Stream Dissolved Oxygen Improvement Feasibility Study for Salt Creek%3A Final Report

              DUPAGE RIVER SALT CREEK WORKGROUP
STREAM DISSOLVED OXYGEN
IMPROVEMENT FEASIBILITY STUDY
FOR SALT CREEK
FINAL REPORT
SEPTMEBER 2009
Prepared by:
HDR Engineering, Inc.
8550 W. Bryn Mawr Ave., Suite 900
Chicago, IL 60603
Job No. 31566
In Association with:
DO Improvement Feasibility Study
Salt Creek Executive Summary
DRSCW i September 2009
Executive Summary
In October 2004, the Illinois Environmental Protection Agency (Illinois EPA) issued a
completed Total Maximum Daily Load (TMDL) Study for Salt Creek. From this study, the
Illinois EPA developed TMDL allocations for various pollutants. The report concluded that
significant reductions in biochemical oxygen demand (BOD) and ammonia would be necessary
in order for the Illinois Dissolved Oxygen (DO) standards to be achieved in Salt Creek during
low-flow, warm conditions, and that the potential removal of one or more existing dams along
lower Salt Creek could offer significant water quality improvements.
Since the publication of the TMDL report, affected communities, municipal wastewater
treatment plant operators, and interested environmental organizations have joined together to
form the DuPage River Salt Creek Workgroup (DRSCW). The mission of the DRSCW is to
study the East and West Branches DuPage River and Salt Creek watersheds in order to gain a
better understanding of environmental impairments that are leading to poor water quality and
impacting aquatic life. The initial focus of the DRSCW, for this project, was to develop a
computer model that would accurately reflect low-flow, warm stream conditions, particularly
DO, along Salt Creek, from which alternatives for improving DO concentrations could be
developed. While working on this task it became apparent that better environmental monitoring
data were needed. At this point the focus of the Workgroup expanded to include design and
implementation of water quality monitoring studies that would generate sound scientific data.
Salt Creek is a highly disturbed urban stream with low channel gradients and extensive
channelization. The portion of lower Salt Creek assessed for this report spans approximately 12
stream miles (19 km), from above the Addison North Wastewater Treatment Plant which is
located at River Mile 22.6 (36.2 km), to the Graue Mill Dam located at River Mile 10.7 (17.1
km). Along this stretch of lower Salt Creek there are three principle existing dams:
Name of Dam
River
Mile
(km)
Bounding Bridges
Nearest
Upstream Downstream Town
Oak Meadows Golf Course
22.9
(36.8)
Elizabeth Dr I-290 Wood Dale
Old Oakbrook
12.5
(20.1)
Oak Brook Rd /
31st St
Fullersburg Woods
Foot Bridge
Oak Brook
Graue Mill
10.7
(17.2)
Fullersburg Woods
Foot Bridge
York Road Hinsdale
Located along and upstream of the study area are seven municipal wastewater treatment plants,
starting at the MWRDGC John Egan Plant at River Mile 29.6 (47.6 km) and extending
downstream to the Elmhurst WWTP at River Mile 17.8 (28.6 km).
DRSCW ii September 2009
Based on two years of continuous DO monitoring, the DO above the Graue Mill Dam (within the
Fullersburg Woods Impoundment) is the lowest on Salt Creek during low flow steady state
conditions. Sediment Oxygen Demand (SOD) results within the Fullersburg Woods
Impoundment are elevated from the quantities of sediment that have accumulated behind the
dam and by the increase in the channel’s wetted perimeter caused by the widening of the channel
in the impoundment. Concurrent with these DO studies, the Workgroup also completed
biological studies on Salt Creek which found that the Graue Mill Dam is acting as a physical
barrier to fish migration, and that habitat quality on in the upstream impoundment was some of
the poorest on the main stem of the river. Related parameters of fish and macro-invertebrate
quality were also significantly degraded above the dam and the stream never fully recovers
upstream.
Since 2005, the DRSCW has conducted extensive monitoring of Salt Creek in order to develop
additional data to support a water quality model on Salt Creek. The model utilized, the QUAL2K
model, includes the capability of diurnally varying headwater / meteorological input data and a
full sediment diagenesis model to compute SOD and nutrient fluxes from the bottom sediment to
the water column. In addition, the QUAL2K model offers options for decay functions of water
quality constituents, re-aeration rate equations, heat exchange, and photo-synthetically available
solar-radiation calculations.
Enhanced model input data were obtained for factors such as headwaters and tributaries, river
distances, model geometry, meteorological data, decay rates, background light extinction, point
sources, temperature, and stream flow. Also, recent DO measurement data were utilized from
the continuous DO monitoring as well as several days of monitoring in 2005. SOD
measurements were conducted on Salt Creek in 2006 and 2007 to provide input data by reach
into the QUAL2K model.
Under low stream flow conditions, the contribution from the point source discharges to Salt
Creek collectively account for 46% of the total flow at the model’s downstream boundary. To
calibrate the model August 2, 2007 data were utilized. Temperatures ranged from 23 to 31oC on
this date, and the stream flow was essentially at low flow conditions. Overall, the model
reasonably predicts the diurnal change in DO.
To verify the model will accurately predict DO changes under varying conditions, the model was
tested for the conditions that existed on June 20, 2006. Overall, the measured minimum DO
levels were lower than the model predicted; however, the results were within acceptable ranges.
Sensitivity runs were completed for changes in SOD and changes in the re-aeration constants.
Both of these variables have a significant impact on the predicted DO values; however, such
changes did not improve the overall model.
Under the Illinois Pollution Control Board’s regulations, DO water quality standards are to be
achieved at all times. Therefore, alternatives need to be evaluated under the most severe
conditions. For a variety of reasons, minimum DO levels occur during the high temperature
extremes. As water temperature increases the amount of dissolved oxygen that the water can
hold decreases resulting in losing oxygen to the atmosphere during periods of photosynthesis
when supersaturation conditions occur. In addition, respiration increases (both in the water
DRSCW iii September 2009
column and in the sediment) with warmer temperatures. From a review of historical temperature
data, Salt Creek can reach temperatures approximately 3oC above the levels recorded in July and
August 2005. This higher stream temperature and low flow along with the average summer
CBOD5 and ammonia discharged from the seven wastewater treatment plants during the summer
of 2005 were used as the baseline worst case scenario. Consistent with the monitoring results,
under the baseline conditions the model predicts that the pool areas created by the dams are the
areas where DO concentrations will be the lowest. In order of priority the lowest DO is
predicted occurs above the Graue Mill Dam, then the Oak Meadows Dam, followed by the pool
at Butterfield Road. Above the Old Oak Brook Dam, the minimum DO predicted was not as
severe.
Significant enhancement of the DO and overall water quality of lower Salt Creek can be
accomplished via the removal/bridging of the low-head dams in the study area. These dams
inhibit the natural linear flow of energy and impede sediment transport, fish migration, feeding
and breeding, macro-invertebrate drift, and downstream nutrient spiraling. With respect to DO,
these low-head dams create impoundments that concentrate sediment and organic material
upstream which actively respires, removing dissolved oxygen from the water. In addition, they
slow the velocity of the water, allowing additional time for the creek water to absorb solar
energy and increase in temperature. This effect is further exacerbated by the increased stream
width created by the impoundment, thereby limiting the extent of riparian shade that can counter
the effect of solar heating.
With respect to the dams along Salt Creek, two options were investigated for this study;
complete removal and partial breaching/bridging. These options are being driven by the primary
design objective of improving the DO content of the stream and a secondary objective to re-establish
biological connectivity, mainly in the form of faunal passage. The social-cultural
characteristics of a dam must be weighed against any modifications to the structure or
impoundment.
Partial breaching involves removing just enough of the structure to allow unimpeded flow except
for during the larger storm events. Under this scenario the impoundment is drained and a free
flowing river restored. The basic concept of bridging is to build a ramp of large rock leading up
to the downstream face of the dam, effectively “bridging” the dam and restoring upstream-downstream
fish passage and possibly canoe passage as well. Common variations of this include
lowering the dam crest in order to decrease the vertical elevation that must be made up
downstream and to reduce the impoundment on the upstream side of the dam. In addition,
notching the dam crest to concentrate flow in the center of the channel is also common. Bridging
also provides interstitial habitat for macro-invertebrates and can also preserve a degree of
elevated water surface upstream.
The characterization and understanding of reservoir sediments is a significant factor (cost)
governing dam removal. In the early 1990s, the sediment above the Graue Mill Dam was
removed and was not deemed contaminated, so it is reasonable to assume that would still be the
case today.
DRSCW iv September 2009
Quantifying the flood impact of any project on the dams being studied is also necessary. As the
dams on Salt Creek are low head dams, that are operated full, there will be little impact on the
floodplain, either upstream or downstream.
Mechanical stream aeration is another option for improving DO levels in critical reaches of a
stream. Available technologies can be divided into three categories: Air-Based Alternatives,
High-Purity Oxygen Alternatives, and Side-Stream Alternatives, each of which can be further
broken down by options. The lowest DO levels on Salt Creek occur within the impoundment
above the Graue Mill Dam. Low DO values have also been noted near Butterfield Road;
however, at this location the stream channel has been excessively widened and low DO periods
could be corrected by restoring the natural channel through this area. In addition, limited DO
data immediately above the Oak Meadows dam indicates that lower DO levels also occur in this
stretch, and the modeling results are consistent with these observations. From a priority
perspective, the lowest DO reach should be addressed first, which is the Fullersburg
Impoundment above the Graue Mill Dam.
The quiescent conditions within the Fullersburg Impoundment are ideal for operating oxygen
systems, as supersaturated DO levels can be readily achieved with minimal loss to the
atmosphere within the impoundment. Side-stream air systems are also possible, but will require
pumping rates that will approach the daily flow in Salt Creek, and elevated SOD within the
impoundment will necessitate more than one side-stream to maintain the desired DO level above
5.0 mg/L. Bubble diffusers laid parallel to the flow within the impoundment would also be a
viable option; however, increased maintenance to maintain the diffuser hoses above the silt after
high-flow periods will be necessary. Surface aerators are not recommended, from an aesthetic
perspective as well as from a maintenance perspective. In all cases, the operation of aeration
devices is needed during the evening hours because when photosynthesis begins in the morning,
DO levels rise above 5.0 mg/L until the early evening hours, when the supplemental aeration
would be restarted. Unlike a dam removal/bridging project, which is basically a one-time cost
for removal/modification, in-stream aeration will require funding in perpetuity. Such an
operation would not improve the existing impediment to fish passage or remove the severe
impairment to aquatic habitat identified at the site.
Using the Baseline Conditions model, various scenarios were evaluated to see what benefits
would occur from various alternatives. Alternative 1 removed all of the pollutant loading from
the seven wastewater treatment plants along Salt Creek. Even with the removal of all of the
pollutants originating from the point source (BOD and ammonia), Salt Creek was unable to
achieve the DO water quality standards of 5.0 mg/L upstream of any of the three dams. Once
again no habitat improvement would accompany such a program.
Alternative 2 modeled removal of the Oak Meadows Dam and partial breaching of the Graue
Mill Dam by 1 foot, 2 feet and 3 feet. Breaching (lowering) the Graue Mill Dam height by 2 feet
is predicted to result in achieving DO water quality standards under the Baseline Conditions, and
lowering the water elevation 3 ft would provide an additional margin of error in the predicted
minimum DO levels. Above the Oak Meadows Dam, the DO improvement was only predicted
to extend less than 1 mile (1.6 km). However, the confidence in the model inputs for the area
above the Oak Meadows Dam are lower than elsewhere on Salt Creek, and additional DO
DRSCW v September 2009
monitoring and recent improvements in the upstream wastewater treatment plant (Itasca) are
expected to result in further DO improvements above the Oak Meadows Dam.
Alternative 3 evaluated in-stream aeration using air-based technology at discreet locations just
upstream of the Oak Meadows and Graue Mill Dams. The model predicts that at each location
two aeration stations will be required to achieve the minimum DO standards above each dam.
Again, at Oak Meadows, there is some uncertainty that with the recent upgrade at the nearest
upstream wastewater treatment plant and the current DO monitoring data, whether one in-stream
aeration station would be sufficient.
Alternative 4 evaluated the use of high-purity oxygen aeration involving the injection of oxygen
above the same two dams. A system of this type can readily supersaturate creek DO levels to
150%. The model predicts that this effort can maintain DO levels above the state water quality
standards for reaches of up to 2.5 miles (4 km) above the Oak Meadows Dam and 1.25 miles (2
km) above the Graue Mill Dam. This achievement would result in the need for only one station
at each location.
Factoring in the capital and operating costs, the net present value for each of the four alternatives
was computed and is presented below for each location (OM-Oak Meadows Dam and GM-Graue
Mill Dam):
Option Net Present Value Comment Fish
Passage/Habitat
Improvement
1 Eliminate Point
Source Pollutants
> $388,000,000 DO above Graue Mill Dam
continues to drop to 3.8 mg/L
No
2 Oak Meadows
Dam Removal
and
Bridging/Partial
breach at Graue
Mill
OM-$250,000
GM-$800,000 to
$1,100,000
Need to verify above Oak
Meadows DO will not drop below
5.0 mg/L
Yes
3 Air based In-stream
Aeration
OM-$1,190,000
GM-$2,050,000
Need to verify above Oak
Meadows DO will remain above
5.0 mg/L with one aeration system
No
4 High purity
Oxygen Addition
OM-$1,410,000
GM-$1,710,000
Need to verify above Oak
Meadows will remain above 5.0
mg/L with one oxygen system
No
Dam removal at Oak Meadows is the low cost option, and has the added benefit of
improvements in the biological community above the dam. However, additional verification is
DRSCW vi September 2009
necessary to demonstrate that the DO above this dam will achieve the water quality standard
given the recent upgrade in the closest wastewater treatment plant.
Bridging or partial breach at Graue Mill is part of the low cost option at this location. However,
the historical value of the Graue Mill Dam must also be factored into the ultimate selected
remedy. The net present value (cost) estimate for the bridging/partial breach includes
consideration of maintaining historical aspects of the dam.
vii
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................ i
1. PROJECT BACKGROUND AND GOALS .................................................................. 1-1
1.1 Project Goal ........................................................................................................ 1-1
1.2 Water Quality Standards ..................................................................................... 1-3
2. EXISTING CONDITIONS ............................................................................................. 2-1
2.1 Geomorphic Assessments ................................................................................... 2-1
2.1.1 Channel Evolution .................................................................................. 2-2
2.1.2 Bank Erosion ........................................................................................... 2-3
2.1.3 Sediment Transport ................................................................................. 2-4
2.2 Stream Characterization ...................................................................................... 2-5
2.3 Flow Data ............................................................................................................ 2-7
2.4 Reach Descriptions ............................................................................................. 2-8
2.5 Habitat Summary .............................................................................................. 2-12
2.6 Dam Site Investigations .................................................................................... 2-13
2.6.1 Oak Meadows Golf Course Dam .......................................................... 2-14
2.6.2 Old Oak Brook Dam ............................................................................. 2-17
2.6.3 Graue Mill Dam .................................................................................... 2-19
2.7 Flood Control Reservoirs .................................................................................. 2-21
2.8 Sediment Oxygen Demand (SOD) Field Measurements .................................. 2-22
2.9 Continuous Dissolved Oxygen Monitoring ...................................................... 2-23
2.10 Biological and Phosphorus Quality .................................................................. 2-26
2.11 Summary ........................................................................................................... 2-28
3. WATER QUALITY MODELING ................................................................................. 3-1
3.1 Conversion of QUAL2E to QUAL2K Model ..................................................... 3-1
3.2 Validation of QUAL2K Model ........................................................................... 3-1
3.2.1 Model Inputs ........................................................................................... 3-2
3.2.2 Calibration and Verification of the Model .............................................. 3-9
3.2.3 Sensitivity Analysis .............................................................................. 3-11
3.2.4 Baseline Model ..................................................................................... 3-11
4. SCREENING FOR DAMS ............................................................................................. 4-1
4.1 Complete Removal.............................................................................................. 4-1
4.2 Partial Breach or Notching.................................................................................. 4-2
4.3 Bridging .............................................................................................................. 4-2
4.4 Issues Common to All Dams .............................................................................. 4-3
4.4.1 Permitting ................................................................................................ 4-3
4.4.2 Reservoir Sediment ................................................................................. 4-4
4.4.3 Flood Impact ........................................................................................... 4-5
5. SCREENING FOR STREAM AERATION ................................................................... 5-1
5.1 Air-Based Alternatives........................................................................................ 5-1
5.1.1 Simple Aeration ...................................................................................... 5-1
viii
5.1.2 Mechanical Aeration ............................................................................... 5-2
5.1.3 Bubble Aeration ...................................................................................... 5-3
5.2 High Purity Oxygen Alternatives........................................................................ 5-3
5.2.1 Simple Oxygenation Using High-Purity Oxygen ................................... 5-4
5.2.2 Pressurized Oxygenation Using High-Purity Oxygen ............................ 5-5
5.3 Air Supplied Side-Stream Alternatives ............................................................... 5-6
5.4 Overview of Aeration Feasible Alternatives....................................................... 5-7
6. EVALUATION............................................................................................................... 6-1
6.1 Baseline Model ................................................................................................... 6-2
6.2 Alternative 1: Eliminate Pollutants in Wastewater Treatment Plant Effluents .. 6-3
6.3 Alternative 2: Dam Crest Drop or Bridging (Graue Mill Dam) and Removal
(Oak Meadows Dam) .......................................................................................... 6-4
6.3.1 Oak Meadows Dam Removal ................................................................. 6-5
6.3.2 Graue Mill Dam ...................................................................................... 6-6
6.4 Alternative 3: In-Stream Aeration Using Air-Based Technology ..................... 6-8
6.4.1 Oak Meadows Golf Course Dam ............................................................ 6-8
6.4.2 Graue Mill Dam .................................................................................... 6-10
6.4.3 Flood Control Reservoirs Use During Low Flow-Warm Conditions ... 6-13
6.5 Alternative 4: High-Purity Oxygen .................................................................. 6-13
6.5.1 Oak Meadows Golf Course Dam .......................................................... 6-13
6.5.2 Graue Mill Dam .................................................................................... 6-13
6.6 Summary of Options ......................................................................................... 6-16
REFERENCES ................................................................................................................ R-1
TABLES
Table 1-1 IPCB DO Standards ............................................................................................ 1-3
Table 2-1 Impacts of Urbanization on Channel Stability .................................................... 2-1
Table 2-2 Municipal Wastewater Treatment Plant Discharges ........................................... 2-8
Table 2-3 Published River Flows ........................................................................................ 2-8
Table 2-4 SHAP Ratings ..................................................................................................... 2-9
Table 2-5 SHAP Scores ..................................................................................................... 2-12
Table 2-6 Qualitative Habitat Evaluation Index................................................................ 2-13
Table 2-7 QHEI Scores by River Mile/km ........................................................................ 2-13
Table 2-8 River Dam Information ..................................................................................... 2-14
Table 2-9 SOD Survey Locations and Results .................................................................. 2-22
Table 2-10 DO Monitoring Locations ................................................................................. 2-24
Table 6-1 Salt Creek POTW Upgrade Estimate Capital Cost for MBR and GAC
Additions ............................................................................................................. 6-4
Table 6-2 Instream Aeration at Oak Meadows Using Fine Bubble Tubing and Air......... 6-11
Table 6-3 Instream Aeration at Graue Mill Using Fine Bubble Tubing and Air .............. 6-12
Table 6-4 High-Purity Oxygen Addition at Oak Meadows .............................................. 6-14
Table 6-5 High-Purity Oxygen Addition at Graue Mill .................................................... 6-15
ix
FIGURES
Figure 1-1 Study Area and Features of Interest .................................................................... 1-2
Figure 2-1 Channel Evolution Model ................................................................................... 2-3
Figure 2-2 Oak Meadows Golf Course Dam ...................................................................... 2-14
Figure 2-3 Left abutment, significant crack ....................................................................... 2-15
Figure 2-4 Mature Tree compromising left training wall ................................................... 2-16
Figure 2-5 View of left abutment and culvert .................................................................... 2-16
Figure 2-6 Water Surface Profile at Oak Meadows Golf Course Dam .............................. 2-17
Figure 2-7 Old Oak Brook Dam ......................................................................................... 2-18
Figure 2-8 Old Oak Brook Dam Sediment Profile ............................................................. 2-19
Figure 2-9 Graue Mill Dam ................................................................................................ 2-20
Figure 2-10 Graue Mill Dam Profile .................................................................................... 2-21
Figure 2-11 DO Values for 2006 .......................................................................................... 2-24
Figure 2-12 DO Values for 2007 .......................................................................................... 2-25
Figure 2-13 DO Values for 2008 at Butterfield Rd. ............................................................ 2-25
Figure 2-14 DO Values for 2008 at Fullersburg Woods ...................................................... 2-26
Figure 2-15 DO Values for 2008 at York Rd., below Graue Mill Dam ............................... 2-26
Figure 2-16 Fish Biodiversity ............................................................................................... 2-27
Figure 2-17 Macro-Invertebrate Quality .............................................................................. 2-27
Figure 2-18 Phosphorus Levels in Salt Creek ...................................................................... 2-28
Figure 3-1 Baseline Stream Temperature for Salt Creek...................................................... 3-5
Figure 3-2 Base Flow for Salt Creek .................................................................................... 3-6
Figure 3-3 Travel Times in Salt Creek ................................................................................. 3-7
Figure 3-4 Comparison Temperature Corrected SOD in Salt Creek .................................... 3-8
Figure 3-5 SOD Rates with the 3°C Increase in June Temperatures .................................... 3-9
Figure 3-6 Predicted vs. Measured Dissolved Oxygen for August 2007 for Salt Creek .... 3-10
Figure 3-7 Predicted vs. Measured Dissolved Oxygen for July 2006 for Salt Creek ......... 3-11
Figure 3-8 Baseline Dissolved Oxygen for Salt Creek ....................................................... 3-12
Figure 5-1 Mechanical Aeration Display ............................................................................. 5-2
Figure 5-2 Bubble Aeration .................................................................................................. 5-3
Figure 5-3 Low Head Oxygenators ...................................................................................... 5-5
Figure 5-4 Diffuser Used for Bubble Aeration ..................................................................... 5-6
Figure 5-5 Side-Stream Aeration Facility............................................................................. 5-7
Figure 6-1 Baseline Dissolved Oxygen for Salt Creek ......................................................... 6-2
Figure 6-2 Baseline Minimum D.O. vs Downstream Distance ............................................ 6-3
Figure 6-3 Dam Removal Minimum D.O. vs Downstream Distance................................... 6-5
Figure 6-4 Fullersburg Woods Footprint with Lowered Dam Elevations ............................ 6-7
Figure 6-5 Fullersburg Woods Footprint with Breaching Option ........................................ 6-8
Figure 6-6 Aeration Alternative Minimum D.O. vs Downstream Distance ....................... 6-10
Figure 6-7 Oxygen Addition Alternative Minimum D.O. vs Downstream Distance ......... 6-16
APPENDICES
A Reach Descriptions
B SOD Reports
C DO Model Inputs, Calibration, Validation and Alternatives
D Public Meeting Reports
DO Improvement Feasibility Study
Salt Creek 1.0 Project Background and Goals
DRSCW 1-1 September 2009
1 PROJECT BACKGROUND AND GOALS
The 2000 National Water Quality Inventory 305(b) Report listed dissolved oxygen as one of the
causes of impairment on lower Salt Creek. In October 2004, the Illinois Environmental
Protection Agency (Illinois EPA) completed a Total Maximum Daily Loads (TMDL) Study for
Salt Creek that developed load allocations for BOD5, ammonia nitrogen, and volatile suspended
solids based on low-flow warm conditions (CH2MHill, 2004). This report concluded that a 56
percent reduction in BOD5 and a 38 percent reduction in ammonia would be necessary to achieve
the dissolved oxygen (DO) standards, or if one dam was removed a 34 percent reduction in
BOD5 and 38 percent reduction in ammonia would be necessary.
There are three dams on Salt Creek identified in the report, the Oak Meadows Golf Course Dam,
the Old Oak Brook Dam, and the Graue Mill Dam located in the Fullersburg Woods Forest
Preserve in Oak Brook. These dams are depicted on Figure 1-1. The impact of these dams on the
DO level in 2004 was not well understood. Data on ambient DO levels as well as critical factors
such as sediment oxygen demand (SOD), an important factor in DO levels at low-flow warm
conditions, were limited.
Since the publication of the 2004 TMDL Report, a group of communities, publicly owned
treatment works (POTWs), and environmental organizations formed the DuPage River Salt
Creek Workgroup (DRSCW) to better understand the causes of degraded water quality and, in
particular, to find ways to improve DO levels in Salt Creek. The focus of the DRSCW was to
develop a sound database of water quality through monitoring, including the use of continuous
DO probes, in conjunction with developing a calibrated dissolved oxygen water quality model
from which a number of alternatives for enhancing stream DO levels could be evaluated.
1.1 Project Goal
The goal of this study is to identify the areas along Salt Creek where low DO occurs during the
warmer, low flow periods, followed by the development of a calibrated DO model from which a
number of alternatives are developed for addressing the low DO areas. These alternatives include
the removal or modification of dams and the construction and operation of in-stream aeration
projects to achieve the water quality standard for dissolved oxygen. In conjunction with this
study, the DRSCW has also collected excellent biological data (fish, benthic, and habitat) which
can be used along with the water quality monitoring data to address biological impairment in a
holistic manner.
This study will identify:
1. Those reaches where the lowest DO levels occur during low flow-warm weather.
2. The primary cause(s) of the low DO based on water quality monitoring, sediment oxygen
demand (SOD) measurements, and modeling.
3. Potential dam sites where complete removal, „bridging,‟ or some other modification
would improve minimum DO levels.
DO Improvement Feasibility Study
Salt Creek 1.0 Project Background and Goals
DRSCW 1-2 September 2009
4. Potential sites where stream aeration equipment would provide an opportunity to raise
minimum DO levels.
DO Improvement Feasibility Study
Salt Creek 1.0 Project Background and Goals
DRSCW 1-3 September 2009
5. Permitting authorities, required permits, and regulatory issues.
6. Environmental impact on water quality and stream habitat, in addition to secondary
impacts and other community issues such as adjacent land use.
7. Financial impacts, including project capital costs (including sediment removal and
disposal costs), operation and maintenance needs, and other costs associated with stream
improvement projects.
8. Dam owners and nearby landowners affected by stream improvement projects, along with
their interest in accommodating such a project, and a description of the impacts of stream
improvement projects.
9. Adjacent associated construction needed as part of stream improvement projects (e.g.,
upstream and downstream stream bank improvements that would be necessary due to
altered water levels, adjacent equipment, electrical feed, equipment access for
maintenance).
10. Other aspects of stream improvement projects that may impact the feasibility of such a
project.
1.2 Water Quality Standards
On January 24, 2008, the Illinois Pollution Control Board (IPCB) adopted revised DO water
quality standards. These standards are presented in Table 1-1.
Table 1-1 - IPCB DO Standards
Measurement Interval
Minimum DO Standard
August – February March – July
At any time 3.5 mg/L 5.0 mg/L
7 day average 4.0 mg/L 6.0 mg/L
30 day average 5.5 mg/L n/a
Minimum DO levels occur in Salt Creek during prolonged hot, dry periods. As the water
temperature rises, the daily minimum DO values become lower. From a practical perspective,
any solution must address prolonged hot, dry periods that can occur in June and July. Based on
in-stream monitoring, the minimum DO standard of 5.0 mg/L during June and July will be more
difficult to achieve than the 6.0 mg/L weekly mean, as photosynthesis increases DO levels
during the daylight hours well above 6.0 mg/L. Therefore, for the purposes of this report,
achieving the minimum DO standard of 5.0 mg/L in June and July will be the basis for
evaluating alternative approaches of dissolved oxygen improvements in Salt Creek.
DO Improvement Feasibility Study
Salt Creek 2.0 Existing Conditions
DRSCW 2-1 September 2009
2 EXISTING CONDITIONS
Before evaluating alternatives for improving the DO in Salt Creek, it is important to understand
the existing stream characteristics. Factors such as stream depth, canopy cover, sediment
accumulation, stream bank erosion, riparian zone composition, wetlands, stream slope, and bank
heights are all important during the alternative development and evaluation process. In addition,
SOD measurements have been completed and continuous DO probes have been installed at
strategic locations along Salt Creek to better understand the DO profile under low-flow warm
conditions.
2.1 Geomorphic Assessments
Natural streams are in constant dynamic equilibrium. Although imperceptible over years or
decades, a stream in equilibrium moves within its floodplain both laterally and vertically over
long time periods. A channel can be in balance with the hydrologic and sediment influences or
can be in rapid transition as a result of changes in the watershed or within the stream corridor.
Urban river systems are often in various states of disequilibrium. The development of Chicago
area watersheds has significantly increased the intensity of land use. The impact of urbanization
on stream systems is well documented and includes changes in the hydrology, water quality,
sediment supply, and ecology. Other impacts include isolation from and reduction of available
floodplain capacity and installation of road crossings and other lateral and vertical controls.
Hence, urbanization can significantly increase stream instability, as shown in Table 2-1.
Table 2-1 - Impacts of Urbanization on Channel Stability
Instability Description Probable Cause
Increase in erosive energy of stream
Channel Straightening – sinuous and low
gradient streams become straight and steeper
Increase in velocity
Larger discharge rates due to impervious
cover, culverts, drain tiles, and storm sewers
Decrease in in-stream channel
roughness
Removal of riparian vegetation and in-stream
woody debris
Decrease in amount and character of
incoming bed load
There is more energy to move bed material
than there is available bed material due to
impervious cover and channel armoring
Change in geotechnical loading
characteristics of the banks
Alteration of baseflow, as well as periods,
levels, and timing of saturation
Change in riparian management Deforestation and turf grass changes
Increase in stream temperatures Loss of canopy cover
DO Improvement Feasibility Study
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From a geomorphic perspective, Salt Creek is a disturbed system, with channel features typical
of those found in large, fully built-out metropolitan areas. When the area was developed, small
tributary streams were either put into pipes and buried or were confined to narrow, straightened
ditches. Floodplains for these headwater channels, as well as the main channel, have been filled
in or separated from waterways by large berms that concentrate flood flows into deeper narrower
channels. Floodplain and drainage surfaces have been covered by pavement and storm water is
now directed into storm sewers that discharge directly into creeks. Where rainfall once seeped
into soils and traveled as groundwater into channels, storm water is now diverted into artificial
waterways and enters the stream as runoff at a higher rate of flow. These processes lower base
flows and increase flood flows, making Salt Creek a “flashy” stream, particularly in its upper
reaches.
2.1.1 Channel Evolution
Schumm (1984) describes the evolution of stream channels (Figure 2-1) that adjust geometry in
response to changes in the watershed. In essence, if a channel needs to adjust its cross sectional
area, it must move through the evolution stages described below until it reaches a new, stable
geometry. The Schumm system classifies streams by their place along a continuum of channel
changes toward the more stable geometry. This process is common in urban systems where
channels are continually adjusting in response to increasing water input, decreasing sediment
load, and often significant physical alteration (channel straightening, floodplain width reduction,
etc.).
It is useful to describe the stages in Figure 2-1 to understand the process. Stage I represents a
stable channel configuration. As sediment load decreases and flood magnitude increase, the
channel begins to erode (incise) into its bed (Stage II). The incision process is followed Stage III,
lateral bank erosion as the bank heights (h) exceed a critical height (hc) and collapse into the
channel. Stage IV occurs when the bed begins to aggrade (deposit) and the channel banks are
approximately equal to the critical stable height. The bank height will continue to decrease until
a bankfull condition is achieved that is consistent with the new bankfull discharge. A new
incipient floodplain will develop and vegetate as part of the final (larger) stable geometry (Stage
V).
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Figure 2-1 - Channel Evolution Model
2.1.2 Bank Erosion
Bank erosion is part of the natural processes within a stable stream and is balanced by deposition
of sediment on floodplains and bars. Erosion provides the needed bed material, allows
recruitment of large woody debris, and encourages channel variability. However, „excess‟ bank
failure associated with unstable riverine systems and massive failures that threaten existing
infrastructure can cause unacceptable environmental impacts and consequences to private and
public resources. Bank failure can generally be attributed to three basic processes (Thorne et al.,
1997): subarial wasting, hydraulic scour, and mass failure. Subarial wasting is not considered to
be the major driving force for Midwestern urban streambank instability and is not discussed
further here.
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The common result of urbanization is a significant increase in bank erosion due to hydraulic
scour of the channel bed and toe of the bank. When changes in land use result in increased water
velocity, streams begin to erode their bed and banks beyond the point of equilibrium. Excess
hydraulic scour generally can be addressed in two ways, either by reducing channel velocity and
thereby reducing erosive force, or by armoring the channel to resist the erosive force. Reduction
of channel velocity can be accomplished either by increasing the area of the channel, increasing
the capacity of the channel and/or floodplain, decreasing flow rates, or modifying slope through
the use of grade controls. Following incision, as noted in the Schumm model above, hydraulic
scour combined with mass failure can lead to extreme bank erosion.
Mass failure of the streambank is often the result of increased hydraulic scour, and/or change in
riparian vegetation management associated with urbanization. There are numerous bank failure
mechanisms due to various loading and resistant conditions, including differences in soil
characteristics and vegetative reinforcement. Streambank soils can vary both vertically and
horizontally, and can generally be classified as cohesive, non-cohesive, and composite (banks
with layers of soil that have significantly different characteristics). Each of these types of
streambanks presents different engineering challenges and different solutions. The equilibrium
processes of scouring and deposition of soil layers within an alluvial valley can provide
significant variability in the soil conditions within the valley. Hence, the type of bank material
can change significantly along a stream length as the stream passes through different
depositional eras.
The ditching, dredging and straightening of channels is termed channelization. The result of
these hydrologic changes in Salt Creek has resulted in dramatic geomorphic changes.
Channelization is perhaps the most common form of channel disturbance throughout Salt Creek,
and its effects vary. Where wide ditches have been excavated, shear stress on the banks is
relatively low, and banks are stable. Because these reaches lack sufficient energy to transport
sediment through the reach, many of these over-widened stretches have aggradation problems,
whereby fines such as silt and sand are deposited. Just above Butterfield Road is an extreme
example of this over-widening. Channelization increases the effective slope of a stream by
allowing water to travel a shorter distance, increasing velocities resulting in incision. The newly
created steeper slope is unstable given the hydraulic conditions, and begins to headcut upstream
until a lower slope is achieved. This often results in deep incision upstream and aggradation
downstream.
Common measures to address mass failure of streambanks include decreasing the load by
reducing bank height, reducing bank slope, improving drainage or planting stabilizing vegetation
(to reduce pore pressure), and/or increasing the resistance to failure by geosynthetic
reinforcement or revegetation.
2.1.3 Sediment Transport
Understanding sediment transport characteristics of a stream is very important in understanding
the stream stability and characteristics. Alluvial streams within urbanizing watersheds frequently
experience rapid channel enlargement. Channel response to urbanization has been described by
Leopold, et al (1964), Hammer (1972), and numerous others. During the initial wave of
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construction, sediment loads reaching the stream from the watershed may be elevated 10 to 100
times compared to pre-construction loads, with the attendant destabilization and sometimes
flooding damages. Typically, high sediment yields during the construction phase are followed by
reduced yields once infrastructure and storm sewer systems are fully built (Kondolf and Keller,
1991). However, as the fraction of the watershed covered by impervious materials increases,
watershed hydrology shifts dramatically. Flow peaks become sharper, higher, and more frequent,
while the sediment loads reaching the channel changes.
In the absence of bed control (e.g. bedrock outcrops in natural channels or hardened stream
crossings in urbanized areas), channels typically respond by incising. When bank heights exceed
a critical threshold for geotechnical stability, mass failure ensues and explosive channel
widening occurs. Sediment supply changes such as local and upstream bank failure, upstream
modifications etc., and transport capacity changes (channel widening, meander cutoffs,
construction of additional crossings, etc.) can make a reach aggrading, in equilibrium, and
degrading over time.
Sediment transport continuity describes the ability of a stream reach to transport the sediment
that it receives from upstream sources. A stream reach is considered to be in equilibrium if it can
transport the sediment it receives within the reach and from upstream sources to downstream
reaches. A reach is considered to be degrading if its transport capacity exceeds the sediment
supply (and hence the river will erode its bank and bed) and aggrading if the supply exceeds the
transport capacity (leading to deposition).
2.2 Stream Characterization
In general, Salt Creek can be characterized as an urban stream with low gradients and extensive
channelization. Canopy cover in the assessed stretches is variable due to development,
channelization activities, and widening of the stream bed. The loss of canopy cover results in
higher summer stream temperatures and in some areas of Salt Creek, the establishment of
excessive rooted vegetation. Flow during low flow periods is dominated by effluent from the
wastewater treatment plants along Salt Creek.
The slope of Salt Creek in the critical stretches is relatively flat, with many reaches having a drop
of less than 1 foot per 1,000 feet. The steepest drop occurs between River Mile 17.5 and 16.8
(28.0 and 26.9 km) below Route 83 and above the over-widened section at Butterfield Road,
where a drop of 4 ft (1.2 m) occurs over a 3,000-foot (1,000 m) reach. Slope is critical as the
stream velocity is influenced by the slope, and stream re-aeration is influenced by the velocity.
In stretches where re-aeration is low (due to flat terrain), maintaining minimum dissolved oxygen
levels becomes more difficult.
The headwaters of Salt Creek have incised in steps, with road crossings sometimes serving as
grade controls, preventing further incision. Road crossings, whether bridges or culverts, can
often be the cause of incision. In some cases, however, rock is placed under bridges to prevent
scour of bridge pilings or abutments, and these rock riffles often act as grade control, preventing
downstream headcuts from migrating further upstream. Salt Creek from Algonquin Road
upstream shows a stepped incision pattern, with the deepest incision being found upstream of
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Plum Grove Road. In some areas, the channel has incised more than 3 ft (1 m), and subsequent
widening has created extremely large channel cross-sections. Landowners have experimented
with various bank stabilization treatments including timber cribs, rock riprap, concrete rubble,
and sheet piling. All of these methods are hard engineering and prevent the channel from
assuming a stable cross-section. Thus the erosional energy of the stream is translated
downstream to other properties.
The many road crossings and dams on Salt Creek act to impound both low flow and high flows,
potentially increasing flooding. The dam at river mile 29.5 (47.5 km) floods over 2.5 miles (4.0
km) of channel, drowns the floodplain and backs water upstream for 3.5 miles (5.6 km),
virtually eliminating any lotic habitat that may have existed. The dams on Salt Creek have also
reduced the river‟s sediment transport ability by capturing sediment behind the dams. This
creates a secondary situation downstream, whereby sediment-starved water erodes bed and banks
and streams become armored, over-widened, and incised.
Floodplain encroachment and development is a major impact to Salt Creek, especially upstream
of River Mile 10.7 (river kilometer 17.1). This is typical of most urban streams, where parkland
and natural openspace is preserved in the downstream reaches and the headwaters are fully
developed. This is the reverse of what is required for streams to function geomorphically and
ecologically. Because the headwaters are where hydrology and sediment transport originate,
development of these areas degrades the stream in its headwaters. Residential development has
the biggest impact on Salt Creek‟s headwaters and continues to confine the channel down to
River Mile 22.0 (35.2 km). Downstream of Interstate Highway 290 (River Mile 22.9 (36.6 km)),
the floodplain is occupied by numerous detention basins. Between river distances 20 and 30 (32
and 48 km), there are 11 such large detention ponds adjacent to the stream channel. All of these
encroachments limit the ability of the stream to meander. If a restored stream is to be allowed to
function geomorphically, it must be allowed to meander across its floodplain. This requires
space, and the limits of meandering must be established. In most cases, however, the stream is
bordered by infrastructure and is then hard armored to prevent meandering.
The riparian area of Salt Creek is largely wooded, but varies in width from 0 feet to 1,000 feet.
As with most urban rivers, stream banks and riparian areas in residential or light industrial
neighborhoods are often armored and most trees are removed. The Forest Preserve system has
retained the floodplain forest community in many reaches. Eight major parks and golf courses
along Salt Creek represent a significant impact to the riparian corridor, as they have removed
most if not all of the riparian trees from the stream banks. Often these reaches are accompanied
by hard armoring, either by A-jacks or riprap.
Hard armoring of stream banks is prevalent along Salt Creek and presents a major impact to the
aquatic ecology and geomorphology of the stream. Hard armoring is sometimes required to
protect infrastructure such as roads and buildings from eminent risk of failure due to eroding
banks. However, much of the hard armoring encountered was in the form of riprap or A-jacks.
A-jacks can also prevent the movement of amphibians and other aquatic species. Animals, such
as turtles and frogs, depend on banks for upland access, reproduction, and breeding. A-jacks
prevent any such use of banks. Installation of these practices was observed upstream of
constricting road crossings and dams, on the inside of meander bands, and along banks that were
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not eroding, in some cases with a bank full height of less than 3 ft (1 m). A-jacks have also been
installed in long reaches of forest preserve land where no infrastructure is present.
Observation of stable reaches throughout Salt Creek point to the importance of woody vegetation
for stability and both artificially and naturally stable reaches repeatedly show that small diameter
material such as cobble and gravel are often adequate to provide toe stability.
Invasive species such as buckthorn and garlic mustard have taken over many sections of
floodplain forest and can influence the geomorphology of the system by increasing floodplain
roughness. Normally, floodplain forests have little understory vegetation and flood flows can
pass freely between large trees. Buckthorn and garlic mustard add significantly to floodplain
roughness, basically filling in the spaces between trees. Eventually, this increased growth may
force more water down the narrow channel width.
The lower reaches of Salt Creek, below the Graue Mill Dam where the stream is allowed to
meander slightly, resemble more natural stream channels with regular riffle-pool sequences,
large woody debris inputs, depositional bars and scour at meander bends.
2.3 Flow Data
The total drainage area in the Salt Creek Basin is approximately 147 square miles (380 km2),
extending through Cook and DuPage Counties. The creek originates in northern Cook County as
the outlet for Busse Lake within the Village of Inverness, flows south into DuPage County
through Oak Brook, and turns east and flows into Cook County, discharging into the Des Plaines
River in Lyons, IL. The total stream length is approximately 45 miles (72 km). There are two
main tributaries on the lower portion of Salt Creek1, Spring Brook and Addison Creeks. In the
segment from Spring Brook Creek to the rivers mouth, there are seven sewage treatment plants,
and the MWRDGC John Egan Water Reclamation Plant is located upstream. From a DO
perspective, the industrial dischargers were not deemed to be contributing deoxygenating waste
to Salt Creek. These point source discharges are presented in Table 2-2, and the locations were
depicted on Figure 1-1.
1 Lower portion here is understood as the portion south of the Busse Woods Dam in Schaumburg
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Table 2-2 – Municipal Wastewater Treatment Plant Discharges
Selected published flows for Salt Creek are listed in Table 2-3.
Table 2-3 - Published River Flows
Location
7-Day 10-Year
Low Flow, cfs
Harmonic Mean
Flow, cfs
Above Elmhurst 36 55
Below Elmhurst 45 74
Western Springs 38 81
Above Addison Creek 36.5 84
Entering Des Plaines 37 100
Combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) contribute to lower DO
levels at low flow conditions through historic deposition, which was measured as part of the
2006 and 2007 SOD studies (HDR and Huff & Huff, 2006 and HDR and Huff & Huff, 2007).
The wet weather DO impacts of these utilities are not included as part of this study.
2.4 Reach Descriptions
In the 2006 303(d) List, two segments of Salt Creek were listed as DO impaired, Segment GL-03
and GL-19. Segment GL-03 starts where Spring Brook Creek enters at River Mile 28.3 (45.3
km), just north of Irving Park Road, and Segment GL-19 is the final 3.1 miles (5.0 km) of Salt
Discharger
River Mile
(km) from
mouth
Elmhurst Wastewater
Treatment Plant
17.8 (28.6)
Salt Creek Sanitary District
Treatment Plant
17.9 (28.8)
Villa Park Wet Weather
Treatment Plant
18.0 (29.0)
Addison South A.J. Larocca STP 20.9 (33.6)
Addison North STP 22.6 (36.4)
Wood Dale South STP 25.3 (40.7)
Itasca STP 25.7 (41.4)
MWRDGC John Egan
Water Reclamation Plant
29.6 (47.6)
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Creek from the junction with Addison Creek to the Des Plaines River. The final stretch of Salt
Creek has low DO levels attributed to the poor water quality from Addison Creek.
The Illinois EPA Qualitative Stream Habitat Assessment Procedure (SHAP) was utilized to
describe each stream segment based on the observations collected during the reconnaissance.
The SHAP index includes factors for bottom substrate, deposition, substrate stability, canopy
cover, pool substrate characterization, pool quality, pool variability, canopy cover, bank
vegetation, top of bank land use, flow-related refugia, channel alteration, channel sinuosity,
width/depth ratio, and hydrologic diversity. Based on the subjective evaluation for the
aforementioned factors, a SHAP score is determined. These values correspond to the ratings
shown in Table 2-4.
Table 2-4 - SHAP Ratings
Rating SHAP Score
Excellent > 142
Good 141 to 100
Fair 99 to 59
Poor < 59
Channelization, lack of canopy cover, effluent dominated low-flows, and other factors all
contribute to the vegetative growth and subsequent lower early morning DO levels.
A reconnaissance of Salt Creek was completed on October 13, 2005, during a period of low-flow
conditions, from the Addison North Wastewater Treatment Plant (River Mile 22.6 (36.2 km)) to
Graue Mill (River Mile 10.7 (17.1 km)). Appendix A includes Figures 2.1 to 2.8 describing the
observations from a float trip through each segment. A description of each segment is provided
below:
Addison N WWTP (River Mile 22.6 (36.1 km)) to Addison S WWTP (River Mile 20.9 (33.6
km))
This 1.7 mile (2.7 km) stretch has a SHAP score of 60, or fair aquatic habitat. Water depth
ranged from 0.6 to 2 ft (0.2 m to 0.6 m), with predominantly a silty-sand substrate until below
Lake Street (River Mile 21.7 (34.7 km)) where the depth increased to 3.0 to 3.3 ft (1.0 to 1.1 m).
The substrate in this pool area is predominantly silt. A concrete “curb” dam is present at River
Mile 22.1 (35.4 km), just upstream of Lake Street, and log jams are backing up flow at Lake
Street. Wildlife observed in this stretch included great blue heron, mallards, king fisher, and
beaver. Good floodplain habitat existed through much of the reach with shallow bank heights
and moderate stream bank erosion. The creek has some meanders in this stretch. North of Lake
Street, the riparian zones were wooded with fair to good canopy cover.
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Addison South WWTP (River Mile 20.9 (33.6 km)) to North Avenue (River Mile 19.5 (31.4
km))
This 1.4 mile (2.2 km) stretch has water depths ranging from 0.3 ft (0.1 m) where stream bottoms
vary from firm clay to silty sand, to pools up to 5 ft (1.5 m) deep with firm clay bottoms.
Immediately below the Addison South WWTP the water depth was 1ft (0.3 m), with a gravel
bottom. A log jam in this location had an accumulation of floating duckweed. Stream banks
were approximately 5 ft (1.5 m) high with virtually no adjoining wetland areas. Just above North
Avenue, soft sediment, 6 inches in depth (15 cm) was present on the inside of the bend,
decreasing to 2 inches (5 cm) of soft sediment in the center. Canopy cover in this stretch was
relatively good.
The SHAP score improved in this stretch to 96; however, still in the “fair” habitat range. This
stretch had fair canopy cover, several riffle run complexes and undeveloped riparian zones. This
stretch was relatively unchannelized and had good stream sinuosity and habitat diversity. Salt
Creek passes through the Cricket Creek Forest Preserve north of North Avenue.
North Avenue (River Mile 19.5 (31.4 km)) to Route 83 (River Mile 18, 1 (29.1 km))
This 1.4 mile (2.2 km) reach includes some long channelized segments and passes between a
former active quarry currently used by DuPage County for flood control and an asphalt plant. A
turbid discharge was present adjacent to the asphalt plant. Below the railroad bridge (River Mile
18.9 (30.4 km)) to Illinois Route 83 there is a good series riffles and the drop in elevation is more
pronounced than the remainder of the creek. There is an oxbow cutoff just above St. Charles
Road (River Mile 18.3 (29.4 km)). South of North Avenue the water depth starts out between 2
and 2.9 ft (0.6 and 0.9 m), with up to 3.9 inches (10 cm) of soft sediment, diminishing to 1 inch
(2.5 cm) of soft sediment in the channelized section without canopy adjacent to the quarry.
The SHAP score in this reach declined to 91, still in the “fair” habitat range. Wildlife observed
included great blue heron, king fisher, mallards, and beaver. In-stream habitat was fair north and
south of the gravel operation. Although the stream was more channelized than the previous
stretch, habitat diversity and canopy cover were good, outside of the stretch adjacent to the
quarry.
Illinois Route 83 (River Mile 18.1(29.1 km)) to Illinois Route 56 (River Mile 16.1 (25.9 km))
The riffles continue below Illinois Route 83 in 1ft to 2 ft (0.3 to 0.6 m) of water over a gravel
substrate. A large storm water outfall is present at River Mile 17.9 (28.8 km) and two WWTP
outfalls (Salt Creek and Elmhurst) are present at River Mile 17.8 and 17.9 (28.6 and 28.8 km),
respectively. Water depth generally continues between 1ft to 2 ft (0.3 and 0.6 m) with a firm
bottom. An additional riffle exists at approximately River Mile 17.2 (27.7 km) and a double
sheet pile dam exists at River Mile 16.9 (27.2 km) by Jackson Street. Salt Creek narrows above
this dam. Below the dam, water depth increases to an average 2.9 ft (0.9 m) with 1 inch (2.5 cm)
of sandy silt sediment over stiff clay.
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Evidence of beaver and muskrat activity is present below this dam for the next 0.5 miles (0.8
km). Salt Creek above Illinois Route 56 (Butterfield Road) opens into a long, wide area, 0.9 to 2
ft (0.3 to 0.6 m) in depth with virtually no canopy cover. At low flow, the stream velocity is
negligible and rooted vegetation has taken hold in the bottom. High levels of aquatic vegetation
are generally considered detrimental to overall DO level, as respiration at night depletes the DO.
Sediment depths are 2.9 to 3.9 inches (7.5 to 10 cm) along both shorelines. Closer toward
Illinois Route 56, the vegetation in the stream begins to subside and stream bank heights increase
to 10.2 to 15.1 ft (3.1 m on the west bank and 4.6 m on the east bank).
The SHAP score for this stretch, 78, remains in the “fair” range for habitat. The habitat diversity
(riffle/run/pool), canopy cover and in-stream habitat are good in the northern half of this stretch.
The southern portion is more channelized with poor canopy cover and poorly vegetated riparian
zones.
Illinois Route 56 (River Mile 16.1 (25.9 km)) to Interstate Route 88 (River Mile 14.3 (23.0 km))
This 1.8 mile (2.9 km) stretch is through developed property in Oak Brook. Below Illinois Route
56, the wide stream run continues, ranging in depth from 0.9 to 2 ft (0.3 to 0.6 m) with a silty
gravel substrate. The canopy improves below Illinois Route 38 (River Mile 15.7 miles (25.3
km), and the creek narrows, and deepens to 2.6 to 3.3 ft (0.8 to 1.0 m). Velocities noticeably
increase and the substrate changes to cobbles and sand. Stream bank stabilization has been
installed below Illinois Route 38 but further downstream serious bank erosion exists.
Salt Creek turns east at River Mile 15.1 (24.3 km), and the water depth deepens to 6 to 7.3 ft (1.8
to 2.2 m). This pool is heavily channelized and has a sand and gravel substrate. As Salt Creek
approaches Interstate Route 88 it becomes shallower (1.2 m).
The SHAP for this segment declines to 69, still in the “fair” habitat range. Similar to the last
stretch, stream habitat quality is greater on the north end. Below Illinois Route 38, the stream
has fair canopy cover and wooded riparian zones providing filtration. Near Interstate Route 88,
the in-stream habitat decreases as Salt Creek becomes a large pool with little habitat diversity.
Interstate Route 88 (River Mile 14.3 (23.0 km)) to Graue Mill Dam (River Mile 10.7 (17.2))
This 3.6 mile (5.8 km) stretch has water depth varying from 1.0 to 5.9 ft (0.3 to 1.8 m). The
northern part of this section flows through two golf courses. Between Interstate Route 88 and
Cermak Road, Salt Creek is 2.6 ft (0.8 m) deep with a mud bottom 2 to 5.9 ft (0.6 to 1.8 m) deep
with gravel substrates. As Salt Creek enters the golf course, it deepens from 2.9 to 5.9 ft (0.9 to
1.8 m) in depth and the banks are lined with caged rocks. The bottom is generally firm through
the golf course. The stream then enters the Fullersburg Woods Forest Preserve south of 31st
Street. The Old Oak Brook Dam is located below 31st Street at River Mile 12.5 (20.1 km). This
section has soft sediment to the north and hard clay to the east/south. Serious bank erosion was
noted south of 31st Street River Mile 12.3 (19.8 km). The last 1.6 miles (2.4 km) of this portion
of Salt Creek is a long pool with clay bottoms upstream transitioning to softer sediments
downstream near the Graue Mill Dam (River Mile 10.7 (17.2 km). The last 330 ft (100 m) of
this segment had 1 ft (0.3 m) of sediment under 4.9 ft (1.5 m) of water.
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The SHAP for this segment was 55, indicating poor habitat quality. The section had poor habitat
diversity, scattered canopy and was mostly deep pools. However, areas with good riparian zones
were present south of Butler National Golf Course and within the forest preserves. It should be
noted that the only in-stream wetlands were noted at the south end of this section.
Below the Graue Mill Dam, DO impairment is identified only in the final 3.1 miles (5 km),
where Addison Creek joins Salt Creek, and the float trip did not include the stretch below the
Graue Mill Dam.
2.5 Habitat Summary
The SHAP scores and the habitat conditions for each segment are summarized in Table 2-5.
Optimal Scores are more than 160 but may range to a maximum of 200.
Table 2-5 - SHAP Scores
Stream Reach
Assessment
Score
SHAP
Limiting Habitat
Conditions
Addison N WWTP to Addison S WWTP
River Mile 22.6-River Mile 20.9, (36.1 – 33.6 km)
60 (Fair) Moderate streambank stabilization
Addison South WWTP to North Avenue
River Mile 20.9-River Mile 19.5, (33.6 – 31.4 km)
96 (Fair)
Undeveloped
riparian zones
North Avenue to Route 83
River Mile 19.5 –River Mile 18.1, (31.4 – 29.1 km)
91 (Fair) Channelized
Illinois Route 83 to Illinois Route 56
River Mile 18.1 – River Mile 16.1, (29.1 – 25.9 km)
78 (Fair)
Poor canopy / riparian zone
(over channelized)
Illinois Route 56 to Interstate Route 88
River Mile 16.1- River Mile 14.3, (25.9 – 23.0 km)
69 (Fair)
Poor habitat diversity, scattered
canopy, deep pools (over channelized)
Interstate Route 88 to Graue Mill Dam
River Mile14.3 –River Mile 10.7, (23.0 – 17.2 km)
55 (Poor)
Poor habitat diversity,
scattered canopy
In addition, the qualitative habitat evaluation index (QHEI) was determined at eight locations on
Salt Creek. The QHEI provides a quantitative assessment of physical characteristics of a stream
and represents a measure of in-stream geography. The seven variables which comprise this
index and the best possible score for each are shown below. The maximum total QHEI score is
100 and is broken down in Table 2-6. The Salt Creek QHEI scores by river km are shown in
Table 2-7. . While QHEI and SHAP rating measure similar metrics, they use different scoring
systems and are not directly comparable to each other. A QHEI score of 60 or above would
designate full support to warm water streams without use impairment.
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Table 2-6 - Qualitative Habitat Evaluation Index
QHEI Component Point Value
Substrate type and quality 20
In-stream cover type and amount 20
Channel morphology – sinuosity, development, channelization stability 20
Riparian zone – width, quality, bank erosion 10
Pool quality – maximum depth, morphology, current 12
Riffle quality – depth, substrate stability, substrate embeddedness 8
Map gradient 10
Table 2-7 - QHEI Scores by River Mile/km
River Mile
(km)
QHEI Score
27.0 (43.4) 67.5
25.0 (40.2) 58.5
22.8 (37.0) 46.5
18.3 (29.5) 84.0
16.5 (26.5) 71.5
13.7 (22.0) 47.5
12.7 (20.4) 40.5
11.0 (17.7) 39.5
The Ohio QHEI scores for similar river miles tend to rate the upriver segments higher than the
Illinois SHAP ratings, but the downriver segments are similar in their categorization
2.6 Dam Site Investigations
Removal or reconfiguration of dams can increase dissolved oxygen in waterways. The three
dams on Salt Creek were investigated to gain an understanding of their characteristics. The
names, locations, and river locations (based on the GIS model) of the three dams on Salt Creek
are listed in Table 2-8, and were depicted in Figure 1-1.
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Table 2-8 - River Dam Information
Name
Year
Built
River Mile
(km)
Bounding Bridges Nearest
Upstream Downstream Town
Oak Meadows Golf
Course Dam
22.9 (36.8) Elizabeth Dr I-290 Wood Dale
Old Oakbrook Dam 12.5 (20.1)
Oak Brook
Rd / 31st St
Fullersburg
Woods Forest
Preserve Foot
Bridge
Oak Brook
Graue Mill Dam at
Fullersburg Woods
10.7 (17.2)
Fullersburg
Woods Forest
Preserve Foot
Bridge
York Rd Oak Brook
The river distances reported in the above table and throughout this report were generated from
GIS data for Salt Creek, supplied by DuPage County. This GIS model closely follows the
existing stream centerlines, and as a result, is different than river linear units published by others.
The length of stream is critical for evaluating water quality, so the most accurate representation
of this parameter as generated by the GIS model was used for this study.
2.6.1 Oak Meadows Golf Course Dam
The Oak Meadows Golf Course Dam is owned by the Forest Preserve District of DuPage
County.
Figure 2-2 - Oak Meadows Golf Course Dam
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A survey of the dam and channel profile was conducted as was a characterization of the amount
of deposited material upstream of the dam during a field visit. Joe Reents, the Oak Meadows
Golf Course Superintendent, was present on site. He indicated that the structure was used
historically to facilitate the collection of irrigation water. However now the course has
constructed a gravity-fed pond to accomplish this task and the dam is no longer needed for this
purpose.
The dam spillway appears to be an all concrete structure. The structure is 30.2 ft (9.2 m) wide
(between abutment edges) with about 2ft (0.6 m) of head at normal flow. The abutments are 2ft
(0.6 m) thick concrete walls with a mixture of materials used as fill. The dam appeared to be in a
slightly degraded condition. The left abutment facing downstream was clearly leaning
downstream, and significant cracks have developed in the concrete (Figure 2-3). Previous
measures had been taken to correct the problem using reinforcing steel tie rods anchored to the
upstream abutment wall. The same problem and mitigation measures occurred in the right
abutment but the wall did not appear to be leaning.
There is a 2.9 ft (0.9 m) culvert pipe located on the left side of the structure which was clogged
on the day of survey with debris. This pipe can provide the means to lower the water surface
below the weir elevation of the structure, assuming the capacity is not exceeded by the discharge
of the creek at the time.
Figure 2- 3 - Left abutment, significant crack
DO Improvement Feasibility Study
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Figure 2-4 - Mature Tree compromising left training wall
Figure 2-5 - View of left abutment and culvert, the steel gate can be seen in the upper right
An investigation into the amount of sediment upstream of the dam indicated an average of about
2 ft (0.6 m) of material in the channel. A total of nine cross sections were taken beginning just
upstream of the dam and extending upstream. Detailed cross sections and locations can be seen
in Appendix B. A profile of the survey through the structure is depicted in Figure 2-6.
DO Improvement Feasibility Study
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Oak Meadows GC Dam Profile
656
658
660
662
664
666
668
670
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Station (ft)
Elevation (ft)
Water Surface
Bed Surface
Depth of Refusal
Crest Elev. 667.08'
Figure 2-6 - Water Surface Profile at Oak Meadows Golf Course Dam
Sediment has accumulated in areas of low velocity within the stream and is not uniform in its
distribution. All of the material consists of semi-consolidated fines. Storage of material within
the small impoundment is still occurring as evidenced by the deposition of material in front of
recently installed A-jack bank protection measures.
Because of the low elevation of the structure, the hydraulic impacts to storm water storage during
flood events are expected to be minor. However, at low flows the dam maintains a fairly constant
pool elevation upstream of the structure that persists for quite a distance because of the low
gradient.
2.6.2 Old Oak Brook Dam
The Old Oak Brook Dam is reported to have been constructed in the 1920‟s by Paul Butler to
maintain an aesthetic pool through his property holdings during low flow periods on Salt Creek.
The dam is now owned by the Village of Oak Brook. Hydraulic studies conducted by
Christopher Burke Engineering in 1989 indicated that the dam provides little, if any, mitigation
during flood events. Further, residents report that the dam frequently becomes submerged
completely during flood events.
DO Improvement Feasibility Study
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Figure 2-7 - Old Oak Brook Dam
Removal of the structure was investigated in 1989. A letter from the Butler National Golf
Course (upstream of the dam) indicated a desire to leave the dam in place and preserve water
levels through the golf course. No other discussion on the merits or detractions of removal was
found.
The original structure of the Oak Brook Dam underwent major rehabilitation approximately 20
years ago. There are two main spillway components - the fixed elevation spillway and a gated
“emergency” spillway. The gated spillway section consists of two steel vertical slide gates
rehabilitated in 1992. The primary spillway is 65 ft (19.8 m) wide, with about 3 ft (1 m) of head
during normal flow, and consists of grouted stone with a concrete cap (no information was found
on when the concrete cap was applied). The condition of the cap could not be determined on the
day of the survey. Areas of the grouted stone spillway have eroded on the downstream face,
leaving an irregular geometry. A report by STS Consultants indicated a concrete filled fabric-form
mat had been applied to the upstream face of the structure in the early 1980‟s. The left and
right retaining walls consist of grouted stone and reinforced concrete overlain to a larger extent
by concrete filled fabriform mats.
Seven cross sections were sampled upstream of the dam to quantify the amount of sediment
upstream. An average of about 1 ft (0.3 m) of material was found upstream of the dam, with the
DO Improvement Feasibility Study
Salt Creek 2.0 Existing Conditions
DRSCW 2-19 September 2009
largest accumulation just upstream of the left retaining wall. It is not known how often the sluice
gates are opened on the structure but sediment upstream of this inlet was minimal, while
downstream, fines had accumulated in the sluice gate channel. Most of the material immediately
upstream of the dam was cohesive fines but the sediment quickly coarsened to sands upstream
near the 31st Street Bridge. There was not an excessive amount of material accumulated behind
the dam.
Old Oak Brook Dam Profile
640
641
642
643
644
645
646
647
648
649
650
0 1000 2000 3000 4000 5000 6000
Station (ft)
Elevation (ft)
Water Surface
Bed Surface
Depth of Refusal
Crest Elev. 648.3'
Figure 2-8 - Old Oak Brook Dam Sediment Profile
Hydraulic computations compiled by a number of studies indicate that the backwater effect of
the dam stretches up to approximately 31st Street during small flood events (less than 10 year
event) and 22nd street during events higher than a 10 year event. The storage provided by the dam
is minimal.
2.6.3 Graue Mill Dam
There is no information on the original structure constructed in the 1850‟s at the site. The site
was purchased by the DuPage Forest Preserve District in 1933 and in 1934 the Civilian
Conservation Corps built the existing concrete structure that stands on the site today. The dam
has a crest length of 132 ft (40.3 m), standing 6.2 ft (1.9 m) in height. The purpose of this
construction was power generation. A side stream mill race is also present, which was used to
house the wheel at Graue Mill. In 1991, the Forest Preserve District retained Harza Engineering
Company to design a dewatering gate on the North side of the dam which allows for periodic
drawdown for maintenance and inspection.
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Figure 2-9 – Graue Mill Dam
The DuPage County Forest Preserve District gives a detailed and exhaustive account of the
structure of the dam which is summarized below from a 1991 Maintenance Plan.
Concrete Spillway: The concrete wall is 2.9 ft (0.9 m) thick supported by a 23 ft (7
m) wide concrete footing. An 8.8 ft (2.7 m) sheet pile wall is installed 9.5 ft (2.9 m)
upstream of the concrete footing. The walls key into the earthen abutments on both
sides. A 10.2 ft (3.1 m) long concrete stilling basin prevents erosion on the
downstream side of the dam.
Earthen Abutments: Both abutments are built on a 19 ft (5.8 m) thick layer of hard
clay overlain by (3.1 m) of dense sand, 2.9 ft (0.9 m) of hard clay, and finally 5.9 ft
(1.8 m) of topsoil on the North abutment, or 4.9 ft (1.5 m) of topsoil over 2 ft (0.6 m)
of dense silt on the South. Tests for seepage conducted by Harza were negative for
both abutments.
Mill Race Channel and Sluice Gate: the Mill Race is 10.1 ft (3.1 m) wide by 210 ft
(64.1 m) long and was used to power the 18 ft (5.5 m) wheel used at Graue Mill.
Water control is provided by a sluice gate.
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Dewatering Slide Gates: 9.8- 14.5 ft (3 - 2.1 m) wide by 3.9 ft (1.2 m) high stainless
steel slide gates comprise the dewatering portion of the dam. The gates are housed in
a reinforced concrete structure located on the North side of the dam.
Eight cross sections were taken above the Graue Mill Dam; detailed information can be viewed
in Appendix B and summarizes in Figure 2-10. There is generally 1 to 2 ft (0.3 to 0.6 m) of
deposition along the channel margins with often little to no deposition in the thalweg of the
channel. This lack of material is likely due to the impact of a dredging project accomplished in
the late 1990s. The channel regains its natural thalweg of coarse material approximately 365 m
upstream of the dam. The material that is being transported by the stream is depositing in a point
bar just downstream of the final bend in the Fullersburg Woods property, starting approximately
700 ft (220 m) above the dam.
Graue Mill Profile
630
632
634
636
638
640
642
644
0 500 1000 1500 2000 2500 3000 3500
Station (ft)
Elevation (ft)
Water Surface
Bed Surface
Depth of Refusal
Crest Elev. 642.7'
Figure 2-10 – Graue Mill Dam Profile
The hydraulic impacts of the dam reach through the Forest Preserve District Property upstream
but do not extend above the Old Oak Brook Dam. The complete removal of the Graue Mill Dam
would result in reducing the flood elevation by approximately 1 ft (0.3 m) for the 100 year event
between the Graue Mill Dam and diminishing toward the Oak Meadows Dam, according to
previous calculations performed by the Forest Preserve District (prior to the new updated FEQ
model). In terms of storm water storage, the reservoir provides little capacity and a general
consensus among past studies indicates the dam has little value in flood mitigation.
2.7 Flood Control Reservoirs
DuPage County Division of Stormwater Management operates two flood control reservoirs along
the main stem of Salt Creek, the Wood Dale Itasca Reservoir at River Mile 42.4 (68.2 km) and
the Elmhurst Quarry Flood Control Facility at River Mile 17.6 (28.3 km). The Wood Dale Itasca
Reservoir has capacity for 1,775 acre-ft (578 million gallons). The Elmhurst Quarry Flood
Control Facility has capacity for 8,300 acre-ft (2,700 million gallons). Aeration of the water
DO Improvement Feasibility Study
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DRSCW 2-22 September 2009
pumped back into Salt Creek is provided by a cascading entrance back into the creek at
Elmhurst. Although not evaluated as part of this study, dewatering both of these reservoirs
during low flow-warmer conditions would improve the DO levels within the creek from the
increased flow and cooler temperatures of this water.
2.8 Sediment Oxygen Demand (SOD) Field Measurements
One of the inputs into a DO model is the Sediment Oxygen Demand, which can be highly
variable as the stream geometry and slope changes. To provide these data, SOD rates were
measured in situ in the summer of 2006 and at additional sites in the summer of 2007. The
complete reports are contained in Appendix B.
Table 2-9 - SOD Survey Locations and Results
Year
Sampled
River
mile
(km)
Location
Average SOD
(g/m2/day) -
Temp. Corrected
to 20 oC
2007 23.0
(37.0)
North of Oak Meadows
Dam/in Golf Course
0.50
2007 22.9
(36.8)
North of Oak Meadows
Dam/in Golf Course
2.27
2007 22.8
(36.7)
South of Oak Meadows
Dam/north of I290
0.84
2007 22.7
(36.5)
South of Oak Meadows
Dam/south of I290
0.19
2006 21.0
(33.8)
Downstream of Addison S
WWTP at Fullerton
0.64
2006 19.5
(31.4)
Downstream of North Ave.,
center of stream bed
0.47
2006 16.2
(26.0)
Butterfield Rd, between the
two bridges, east bank
2.31
2006 13.9
(22.4)
Upstream of Cermak, Route
22
1.02
2007 12.7
(20.4)
Above (North) of 31st St 1.19
2007 12.5
(20.1)
Downstream of 31st St,
above Old Oak Brook Dam
1.20
2006 12.5
(20.1)
Downstream of 31st St,
above Old Oak Brook Dam
1.38
2007 12.2
(19.6)
Spring Rd Salt Creek
junction (north of road)
0.91
2007 11.4
(18.3)
Northern Fullersburg Woods
Impoundment
2.09
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2006 11.1
(17.9)
Footbridge at Fullersburg
Woods
2.52
2007 11.0
(17.7)
Southern Fullersburg Woods
Impoundment
1.76
2006 10.8
(17.4)
Upstream of Graue Mill
Dam
1.90
2007 10.7
(17.2)
Upstream of Graue Mill
Dam
2.70
2007 10.6
(17.1)
Downstream of York Rd 1.79
2007 10.1
(16.3)
Wide Channel north of
Office Park
1.36
2006 7.9
(12.7)
Downstream (East) side of
Wolf Rd
3.59
A bottom substrate composed of fine-grained sediments (clay, silt and sand) is conducive to
measuring SOD; coarse materials (gravel, cobbles and boulders) are not because it is difficult to
achieve a seal on the bottom of the chamber. High SOD rate is generally associated with a high
organic content of the sediment. Slow moving reaches of the river are areas where fine-grained,
organic sediments are likely to be found. When the field crews arrived at each station, the river
bottom was viewed or probed to estimate the percent bottom coverage of fine-grained sediment.
The width and depth of the river were also measured and recorded. The fine-grained sediment
area was identified as a suitable location for deployment of SOD measurement chambers.
Elevated water temperature was preferred for these measurements to reduce the modeling
uncertainty associated with applying a temperature adjustment coefficient based on the literature.
Field measurements were performed on five days during a period when there was no
precipitation on that day and the preceding day. On each day of the field survey, SOD was
measured at two to three stations. Water temperature ranged from 23.3oC to 28.8oC with an
average of 25.1oC. Table 2-10 presents the SOD results for the two summers corrected to a
constant 20oC ambient water temperature.
With the exception of the Wolf Road at River Mile 7.9 (12.7 km) SOD value, the highest SOD
values recorded were in the Fullersburg Woods Impoundment above the Graue Mill Dam.
Elevated SOD values were also recorded above the Oak Meadows Dam and at Butterfield Road
where the width of Salt Creek expands significantly, resulting in lower stream velocities and
sediment deposition during lower flow periods.
2.9 Continuous Dissolved Oxygen Monitoring
The DRSCW monitored DO at three locations along Salt Creek during the summer months from
2006 to 2008. These locations are at Butterfield Road, within Fullersburg Woods Forest Preserve
0.4 miles (0.6 km) above the dam, and at York Road immediately below the Graue Mill Dam.
In addition MWRDGC maintained four 4 sondes on Salt Creek. The DO monitoring locations
DO Improvement Feasibility Study
Salt Creek 2.0 Existing Conditions
DRSCW 2-24 September 2009
were depicted on Figure 1-1. All DO data was collected according to the QAPP agreed on
between the Illinois EPA and the DRSCW. Calibration of the probes for the other parameters
listed was carried out according to the manufacturer‟s recommendations.
Table 2-10 - DO Monitoring Locations
A summary of the minimum DO values for 2006 from the DRSCW probes are presented in
Figure 2-11. At Butterfield Road, DO values in June and July were recorded below the 5.0
mg/L minimum DO standard, although the majority of the days achieved the minimum standard.
In Fullersburg Woods, minimum DO values below 5.0 mg/L were common in June 2006 while
downstream of the dam the DO levels were consistently above the minimum standard and
showed less variation.
Figure 2-11 DO values for 2006
Figure 2-12 presents the DO results for the 2007 monitoring. The results are similar to the
previous year. At Butterfield Road, DO levels in August dropped below 3.5 mg/L, the minimum
DO standard for August, and in June levels below 5.0 mg/L were also reported. The minimum
DO values in Fullersburg Woods in 2007 were below 5.0 mg/L for approximately 50% of the
days in June, and also levels in July were below 5.0 mg/L. In August, the minimum was reported
as less than 3.5 mg/L.
Station
River mile
(km)
Location Crossroad Steward
SCBR
16.1 (25.9)
Elmhurst Butterfield Road
Conservation
Foundation
SCFW
11.1 (17.9) Oak Brook
Fullersburg
Woods Forest
Preserve
City of Elmhurst
SCYR 10.6 (17.0) Oak Brook York Road City of Elmhurst
DO Improvement Feasibility Study
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DRSCW 2-25 September 2009
Figure 2-12 DO values for 2007
To show the diurnal variation, a sign of plant/algae activity, the time plots for the same three
stations in 2008 are depicted in Figures 2-13, 2-14, and 2-15. At Butterfield Road, a DO swing
on the order of 3 mg/L was typical, with minimum DO levels reaching 2.5 mg/L. The low DO
results recorded in September are associated with a large rain event that likely re-suspended in-stream
sediments (although wash-off of CBOD materials and CSO operation cannot be ruled
out). At Fullersburg, DO levels below 4 mg/L were reported in June, and in August approached
2.0 mg/L. DO swings at Fullersburg were typically 3 mg/L in May and June and less in July.
After the heavy rains in early September, the DO swings were less than 0.5 mg/L reflecting the
flushing of the algae out of the impoundment. At York Road, minimum DO levels were
consistently above 5.0 mg/L, and the diurnal swing was consistently less than 2.0 mg/L.
DO for SCBR May-September 2008
0
2
4
6
8
10
12
14
05/02/08
05/16/08
05/30/08
06/13/08
06/27/08
07/11/08
07/25/08
08/08/08
08/22/08
09/05/08
09/19/08
Time
DO (mg/L)
LDO mg/l
Figure 2-13 DO values for 2008 at Butterfield Rd
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DO for SCFW April-October 2008
0
2
4
6
8
10
12
04/17/08
05/01/08
05/15/08
05/29/08
06/12/08
06/26/08
07/10/08
07/24/08
08/07/08
08/21/08
09/04/08
09/18/08
10/02/08
Time
DO (mg/L)
LDO
Figure 2-14 DO values for 2008 at Fullersburg Woods
Note, LDO stands for Luminescent DO, which refers to the method/equipment
used for measurement.
DO SCYR May-October 2008
0
2
4
6
8
10
12
05/22/08
05/29/08
06/05/08
06/12/08
06/19/08
06/26/08
07/03/08
07/10/08
07/17/08
07/24/08
07/31/08
08/07/08
08/14/08
08/21/08
08/28/08
09/04/08
09/11/08
09/18/08
09/25/08
10/02/08
10/09/08
Time
DO (mg/L)
LDO mg/l
Figure 2-15 DO values for 2008 at York Rd, below Graue Mill Dam
2.10 Biological and Phosphorus Quality
In conjunction with the DO monitoring and addressing low flow low DO issues, the DRSCW
was also collecting extensive fish and macro-invertebrate data on Salt Creek (Midwest
Biodiversity Institute, 2008). Figure 2-16 summarizes the Index of Biotic Integrity (IBI) for the
fish collected. Moving downstream from the mouth, the biodiversity scores are higher (better)
above the Fullersburg Woods Impoundment, where a sharp drop in fish biodiversity occurs.
Downstream of the Graue Mill Dam, the highest (best) biodiversity scores on Salt Creek were
recorded. Nineteen fish species were found below the Graue Mill Dam, while only 13 species
were collected above this dam. The spike in IBI immediately below the dam is probably due to
crowding as fish migrating upstream encounter the barrier (for example white suckers were
found downstream of Graue Mill Dam). Wastewater treatment plant and CSO locations are also
depicted in Figure 2-16. There is no consistent change in IBI scores above or below treatment
plants. Biodiversity scores are the poorest near Butterfield Road, where as described previously
DO Improvement Feasibility Study
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DRSCW 2-27 September 2009
the creek as been over-widened resulting in very low velocities, sediment deposition, and the
establishment of excessive rooted vegetation. This is also downstream of a number of CSO
points.
Figure 2-16 Fish Biodiversity
Figure 2-17 presents the macro-invertebrate quality index, as well as calculated QHEI
(Qualitative Habitat Evaluation Index) scores. A similar deterioration in quality occurs with the
benthic organisms as with the fish at the Graue Mill Dam; however, further upstream the benthic
index improves to levels observed downstream of the Graue Mill Dam.
Figure 2-17 Macro-Invertebrate Quality
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The Illinois Nutrient Standard Workgroup has conducted extensive research over the past five
years on the correlation between nutrients, algae, and minimum DO levels. Several findings
from this group‟s research are that on mid-sized streams in Illinois; nutrients are never limiting
sestonic, periphyton or macro-algae growth, but rather light, substrate, and stream velocities are
important factors (David, M., et al., 2007). For phosphorus to be controlling, the Illinois
research suggests that the total phosphorus needs to be less than 0.07 mg/L (Ibid). Figure 2-18
presents the total phosphorus measured levels along Salt Creek. In the headwaters, the levels are
near the 0.07 mg/L level, and quickly increase above 0.10 mg/L by RM 32 (51.5 km). Above the
first wastewater treatment plant, the total phosphorus is typically above 0.2 mg/L. The total
phosphorus level in the lower 25 miles (40 km) remains steady at an average of approximately
0.7 mg/L.
Figure 2-18 Phosphorus Levels in Salt Creek
Figure 2-18 Phosphorus Levels in Salt Creek
2.11 Summary
Salt Creek is a highly disturbed urban stream, with low channel gradients and extensive
channelization. The wastewater treatment plants contribute a significant percentage of the total
phosphorus on Salt Creek; however, above the first treatment plant, the phosphorus
concentrations are already above the level that has to be attained for phosphorus to become a
limiting factor for plant and algal growth. The flow contributed by the wastewater treatment
plants during low flow reduces temperatures and increases stream velocities, both key factors in
reducing plant and algal growth when phosphorus levels are above 0.07 mg/L.
4 5
1 2 3 6 7 8 9
40 30 20 10 0
River Mile
0.01
0.10
1.00
10.00
Total Phosphorus mg/l
1 MWRDGC Egan WRP 4 Wood Dale South STP 7 Salt Creek Sanitary District
2 Itasca STP 5 Addison North STP 8 Elmhurst WWTP
3 Wood Dale North STP 6 Addison South-A.J. Larocca STP 9 Addison Creek
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DRSCW 2-29 September 2009
The continuous DO monitoring has identified the DO above the Graue Mill Dam as the lowest
on Salt Creek. SOD results in the Fullersburg Woods Impoundment (above the Graue Mill Dam)
are elevated from the sediment that has accumulated behind the dam, a factor accentuated by the
residence time and geometry of the impoundment. (Longer retention times allow for greater
depletion of the DO in the water column.) The biological studies have also shown that the Graue
Mill Dam is acting as a physical barrier to fish migration, and the fish biodiversity above the
dam is the significantly lower than that below the dam.
From the results presented in this section, a dissolved oxygen model was developed, which is
presented in the next section. The model was used to prioritize projects and develop alternatives.
From this model, alternatives for improving DO levels within Salt Creek are developed in
following sections.
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DRSCW 3-1 September 2009
3 WATER QUALITY MODELING
The Illinois Water Quality Report 2006 identifies Salt Creek as impaired for a number of water-borne
pollutants including low dissolved oxygen. Modeling analyses of Salt Creek were
conducted in order to allocate allowable waste loads for BOD5 and ammonia using a water
quality model called QUAL2E. The original (QUAL2E) TMDL water quality model of Salt
Creek was calibrated using field sampling data collected in June 1995. Since the TMDL reports
in October 2004, the DuPage River Salt Creek Workgroup has improved the database from
which a calibrated model could be developed.
The purpose of water quality modeling is to identify locations of low DO and then quantitatively
evaluate the effects of alternatives used to improve DO. The modeling tool used in the TMDL
study (QUAL2E) has been updated with a more user-friendly interface, more flexible inputs and
convenient post-processing tools. The updated version of QUAL2E is called QUAL2K and was
developed for the USEPA by Steve Chapra, et al., at Tufts University (Chapra et al. 2005).
Model theory, equations and parameters are described completely in the QUAL2K Users
Manual. Model conversion to QUAL2K from QUAL2E and validation of the new modeling tool
(QUAL2K) are described herein.
3.1 Conversion of QUAL2E to QUAL2K Model
The fundamental utility of QUAL2E and QUAL2K is essentially the same; they are one-dimensional,
steady-state models to predict DO and associated water quality constituents in
rivers and streams. However, QUAL2K has more refined features such as the capability of
diurnally varying headwater / meteorological input data and a full sediment diagenesis model to
compute sediment oxygen demand (SOD) and nutrient fluxes from the bottom sediment to the
water column. In addition, the QUAL2K model offers more options for decay functions of water
quality constituents, reaeration rate equations, heat exchange and photo-synthetically available
solar-radiation calculations.
As the fundamental theoretical underpinnings of both models are similar, the objective of this
subtask was to use the input data previously used in QUAL2E and produce QUAL2K outputs
that are similar to the results found in the TMDL reports. Since QUAL2E input data files were
not available, the listings of input data in the appendices of the TMDL reports were used to
prepare the input to QUAL2K. The QUAL2E model set-up was closely followed to reproduce
those results by applying QUAL2K instead of QUAL2E. The more refined features in the
QUAL2K, described above, were not implemented in order to adhere, at least initially, to the
QUAL2E modeling process. Model boundaries, running from the spillway at Busse Woods Dam
to the confluence of Salt Creek and the Des Plaines River remained the same. Subsequently, we
independently evaluated the selection of model formulations and functions and parameter
evaluations for Salt Creek as described in section 3.2.
3.2 Validation of QUAL2K Model
After converting the QUAL2E model to QUAL2K, recent DO measurement data were needed to
validate the QUAL2K model. Several potential sources of data include the DuPage County field
DO Improvement Feasibility Study
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DRSCW 3-2 September 2009
samples from the summer of 2005, the Metropolitan Water Reclamation District of Greater
Chicago (MWRDGC), and newly installed DRSCW DO probes along Salt Creek.
The DO in Salt Creek was measured by DuPage County during several days starting on July 8,
2005 and ending on August 10, 2005. The field data consist of date, time, station number, cross-section
position (left, middle, right) sample depth and DO. It is important to note that the
measurements were performed during daylight only so that the cyclically low DO due to
respiration of phytoplankton during the night time was not captured.
The MWRDGC has continuous measurements of DO and temperature at three stations along Salt
Creek: JFK Boulevard (River Mile 28.7 (46.2 km), Thorndale Avenue (River Mile 26.9 (43.3
km) and Wolf Road (River Mile 8.1 (13.0 km). The first station is situated near the upstream
boundary of the model and these data were used to specify headwater conditions. The second
station is 3.1 miles (5 km) from the model upstream boundary such that the elapsed travel time to
this point is limited and therefore only minimal change in simulated water quality would be
expected. The third MWRDGC station is located more than 3.1 miles (5 km) downstream of the
Graue Mill Dam, and is not within the extent where alternative aeration projects are being
considered. The DO and temperature measurements at Wolf Road were reviewed to see the
diurnal variation. However, these data are not graphically compared to the model results because
the selection of the time when the creek was at steady-state conditions could not be made without
the stream flow data.
Reach lengths were modified in QUAL2K based on up to date GIS data developed as part of this
project as opposed to USGS River Mile information used in QUAL2E. River mile /km
differences for Salt Creek were as high as 2.4 miles (3.8 km) in the upstream reaches (near River
Mile 25 (40.2 km) and gradually decreased with distance downstream between the GIS and
USGS data.
The DO data were plotted against river distance to show the range in DO and provide an
approximate basis for comparing QUAL2K results. As QUAL2K is a steady-state model, it
assumes that stream conditions, such as flow, point source discharge and loadings, are constant
in time. Sampling to collect data for comparison to a steady-state model is normally performed
during periods when flow and other conditions are relatively constant. However, the initial DO
data may not reflect steady-state conditions because of the variability in flow, meteorology, point
source loadings and headwater conditions during the 32 day sampling period.
Water quality data were collected in 2006 and 2007 to improve the calibration of the QUAL2K
model of Salt Creek. DO and temperature were measured continuously at seven sampling
stations, as described in Section 2. Sediment Oxygen Demand (SOD) was measured in situ at
eight stations in the summer of 2006 and another eight stations in the summer of 2007 to provide
data for estimating the SOD model parameter in Salt Creek.
3.2.1 Model Inputs
This section describes the model inputs developed to simulate the period of DO data collection,
as well as changes to the hydraulic characteristics (i.e., stream slope, depth and width data)
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necessary to reflect findings obtained during the field data collections (see Section 2.0, Existing
Conditions for more details) and additional data collected. Reaction rate coefficients that depend
on stream depth and velocity, such as the reaeration rate coefficient and the BOD oxidation
coefficient, were also changed to reflect the changes in the hydraulic data. Other model
parameter values from QUAL2E were also changed in QUAL2K in an attempt to improve its
ability to simulate conditions in Salt Creek as explained below.
USGS flow data for the summers of 2006 and 2007 were presented graphically to identify
periods of low flow that would be suitable for model calibration and verification. Precipitation
data were also plotted to show that dry weather conditions occurred during the identified low
flow periods and there were no significant wet-weather sources (storm water, combined sewer
overflows) at these times. The model was calibrated using data for the low flow period of August
1-4, 2007 and verified for the low flow period of June 19-21, 2006. Model projections of
baseline conditions and management alternatives were based on these conditions, when most of
the flow comes from point source discharges. Input data for flow and point sources are specific
for the selected time periods or the model projections. Input data for other model parameters are
the same for both time periods and the model projections, unless noted otherwise. Reaction rates
(decay, re-aeration) are input at a single temperature and adjusted internally by QUAL2K to the
temperature calculated by the model. SOD for each reach is based on the temperature and the
measured SOD rate in that reach.
Headwaters and Tributaries: Headwater flows were taken from USGS flow data for
the selected periods. Flows from point sources were accounted for in calculating
flows with distance upstream of the gaging stations. Tributary flow was also
estimated based on the ratio of flow to drainage area at the gaging station and the
estimated drainage area of the tributary. The hourly DO at the headwater of Salt
Creek was based on the Busse Lake Dam station continuous DO measurements from
MWRDGC. This station is located near the headwater of the main reach of the Salt
Creek, and therefore is representative of the boundary conditions of the model. The
same diurnal variations of DO and water temperature were also implemented for the
tributaries. The DO, CBOD5, and ammonia concentrations of the tributaries were
assumed to be the same as the QUAL2E model.
River Distances: As mentioned earlier, stream reach lengths were modified in
QUAL2K based on GIS data developed for this project whereas USGS information
was previously used in the QUAL2E model.
Model geometry: Main channel slopes were revised using the Digital Elevation
Model (DEM) developed by USGS for Salt Creek. The DEM is publicly available in
a GIS format and elevation information for end points of each reach segment was
extracted from the overlay of the DEM and reach end points set up in QUAL2K. In
addition, impoundment areas, where there are occurrences of hydraulic backup and
sedimentation due to the presence of dams, were delineated as a refinement in
QUAL2K. This was done by subdividing the appropriate QUAL2E model reach into
two reaches for QUAL2K, a free-flowing reach and an impounded reach. Water depth
information was taken from the Existing Conditions Report (see Section 2.0). ). A
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sediment survey of the Fullersburg Woods Dam Impoundment, supplied by the Forest
Preserve District of DuPage County (1997) was used to set the geometry of the
reaches in this part of the model. These changes of channel slope, depth and velocity
in impounded areas would potentially change reaeration rates and BOD
deoxygenation rates as explained under “decay rates” below.
Meteorological Data: Air, dew point temperatures were changed to represent more
reasonable local effect of weather for a period with which model validation was
compared. Other meteorological inputs such as wind speed, cloud cover and shades
were set to 0 m/s, 30% and 0%, respectively. As the primary intent of the model is to
simulate hot, low flow conditions, precipitation data are not included as input.
Decay Rates: As stated, changes to the stream geometry indicated that reaction rate
coefficients would also change. CBOD, nitrification and settling rates of various
water quality constituents were changed using stream characteristics and a more
reasonable range based on Chapra 1997, Thomann and Mueller 1987 and EPA 1985.
Velocity and depth are generally calculated by QUAL2K except for impounded
reaches, where these data are taken from the Existing Conditions section and directly
input to the model. Appendix C includes the inputs for the decay rates and reaeration
rates in Salt Creek.
Background Light Extinction: In an effort to account for the fact that the model
lacks absorption and back scatter of light by particulates (total suspended solids (TSS)
was not simulated in the model), a higher background light extinction rate was used
compared to QUAL2E inputs. Appendix C includes the light and heat inputs.
Point Sources: There are seven municipal wastewater treatment plants that discharge
into Salt Creek. These are depicted on the graphs developed by letter code, as
summarized below:
Point Source Label River Mile (km) from Mouth
Egan a 29.6 (47.6)
Wood Dale N b 25.7 (41.4)
Wood Dale S c 25.3 (40.7)
Addison N d 22.6 (36.4)
Addison S e 20.9 (33.6)
Salt Creek SD f 17.9 (28.8)
Elmhurst g 17.8 (28.6)
Monthly Discharge Monitoring Reports (DMR) monthly average pollutant loadings
for August 2007 and June 2006 were utilized as representative of low flow, warm,
summer effluent quality. The monthly average values were used to set discharge
flows, CBOD5 and ammonia concentrations.1 Other effluent data, such as organic
1 Actual performance data over a month period is more representative of true worst case conditions, as opposed to
assuming all treatment plants are discharging at their daily permitted maximum limits under dry, warm conditions.
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nitrogen, nitrate, phosphorus and DO concentrations, were not available in the DMR
data; therefore, the previous QUAL2E inputs were used.
Temperature: Temperature is calculated by QUAL2K and compared to the
measurement data for the calibration and verification model runs. Model projections
were based on setting air temperature so that the stream reached temperatures
approximately 3oC warmer than average temperatures observed in July and August
2005.
Based on historical temperature data, the stream temperature reaches temperatures
approximately 3oC warmer than was observed in June/July 2005. Figure 3-1 depicts
the stream temperature that would be used for the baseline conditions, reflecting the
worst case conditions.
Figure 3-1. Baseline Stream Temperature for Salt Creek
Flow: Figure 3-2 depicts the base flow predicted in Salt Creek based on the actual
discharges from the wastewater treatment plants in June 2005 and the base flow.
Model projections are based on the flow in this Figure. The resulting travel times
under low flow conditions is presented in Figure 3-3. The overall travel time from the
Salt Creek Mainstem
0
5
10
15
20
25
30
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
Temperature (oC)
Temp(C) Average Temp(C) Minimum Temp(C) Maximum
Point Source July Daily Average Data August Daily Average Data
Monthly Average of June 2005 DMR Condition with 3 o C Increased Plant Discharge and Air Temperature
a b c d e f g
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most upstream wastewater treatment plant (Egan) to the mouth is on the order of 5
days under low flow conditions.
Figure 3-2. Base Flow for Salt Creek
Salt Creek Mainstem
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
Flow (m3/s)
Q, m3/s Point Source
Monthly Average of June 2005 DMR Condition with 3 o C Increased Plant Discharge and Air Temperature
a b c d e f g
Figure 3-2. Base Flow for Salt Creek
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Salt Creek Mainstem
0.0
1.0
2.0
3.0
4.0
5.0
6.0
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
Travel Time (day)
trav time, d Point Source
Monthly Average of June 2005 DMR Condition with 3 o C Increased Plant Discharge and Air Temperature
a b c d e f g
Figure 3-3. Travel Time in Salt Creek, June 2005
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Sediment Oxygen Demand: The SOD rates in the TMDL QUAL2E model input
listings estimated at 0.2 to 1.5 g/m2/d for Salt Creek were lower than expected for the
existing conditions. SOD measurements were conducted on Salt Creek in 2006 and
2007 to improve input into the QUAL2K model. The Salt Creek SOD Reports for
2006 and 2007 are included in Appendix B. The SOD measured at ambient
temperature in Salt Creek ranged from a minimum of 0.28 g/m2/day to a maximum of
3.60 g/m2/day. The highest SOD was observed in the impoundment upstream of
Graue Mill Dam, and at a single site below the Graue Mill Dam, which does not
appear representative of this stretch. Figure 3-4 presents comparisons of the SOD
results during the 2006 and 2007 surveys, adjusted to a water temperature of 20oC.
The 2007 SOD rates are similar to the 2006 SOD rates in the impoundments of the
Old Oak Brook and Graue Mill Dams.
Using the base temperature (see above), the measured SOD rates were adjusted. Figure 3-5
presents the SOD rates with the 3oC increase in June temperatures for each segment of the creek.
Figure 3-4. Comparison Temperature Corrected SOD in Salt Creek
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Figure 3-5. SOD rates with the 3oC increase in June temperatures
3.2.2 Calibration and Verification of the Model
Under low stream flow conditions, the contribution from the point source discharges to Salt
Creek collectively account for 46% of the total flow at the model’s downstream boundary. To
calibrate the model data from August 1-4, 2007 were utilized and the graph is labeled August 2,
2007. The model inputs are included in Appendix C, and the predicted DO versus measured DO
at specific locations is depicted in Figure 3-6. Stream temperatures ranged from 23 to 31oC on
this date, and the stream flow was essentially at low flow conditions. The model, as presented in
Figure 3-6, predicted higher minimum DO values above Oak Meadows Dam and below the
Graue Mill Dam, generally by less than 1 mg/L. However, overall, the model reasonably
predicts the average DO and the diurnal variation in DO.
To verify the model will accurately predict DO changes under varying conditions, the model was
run for the conditions on June 19-21, 2006 and the graph is labeled June 20, 2006. Input data are
presented in Appendix C, and the model prediction is presented in Figure 3-7, along with actual
DO measurements. A larger diurnal swing in DO was present above the Old Oak Brook Dam
than predicted. This is attributed to an increase in algal and aquatic plant population. Measured
DO minimum levels were also lower than the model predicted; however, the results were within
Salt Creek Mainstem
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
SOD (g/m2/d)
SOD gO2/m^2/d SOD-data Prescribed SOD gO2/m2/d Point Source
Monthly Average of June 2005 DMR Condition with 3 o C Increased Plant Discharge and Air Temperature
a b c d e f g
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Salt Creek (8/2/2007) Mainstem
0
2
4
6
8
10
12
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
DO (mg/L)
DO(mgO2/L) DO (mgO2/L) data DO(mgO2/L) Min DO(mgO2/L) Max
Minimum DO-data Maximum DO-data DO sat Point Source
Oak Meadows Golf Course dam Old Oak Brook dam Fullersburg Woods Dam (Graue Mill)
Comparisons of Observed and Predicted Dissolved Oxygen: 2007 Calibration Run
a b c d e f g
0.5 mg/L. Model results overall showed excellent agreement with observed conditions in the
calibration model and the validation models.
Figure 3-6. Predicted vs. Measured Dissolved Oxygen for August 2007 for Salt Creek
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Salt Creek (6/20/2006) Mainstem
0
2
4
6
8
10
12
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
DO (mg/L)
DO(mgO2/L) DO (mgO2/L) data DO(mgO2/L) Min DO(mgO2/L) Max
Minimum DO-data Maximum DO-data DO sat Point Source
Oak Meadows Golf Course dam Old Oak Brook dam Fullersburg Woods Dam (Graue Mill)
Comparisons of Observed and Predicted Dissolved Oxygen: 2006 Validation Run (6/19/06 to 6/21/06)
a b c d e f g
Figure 3-7. Predicted vs. Measured Dissolved Oxygen for July 2006 for Salt Creek
3.2.3 Sensitivity Analysis
Sensitivity runs were completed for changes in both SOD and re-aeration constants. These
results are presented in Appendix C. Both of these variables have a significant impact on the
predicted DO values; however, such changes do not improve the overall predictions compared to
the actual results.
3.2.4 Baseline Model
The value of a model is to predict worst case conditions and the impacts of improvement
alternatives on those conditions. In modeling the worst case scenario, temperature is a prime
factor, as the temperature increases, the saturation (solubility of oxygen) of DO in water
decreases and respiration increases (both in the water column and in the sediment). Recall, from
a review of historical temperature data, the stream can reach temperatures approximately 3oC
above the levels recorded in July and August 2006. This temperature and low flow, with the
average summer CBOD and ammonia discharged from the seven wastewater treatment plants
was used as the baseline worst case scenario. Figure 3-8 presents this baseline model. From this
model, alternatives for improving DO levels can be evaluated, and this is done in Section 6. The
Baseline Model predicts minimum DO levels just above the Oak Meadows Dam reaching 3.5
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Salt Creek Mainstem
0
1
2
3
4
5
6
7
8
9
10
11
50 45 40 35 30 25 20 15 10 5 0
Distance from downstream (km)
DO (mg/L)
DO(mgO2/L) DO(mgO2/L) Min DO(mgO2/L) Max DO sat Point Source
Monthly Average of June 2005 DMR Condition with 3 o C Increased Plant Discharge and Air Temperature
a b c d e f g
Oak Meadows Golf Course dam Old Oak Brook dam Fullersburg Woods Dam (Graue Mill)
mg/L. At the Old Oak Brook Dam, the minimum DO predicted is at 4.1 mg/L, and just above the
Graue Mill Dam, minimum DO levels are predicted to reach 1.2 mg/L. The model, consistent
with the monitoring results, predicts under these extreme conditions that the pool areas created
by the dams are the areas with the lowest DO levels. The Old Oak Brook Dam’s impact on the
upstream DO levels is less pronounced than in the pools above the other two dams.
Figure 3-8. Baseline Dissolved Oxygen for Salt Creek
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0B4 SCREENING FOR DAMS
Small, low-head dams impose a number of negative impacts on rivers through both their nature
and their number. Dams inhibit the natural linear flow of energy in the stream system, be it in
the form of flowing water, sediment transport, fish migration, macroinvertabrate drift, or
downstream nutrient spiraling. Specific to the impact on dissolved oxygen, dams create
impoundments that concentrate sediment and organic material upstream which actively respires,
removing dissolved oxygen from the water. In addition, dams slow the velocity of the water,
allowing additional time for sediment decomposition to remove oxygen from the water column
and for solar energy to increase water temperature (water temperature is inversely correlated to
waters capacity to hold dissolved oxygen). These effects are further exacerbated as dams
increase the width of the stream, increasing the water column/sediment interface and limiting the
extent that riparian shade can counter the effect of solar heating. As water temperatures increase,
the re-aeration rate from the atmosphere decreases because the DO saturation value decreases
with increasing temperatures.
Complete removal or retrofitting of dams is an increasingly utilized tool to eliminate the
disruptive influence that dams create within the fluvial system. The impacts of dams on
sediment continuity, flood conveyance, and aquatic flora and fauna have been well documented
in the literature. However, there is little guidance that exists for handling a dam removal or
retrofit. Questions about the fate of impoundment sediment, mechanisms for dewatering, and
short versus long term impacts to the health of the stream dominate any dam removal or
modification project, and must be addressed prior to the actual project.
The three options being investigated in this study are: complete removal; partial breach, and
partial removal with bridging. These options are being driven by the primary design objective of
improving the DO content of the stream. A secondary design objective is to re-establish
biological connectivity, mainly in the form of faunal passage.
1B4.1 Complete Removal
Complete dam removal involves the removal of the entire dam structure. The most common
case for removal is to eliminate the legal definition of a dam at a particular site, thereby
removing liability and responsibility from the owner. Usually dams have exceeded their design
life, and the cost of rehabilitation is greater than the cost of removal. Ecological benefits can be
significant.
Complete removal can occur in a number of ways based on site conditions and budget. Dams
with a substantial amount of sediment behind the structure are typically drawn down in stages to
minimize the downstream transport of sediment. Sediment in the dewatered impoundment can
be excavated and/or stabilized in place, depending on the type and quality of material (i.e., silt
versus sand and contaminated versus non-contaminated).
Depending on the size of the impoundment, varying levels of restoration of the new channel are
required. In large impoundments, the effort for restoration is great, while in narrow
impoundments, the restoration effort may be less extensive.
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There is a broad range of effort that can be dedicated to restoration of the site based on funding,
aesthetics, resource use, aquatic and terrestrial wildlife needs, hydrology, and sediment transport.
A passive approach (minimal effort) to channel rehabilitation might include the excavation of a
fairly straight, perhaps oversized channel through the impoundment. This would allow the
stream to do most of the work of recovery, creating its own path and allowing flood and
groundwater hydrology to dictate the riparian vegetation regime over a prolonged timescale.
Time scales for the completion of this restoration can range from decades to centuries depending
on site conditions. Alternatively, active channel restoration, requiring the largest effort, would
involve the complete construction of a functioning floodplain and sinuous channel similar to
what existed prior to dam construction. The geometry of this channel would emulate the
historical channel but would be designed to function appropriately within the constraints of
modern hydrology and sediment loading. This active restoration option could be constructed
within a few months but for a greater cost. The costs and time scales for these approaches are
drastically different to achieve the same ultimate outcome, the re-establishment of an intact
fluvial system.
4.2 Partial Breach or Notching
Breaching includes everything from a simple v-notch weir to removal of a section of a dam
(partial breach). Depending upon the design, sediment transport and fish passage can usually be
achieved. However, if the velocity through the breach is too great, fish passage may not occur,
and safety issues to paddlers could also result.
2B4.3 Bridging
The third option is bridging. The basic concept is to build a ramp of large rock leading up to the
downstream face of the dam. The ramp effectively “bridges” the dam by providing upstream-downstream
fish passage and possibly canoe passage. Common variations to this include
partially removing or lowering the dam crest in order to decrease the vertical elevation that must
be made up downstream and to reduce the impoundment on the upstream side of the dam. In
addition, notching the dam crest (alternative 2) to concentrate flow in the center of the channel is
also commonly employed with bridging.
Bridging provides fish passage and aeration as well as some interstitial habitat for macro-invertabrates.
It also preserves a fixed water surface elevation upstream. Bridging, resulting in a
lower pool elevation, will reduce retention time, impoundment water temperatures, and sediment
deposition. Bridging does not remove the legal designation of a dam at the site. The State of
Illinois’ definition of a dam is “any structure built to impound or divert water.” Thus the
responsibility for maintaining and monitoring the structure will remain with the dam owner.
There is a possibility for the hazard classification of the structure to be downgraded if partial
removal diminishes the hydraulic impact of the structure.
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3B4.4 Issues Common to All Dams
There are several issues that need to be addressed for projects with modifications to existing
dams. Permitting by federal, state, and local agencies, characterization and disposal of sediments
removed from dam impoundments, and impacts of dam removal on flooding must be considered.
4.4.1 Permitting
In Illinois, the resource agencies generally recognize the ecological benefits of dam
removal/bridging projects. However, the historical characteristics of a dam must be weighed
against any modifications to a structure. Storm water and wetland impacts are two other central
issues around any project that will modify/remove a dam. There are three levels of permitting
that will be required for each project, with variations on each depending on the design method
chosen. The Joint Permit Application Packet is designed to simplify the approval process for the
applicant seeking project authorizations from the U.S. Army Corps of Engineers, the Illinois
Department of Natural Resources Office of Water Resources, and the Illinois Environmental
Protection Agency.
Federal Level – At the federal level, the Army Corps of Engineers has jurisdiction over any
design that will impact wetlands or waterways. Because DuPage County’s regulations are more
stringent than the Federal Laws, a memorandum of understanding has been in place that allows
much of the permit review for the Federal 401/404 permit to be accomplished by the County. An
Environmental Assessment will be required for any dam modification/removal project if federal
funds are utilized. A Regional 404 permit would be applied for dam removal or modification.
State Level – Permitting from the State of Illinois involves primarily the Illinois Department of
Natural Resources (IDNR) and the Illinois Historic Preservation Agency. Within the Joint
Permit Application process, there are several layers of review that require the approval of various
agencies. The IDNR Office of Water Resources has established requirements for applications
for permits to remove dams, detailed in Section 3702 of the State Administrative Code. The
Office of Water Resources handles aspects mainly related to the construction (removal) process,
such as the plan for dewatering and upstream restoration and the impacts to the flood profile.
The IDNR Office of Realty and Environmental Planning will perform a review of the project to
ensure no impacts to threatened or endangered species.
A review will be done by the Illinois Historic Preservation Agency to ensure no potential
impacts exist to state historic or archaeological resources. This Agency has consistently
determined that dams have historical significance. This would certainly be true for the Graue
Mill Dam; therefore, any modifications will be closely reviewed by this Agency and the conflict
between the ecological benefits and changes to a historical structure will have to be weighed.
If federal funds are used to remove Graue Mill Dam, a Section 106 analysis may be needed.
Additional regulations that may apply depending on the project include Part 3708 – Floodway
Construction in Northeastern Illinois.
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The Illinois EPA provides water quality certifications (401) for Individual 404 permits; however,
this project analysis is not necessary for Regional Permits. Previous dam removal projects have
only required a Regional Permit.
County Level - DuPage County permitting requirements are more stringent than most State or
Federal requirements. As a result, once the county requirements are met for various items held
in common among both state and federal regulatio