormwater management manual and municipal
DEV2 Municipal Code and the • • • Engineering 30,2023. code that affect stormwater.
Stormwater Management
Manual (SWMM)
OM1 Sweep Curbed Arterial and • • • Public Works 1) Implement the street sweeping program. 1) Report curbmiles swept and amount of debris collected.
Residential Streets
1) Use the minimum amount of deicing materials required to provide public safety 1) Report the volume of de-icing materials used
Deicing and Leaf Pick Up 2) Each fall,target high leaf-fall streets for additional sweeping or catch basin/inlet 2) Report the volume of leaves collected from city.
0M2 • • • Public Works cleaning to prevent flooding. 3)Summarize any assistance with neighborhood leaf collection events such
Activities
3) Provide opportunities for neighborhood-wide leaf collection events such as drop-off as drop-off boxes.
boxes.
Reduce Pollutants Public Works, Parks 1) Annually inventory pesticides applied to public property. 1) Report on the quantity and type of pesticides applied to City property.
PEST1 associated with Pesticides, 0 • 0 and Recreation,
Herbicides,and Fertilizers Engineering
Update the Integrated Public Works, Parks 1) Update the Integrated Pest Management Plan,as needed,to reflect currently 1) Report on changes to the City's IPM Plan
PEST2 Pest Management 0 • 0 and Recreation accepted integrated pest management principals.
Practices
Implement Program to 1) Implement and track strategies to reduce the impact of stormwater from public 1) Report on strategies and methods used to reduce stormwater volumes
0M4 Reduce the Impact of • • • Public Works, facilities from public facilities.
Stormwater Runoff from Engineering
Municipal Facilities
Minimize Cross 1) Abate all cross connections upon discovery. 1) Report the number of cross connections,the affected watersheds, and
Connections to the follow-up actions.
ILL3 • 0 0 Public Works
Stormwater Conveyance
System
Inspect, Maintain,and 1) Inspect the public stormwater system (stormlines,culverts, ditches, and inlets). 1) Report the number or feet of the public stormwater system inspected.
0M5 Repair the Public • 0 • Public Works 2) Based on the results of inspections and citizen complaints, maintain or repair the 2) Report the number or feet of the public stormwater system maintained,
Stormwater System public stormwater system repaired,or replaced.
1) Inspect, maintain, and repair public catch basins as needed. 1) Report the number and percent of catch basins inspected and maintained
0M6 Inspect, Maintain, and • • • Public Works annually.
Repair Public Catch basins
2) Report the amount of debris removed.
1) Inspect and maintain public water stormwater facilities. 1) Report on the number and type of public stormwater facilities inspected
Inventory, Inspect,and 2) Maintain an inventory of private water quality facilities with operations and and maintained.
0M7 Maintain Stormwater • • • Engineering, Public maintenance(O&M)agreements. 2) Report on the number and type of private stormwater constructed and
Works 3) Annually inspect 10 percent of private water quality facilities for which an O&M the affected watersheds.
Facilities
agreement is on file with the City. 3) Report on the number of private stormwater facilities inspected and the
results of those inspections.
Key to pollutant symbols: A full circle(•)indicates the BMP is expected to address the parameter.An empty circle(0)indicates the BMP may be expected to address the parameter.A blank cell indicates that the effect of the BMP is unknown at this time.
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Appendix C: Effective Shade Modeling Methods
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
Appendix C
Effective Shade Modeling Methods
This appendix documents the methods used to obtain estimates of effective shade using DEQ's HeatSource
model reported in Section 3.The modeling consisted of the following steps:
1. Replacing the City's existing bare earth topographic model and streams map based on 2014 LiDAR data.
2. Developing a three-dimensional forest canopy height model using 2014 LiDAR data and 2013
multispectral images
3. Mapping riparian sensitive lands buffers based on City Code, related land use laws, City policies, and
Metro Title 3 and 13 requirements.
4. Using the existing canopy model, as well as existing GIS data,to support HeatSource modeling of
effective shade for all streams within the outermost of the City limits and the City USB. Note that there
are portions of both unincorporated Multnomah County and Clackamas County within our urban
services boundary, and adjacent cities of Portland and West Linn, all of which have their own Title 3
buffers.
I. Data Sources
The modeling exercise depended on the following data sources:
• Lidar flown August-September 2014.The City performed modeling using preliminary data
delivered directly to DOGAMI in mid-November 2014;these data did not go through
DOGAMI's QA/QC process. DOGAMI finds few errors in raw LiDAR topographic data, but finds
that their QC process is invaluable for the contemporaneous multi-spectral data. For this
reason,the City elected to perform the modeling using preliminary LiDAR topographic data.
Raw LAS-format files were used to allow examination of multiple return signals (rather than
first-and last-return only)to get a better idea of the density and structure of the forest
canopy in the vicinity of City streams. Metro now anticipates distributing the fully QC'd
package of LiDAR data and associated 2014 multispectral images on or about June 5, 2015.
• Multispectral images flown by Metro during leaf-on, 2013.
• City of Lake Oswego Enterprise GIS data for tax lots, existing sensitive lands overlay zones,
USB and City Limits boundaries.
• Oregon Geospatial Data Clearinghouse for GIS data on ecoregion boundaries, fish
distribution, and 1851 plant community/land cover distribution as reconstructed by the
University of Oregon
• US Geological Survey(USGS) Historical Topographic Map Explorer.
(http://historicalmaps.arcgis.com/uses/)to obtain c. 1914 and later topographic data as an
aid to determining pre-development topographic conditions.
II. Map Updates and Related Derived Data
Updates to the City's topographic data were made using the LiDAR bare earth model.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
1. Channel centerline location
Using the new topographic data, the location of each stream centerline was reviewed. Where
warranted by the topography,the location of the channel centerline was revised (Figure C-1).
Channel top of banks were digitized where they could be distinguished.The classification of
open channels into streams subject to the Clean Water Act and ditches followed the
definition of ditch in OAR 141-085-0510(28). Open channels were classified as ditches that
were dug to provide roadside or other drainage, but that were otherwise not following the
underlying natural topographic patterns as determined from historic USGS mapping.
Previous location of channel centerline Revised channel centerline location
relative to the new topographic data
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Figure C-1. Example of stream channel centerline correction using new LiDAR topography data
2. Channel width
The HeatSource model requires channel width as a model input. However,the City has
relatively little data on stream channel width other than at water quality or
macroinvertebrate sampling stations. Most streams are non-navigable, and private property
limits access to them.Stream banks did not show up on LiDAR-based topography for most
channels less than approximately 30 feet wide.Therefore, channels were segregated into
width classes based on the limited data and understanding of channels where visible from
public rights of way. Channel width classes were created as approximations of geomorphic
bankfull width. Streams were designated as Primary and Secondary stream types by Metro's
Title 3 upstream drainage basin criteria alone, recognizing that the City also doesn't have
robust data on the location of transition from intermittent(typically in headwater areas)to
perennial streams:
• Primary Protected Water Features include: all perennial streams, intermittent streams
draining greater than 100 acres,Title 3 wetlands, natural lakes, and perennial springs.
• Secondary Protected Water Features include intermittent streams draining 50-100
acres.
• Unclassified: intermittent streams draining<50 acres.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
Channel width observations were used to develop approximate bankfull width classes for
these specific stream types. Buffers of the following dimensions from stream centerlines
were used to create stream polygons that were subsequently used to estimate TMDL targets
and model effective shade:
• Primary Protected Water Features (streams) > 20 ft wide: 15-ft buffer (30-ft width) or
delineated top of bank where clearly visible from hillshade model.
• Primary Protected Water Features< 20 ft wide: 10-ft buffer(20-ft total bankfull width).
• Secondary Protected Water Features—5-ft buffer(10-ft total bankfull width).
• Unclassified—2.5-ft buffer on centerline (5-ft total bankfull width).
3. Channel ravines
In areas with adjacent steep slopes (25%slope or greater),the stream corridor ravine was
mapped up to gentler upland areas beyond steep slope segments. Slope, hillshade, and
elevation layers were used to refine observations of top of bank and delineate edge of steep
side slope areas around streams (Figure C-2).
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/ edge of adjacent steep slopes
greater than26% Primary Stream Slope%
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Figure C-2. Example of channel ravine mapping
Ill. Canopy Height Model
The three-dimensional forest canopy height model was developed from the multi-spectral imagery
and LiDAR topography. Four band imagery includes an invisible near infrared band that GIS software
can make use of to calculate the Normalized Difference Vegetation Index (NDVI).The NDVI is
calculated using values from the red and near infrared bands from the imagery.As shown below,
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
NDVI is a great indicator of vegetation and forms the basis for a two dimensional understanding of
the distribution of vegetation across the City.
From the point cloud information, a Normalized Digital Surface Model (nDSM)was generated. The
nDSM represents the height above ground of all objects. By using information such as height and
slope from the nDSM with NDVI and 4 bands from the imagery, a vegetation canopy was developed
(Figure C-3).The vegetation canopy model was draped over the nDSM to form a canopy height
model (Figure C-4). Only vegetation greater than 4-feet in height was used for effective shade
modeling. Figure C-4 shows a detail of the canopy height model. Figure C-5 shows the City-wide
canopy height model. While Figure C-5 looks like an aerial photograph, it is not. Instead, the canopy
height above bare earth is shown in progressively darker shades of green, while buildings,
pavement, and low-lying vegetation is shown in grey.
True Color (Visible) False Color Normalized Differenc=
R: Red(Band 1) R: Near Infrared (Band 4) Vegetation Index
G:Green(Band 2) G:Blue(Band 3) NDVI _ (NIR—Red)
B: Blue (Band 3) B:Green (Band 2) (N1R+ Red)
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IV. Resource Protections
The resource protection overlay determines the riparian areas subject to development protections,
with minor exceptions such as 1) no more than 700 sq ft intrusion for modifications of an existing
building and 2) no more than 200 sq ft intrusion for new development. Construction setbacks
beyond the overlay district, not included in this analysis, are:
• 10 feet for buildings, streets, driveways, sidewalks and hard-surface pathways
• 3 feet for patios, pools, spas, and retaining walls
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
+''.,., - `. Canopy Height "Model (Raster) :'1
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The City's stream buffer protections pre-date Metro's Title 3. Buffers are variable based on habitat
quality, as determined by staff. "Class I" stream corridors and wetlands have a habitat assessment
score (HAS) of more than 50. Stream corridors and wetlands that have a HAS of 35-49 or have a
"high" ranking for scenic values are defined as "Class II" stream corridors and wetlands. Protected
canopy buffers on each side of the stream or beyond the edge of the wetland were created based
on the following dimensions:
Table C-1. RP Overlay District Dimensions
RP Buffer Width (ft
Resource Category Buffer Measuring Point Beyond Measuring Point)
Class I Stream 10'outward from channel centerline,or geomorphic 30-50 ft each side of
bankfull width,whichever is greater channel
Class I Wetland Delineated wetland boundary 30 ft
Class II Wetland abutting Class I 10'outward from channel centerline,or geomorphic 25-50 ft each side of
Stream Corridors bankfull width channel
Class II Wetland Delineated wetland boundary 25-50 ft
Streams and wetlands with Slope break point between the adjacent steep slope,
adjacent slopes>=25%(14 and gentler upland areas beyond the steep slope
degrees) extending beyond the segments.Small floodplain segments inset in a ravine As described above
geomorphic top of bank or do not constitute the edge of the stream corridor. See
delineated wetlands boundary Figure 4(main body of plan)and C-2.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
The resource conservation (RC) overlay zones are a supplemental protection measure for Metro
Title 3 and also used for Title 13 protections.2 Resource protections are conferred to 85%of the RC
district on each lot. Where RC overlay was removed from private properties in 2015 (Ordinance
2687), RP buffers were widened to a maximum of 50 feet to maintain an equivalent level of
protection; hence,the buffer width ranges in Table C-1.
On some parcels, City staff has performed an on-the-ground delineation of the RP and RC districts.
Where that is available in GIS, it takes precedence over the dimensions in Table C-1.The GIS data
are regularly updated to reflect the locations of approved delineations.
V. Effective Shade Modeling
The HeatSource model application by the City used several steps. First, the TTools module was used
to extract data from the larger GIS dataset. Next,the HeatSource model was run based on the
documentation cited above, with a minor modification to account for the greater resolution in the
current LiDAR data.This section describes the key assumptions and approaches used by the City in
this effort.
1. TTools v. 9:
TTools is a series of Python scripts that are used to extract data needed by the Heat Source
model, which models instream thermal conditions associated with riparian shading.
a. Script 1 —Segment Stream
The first script takes the stream centerlines as inputs and creates evenly spaced points along
each centerline. A distance of 25 feet between model points was used to provide a very
continuous representation of effective shade along each stream. Breaks in streams (e.g., due
to piped intervals) caused some points to be slightly closer or farther away than that distance.
Piped intervals were not modeled.
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Figure C-6. Output of Script 1 showing location of nodes for which HeatSource results are calculated.
2 Additional details on Title 3 and 13,and the City's compliance,are found in Appendix D.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
The following fields are added to the GIS dataset at each node with this script:
• a unique Node ID
• a unique ID for each stream segment
• distance of the node from the start of the stream segment, and
• the geographic coordinates for the node.
b.Script 2—Channel Width and Orientation
Script output data through this step were used in both the HeatSource modeling and for
determining the TMDL effective shade target for each node, as described in Section 3.1.The
second script adds:
• Stream azimuth, i.e., the direction (degrees from north) of the stream at the location of
each node.
Distance to each side of the channel and the channel width at each node, using a polygon or
lines representing the stream channel. For this step,the City's channel width classes were
used to develop the stream polygons.These widths should be considered bankfull rather than
wetted width.This may result in a slight underestimation of the TMDL target. At least once
during each implementation plan cycle as effective shade is assessed, any new data on
channel width will be used to re-evaluate channel width classes. As sufficient data on channel
geometry is developed, the width basis may be adjusted to use bottom width or wetted
width.
c.Script 3—Sample Elevation Gradient
This script uses the nodes and the bare earth DEM raster surface to find the lowest elevation
near each node and calculates the downstream gradient.This script adds data to two fields:
• Invert elevation
• Downstream channel gradient.
•
•
Figure C-7. Output of Script 3 showing stream centerlines, nodes, and channel area polygons.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
d.Script 4—Measure Topographic Angles
The fourth script uses a maximum search distance, and calculates maximum topographic
angles in sample directions at each node.These values are used to account for topographic
shade. Points are created in a new feature class that represent the highest topographic
angles from each node.The maximum angle values in each direction sampled are added as
new fields for each node.
e.Script 5—Sample Landcover
The last script creates a new point feature class that is used to sample the ground elevation
and the canopy height around each node. Inputs for this tool are the bare earth elevation
raster and a canopy height raster.The points are created at 8 defined angles (N, NE, E, SE, S,
SW, W, NW)from each node at equidistant intervals. For the purposes of this project, the
City created 15 horizontal sample points at each angle spaced at 3 meter intervals from
each node.Therefore, a radius around each node of about 45 meters of canopy could be
accounted for in the effective shade analysis.The height of vegetation and the bare earth
elevation at each sample point and the canopy height are associated with the node.This
allows for modeling effective shade from both local topography and tree canopy.
f. Script 6--Scenario Development
Before running this last script, two copies of the nodes feature class are created.The script
is then run twice, with each one using a different raster for the canopy height input.The
two different canopy height models represent 1) current canopy conditions, and 2) canopy
within existing protected riparian buffers.
The two scenarios for our focus area are displayed below with the sample points with the
different canopy height models. Darker green canopy represents taller trees in the raster.
The landcover/elevation sample points are shown for one node.There are 8 azimuths
sampled for each node. Both the average elevation and average canopy height that are
recorded for each azimuth are added as a field to the node (a total of 16 fields; 8 for
elevation and 8 for canopy height).
Current canopy conditions.This scenario accounts for canopy both inside and outside of protected
riparian buffers.The canopy height model is shown in green; darker green indicates higher trees, as
indicated in the scale on figure C-4.The "star" graphic in Figure C-8 shows the location of the canopy
and topographic sampling points (shown in yellow) used to model effective shade at a single node
(red).
Existing Protection: Red outlines in Figure C-9 represent the existing RP overlays and 50%of the
existing RC overlays adjacent to RPs that comprise the riparian buffers. Again,the yellow dots
represent the samples taken for the elevation and canopy height for that single node. Samples like
this are taken for each node. Any canopy outside the protected area will have a height of zero
associated with that point.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
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Figure C-9. Example of data used for HeatSource modeling at each node for canopy in existing protected
riparian buffers.
2. Effective Shade from HeatSource/Shade-a-lator
HeatSource has a component called Shade-a-lator, an excel spreadsheet model, that calculates
the effective shade from the data gathered at each node using the TTools scripts. Most of the
nodes fields are used as inputs to calculate effective shade using HeatSource.The HeatSource
excel workbook has 4 sheets that are necessary to fill out to run the Shade-a-Lator component.
Detailed steps for running Shade-a-Lator are provided by the Willamette Partnership (2014) and
can be accessed here: http://willamettepartnership.org/wp-content/uploads/2015/02/Shade-a-
lator-v8.0.5-8.0.8-Protocol-2014-03-20.pdf
Sheet 1: "Heat Source Inputs" is used to set up the conditions under which the other sheets will
be set up. Many of these inputs receive the defaults as defined in Willamette Partnership's
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
documentation. Other inputs allow you to specify project-specific conditions for which the City
obtained guidance from DEQ.These include:
• Modeling start and end date (both are August 1st)
• Distance steps and transverse sample rates that were used for the TTools data,
• Whether inputs are based on use of LiDAR or vegetation classes
• A land cover canopy density(based on ecoregion as was done in the TMDL analysis,
modeling assumed 75%for streams located in Prairie Terrace ecoregion and 90%for
streams located in Valley Foothills ecoregion; see Figure C-10)
• Stream "overhang"for LiDAR data (geometry of overhanging branches; a standard of 0
meters was used given the superior geometric resolution of the newly acquired LiDAR data)
• Vegetation calculation method ("point" if using LiDAR, "zone" if using vegetation classes)
Sheet 2: "TTools Data" can be completed by copying and pasting the tables directly from the
desired nodes feature class that is output of the analysis described above.This allows
HeatSource to access all of the data that was acquired at each node for the desired scenario
including topographic elevation and vegetation heights from the transverse sample points.
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix C
Sheet 3: "Morphology Data" is populated using more information from the nodes feature class
including the elevation, gradient, and bottom width at each node.The other inputs are set at the
defaults provided in the spreadsheet—they define sediment heat exchange and hyporheic flow
which do not affect the Shade-a-Lator component results.
Sheet 4: "Continuous Data: is not necessary for Shade-a-Lator, but HeatSource needs at least
one value in the "continuous node" column to run.
After the 4 sheets have been populated, Shade-a-Lator can be run using the Add-Ins toolbar.The
results of Shade-a-Lator are shown in the "Chart-Shade" sheet of the file which lists the "effective
shade" and "view to sky" percent for each node and provides a chart of these values. The chart is
only useful if the nodes are listed in order of their location on along the target stream. If you are
running Shade-a-Lator for all streams within a City the chart is not useful.
The effective shade at each node for the City's two scenarios (current conditions, and existing protection)
can be joined back with the Nodes GIS feature class based on the unique Node ID. The effective shade for all
scenarios are stored in a single table along with each nodes information that was collected in TTools.
Existing measurements of effective shade are not available for the City, so there are no data to fully calibrate
the model. However, measurements of percent canopy were obtained with a spherical densitometer at 10
sites around the City during recent macroinvertebrate sampling (Cole, 2014). Results are shown in Figure C-
11.These measurements are in line with calculated effective shade values at these locations.
Modeling results are provided in Section 3.2 of the main body of this document.
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Appendix D: Summary of Title 3/Title 13
Requirements
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix D
Appendix D
Summary of Title 3/Title 13
Requirements
Title 3
Title 3, specifically the Title 3 model ordinance,was developed in 1997 by Metro, which is a regional
government serving the Portland metropolitan area including 25 cities.The purpose of Title 3 is to
implement the Oregon Statewide Land Use Goals 6 and 7 that address the protection of streams, rivers,
wetlands, and floodplains.Title 3 provides protection by avoiding, limiting, or mitigating the impact on these
areas from development.Title 3 limits development in identified water quality resource areas (WQRAs) and
flood management areas (FMAs) and it limits development that would cause any extent of erosion within
the Metro Boundary.Title 3 defines the WQRA as the protected water feature and associated vegetated
corridor adjacent to the water feature and provides the method for determining the appropriate width of
this vegetated corridor(See Table D-1). Native vegetation within the WQRA should be maintained,
enhanced or restored, if disturbed. Metro developed the Water Quality and Flood Management Areas map
identifying these areas with input from the cities and counties within the Metro region.
The cities and counties within the Metro region were given three alternatives for implementing Title 3:
1. Amend comprehensive plans and ordinances to adopt all or part of the Title 3 model ordinance or
language that substantially complies with the Title, and adopt either the Metro Water Quality and Flood
Management Area map or a map that substantially complies with the Metro map;
2. Demonstrate that existing city and county comprehensive plans and ordinances already substantially
comply with the performance standards and the intent of Title 3; or
3. A combination of the first two alternatives that substantially complies with all performance standards of
Title 3.
The City of Lake Oswego achieved compliance with Title 3 in 2011 under the substantial compliance
provision (option 2).After revising its sensitive lands program in 2015 (Ordinance 2687), it remained in
substantial compliance with Title 3.
Title 13
Title 13 was created by Metro in 2006 in response to Oregon Statewide Land Use Goal 5 which protects
natural resources and open space.Title 13 provides guidance for local jurisdictions to 1) conserve, protect,
and restore a continuous ecologically viable streamside corridor that is integrated with upland wildlife
habitat, and 2) control and prevent water pollution in order to protect public health and improve the
region's water quality.
Title 13 focuses on regulating development that would affect riparian or upland wildlife habitat, as
documented on the Habitat Conservation Area (HCA) map that Metro has produced.The HCA map was
created by Metro and intended for adoption by local jurisdictions in the same manner as the Water Quality
and Flood Management Areas map developed for Title 3 compliance. HCA priority levels (high, medium, and
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix D
low)were assigned to areas by cross-referencing habitat classifications (e.g., Class I and Class II Riparian and
Class A and Class B Upland Wildlife) and urban development values.
Table D-1. Stream Buffer Widths from Metro's Title 3 (Table 3.07-3 of Sec 3.07.340(B)(2)"a)
Slope Adjacent Width of
Protected Water Feature to Protected Starting Point for Measurements from Vegetated
Type Water Feature Water Feature Corridor
Primary Protected Water • Edge of bankfull flow or 2-yr storm level
Features' <25% • Delineated edge of Title 3 wetland 50 ft
Primary Protected Water >25%for 150ft • Edge of bankfull flow or 2-yr storm level
Features' or more5 • Delineated edge of Title 3 wetland 200 ft
Distance from
starting point of
measurement to
top of ravine
Primary Protected Water >25%for less • Edge of bankfull flow or 2-yr storm level (break in >_25%
Features' than 150fts • Delineated edge of Title 3 wetland slope)3, plus 50 ft4.
Secondary Protected Water • Edge of bankfull flow or 2-yr storm
Features' <25% • Delineated edge of Title 3 wetland 15 ft
Secondary Protected Water • Edge of bankfull flow or 2-yr storm level
Features2 >_25% • Delineated edge of Title 3 wetland 50 ft
Primary Protected Water Features include: all rivers,perennial streams,and streams draining greater than 100 acres,Title 3
wetlands,natural lakes and springs.
2 Secondary Protected Water Features include intermittent streams draining 50-100 acres.
3 Where the Protected Water Feature is confined by a ravine or gully,the top of ravine is the break in the>_25%slope(see slope
measurement in Appendix).
4 A maximum reduction of 25 ft may be permitted in the width of vegetated corridor beyond the slope break if a geotechnical
report demonstrates that slope is stable. To establish the width of the vegetated corridor,slope should be measured in 25-ft
increments away from the water feature until slope is less than 25%(top of ravine).
5 Vegetated corridors in excess of 50ft for primary protected features,or in excess of 15-ft for secondary protected features,
apply on steep slopes only in the uphill direction from the protected water feature.
(Metro Ordinance 98-730C,Sec.1.)
New development restrictions differ depending on the HCA priority level as well as zoning type.
Cities and counties are given three alternatives for implementation of Title 13:
1. Adopt Title 13 model ordinance and map;
2. Demonstrate that the existing or amended comprehensive plan and ordinances "substantially" comply
with the title, and existing or adopted maps also comply with Metro's HCA map; or
3. Demonstrate that an alternative program with comparable protection and restoration results has been
implemented.
Several exemptions are allowed for various reasons and are outlined specifically in the title. In essence,Title
13 promotes vegetative buffers around water bodies for protection of wildlife habitat through the
preservation and improvement of designated habitat conservation areas.Title 13 and its corresponding
model ordinance describe specific design and construction practices to minimize impacts on wildlife
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix D
corridors and fish passage. Performance and implementation objectives and measurable targets are outlined
in the title, specifically related to design and construction practices that would be employed.
Metro monitors the region's progress toward implementation of Title 13, and cities and counties are
required to submit progress reports on their efforts (Metro 2005).
Title 3 and Title 13 Comparison
Both Title 3 and Title 13 promote the protection of vegetative buffers around water bodies.The goal for
Title 3 is to protect water quality and flood areas while Title 13 aims to protect and improve riparian and
wildlife habitat. Because Title 3 and Title 13 have different goals, the methods for implementation and
performance standards are not identical.Title 13 is more specific than Title 3 in that it has specific numerical
targets. However,Title 13 also enables the cities to use their own discretion when defining the protective
buffer areas by evaluating the economic effects (urban development values),which is not a component of
Title 3 (Metro 1998 and Metro 2005).Title 13 also provides for alternatives to regulatory protections alone
(option 3).The City of Lake Oswego achieved compliance with Title 13 in 2011.The City revised its sensitive
lands program in 2015 (Ordinance 2687) but maintained substantial compliance with Title 13.
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Appendix E: Temperature Management Strategies
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix E
Table E-1. TMDL Implementation Plan Strategies for Temperature3
Stabilizes or Improves
Reduces P (pH & Hg&TVS Responsible
BMP Strategy Temperature Bacteria chlorophyll a) (DO) Department Measurable Goal Annual Tracking Measures
1) Report on modifications of the municipal code and planning documents related to the
1) Update municipal code, as needed,to Sensitive Lands program and the temperature TMDL.
stabilize stream temperatures
2) Report on the number of building permits and land use applications in sensitive lands
• o Unknown • Planning and 2) Implement and enforce LOC Chapter 50 to or within 50 feet of non-regulated stream corridors
Engineering address Title 3 and Title 13 requirements
relative to riparian buffer widths needed to 3) Report on enforcement actions within riparian corridors or areas with sensitive lands.
provide effective shade. 4) Report on stream buffer modifications and their effect on shade and the temperature
Implement the Sensitive TMDL.
Lands municipal code
including the Sensitive Areas 1) Conduct targeted field surveys of riparian 1) Report on completed field surveysand ri riparian projects that implement the
Riparian Area Overlay Zone(LOC corridors(with public access)to identify areas p p p p p
Management: that can implement the 2015 hydromodification assessment.
50.05.010),Tree Protection • 0 • • Engineering p
Preserve Existing Ordinance(LOC 55.08), and hydromodification assessment. 2) By June 30, 2019, implement at least one hydromodification mitigation project on
Forest Canopy other related ordinances to 2) Implement hydromodification projects public land or right-of-way
preserve existing riparian
canopy in riparian buffers. 1) Report availability of updated LIDAR data and progress towards evaluating canopy
1) Evaluate existing canopy cover in the City's coverage and effective shade.
jurisdiction and effective shade in riparian 2) Within 2 years of receiving updated LIDAR data, evaluate effective shade on riparian
• 0 0 0 Engineering corridors, using the HeatSource model or its corridors within the City's jurisdiction relative to the 2014 baseline conditions.
equivalent,within 2 years of receiving new 3) Within 3 years of receiving updated LIDAR data, identify stream reaches on public
LIDAR data. land and private open space that are below shade targets and prioritize project areas
that will have the greatest effect on stabilizing stream temperatures.
1) Implement the Habitat Enhancement
Program (HEP). 1) Report on revisions to the HEP prioritization criteria.
2) Use a portion of HEP funds for projects on 2) Report on HEP expenditures for public and private properties including the affected
private riparian or directly connected upland watershed, number of acres under active restoration, number of acres being monitored
• 0 • • Parks and areas. or maintained, and hours of public education.
Engineering
3) Target areas that can reduce 3) By June 30, 2023, evaluate habitat enhancement projects on public and private lands in
hydromodification,stabilize stream regard to their effect on hydromodification,stream temperatures,canopy coverage,and
Riparian Area Promote restoration, temperatures, leverage public funds,and public education.
Management: rehabilitation,and I increase public education.
Increase Existing enhancement of riparian
Shade and Habitat habitat on public and private 1) Partner with local watershed councils and
Quality land. non-profit organizations to support riparian 1) Report on City partnering efforts and financial contributions to watershed councils and
activities or public education. Prioritize non-profit groups.
• 0 • • Engineering efforts that provide watershed education to 2) By June 30, 2023,assess the effect of the partnerships and events on
students, reduce hydromodification,and/or hydromodification,effective shade,and education.
stabilize stream temperatures
1) Continue City participation in the Backyard 1) Report on completed BHCP certifications including whether it is in a riparian area,
• • 0 0 Planning Habitat Certification Program (BHCP)or,a directly connected upland. Report on technical and financial assistance provided either to
functionally equivalent program. Direct BHCP BHCP or its participants by City staff
3 TMDL=Total Maximum Daily Load; BMP=Best Management Practice;P=Phosphorous;Hg=Mercury;TVS=Total Volatile Solids; DO=Dissolved Oxygen; •=BMP is expected to increase water quality o=BMP may increase water quality
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Lake Oswego TMDL Implementation Plan 2019-2023 Appendix E
Table E-1. TMDL Implementation Plan Strategies for Temperature3
Stabilizes or Improves
Reduces P (pH & Hg&TVS Responsible
BMP Strategy Temperature Bacteria chlorophyll a) (DO) Department Measurable Goal Annual Tracking Measures
efforts toward riparian area restoration where 2) Report on any partnerships with other regional or local groups targeting habitat
appropriate. enhancement efforts.
2) When available and funding allows, partner
with other regional or local groups targeting
habitat enhancement
1) Continue support of planning and project 1) Report on master planning efforts and actions taken by Parks that positively influence
• • o o Parks assistance toward enhancement of riparian riparian areas and directly connected upland areas especially in regard to increasing
areas,with emphasis on riparian shade. effective shade.
1) Determine feasible sites, if any,for refugia preservation or enhancement using the
2016-2017 USGS study of the lower Willamette River by June 30, 2020.
1) Determine projects to enhance or maintain
Cold Water Refugia • 0 • • Engineering cold water refugia 2) By June 30,2021,develop an implementation strategy including funding, partnerships,
and general design requirements or protection strategies.
3) By November 1,2022, begin design or implementation of initial project.
Prioritize low impact
Stormwater
development approaches 1) Require infiltrating or LIDA stormwater 1) Report, by watershed,on the amount of impervious area treated by each type of
Management (LIDA)and infiltration for • • o • Engineering facilities where feasible stormwater facility.
Manual
stormwater management.
1) Using social media and other public
education methods, inform City residents 1) Report on the efforts to educate citizens about stream temperature effects on aquatic
• Unknown • 0 Engineering about the importance of stream temperature life.
for aquatic life and/or water.
Public Education for Promote stewardship and 1) Promote the City's urban forestry programs
Temperature enhancement opportunities • Unknown • 0 Planning such as Arbor Week, Urban &Community 1) Report on the number of urban forestry events provided by the City.
Management of riparian areas in the City. Forest Workshops,etc.
1) Promote regional or local programs targeted 1) Report on number of events promoted by the City that enhance riparian habitat(or
• • • • Parks, at improving habitat on private property,e.g. directly connected upland habitat)through social media or other public education
Planning Friends groups and the BHCP program. outlets.
1) Conduct water quality monitoring as
required by the NPDES MS4 permit. 1) Summarize the results of grab sample water quality monitoring, including temperature.
Monitor streamflow and 2) Maintain continuous monitoring stations as 2) Summarize information from the continuous monitoring stations
Environmental temperature in streams to required by the MS4 permit
0 0 0 o Engineering 3) Report on changes to water quality monitoring efforts.
Monitoring document water quality 3) If the intergovernmental agreement(IGA) is
trends. I maintained by all Clackamas co-permittees, 4) Report on changes to the IGA with Clackamas co-permittees on the USGS gaging station
I continue funding the USGS gaging station (Tualatin River at West Linn)
on the Tualatin River at West Linn
3TMDL=Total Maximum Daily Load; BMP=Best Management Practice; P=Phosphorous; Hg=Mercury;TVS=Total Volatile Solids; DO=Dissolved Oxygen; •=BMP is expected to increase water quality o=BMP may increase water quality
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