Lake Ballinger Watershed Modeling
Prepared for:
City of Edmonds
Prepared by:
Northwest Hydraulic Consultants
Seattle, WA
September 2013
Table of Contents
1
Introduction ......................................................................................................................................... 1
2
Observed Data ...................................................................................................................................... 2
3
Model Development ............................................................................................................................ 3
4
3.1
Modeled Scenarios........................................................................................................................ 3
3.2
Hydraulic Model ............................................................................................................................ 4
3.3
Hydrologic Model .......................................................................................................................... 5
3.3.1
Hydrometeorological Data .................................................................................................... 5
3.3.2
Subbasin Delineation ............................................................................................................ 5
3.3.3
Basin Soils and Land Cover .................................................................................................... 6
3.3.4
Groundwater ......................................................................................................................... 6
3.3.5
FTABLEs ................................................................................................................................. 6
Model Calibration................................................................................................................................. 8
4.1
Hydraulic Model ............................................................................................................................ 8
4.2
Hydrologic Model .......................................................................................................................... 8
5
Results ................................................................................................................................................ 10
6
References .......................................................................................................................................... 11
Lake Ballinger Watershed Modeling
i
List of Figures
Figure 1 Lake Level Gage Data
Figure 2 Stage and Flow at Hall Creek Gage
Figure 3 Stage and Flow at McAleer Creek Gage
Figure 4 Scatter Plot of Hall Creek Gage Data
Figure 5 Scatter Plot of McAleer Creek Gage Data
Figure 6 Difference Between Observed and Gage Lake Level Data
Figure 7 HEC-RAS Model
Figure 8 Model Cross Section with and without Outlet Control Structure
Figure 9 Comparison of Model Cross Sections from Lake Outlet to the First Bridge
Figure 10 HSPF Subbasins
Figure 11 HSPF Subbasin Soils
Figure 12 HSPF Land Cover
Figure 13 HSPF Land Use
Figure 14 Comparison of Observed and Simulated Flow at McAleer Creek Outlet Weir
Figure 15 Hall Creek Observed versus Simulated Flow
Figure 16 Simulated and Observed Lake Levels 2001-2013
Figure 17 Simulated and Observed Lake Levels WY 2002
Figure 18 Simulated and Observed Lake Levels WY 2003
Figure 19 Simulated and Observed Lake Levels WY 2004
Figure 20 Simulated and Observed Lake Levels WY 2005
Figure 21 Simulated and Observed Lake Levels WY 2006
Figure 22 Simulated and Observed Lake Levels WY 2007
Figure 23 Simulated and Observed Lake Levels WY 2008
Figure 24 Simulated and Observed Lake Levels WY 2009
Figure 25 Simulated and Observed Lake Levels WY 2010
Figure 26 Simulated and Observed Lake Levels WY 2011
Figure 27 Simulated and Observed Lake Levels WY 2012
Figure 28 Simulated and Observed Lake Levels WY 2013
Figure 29 Simulated and Observed Peak Lake Levels
Figure 30 Lake Ballinger Frequency Plots
Lake Ballinger Watershed Modeling
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List of Tables
Table 1 Manual WSE and Flow Measurements on McAleer Creek
Table 2 Comparison of Lake Level Gage Data and Observed Measurements
Table 3 Effective Impervious Area Factors
Table 4 Subbasin Area, Impervious Area, and Effective Impervious Area
Table 5 Hall Creek Long Term Volumes
Table 6 Hall Creek Observed Versus Simulated Peaks and Volumes
Table 7 Lake Level Frequency Analysis
Table 8 Percentage of Total Runoff Volume and Total Area from Each Jurisdiction
List of Photos
Photo 1 Downward looking sonic meter located at head of McAleer Creek and operated by the City of
Mountlake Terrace.
Photo 2 First culvert downstream of the lake outlet control weir. This culvert was replaced with a
bridge in July 2013.
Photo 3 Discharge measurement at the control weir on March 10, 2011.
Photo 4 Lake outlet control weir during the summer, with stop logs exposed.
Photo 5 Setting high water marks on McAleer Creek on March 14, 2011. These HWMs were used for
model calibration.
Photo 6 The lake outlet weir influence shown being drowned out on March 14, 2011. The water surface
elevation at the weir is 279.4 feet (NGVD29), which is just greater than a 2-year flood on Lake
Ballinger.
Lake Ballinger Watershed Modeling
iii
1 Introduction
Lake Ballinger is a 105-acre lake located between the cities of Edmonds and Mountlake Terrace. The lake
has been the focus of numerous engineering and scientific studies in the last 30 years. These studies
primarily addressed problems related to water quality or stormwater runoff contributing to flooding and
property damage. Recently, the City of Edmonds has been especially concerned with lake flooding of
some lakeside residences and is exploring possible solutions.
The water level in Lake Ballinger is primarily a function of precipitation and resulting runoff from the five
square mile tributary watershed. In 1942, Washington State Superior Court provided a Notice and Order
that authorized installation of a control weir at the lake outlet in an attempt to alleviate damage from
floodwaters and protect fish and game within the lake. The Notice and Order also established a
maximum lake level to be controlled by the weir and authorized formation of a tax district to pay for
operation and maintenance of the weir.
In 1982, the Order was re-adjudicated to reset the weir level to reduce flooding and drainage impacts
due to storm events and to allow operation of a new water quality piping system in the lake. The
operation and maintenance manual for the water quality piping system required the weir be set
between 277.4 feet1 in the summer and 276.5 feet in the winter. The influence of the control structure
on water level has been the focus of some debate and more than one study by the adjacent
municipalities.
To assess the influence of the control structure on water levels, specifically flooding levels, an accurate
numeric model of the Lake Ballinger watershed is necessary. Northwest Hydraulic Consultants (NHC)
was contracted by the City of Edmonds in 2011 to peer review previous hydrologic modeling of the Lake
Ballinger watershed. The peer review noted strengths and deficiencies of the prior modeling but
ultimately concluded that to improve model accuracy, calibration data beyond observed lake levels was
needed.
Subsequent to the peer review, the City of Mountlake Terrace initiated three specific actions to begin to
address flooding on Lake Ballinger. The first was to install discharge monitoring gages on Hall Creek and
McAleer Creek to be used eventually for model calibration. The second was to assess the impact to flood
levels of three culverts on McAleer Creek immediately downstream of Lake Ballinger. Their flowconstricting effect was documented by NHC (NHC 2011a), and one culvert has been replaced with a nonconstricting bridge with the other two culverts scheduled for demolition in 2014. The third action was to
sponsor a project by the University of Washington Geographic Information System (GIS) Certificate
Program to investigate and document the total impervious surfaces in the Lake Ballinger watershed.
In early 2013, following the accumulation of more than a year of data collection at the Hall and McAleer
Creek stream gages, the City of Edmonds contracted NHC to construct new modeling of the watershed.
The models were to be focused specifically on simulating lake levels for the purpose of assessing its
response to the lake outlet control structure. This report documents the development, calibration, and
results from the new hydraulic and hydrologic models.
1
All elevations in this report are referenced to the National Geodetic Vertical Datum from 1929 (NGVD29) to be
consistent with the current Superior Court Order.
Lake Ballinger Watershed Modeling
1
2 Observed Data
Observed data were collected, compiled, and/or reviewed for the purpose of calibrating the hydrologic
and hydraulic models. Data included Lake Ballinger water levels, continuous discharge and stage records
for Hall and McAleer Creeks, and several direct discharge measurements taken at the outlet control
structure.
The water level in Lake Ballinger has been continuously monitored by Mountlake Terrace since 1981.
Prior to 2001, these data are only available on archived strip charts. With the exception of annual peaks,
these data were not used for model calibration because of the availability of more recent digital records.
Beginning in July 2001, the gaging station was upgraded to a downward-looking sonic water level sensor
(Photo 1). Hourly data from this sensor covering the period from 2001 to 2013 were compiled by NHC
(see Figure 1). Note that the gage was tipped over by a large log during the December 2007 flood and
therefore did not record the peak stage for this large event. Although the gage was reinstalled three
months after the event, it did not function properly until it was recalibrated sometime in 2009
(Mountlake Terrace, personal communication).
Discharge and stage records were collected by the City of Mountlake Terrace with assistance from NHC
on Hall Creek and McAleer Creek. The Hall Creek records span December 2011 to the present and the
McAleer Creek data span March 2012 to July 2013. Both meters are Isco brand velocity-area flow
sensors. The Hall Creek gage is located at the box culvert under 228th Street SW and the McAleer Creek
gage was located in the first culvert downstream of the lake outlet control weir, shown in Photo 2. Note
that this gage was removed in July 2013 as part of the culvert replacement project constructed by
Mountlake Terrace. The records at these gages that were available for calibration are displayed in Figure
2 and Figure 3. Scatter plots showing the depth and velocity readings for both gages are found in Figure
4 and Figure 5. The McAleer Creek scatter plot clearly illustrates that the gage velocity sensor was not
operating properly. The malfunction was discussed with Isco and determined to be caused by one of two
conditions: either it was due to very clean and/or slow-moving water that does not provide an adequate
signal, or there was a bad electronic component. Regardless of the cause, the McAleer Creek discharge
values are not credible and were not used for model calibration, though the depth measurements are
still considered reliable.
In addition to the continuous flow recorders, six water surface elevation and flow measurements were
made by Mountlake Terrace or NHC using a pygmy meter at or near the lake outlet weir (Photo 3) as
well as one low flow measurement on Hall Creek. The six measured elevations, shown in Table 1, were
compared to the elevations reported by the sonic water level sensor in order to verify the accuracy of
the sensor. A tabulation of this comparison is found in Table 2 and is illustrated graphically in Figure 6.
As expected, the sonic sensor reading closely tracks the observed elevations at low lake stages. As the
lake level increases, the water surface recorded by the sonic sensor is higher than the measured water
surface at the weir because the sonic sensor is located 115 feet upstream of the control structure.
Lake Ballinger Watershed Modeling
2
3 Model Development
Two models were developed to simulate the water surface elevation on Lake Ballinger and to assess the
influence of the control structure on the water levels. While both models were necessary for this
investigation, their application evolved as the project progressed. As envisioned at the project onset, a
hydrologic model of the watershed upstream of the lake would be constructed and used only to
generate inflows to the hydraulic model. A hydraulic model would encompass Hall Creek, Lake Ballinger,
and McAleer Creek as far as Interstate-5 and would be run for the full record of continuous inflows. This
application of the models was considered the best method to replicate any hydrodynamics associated
with raising and lowering of the outlet weir crest according to the operations manual and also to
evaluate alternatives to mitigate lake flooding by modifying the weir operations. This modeling
sequence had the added advantage of using the graphical interface in HEC-RAS when calibrating the
model.
However, stability issues associated with the long term simulation in the hydraulic model that could not
be resolved within the constraints of the project necessitated changing the modeling approach. The
revised approach involved modifying the hydrologic model to route the simulated runoff into and
through Lake Ballinger, leveraging the hydraulic model to construct several pivotal flow routing tables.
This modeling sequence had the advantage of being more numerically stable with considerably shorter
computation time, which allowed a large number of scenarios to be evaluated during calibration.
3.1 Modeled Scenarios
The primary purpose of this investigation was to evaluate lake level response to the outlet control
structure. Once identified, alternatives to reduce the frequency of flooding on Lake Ballinger could be
similarly investigated. To accomplish this, the following three conditions were simulated using the
numeric models.



Existing Conditions: This scenario represents the water conveyance system in the years prior to
July 2013 when the first culvert downstream of the outlet control structure was replaced with a
precast concrete bridge. The now-removed culvert acted as a downstream control at higher lake
levels. Note that the nomenclature “existing conditions” is somewhat misleading since it does
not represent hydraulic conditions in the system at the time of writing.
With Bridges: This scenario represents the system as if all three culverts in the Nile Golf Course,
sandwiched between Lake Ballinger and Interstate-5, were replaced with bridges with low
chords above the 100-year lake elevation. This scenario is expected to be realized in 2014 when
the remaining two culverts in the golf course are replaced.
With Bridges, No Weir: This is a hypothetical condition whereby the three culverts have been
replaced with the already designed bridges AND the lake outlet control structure has been
completely removed from McAleer Creek. This condition assumes no changes to McAleer Creek
beyond those specified in the culvert replacement drawings. This alternative represents a “best
case” scenario to reduce flooding exacerbated by the control weir.
Lake Ballinger Watershed Modeling
3
3.2 Hydraulic Model
An unsteady hydraulic model was built that encompasses Hall Creek, Lake Ballinger, and McAleer Creek
as far downstream as Interstate-5, as shown in Figure 7. The model was developed using HEC-RAS,
which is a one-dimensional, step-backwater program created by the US Army Corps of Engineers. The
HEC-RAS model was used to generate flow routing tables (FTABLEs) for Hall Creek and, most
importantly, the outlet control structure, that were used in the hydrologic model.
The basis for the hydraulic model was a HEC-RAS model developed for the McAleer Creek Culvert
Replacement and Enhancement Project (NHC 2011b) for the City of Mountlake Terrace. This earlier HECRAS model was extended to include Hall Creek up to Hall Lake, and the McAleer Creek reach was revised
to allow a more flexible representation of the control weir.
The Hall Creek cross sections were cut from 2003 LiDAR as no in-channel survey data was available.
Aside from a 2-foot wide pilot channel, no attempt was made to modify the in-channel profile. The only
hydraulic structure included in this reach is the box culvert under 228th Street SW, which houses the Hall
Creek flow monitor. The channel roughness coefficient for all of Hall Creek was assigned at 0.035, and
the overbank value was set at 0.07.
Hall Creek drains into Lake Ballinger, which is modeled as a storage area in HEC-RAS. The stage-volume
relationship for the lake was borrowed from a prior HSPF model (Clear Creek Solutions 2008). The live
storage portion of the stage-volume relationship was verified against the 2003 LiDAR and found to be
similar.
The McAleer Creek reach, located downstream of Lake Ballinger, is unchanged from the previous model
with the exception of the outlet weir. The outlet weir was converted to an open-air overflow gate and
two smaller gates added to represent the hypolimnetic system and seepage between the stop logs. The
elevation of the overflow gate was seasonally adjusted to the height of the stop logs, shown in Photo 4,
as specified in the Operation and Maintenance Guide (KCM 1984).
In addition to the Existing Conditions hydraulic model, two additional geometries were created to
represent the completed culvert replacement project (labeled With Bridges) and also to represent the
completed culvert replacement project with the outlet weir removed (labeled With Bridges, No Weir).
The With Bridges model was created by replacing the culverts with bridges according to the final project
drawings. The With Bridges, No Weir geometry further modifies the With Bridges geometry by
completely removing the outlet control structure from McAleer Creek. Figure 8 illustrates how the
control structure appears in the hydraulic model for each of the three scenarios. Note that the outlet
control structure, shown in gray, occupies roughly 50% of the channel below elevation 280 feet. With
the control structure removed, there is no constriction through the outlet reach. Figure 9 plots the cross
sections bounding the outlet structure. Therefore, the With Bridges, No Weir geometry represents the
best possible configuration for reducing flood levels that does not involve modifying the channel or
increasing the size of the culvert under Interstate-5.
Lake Ballinger Watershed Modeling
4
3.3 Hydrologic Model
An HSPF rainfall-runoff model was developed, calibrated, and applied to simulate a 65-year record of
flows for the basin. Hydrologic Simulation Program FORTRAN (HSPF) is a sophisticated computer
modeling program that simulates land surface and in-stream hydrologic processes on a continuous
basis. Continuous hydrologic modeling is of particular value in this case because it enables investigation
of the relationship between the water surface in Lake Ballinger and the operation of the outlet control
weir throughout the year, from the dry season to the wet season.
In general, the process of developing the HSPF model included the following steps:





Collection of hydrometeorological (precipitation and evaporation) data for the watershed,
Segmentation of the watershed into smaller modeling subbasins,
Analysis of soils and land use to determine the runoff characteristics of each subbasin,
Estimation of stage-area-volume-discharge relationships for flow routing, and
Determination of appropriate hydrologic response parameters based on available data.
The following sections describe how these steps were accomplished.
3.3.1
Hydrometeorological Data
The hydrologic model used 15-minute precipitation data obtained from two sources: Paine Field in
Everett and Brugger’s Bog in Shoreline. The Everett portion of the record, which was originally prepared
for Snohomish County, extends from 10/1/1948 to 10/1/1991. The rainfall was extended from
10/1/1991 to 5/31/2013 using data from the King County Brugger’s Bog gage (KC 35u). The daily
evaporation time series was obtained from the Puyallup evaporation station and extended through
5/31/2013 using monthly averages. A pan constant of 0.75 was used to convert pan evaporation to
potential evapotranspiration.
3.3.2
Subbasin Delineation
The modeled watershed boundary was provided by Mountlake Terrace and approved by Edmonds. The
boundary was identical to that used by the University of Washington GIS Certificate Program to
investigate and document the total impervious surfaces in the Lake Ballinger watershed. NHC conducted
a cursory review of the boundary using the best available topographic and pipe layers and identified no
issues that merited modifying the boundary. The watershed was divided into nine individual subbasins.
The subbasins were delineated at the outlets of Hall, Echo, and Chase Lakes, at two large detention
facilities (the Top Foods vault in Edmonds and the Ice Arena facility in Mountlake Terrace), where Hall
Creek crossed municipal boundaries, and at the location of the flow recorder on Hall Creek. The nine
subbasins are illustrated in Figure 8. To allow the runoff contribution from each municipality in the basin
to be calculated, the subbasins were further split based on jurisdictional boundaries, resulting in a total
of 23 subbasins.
It should be noted that representation of the drainage downstream of Echo Lake is not entirely accurate.
The western third of subbasin 800 should be routed into subbasin 700 then into Lake Ballinger, while the
portion of subbasin 700 south of N 205th Street should be part of subbasin 800. This inaccuracy was
discovered late in the project, at which point modifying the subbasins was not warranted. For the
purpose of this project, this inaccuracy is not significant because all the water arrives in Lake Ballinger
with minimal detention. However, if flow monitoring data are collected in this portion of the basin in the
future, the subbasin delineation should be revisited.
Lake Ballinger Watershed Modeling
5
3.3.3
Basin Soils and Land Cover
Land surface runoff response is dictated by the extent of impervious surfaces in a watershed and the
nature of the pervious surfaces, in terms of their ability to store and infiltrate precipitation. Soils and
land cover mapping were used to classify different hydrologic response units in the basin.
The soils/surface geology for the drainage basin were digitized from mapping performed by the Pacific
Northwest Center for Geologic Mapping Studies (GeoMapNW) (Booth et al 2004). Figure 9 shows the
soils in the basin are primarily till, with alluvial and outwash pockets in and near the stream corridor.
Total impervious area (TIA) and initial land use GIS layers produced by UW GIS Certificate program
students (King 2012) were provided by Mountlake Terrace. The TIA coverage was developed through an
image analysis of 2009 and 2011 National Agriculture Imagery Program (NAIP) orthophotos, calibrated
against detailed TIA data previously mapped for parts of Mountlake Terrace. Land use categories were
defined from parcel zoning information and aerial photo inspection.
Land cover describes the physical land surface, i.e. the type of vegetation or other surface covering. NHC
developed a basinwide land cover layer from the TIA coverage and aerial photos. Major lakes (Lake
Ballinger, Hall Lake, and Echo Lake) and forested areas were delineated from the 2011 NAIP orthophoto.
Areas not classified as impervious, lake, or forest were mapped as grass. Figure 10 illustrates the land
cover in the basin.
Land use describes the type of development or activities present on the land surface. For purposes of
the HSPF modeling, land use was used to estimate characteristic effective impervious area ratios, i.e. the
percentage of the total impervious surface that is directly connected to a drainage system. Non-effective
impervious surfaces typically run off over pervious surfaces, such as lawns, and their runoff generation is
assumed to be more characteristic of the pervious surface (grass in this case). NHC reviewed the land
use coverage obtained from Mountlake Terrace and made minor modifications based on the 2011 NAIP
orthophoto. The land uses were consolidated into the eight categories shown in Figure 13. Initially each
of these land use categories was assigned an effective impervious area (EIA) factor (shown in Table 3)
based on the Hydrologic Modeling Protocols developed for Snohomish County’s Drainage Needs Report
studies (Snohomish County 2002). The total area, impervious area, and effective impervious area for
each subbasin can be found in Table 4.
3.3.4
Groundwater
Regional groundwater routing has the potential to significantly impact lake levels. A 2008 hydrogeologic
study of the Lake Ballinger watershed was conducted by Golder and Associates. This study reviewed
existing literature on the hydrogeologic conditions in the region and analyzed local precipitation data,
Lake Ballinger water surface elevations, and groundwater elevation data from nearby wells. The study
concluded that Lake Ballinger, Hall Creek, and the lower reaches of McAleer Creek are all discharge
areas for shallow groundwater (Golder 2008). Based on this study, all groundwater generated within the
watershed was assumed to reach the streams and lake.
3.3.5
FTABLEs
HSPF uses user-defined stage-area-volume-discharge relationships, called FTABLEs, to route runoff and
calculate downstream flows. For the Lake Ballinger model, the FTABLEs for all subbasins represent either
storage within lakes, large detention facilities, the storm drainage system, or Hall Creek. Originally,
subbasin runoff was not routed within HSPF but instead extracted for use in the HEC-RAS model.
However, as the project progressed and the modeling sequence evolved, FTABLEs representing storage
within Hall Creek and Lake Ballinger itself were added.
Lake Ballinger Watershed Modeling
6
The Echo and Hall Lake FTABLEs were built using discharges calculated with HY8, which is a simple
culvert analysis program sponsored by the FHWA. The analysis assumes each lake outlet culvert
provides hydraulic control of the lake level. Live storage for each lake was determined using 2003 LiDAR.
The Chase Lake FTABLE was extracted directly from the Snohomish County Chase Lake HSPF model
(Snohomish County 2002).
The two largest detention facilities in the basin, according to records provided by Edmonds and
Mountlake Terrace, are the Top Foods vault in Edmonds and the Ice Arena facility in Mountlake Terrace.
FTABLEs for both were developed from as-built drawings provided by the respective jurisdictions.
FTABLEs representing four reaches of Hall Creek (200, 300, 400, and 500) were developed using the HECRAS model. The remaining upland subbasins were assigned FTABLEs representing the small storage
within the stormwater pipes and swales in the subbasins. Ratings were calculated based on Manning’s
flow equations using the size and average slope of the subbasin to estimate pipe sizes and lengths.
The most pivotal routing table within HSPF is that representing Lake Ballinger. This FTABLE reflects
downstream influence from multiple sources including the outlet structure, culverts including that
underneath Interstate-5, and the hydraulic roughness in McAleer Creek. The stage-volume relationship
for the Lake Ballinger FTABLE was extracted from a previous HSPF model (Clear Creek 2008). The stagedischarge relationship was computed from the HEC-RAS model. The stage-discharge relationship was
modified for the three simulated scenarios: Existing Conditions, With Bridges, and With Bridges, No
Weir. For the Existing Conditions and With Bridges scenarios, stage-discharge relationships were
computed for the seasonal outlet weir settings specified in the Operation and Maintenance Guide (KCM
1984).
Lake Ballinger Watershed Modeling
7
4 Model Calibration
The Existing Conditions models were calibrated to observed data including Lake Ballinger water levels,
continuous discharge and stage records for Hall and McAleer Creeks, and the direct discharges
measured at the outlet control structure. The hydraulic model was calibrated first and then used to
produce FTABLEs embedded into the HSPF model, which was subsequently calibrated.
4.1 Hydraulic Model
The McAleer Creek reach of the Existing Conditions HEC-RAS model was originally calibrated for the
McAleer Creek Culvert Replacement and Enhancement Project (NHC 2011b). Calibration data included
high water marks set during a 2-year flood in March 2011 (Photo 5) as well as the peak lake stage for the
New Year’s Day 1997 flood. The now-extended HEC-RAS model was run with a range of discharges to
evaluate the stage-discharge relationship at the outlet structure. This relationship was compared to the
six observed measurements listed in Table 1. Figure 14 graphically illustrates the agreement between
the observed and modeled data. Many hydraulic parameters were tested in an attempt to more closely
match the observed data, but no combination proved better than the original parameters established
for the Culvert Replacement and Enhancement project.
4.2 Hydrologic Model
The Existing Conditions HSPF model was calibrated to the recorded Hall Creek flows and Lake Ballinger
stages. Calibration proved challenging as the simulated long term volumes were slightly low compared
to observed flows in Hall Creek, but the simulated peak lake levels tended to be high. Significant effort
was expended trying to increase discharge from the lake faster and/or reduce the lake inflow without
significantly reducing the volume passing by the Hall Creek gage, which agreed well with observed data.
Efforts to increase discharges from the lake necessitated modifications to the HEC-RAS model, which
adversely affected the stage-discharge calibration illustrated in Figure 12. Modifications to the HSPF
model to reduce lake inflow proved fruitless as the simulated lake levels were relatively insensitive to
reasonable changes in Hall Creek routing, soil parameters, and/or reduction of inflow from the ungaged
portion of the basin (south of 228th Street SW).
Given the large impervious response in the basin, the primary calibration adjustment was to reduce the
EIA factors shown in Table 3. Reductions were made after reviewing the pipe layers and assuming the
connectivity in the basin is relatively low. The final EIA for each subbasin is listed in Table 4.
Table 5 indicates that the calibrated HSPF model is slightly low, but very reasonable, with respect to
reproducing long term volumes at the Hall Creek gage. Note that at low flows, the observed flow data is
questionable as the velocity sensor becomes less accurate. If these low flows are ignored, agreement
between the modeled and observed data improves (Table 5). In addition to long term volumes, the nine
largest events during the data collection period were examined. Both the peak flows and total volumes
for these events were computed and are shown in Table 6 and Figure 15. The HSPF model simulates
event volumes well and peak flows reasonably. Additional refinement of the storage-discharge
relationships upstream of the Hall Creek gage may improve the simulation of peak flows.
The simulated and observed lake levels for water years 2002 to 2013 are shown in Figure 16. Figure 17
through Figure 28 display the same data but for each water year. A comparison of simulated and
observed peak lake levels from 1981 through 2012 is plotted in Figure 29. The plots indicate that the
model does well at reproducing observed lake levels, though it tends to over-predict peaks in certain
events. The high bias averages 0.14 feet for all peaks shown in Figure 15. If only events with an observed
Lake Ballinger Watershed Modeling
8
stage greater than 279.6 feet are considered, which is the lowest first floor elevation of any home
surrounding the lake, the bias averages +0.09 feet.
Lake Ballinger Watershed Modeling
9
5 Results
Continuous simulation models representing three scenarios (Existing Conditions, With Bridges, and
With Bridges, No Weir) were executed from October 1948 through May 2013 at 15-minute timesteps. A
frequency analysis was conducted on the annual peak lake levels using the method of moments to fit a
Log-Pearson Type III distribution. The frequency plots are displayed on Figure 30 and tabulated in Table
7. The statistics, based on a continuous simulation of 65 years, reaffirm the assertions made in the
McAleer Creek Culvert Replacement and Enhancement Project technical memo (NHC 2011b). The
modeling indicates that:


A reduction in lake stage of approximately 0.5 feet at the 100-year flood level is associated with
replacing the three culverts in the Nile Golf Course with high spanning bridges, and
Completely removing the outlet control structure at the head of McAleer Creek has almost no
influence on flood levels (reduction of 0.1 feet at the 100-year level).
The minimal influence of the outlet weir at flood levels is intuitive considering the weir crest is lowered
to 276.5 feet in the winter and flood levels begin at 279.6 feet (the lowest finished floor elevation of any
home surrounding the lake). When the lake level is at or above this first floor elevation, the weir crest is
overtopped by at least three feet of water and its influence is completely drowned out (Photo 6),
shifting control downstream.
In addition to assessing lake levels, the Existing Conditions model was used to determine the percentage
of total runoff generated from each municipality within the Lake Ballinger watershed. The runoff volume
distribution is shown in Table 8. Note that only the two largest detention facilities in the watershed were
included in the HSPF model. There are numerous smaller flow control facilities in the drainage area that
were not included. These facilities, if operated and maintained properly, will reduce peak flows but will
have minimal impact on lake level, which is driven by runoff volume.
Lake Ballinger Watershed Modeling
10
6 References
Booth Derek, Cox Brett, Troost Kathy, Shimel Scott, January 2004, Composite geologic map of the SnoKing area: University of Washington, Seattle-Area Geologic Mapping Project, scale 1:24,000.
Clear Creek Solutions Inc., 2008, Lake Ballinger Lake Level and Outlet Study, Prepared for the City of
Edmonds.
Golder Associates Inc, December 2008, Hydrogeologic Conditions, Greater Hall Lake, Hall Creek, Chase
Lake, Echo Lake, Lake Ballinger and McAleer Creek Watershed, prepared for Otak Inc.
KCM, March 1984, Lake Ballinger Restoration Project Operation and Maintenance Guide, Prepared for
the City of Mountlake Terrace.
King Quentin, Quinlan Becky, Kilcline Bills Beth, Lottsfedlt Erik, June 2012, Documentation for the GIS
Analysis of the Lake Ballinger Basin Impervious Surface and Land Use, UW GIS Certificate Program
through the Office of Professional and Continuing Education.
NHC, January 2011a, Peer Review of Lake Ballinger Models, prepared for City of Edmonds.
NHC, November 2011b, Hydraulic Modeling of McAleer Creek, prepared for Perteet.
Snohomish County, December 2002, Swamp Creek Drainage Needs Report, Snohomish County.
Lake Ballinger Watershed Modeling
11
Lake Ballinger Lake Level
281.0
Gage knocked down in the December 2007 event. Last wse elevation recorded was not the peak.
280.5
Gage reinstalled, but not calibrated.
280.0
Gage recalibrated during 2009
Elevation [ft NGVD29]
279.5
279.0
278.5
278.0
277.5
277.0
276.5
Hypolimnetic system shut down in December 2008.
276.0
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
Figure 1
Hall Creek Stage Data
7
6
Stage[ft]
5
4
3
2
Sensor Malfunction
1
0
Nov‐11
Feb‐12
May‐12
Aug‐12
Nov‐12
Feb‐13
May‐13
Aug‐13
Feb‐13
May‐13
Aug‐13
Figure 2
Hall Creek Flow Data
250
Flow [cfs]
200
150
100
50
0
Nov‐11
Sensor Malfunction
Feb‐12
May‐12
Aug‐12
Nov‐12
McAleer Creek Stage Data
4
Stage [ft]
3
2
Power Supply Problems
1
0
Nov‐11
Feb‐12
May‐12
Aug‐12
Nov‐12
Feb‐13
May‐13
Aug‐13
Feb‐13
May‐13
Aug‐13
Figure 3
Flow [cfs]
McAleer Creek Flow Data
40
35
30
25
20
15
10
5
0
‐5
‐10
Nov‐11
Power Supply Problems
Feb‐12
May‐12
Aug‐12
Nov‐12
Hall Creek Scatter Plot
10
8
Depth [ft]
6
4
2
0
0
1
2
3
4
5
Velocity [ft/s]
6
7
8
9
Figure 4
10
McAleer Creek Scatter Plot
4
Depth [ft]
3
2
1
0
‐1
‐0.5
0
0.5
1
1.5
Velocity [ft/s]
2
2.5
3
3.5
Figure 5
Difference Between Observed Weir WSE and Gaged Lake WSE
0.4
0.3
Observed Weir wse ‐ Gaged Lake wse
Elevation Difference [ft]
0.2
0.1
0
‐0.1
‐0.2
‐0.3
276
276.5
277
277.5
278
Lake Gage WSE [ft]
278.5
279
279.5
280
Figure 6
Lynnwood
200
Edmonds
100
300
350
450
600
Esperance (Snohomish County)
500
450
400
Mountlake Terrace
700
800
Shoreline
Legend
900
WA Reference Map
Lake Ballinger Watershed Modeling
HEC RAS Model
Jurisdictional Boundaries
HSPF Subbasins
RAS XS
RAS Streamline
Scale - 1:36,000
1,800 900
0
1,800
3,600 Feet
Storage Areas
Northwest Hydraulic Consultants
project no. 200101
Ü
21-Aug-2013
Figure 7
Model Cross Section with and without Outlet Control Structure
Cross Section with Outlet Control Structure Existing Conditions and With Bridges
Cross Section with Outlet Control Structure Removed With Bridges, No Weir
Figure 8
Comparison of Model Cross Sections from the Lake Outlet to the First Bridge
290
288
Elevation [ft]
286
284
282
Lake Outlet
280
US Outlet Control Structure
278
DS Outlet Control Structure
276
US Bridge
274
0
20
40
60
Station [ft]
80
100
120
Figure 9
Lynnwood
200
Edmonds
Sc
r ib
Cr
er
ee
k
ls
100
ek
H
al
300
C re
350
450
Mountlake Terrace
kW
ee
es
t
400
Cr
500
on
Esperance (Snohomish County)
450
Ly
600
l ee r
Cr e
Cr
Lyon
C
ek
r eek
M cA
L y on
W
700
Lyon Creek West
reek
nC
t
ee
kE
as
t
Lyo
es
800
Shoreline
Legend
900
Subbasin ID
Subbasin DescriptionMountlake
100
Contributes to Hall Lake
Delineated to where Hall Creek crosses boundary
between Lynnwood and Mountlake Terrace
200
300
Intermediate subbasin
350
Contributes to Top Foods Detention Facility
400
Delineated to Hall Creek Gage
450
Contributes to Ice Arena Detention Facility
500
Delineated to the mouth of Hall Creek
600
Contributes to Chase Lake
700
Contributes Local runoff to Lake Ballinger
Delineated to where main stormwater line crosses
800
boundary between Shoreline and Edmonds
900
Contributes to Echo Lake
WA Reference Map
Lake Ballinger Watershed Modeling
HSPF Subbasins
Streams
Jurisdictional Boundaries
HSPF Subbasins
Scale - 1:36,000
1,750 875
0
1,750
Northwest Hydraulic Consultants
3,500 Feet
project no. 200101
Ü
21-Aug-2013
Figure 10
Lynnwood
200
Edmonds
Sc
rib
Cr
er
k
ee
l ls
Ha
300
Cre
100
ek
350
450
500
400
Mountlake Terrace
t
es
kW
ee
Cr
Esperance (Snohomish County)
450
on
Ly
600
Cr e
ek
902
M cA
lee r
ek
re
Lyon
Cre e
k
700
t
Ly on
C
reek W
Lyon Creek West
nC
Ea
st
Lyo
es
800
901
Shoreline
900
WA Reference Map
Legend
Streams
HSPF Subbasins
Jurisdictional Boundaries
Soils
Lake Ballinger Watershed Modeling
HSPF Soils
Custer-Norma
Outwash
Till
Scale - 1:36,000
1,800 900
0
1,800
Northwest Hydraulic Consultants
3,600 Feet
project no. 200101
Ü
21-Aug-2013
Figure 11
Lynnwood
200
Edmonds
Sc
rib
Cr
er
k
ee
l ls
Ha
300
Cre
100
ek
350
450
500
400
Mountlake Terrace
t
es
kW
ee
Cr
Esperance (Snohomish County)
450
on
Ly
600
ek
re
Lyon
Cre e
k
Cr e
ek
902
M cA
lee r
Ly on
C
reek W
700
t
Lyon Creek West
nC
Ea
st
Lyo
es
800
901
Shoreline
Legend
Streams
900
WA Reference Map
Lake Ballinger Watershed Modeling
HSPF Land Cover
HSPF Subbasins
Jurisdictional Boundaries
Land Cover
Forest
Grass
Scale - 1:36,000
1,800 900
0
1,800
3,600 Feet
Impervious
Water
Northwest Hydraulic Consultants
project no. 200101
Ü
21-Aug-2013
Figure 12
Lynnwood
200
Edmonds
Sc
rib
Cr
er
k
ee
l ls
Ha
300
Cre
100
ek
350
450
500
400
Mountlake Terrace
t
es
kW
ee
Cr
Esperance (Snohomish County)
450
on
Ly
600
ek
re
Lyon
Cre e
k
Cr e
ek
902
M cA
lee r
Ly on
C
reek W
700
t
Lyon Creek West
nC
Ea
st
Lyo
es
800
901
Shoreline
Legend
Streams
900
Land Use
HSPF Subbasins
Manufacturing and Commercial
Jurisdictional Boundaries
Residential, 1-4 units
WA Reference Map
Lake Ballinger Watershed Modeling
HSPF Land Use
Residential, 5 plus units
Transportation
Schools
Parks, Rec, Churches & Cemeteries
Scale - 1:36,000
Undeveloped
Water
1,800 900
0
1,800
Northwest Hydraulic Consultants
3,600 Feet
project no. 200101
Ü
21-Aug-2013
Figure 13
Comparison of Observed and Simulated Flows at McAleer Creek Outlet Weir 100
90
Measured Flow
HEC RAS Flow
Flow at Outlet Weir [cfs]
80
70
60
50
40
30
20
10
0
276.0
276.5
277.0
277.5
278.0
278.5
279.0
WSE at Outlet Weir [ft NGVD29]
279.5
280.0
280.5
281.0
Figure 14
Hall Creek Observed and Simulated Flow
November 27 ‐ December 7 2012
Simulated
3/17/12
3/21/12
200
180
160
140
120
100
80
60
40
20
0
3/27/12
Observed
Simulated
3/31/12
4/04/12
Observed
Simulated
11/18/12
11/20/12
11/22/12
12/05/12
200
180
160
140
120
100
80
60
40
20
0
12/15/12
Observed
Simulated
12/19/12
200
180
160
140
120
100
80
60
40
20
0
12/23/12
12/23/12
Simulated
12/31/12
Simulated
1/09/13
1/11/13
1/13/13
200
180
160
140
120
100
80
60
40
20
0
1/23/13
Observed
Simulated
1/26/13
1/29/13
2/01/13
2/04/13
April 4 ‐ April 9 2013
Observed
12/27/12
Observed
January 23 ‐ February 3 2013
December 23 ‐ December 30 2012
Flow [cfs]
Flow [cfs]
November 16 ‐ November 22 2012
200
180
160
140
120
100
80
60
40
20
0
11/16/12
12/01/12
200
180
160
140
120
100
80
60
40
20
0
1/07/13
December 15 ‐ December 23 2012
Flow [cfs]
Flow [cfs]
March 25 ‐ April 6 2012
Simulated
Flow [cfs]
3/13/12
Observed
Flow [cfs]
Observed
200
180
160
140
120
100
80
60
40
20
0
11/27/12
January 7 ‐ January 12 2013
Flow [cfs]
200
180
160
140
120
100
80
60
40
20
0
3/09/12
Flow [cfs]
Flow [cfs]
March 9 ‐ March 23 2012
200
180
160
140
120
100
80
60
40
20
0
04/04/13
Observed
Simulated
04/06/13
04/08/13
04/10/13
Figure 15
Simulated and Observed Lake Water Surface Elevation
282.0
281.5
281.0
Gage knocked down in the December 2007 event. Last wse elevation recorded was not the peak.
Gage reinstalled, but not calibrated.
Elevation [ft NGVD29]
280.5
Gage recalibrated during 2009
280.0
279.5
279.0
Observed
Simulated
278.5
278.0
277.5
277.0
276.5
Hypolimnetic system shut down in December 2008.
276.0
Figure 16
Simulated and Observed Lake Water Surface Elevation
WY 2002
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 17
Simulated and Observed Lake Water Surface Elevation
WY 2003
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 18
Simulated and Observed Lake Water Surface Elevation
WY 2004
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 19
Simulated and Observed Lake Water Surface Elevation
WY 2005
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 20
Simulated and Observed Lake Water Surface Elevation
WY 2006
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 21
Simulated and Observed Lake Water Surface Elevation
WY 2007
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 22
Simulated and Observed Lake Water Surface Elevation
WY 2008
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 23
Simulated and Observed Lake Water Surface Elevation
WY 2009
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 24
Simulated and Observed Lake Water Surface Elevation
WY 2010
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 25
Simulated and Observed Lake Water Surface Elevation
WY 2011
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 26
Simulated and Observed Lake Water Surface Elevation
WY 2012
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 27
Simulated and Observed Lake Water Surface Elevation
WY 2013
282.0
281.5
281.0
280.5
WSE [ft NGVD29]
280.0
279.5
279.0
Observed
278.5
Simulated
278.0
277.5
277.0
276.5
276.0
Figure 28
281.0
20‐Dec‐12
21‐Nov‐12
31‐Oct‐12
13‐Dec‐10
15‐Jan‐10
22‐Nov‐09
3‐Apr‐09
8‐Jan‐09
4‐Dec‐07
27‐Dec‐06
15‐Dec‐06
22‐Nov‐06
13‐Nov‐06
30‐Jan‐06
6‐Jan‐06
6‐Nov‐05
11‐Dec‐04
30‐Jan‐04
19‐Nov‐03
21‐Oct‐03
16‐Dec‐02
28‐Jan‐02
8‐Jan‐02
17‐Dec‐01
1‐Dec‐01
23‐Nov‐01
15‐Nov‐01
2‐Jan‐97
15‐Sep‐96
24‐Apr‐96
9‐Feb‐96
11‐Dec‐95
20‐Dec‐94
10‐Dec‐93
31‐Jan‐92
5‐Mar‐91
5‐Feb‐91
4‐Dec‐90
25‐Nov‐90
5‐Oct‐90
6‐Dec‐87
4‐Mar‐87
19‐Jan‐86
20‐Nov‐83
277.0
Gage stopped functioning during Dec 2007 event. Observed value may not be peak.
281.5
Simulated
282.0
MLT Gage
282.5
These events were preceded by significant snowfall. How the snow melt is distributed can have a significant effect on the simulated peak.
280.5
280.0
279.5
279.0
278.5
Lake Level in ft [NGVD 29]
Comparison of Selected Large Peak Stages on Lake Ballinger
283.0
278.0
277.5
Figure 29
Annual Peak Frequency Analysis. 1 hour fixed window average.
Fit Type:Log Pearson III distribution using the method of Moments, Hosking Plotting Position
283.
Ret Period(years)-->
2
5
10
Existing Conditions
/LAKE
BALLINGER/SB 710/STAGE//15MIN/HSPF-CUR/
/LAKE
BALLINGER/SB 710/STAGE//15MIN/HSPF-CUR/
With Bridges
/LAKE
BALLINGER/SB
With Bridges,
No Weir710/STAGE//15MIN/HSPF-CUR/
25
100
500
1
0.2
Jan 2 1997
282.
Dec 4 2007
Jan 19 1986
281.
280.
279.
278.
277.
99
96
90
80
50
20
Percent Chance Exceedance
10
4
Figure 30
Table 1 Manual WSE and Flow Measurements on McAleer Creek
Date and Time
Observed WSE
Observed Flow
Location
[ft]
[cfs]
3/10/11 15:15
278.70
25.5
Outlet Weir
3/14/11 13:15
279.70
56.0
Outlet Weir
11/22/11 13:53
278.40
14.7
Outlet Weir
11/22/11 14:15
NA
17.0
~30 ft Upstream of Weir
11/22/11 14:55
278.40
14.8
Outlet Weir
11/23/11 15:28
279.90
59.8
Outlet Weir
5/1/13 17:00
276.90
3.0
Outlet Weir
Table 2 Comparison of Lake Level Gage Data and Observed Measurements
Date and Time
Observed WSE
Gage WSE
Elevation Difference
[ft]
[ft]
[ft]
276.831)
276.77
0.06
277.09
1)
277.04
0.05
276.65
1)
276.60
0.05
276.75
1)
276.72
0.03
278.40
2)
278.45
-0.05
279.40
2)
279.65
-0.25
278.10
2)
278.09
-0.01
278.10
2)
278.13
-0.03
279.60
2)
279.76
-0.16
10/18/2011
11/4/2011
11/16/2011
12/13/2011
3/10/11 15:15
3/14/11 13:15
11/22/11 13:53
11/22/11 14:55
11/23/11 15:28
1) Observed WSE calculated using measure down from top of aluminum weir gate (279.8) to water
surface.
2) Observed WSE calculated using measure down from water surface to sill at outlet weir (276.5).
Lake Ballinger Watershed Modeling
Table 3 Effective Impervious Area Factors
Land use
Initial EIA Factor
Calibrated EIA Factor
[%]
[%]
Manufacturing and Commercial
95
95
Residential 1-4 Units
40
20
Residential 5 plus Units
80
40
Transportation
95
60
Schools
80
40
Parks, Rec, Churches & Cemeteries
80
40
Undeveloped
80
30
Table 4 Subbasin Area, Impervious Area, and Effective Impervious Area
Area
Subbasin
[ac]
Total
Impervious
Area
Effective
Impervious
Area
[ac]
[ac]
Percentage
of Effective
Impervious
Area
100
341.5
133.8
66.2
19.4%
200
385.9
214.7
143.8
37.3%
300
704.7
368.1
242.8
34.5%
350
10.2
8.3
7.9
77.0%
400
103.6
41.4
24.0
23.1%
450
11.7
6.5
2.4
20.9%
500
402.9
171.1
88.7
22.0%
600
127.4
43.6
15.2
11.9%
700
659.4
231.5
128.9
19.6%
800
265.1
92.9
40.6
15.3%
900
216.2
109.9
60.8
28.1%
Table 5 Hall Creek Long Term Volumes
Total Volume
%Diff
[ac-ft]
OBS
4873
SIM
4309
Lake Ballinger Watershed Modeling
Volume Above 5 cfs
%Diff
[ac-ft]
-11.6%
3738
3403
-9.0%
Table 6 Hall Creek Observed Versus Simulated Peaks and Volumes
Date
Peak Flow
[cfs]
March 9 - 23 2012
March 25 - April 6 2012
Nov 16 - Nov 22 2012
Nov 27 -Dec 7 2012
Dec 15 - Dec 23 2012
Dec 24 - Dec 30 2012
Jan 7 - Jan 12 2013
Jan 23 - Feb 3 2013
Apr 4 - Apr 9 2013
OBS
SIM
OBS
SIM
OBS
SIM
OBS
SIM
OBS
SIM
OBS
SIM
OBS
SIM
OBS
SIM
OBS
59.3
57.4
56.7
55.7
182.7
168.2
90.9
100.0
92.0
74.3
62.6
38.2
74.0
73.1
57.7
47.0
65.6
SIM
89.8
% Diff
-3.1%
-1.7%
-7.9%
10.0%
-19.2%
-39.0%
-1.1%
-18.5%
36.9%
Volume
[ac-ft]
350.0
290.2
248.2
201.3
355.3
398.6
340.5
362.9
412.5
357.1
209.3
159.2
192.4
201.5
258.6
224.7
122.6
170.3
% Diff
-17.1%
-18.9%
12.2%
6.6%
-13.4%
-24.0%
4.7%
-13.1%
38.9%
Table 7 Lake Level Frequency Analysis
Water Surface Elevation
[ft]
Return Period
[yr]
Existing Conditions
Bridges and Weir
Bridges no Weir
2
279.2
279.0
278.9
10
280.4
280.1
279.9
50
281.5
281.1
281.0
100
282.0
281.5
281.4
Lake Ballinger Watershed Modeling
Table 8 Percentage of Total Runoff Volume and Total Area from Each Jurisdiction
Jurisdiction
Area
% of Total Area
Volume
% of Total Volume
[ac-ft]
Lynnwood
699
22%
84044
23%
Mountlake Terrace
821
25%
85641
23%
Edmonds
793
25%
92241
25%
Snohomish County
264
8%
29972
8%
Shoreline
653
20%
73736
20%
Lake Ballinger Watershed Modeling
Photo 1 Downward looking sonic meter located at head of McAleer Creek and operated by the City of
Mountlake Terrace.
Photo 2 First culvert downstream of the lake outlet control weir. This culvert was replaced with a
bridge in July 2013.
Lake Ballinger Watershed Modeling
Photo 3 Discharge measurement at the control weir on March 10, 2011.
Photo 4 Lake outlet control weir during the summer, with stop logs exposed.
Lake Ballinger Watershed Modeling
Photo 5 Setting high water marks on McAleer Creek on March 14, 2011. These HWMs were used for
model calibration.
Photo 6 The lake outlet weir influence shown being drowned out on March 14, 2011. The water surface
elevation at the weir is 279.4 feet (NGVD29), which is just greater than a 2-year flood on Lake Ballinger.
Lake Ballinger Watershed Modeling