Flood Insurance Study Users

The Federal Emergency Management Agency in Cooperation with DuPage County, Illinois Presents:

FLOOD INSURANCE

STUDY

A Report of Flood Hazards in:

DUPAGE COUNTY, ILLINOIS AND INCORPORATED AREAS

Prepared, in parts, by:

FEMA Region V Nika Engineering 536 South Clark Street 421 Mill Street Chicago, Illinois 60605 and Batavia, Illiois 60510

March 2007 1 7043CV000A

NOTICE TO FLOOD INSURANCE STUDY USERS

Communities participating in the National Flood Insurance Program have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) may not contain all data available within the repository. It is advisable to contact the community repository for any additional data.

Part or all of this FIS may be revised and republished at any time. In addition, part of this FIS may be revised by the Letter of Map Revision process, which does not involve republication or redistribution of the FIS. It is, therefore, the responsibility of the user to consult with community officials and to check the community repository to obtain the most current FIS components.

Initial Countywide FIS Effective Date: December 4, 1985 Revised Countywide FIS Date: June 16, 2004 FLOOD INSURANCE STUDY DuPAGE COUNTY, ILLINOIS

TABLE OF CONTENTS

Page # 1. INTRODUCTION 1 1.1. Purpose of Study 1 1.2. Authority and Acknowledgments 1 1.3. Coordination 5 1.4. Regional Participation and Progress 7 2. AREA STUDIED 8 2.1. Scope of Study 8 2.2. Community Description 8 2.3. Watershed Description 8 2.3.1. DesPlaines River (DP) 9 2.3.1.1. Geographical Description 9 2.3.1.2. Principal Flood Problems 9 2.3.1.3. Flood Protection Measures 11 2.3.2. DuPage River (DU) 13 2.3.2.1. Geographical Description 13 2.3.2.2. Principal Flood Problems 13 2.3.2.3. Flood Protection Measures 13 2.3.3. East Branch DuPage River (EB) 14 2.3.3.1. Geographical Description 14 2.3.3.2. Principal Flood Problems 14 2.3.3.3. Flood Protection Measures 18 2.3.4. Fox River (FR) 21 2.3.4.1. Geographical Description 21 2.3.4.2. Principal Flood Problems 21 2.3.4.3. Flood Protection Measures 22 2.3.5. Salt Creek (SC) 23 2.3.5.1. Geographical Description 23 2.3.5.2. Principal Flood Problems 23 2.3.5.3. Flood Protection Measures 25 2.3.6. Sawmill Creek (SW) 27 2.3.6.1. Geographical Description 27 2.3.6.2. Principal Flood Problems 27 2.3.6.3. Flood Protection Measures 27 2.3.7. West Branch DuPage River (WB) 29 2.3.7.1. Geographical Description 29 2.3.7.2. Principal Flood Problems 29 2.3.7.3. Flood Protection Measures 33

TABLE OF CONTENTS - continued

3. ENGINEERING METHODS & FLOOD PLAIN MANAGEMENT APPLICATIONS 36

Note: The following subsections under ENGINEERING METHODS & FLOODPLAIN MANAGEMENT APPLICATIONS do not have page numbers and are clearly marked as tabs. Each tributary shall contain the following elements: Tributary Description, Hydrologic Analysis, Hydraulic Analysis, Flood Boundaries, Floodways and Flood Profiles. As tributaries are updated and approved, these individual tributary tabs can be quickly replaced without the additional work of updating the Table of Contents. The tabs contained herein are as follows: 3.1. DesPlaines River (DP) 3.1.1. Main Stem (DPDP) 3.1.2. Addison Creek (DPAC) 3.1.3. Bensenville Ditch (DPBD) 3.1.4. Black Partridge Creek (DPBP) 3.1.5. Crystal Creek (DPCT) 3.1.6. Flagg Creek (DPFC) 3.1.7. Willow Creek (DPWL) 3.2. DuPage River (DU) 3.2.1. Lily Cache (DULC) 3.2.2. Springbrook #2 (DUSG) 3.3. East Branch DuPage River (EB) 3.3.1. Main Stem (EBEB) 3.3.2. Armitage Creek (EBAR) 3.3.3. Army Trail Road Tributary (EBAT) 3.3.4. Crabtree Creek (EBCR) 3.3.5. Tributary #1 (EBE1) 3.3.6. Tributary #2 (EBE2) 3.3.7. Tributary #3 (EBE3) 3.3.8. Tributary #6 (EBE6) 3.3.9. Tributary #7 (EBE7) 3.3.10. Glen Crest Creek (EBGL) 3.3.11. Glen Park (EBGP) 3.3.12. Lacey Creek (EBLA) 3.3.13. Prentiss Creek (EBPR) 3.3.14. Rott Creek (EBRC) 3.3.15. St. Joseph Creek (EBSJ) 3.3.16. Swift Meadows (EBSM) 3.3.17. 22nd Street (EBTS) 3.3.18. Willoway Brook (EBWI) 3.4. Fox River (FR) 3.4.1. Brewster Creek (FRBC) 3.4.2. Indian Creek (FRIC) 3.4.3. Norton Creek (FRNC) 3.4.4. Waubansee Creek (FRWA)

TABLE OF CONTENTS - continued 3.5. Salt Creek (SC) 3.5.1. Main Stem (SCSC) 3.5.2. Bronswood Creek (SCBW) 3.5.3. Devon Avenue Tributary (SCDA) 3.5.4. Ginger Creek (SCGC) 3.5.5. Oak Brook Tributary (SCOB) 3.5.6. Spring Brook Creek (SCSB) 3.5.7. Sugar Creek (SCSU) 3.5.8. Westwood Creek (SCWC) 3.6. Sawmill Creek (SW) 3.6.1. Sawmill Creek (SWSW) 3.6.2. Wards Creek (SWWD) 3.7. West Branch DuPage River (WB) 3.7.1. Main Stem (WBWB) 3.7.2. Cress Creek (WBCC) 3.7.3. Ferry Creek (WBFE) 3.7.4. South of Foxcroft (WBFX) 3.7.5. Klein Creek (WBKC) 3.7.6. Kress Creek (WBKR) 3.7.7. Spring Brook #1 (WBSP) 3.7.8. Steeple Run Tributary (WBSR) 3.7.9. Tributary #1 (WBW1) 3.7.10. Tributary #2 (WBW2) 3.7.11. Tributary #3 (WBW3) 3.7.12. Tributary #4 (WBW4) 3.7.13. Tributary #5 (WBW5) 3.7.14. Tributary #6 (WBW6) 3.7.15. Tributary #7 (WBW7) 3.7.16. Tributary #8 (WBW8) 3.7.17. Winfield Creek (WBWF) 3.7.18. Winding Creek (WBWG)

4. INSURANCE APPLICATION 41 4.1. Reach Determinations 41 4.2. Flood Hazard Factors 41 4.3. Flood Insurance Zones 41 4.4. Flood Insurance Rate Map Description 43 5. OTHER STUDIES 44 6. LOCATION OF DATA 46 7. REFERENCES AND BIBLIOGRAPHY 47

FIGURES

Figure 1 - Floodway Schematic 40

iii

TABLE OF CONTENTS - continued

TABLES

Table 1 - Tributary Study Acknowledgements 2

Table 2 - Initial and Final CCO Meetings 5

Table 3 - Flagg Creek Recorded Flood Discharges 10

Table 4 - East Branch DuPage River Flood Stages at Army Trail Road 14

Table 5 - East Branch DuPage River August 1972 Recorded Flood Crests 15

Table 6 - Prentiss Creek Flood of Record Recorded Flood Crests at Route 53 17

Table 7 - Spring Brook Salt Creek Flood Stages 24

Table 8 - USGS Recorder Gage of Salt Creek at Western Springs 25

Table 9 - Winfield Creek Gage Readings for 1972 Flood Event 32

EXHIBITS (as can be found in each corresponding tributary TAB in section 3.0)

Exhibit 1 - Flood Profiles Addison Creek (DPAC) Panel 01P Addison Creek Tributary No. 1 (DPAC) Panel 02P Addison Creek Tributary No. 2 (DPAC) Panel 03P Addison Creek Tributary No. 3 (DPAC) Panels 04P-05P Armitage Ditch (EBAR) Panels 30P-31P Armitage Fork (EBAR) Panel 32P Bensenville Ditch (Silver Creek) (DPBP) Panels 06P-07P Brewster Creek (FRBC) Panels 85P-86P Briarwood Ditch (SCGC) Panel 98P Bronswood Tributary (SCBW) Panels 91P-93P Crabtree Creek (EBCR) Panels 33P-35P Cress Creek (WBCC) Panel 150P Des Plaines River (DPDP) Panels 08P-09P Devon Avenue Tributary (SCDA) Panel 94P East Branch DuPage River (EBEB) Panels 36P-43P East Branch Sawmill Creek (SWSW) Panels 144P-145P East Branch Tributary No. 1 (EBE1) Panels 44P-45P East Branch Tributary No. 2 (EBE2) Panel 46P East Branch Tributary No. 3 (EBEB) Panels 47P-48P East Branch Tributary No. 4 (EBGL) Panels 49P-50P

TABLE OF CONTENTS - continued East Branch Tributary No. 5 (EBWI) Panels 51P-53P St. Procopius Creek (EBE6) Panels 54P-55P East Branch Tributary No. 7 (EBE7) Panels 56P-57P Ferry Creek (WBFE) Panels 151P-154P Ferry Creek Tributary No. 1 (WBFE) Panels 155P-157P Flagg Creek (DPFC) Panel 21P Ginger Creek (SCGC) Panels 95P-97P Heritage Oaks Tributary (SCGC) Panel 99P Klein Creek Tributary No. 1 (WBKC) Panels 167P-168P Klein Creek Tributary No. 2 (WBKC) Panel 169P Klein Creek Tributary No. 3 (WBKC) Panel 170P Klein Creek (WBKC) Panels 161P-166P Kress Creek (WBKR) Panels 171P-177P Lacey Creek (EBLA) Panels 58P-60P Lombard Tributary (SCGC) Panel 100P Mays Lake Tributary (SCGC) Panels 101P-102P Meacham Creek (SCSB) Panels 114P-115P Midwest Club Tributary (SCGC) Panel 103P North Branch St. Joseph Creek (EBSJ) Panel 80P Norton Creek (FRNC) Panel 87P Norton Creek Tributary (FRNC) Panel 88P North Unnamed Creek (DPWL) Panel 24P Plainfield Road Ditch (DPFC) Panels 17P-18P Prentiss Creek (EBPR) Panels 61P-64P Rott Creek (EBRC) Panels 65P-68P Salt Creek (SCSC) Panels 116P-130P Sawmill Creek (SWSW) Panels 136P-140P Sawmill Creek Tributary No. 1 (SWSW) Panels 148P-149P Sawmill Creek Tributary No. 3 (DPDP) Panels 10P-15P South Branch St. Joseph Creek (EBSJ) Panels 81P-82P South Fork Westwood Creek (SCWC) Panel 135P South Unnamed Creek (DPWL) Panel 23P Spring Brook Creek (SCSB) Panels 106P-112P Spring Brook No. 1 (WBSP) Panels 180P-184P Spring Brook No. 2 (DUSG) Panels 25P-29P Spring Road Tributary (SCOB) Panels 104P-105P St. Joseph Creek (EBSJ) Panels 69P-75P St. Joseph Creek Tributary (EBSJ) Panel 83P Sugar Creek (SCSU) Panels 131P-132P Sugar Creek Tributary A (SCSU) Panel 133P Tributary 1(A) (EBSJ) Panels 76P-78P Tributary 2(B) (EBSJ) Panel 79P Unnamed Creek (South of Foxcroft Road) (WBFX) Panels 158P-159P Unnamed Stream (North of 22nd Street) (EBTS) Panel 84P Unnamed Creek (South of 87th Street) (WBFX) Panel 160P

TABLE OF CONTENTS - continued Unnamed Tributary to Kress Creek (WBKR) Panels 178P-179P WardsCreek (SWWD) Panel 146P-147P Waubansee Creek (FRWA) Panels 89P-90P West Branch DuPage River (WBWB) Panels 185P-196P West Branch Sawmill Creek (SWSW) Panels 141P-143P West Branch Tributary No. 1 (WBW1) Panels 197P-198P West Branch Tributary No. 2 (Country Creek) (WBW2) Panels 199P-200P West Branch Tributary No. 3 (WBW3) Panels 201P-202P West Branch Tributary No. 4 (WBW4) Panels 203P-204P West Branch Tributary No. 5 (WBW5) Panel 205P West Branch Tributary No. 6 (WBW6) Panels 206P-208P West Branch Tributary No. 7 (WBW7) Panels 209P-211P West Branch Tributary to Spring Brook Creek (SCSB) Panel 113P Westwood Creek (SCWC) Panel 134P Winfield Creek (WBWF) Panels 212P-217P Winding Creek (WBWG) Panels 218P-219P 59th Street Ditch (DPFC) Panel 22P 63rd Street Ditch (DPFC) Panels 19P-20P 79th Street Ditch (DPFC) Panel 16P

Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map

1.0 INTRODUCTION

1.1 Purpose of Study

This countywide Flood Insurance Study (FIS) investigates the existence and severity of flood hazards in, or revises and updates previous FISs/Flood Insurance Rate Maps (FIRMs) for the geographic area of DuPage County, Illinois, including: the Villages of Addison, Bartlett, Bensenville, Bloomingdale, Carol Stream, Clarendon Hills, Downer’s Grove, Glen Ellyn, Glendale Heights, Hinsdale, Itasca, Lisle, Lombard, Oakbrook Terrace, Roselle, Villa Park, Warrenville, Wayne, Westmont, Wheaton, Willowbrook, Winfield, Wood Dale and Woodridge; the Cities of Aurora, Darien, Elmhurst, Naperville, Oak Brook, and West Chicago, and the unincorporated areas of DuPage County (hereinafter referred to collectively as DuPage County).

The FIS and FIRMs for DuPage County will also show the portion of the Villages of Bolingbrook, Burr Ridge, Elk Grove, Hanover Park, Schaumburg, and Wayne; the Cities of Chicago and St. Charles that lie within DuPage County. The remaining portions of these communities lie within other counties; these communities have, therefore, been shown on DuPage County FIRMs for informational purposes only. The information contained on the DuPage County FIS for these communities is not to be used for flood insurance purposes.

This FIS aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This FIS has developed flood risk data for various areas of the county that will be used to establish actuarial flood insurance rates. This information will also be used by DuPage County to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP), and will also be used by local and regional planners to further promote sound land use and floodplain development. Minimum floodplain management requirements for participation in the NFIP are set forth in the Code of Federal Regulations at 44 CFR, 60.3.

In some States or communities, floodplain management criteria or regulations may exist that are more restrictive or comprehensive than the minimum Federal requirements. In such cases, it shall be understood that the state (or other jurisdictional agency) shall be able to explain these requirements and criteria.

1.2 Authority and Acknowledgments

The sources of authority for this FIS are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973.

For each tributary in DuPage County, Table 1: “Tributary Study Acknowledgements” lists the organizations and companies responsible for the development of the hydrologic and hydraulic analysis. For those organizations and companies contracted by FEMA to perform such

analysis, a contract number and corresponding project order number were included. The listed finish date is the original date of study completion and does not reflect updates as a result of Letters of Map Revision (LOMR). Further Hydrologic and Hydraulic information for each tributary can be located in Section 3.0.

Table 1: Tributary Study Acknowledgements Hydrologic and Hydraulic Study Watershed Tributary Analysis Performed By: FEMA Contract Numbers Completion Des Plaines Donohue and Associates, Inc. study Addison Creek Stormwater Addison Creek Sep-88 Management System Evaluation, DuPage and Cook Counties, Illinois Illlinois Department of Transportation study Strategic Bensenville Ditch Dec-87 Planning Study for Flood Control - Bensenville Ditch Black Partridge Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Apr-79 Creek of Engineers 76, P.O. No. 19 Flagg Creek Harza Engineering Company Contract No. H-4562 and H-3978 Aug-78 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Willow Creek Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Main Stem Apr-79 of Engineers 76, P.O. No. 19 DuPage River Lily Cache Harza Engineering Company Contract No. H-3978 Feb-79

Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps Spring Brook #2 75, P.O. No. 21 and IAA-H-7-76, P.O. Feb-78 of Engineers No. 1 East Branch Inter-Agency Agreement No. IAA-H-16- Chicago District, U.S. Army Corps DuPage Armitage Creek 75, P.O. No 19, and Inter-Agency Nov-76 of Engineers River Agreement No. IAA-H-7-76, P.O. No. 1 Army Trail Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Apr-79 Tributary of Engineers 76, P.O. No. 19 Inter-Agency Agreement No. IAA-H-16- Chicago District, U.S. Army Corps Crabtree Creek 75 P.O. No. 21 and Inter-Agency Jan-77 of Engineers Agreement No. IAA-H-7-76, P.O. No. 1 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #1 Apr-79 of Engineers 76, P.O. No. 19 Camp Dresser and McKee: DEC Tributary #2 Floodplain Mapping Report for East Apr-02 Branch DuPage River Tributary #2 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #3 Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #6 Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #7 Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Glen Crest Creek Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Glen Park Apr-79 of Engineers 76, P.O. No. 19

Inter-Agency Agreement No. IAA-H-16- Chicago District, U.S. Army Corps Lacey Creek 75 P.O. No. 19 and Inter-Agency Nov-81 of Engineers Agreement No. IAA-H-7-76, P.O. No. 1 Inter-Agency Agreement No. IAA-H-16- Chicago District, U.S. Army Corps Prentiss Creek 75 P.O. No. 21 and Inter-Agency Jan-77 of Engineers Agreement No. IAA-H-7-76, P.O. No. 1 Inter-Agency Agreement Numbers IAA- Chicago District, U.S. Army Corps Rott Creek H-16-75, P.O. No.; and IAA-H-7-76, Sep-77 of Engineers Amendment No. 3 to P.O. No.1 Inter-Agency Agreement No. IAA-H-16- Chicago District, U.S. Army Corps 75 P.O. No. 19 and Inter-Agency St. Joseph's Creek of Engineers; and Harza Engineering Sep-77 Agreement No. IAA-H-7-76, P.O. No. 1; Company and Contract No. H-4562 respectively Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Swift Meadows Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- 22nd Street Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Willoway Brook Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Main Stem Sep-77 of Engineers 76, P.O. No. 19 Fox River Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Brewster Creek Apr-79 of Engineers 76, P.O. No. 19 U.S. Department of Agriculture and U.S. Soil and Conservation Service, Indian Creek Floodplain Management Study - Jun-86 Indian Creek and Tributaries, Kane and DuPage Counties, Illinois Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Norton Creek Apr-79 of Engineers 76, P.O. No. 19 Flood Insurance Studies for the City Waubansee Creek of Aurora and Kane and DuPage May-86 Counties Sawmill Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Wards Creek Apr-79 Creek of Engineers 76, P.O. No. 19 Harza Engineering Company; Contract No.H-3978; and Inter-Agency Main Stem Chicago District, U.S. Army Corps Agreement No. IAA-H-7-76, P.O. No. 19 Apr-79 of Engineers respectively Salt Creek Bronswood Illinois State Water Survey; Harza Contract No. H-3942; and Contract No. Sep-78 Tributary Engineering Company H-4562 respectively Devon Avenue Inter-Agency Agreement No. IAA-H-17- Soil Conservation Service Nov-76 Tributary 75, P.O. No. 4 DuPage County DEC: Floodplain Ginger Creek Mapping Report for Ginger Creek - Aug-94 Salt Creek Oak Brook Illinois State Water Survey Contract No. H-4522 Sep-78 Tributary

Contract No. H-4522; and Inter-Agency Agreement No. IAA-H-17-75, P.O. No.4 respectively; with additional portions of Spring Brook studied by the U.S. Spring Brook Illinois State Water Survey; and Soil Department of Agriculture, Weston Sep-79 Creek Conservation Service Environmental Consultants, the Chicago District of the U.S Army Corps of Engineers, and the Illinois Division of Water Resources.

Sugar Creek Illinois State Water Survey Contract No. H-3942 Sep-78 Westwood Creek Harza Engineering Company Contract No. H-3809 Sep-76 Inter-Agency Agreement No. IAA-H-18- Soil Conservation Service; and the Main Stem 75, P.O. No. 4 and 6; and Contract No. H- Sep-78 Illinois State Water Survey 3942 respectively West Branch Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps DuPage Cress Creek 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers River 1 Inter-Agency Agreement No. IAA-H-7- Chicago District, U.S. Army Corps 76, P.O. No. 1 and Inter-Agency Ferry Creek May-77 of Engineers Agreement No. IAA-H-16-75, P.O. No. 19 Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps So. of Foxcroft 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers 1 Inter-Agency Agreement No. IAA-H-7- Chicago District, U.S. Army Corps Klein Creek 76, P.O. No. 19 and Amendment No.2 to Feb-78 of Engineers P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Kress Creek Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Spring Brook #1 Apr-79 of Engineers 76, P.O. No. 19 Inter-Agency Agreement Nos. IAA-H-16- Steeple Run Chicago District, U.S. Army Corps 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 Tributary of Engineers 1 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #1 Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #2 Apr-79 of Engineers 76, P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #3 Apr-79 of Engineers 76, P.O. No. 19 Inter-Agency Agreement No. IAA-H-7- Chicago District, U.S. Army Corps Tributary #4 76, P.O. No. 19 and Amendment No.2 to Feb-78 of Engineers P.O. No. 19 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Tributary #5 Apr-79 of Engineers 76, P.O. No. 19 Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps Tributary #6 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers 1 Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps Tributary #7 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers 1

Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps So. of 87th 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers 1 Chicago District, U.S. Army Corps Inter-Agency Agreement No. IAA-H-7- Winfield Creek Feb-78 of Engineers 76, P.O. No. 19 Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps Winding Creek 75, P.O. No. 21 and IAA-H-7-76, P.O. No Feb-78 of Engineers 1 Inter-Agency Agreement Nos. IAA-H-16- Chicago District, U.S. Army Corps Main Stem 75, P.O. No. 21 and IAA-H-7-76, P.O. Feb-78 of Engineers No. 1 and 19

1.3 Coordination

An initial Consultation Coordination Officer’s (CCO) meeting is held with representatives of the communities, FEMA, and the study contractors to explain the nature and purpose of the FIS, and to identify the streams to be studied by detailed methods. A final CCO meeting is held typically with representatives of the communities, FEMA, and the study contractor to review the results of the FIS.

The dates of the initial and final CCO meetings held for DuPage County and the incorporated communities within its boundaries are shown in Table 2: “Initial and Final CCO Meetings”

Table 2: Initial and Final CCO Meetings Initial CCO Final CCO Tributary Watershed Community Date Date Acronym Village of DPAC EBAT EBE1 EBEB EBSM Addison * 10-Nov-76 SCSB SCSC SCWC DUSG FRIC FRWA WBFE City of Aurora 18-Nov-93 24-Apr-96 WBWB Village of Bartlett Jan-76 15-Sep-80 FRBC FRNC WBW2 WBWB Village of Bensenville 4-Oct-84 13-Oct-88 DPAC DPBD DPWL Village of EBAT EBEB EBSM SCSB Bloomingdale 19-Jul-77 28-May-80 WBKC WBW1 WBW4 WBWB City of Bolingbrook * * DPLL EBEB Village of Burr Ridge Mar-76 4-May-79 DPDP DPFC SWSW Village of Carol EBAR WBKC WBW4 WBWB Stream Jan-75 19-Jan-81 WBWF Village of Clarendon Hills Jul-77 16-Aug-79 DPFC SCBW DPBP DPDP DPFC DPLL EBPR City of Darien * 29-Jan-79 EBSJ SWSW SWWD Village of EBEB EBGP EBLA EBPR EBSJ Downer’s Grove Jan-75 30-Jun-77 EBTS SCBW SCGC SWSW

SWWD

Elk Grove Village * * DPWL SCSC City of Elmhurst 4-Aug-80 8-Jan-80 DPAC SCSC SCSU Village of Glen EBE2 EBEB EBGL EBWI WBSP Ellyn Dec-75 * WBWF Village of EBAR EBAT EBE2 EBEB WBKC Glendale Heights * * WBWF Village of WBKC WBW1 WBW2 WBW4 Hanover Park Jan-76 1-Jun-77 WBWB Village of Hinsdale Jul-77 3-Dec-79 DPFC SCBW SCSC Village of Itasca Jan-75 26-Oct-76 SCDA SCSB SCSC EBE6 EBEB EBPR EBRC EBSJ Village of Lisle Dec-74 2-Jun-77 EBWI WBSR WBW6 WBW7 EBE1 EBE3 EBEB EBGL EBGP Village of EBLA EBTS SCGC SCSC SCSU Lombard Dec-75 12-Sep-77 SCWC DUSG EBE6 EBE7 EBEB EBRC FRWA WBCC WBFE WBFX WBSR WBW6 WBW7 WBW8 City of Naperville * * WBWB WBWG Village of Oak Brook Aug-76 10-Jan-80 EBLA SCBW SCGC SCOB SCSC Village of Oakbrook Terrace 30-Mar-77 30-Jan-80 SCGC SCOB SCSC SCSU Village of Roselle * * SCSB WBW1 WBWB Village of Schaumburg 13-Feb-75 17-Nov-77 SCSB WBWB City of St. Charles Dec-77 14-Oct-80 FRNC WBKR Village of Villa Park Aug-76 21-Jan-80 SCSC SCSU SCWC Village of EBRC WBCC WBFE WBSP Warrenville * * WBWB Village of Wayne * 16-Jan-81 FRBC FRNC WBWB City of West FRNC WBKR WBW3 WBW4 Chicago 21-Jan-76 15-Sep-77 WBW5 WBWB Village of Westmont Jul-77 29-Oct-79 DPFC EBSJ SCBW SCGC Village of EBEB EBGL EBRC EBWI Wheaton * * WBKC WBSP WBWF Village of Willowbrook * 10-Jan-79 DPFC SWSW Village of Winfield 5-Jan-76 21-Jun-77 WBKC WBW5 WBWB WBWF Village of Wood DPAC DPBD DPWL SCSB SCSC Dale * * SCWC DPBP DPDP DPLL EBCR EBE6 Village of EBE7 EBEB EBPR SWSW Woodridge * 22-Jul-76 SWWD

1.4 Regional Participation and Progress

After experiencing the damaging effects of flooding from the August 1987 flood event, DuPage County began to take measures to protect against future flooding. In 1989, the county began construction of over $100 million in flood control projects, the strict enforcement of a comprehensive stormwater and floodplain ordinance, and the development of updated regulatory floodplain maps throughout the county. These principal improvements were managed by a new entity, the Stormwater Management Division (SMD). This new organization is a division of the DuPage County Department of Environment Concerns (DEC). The SMD has managed the planning, design, and construction of many major flood control facilities over the last 12 years. The main purpose of the SMD implements the countywide stormwater ordinance. The SMD developed the countywide stormwater and floodplain ordinance in 1991, and started enforcement of the ordinance in February 1992. In 2000, DEC became the Department of Development and Environmental Concerns, and is still known as the DEC.

In the effort to update aging flood plain maps, DuPage County DEC has devoted funds and efforts to develop more comprehensive hydrologic and hydraulic models for all currently mapped FEMA floodplain areas. These models, the majority of which utilizes 1-dimensional unsteady-state hydraulics, are in varied stages of development. When a tributary model has successfully passed DEC’s statistical scrutiny, the Flood Plain Mapping Report is submitted to FEMA for approval and a subsequent LOMR process. When this LOMR is approved, all information presented about the tributary in section 3.0 of this FIS will be removed and replaced with the new data. Per an agreement between FEMA and DuPage County, any further updates to these new models shall be the responsibility of DEC with oversight remaining at FEMA Region V.

Therefore, when using this report for regulatory purposes it is important to understand that this FIS, a compilation of 57 tributaries, shall be in a changing state, but it will reflect at all times the best-available, FEMA- approved information.

2.0 AREA STUDIED

2.1 Scope of Study

This FIS covers the geographic area of DuPage County, Illinois. For a list of all watersheds and tributaries that have been explicitly modeled or studied for the purposes this FIS, please refer to Table 1 in Section 1.0 for quick reference, or Section 3.0 for more detailed watershed information. Limits of each detailed study are indicated on the Flood Profile (found in each tributary study breakdown within Section 3.0) and/or on the FIRM panel.

2.2 Community Description

DuPage County is situated in northeastern Illinois, approximately 25 miles directly west of the City of Chicago. DuPage County is bordered by Cook County on the north and east, Will County on the south, and Kane County on the west. The county encompasses 332.1 square miles and has a residential population of 904,161 according to the 2000 U.S. Census. The gross residential density at year 2000 was 2,722 people per square mile. Approximately 200 square miles or 60 percent of the county is in unincorporated areas.

Temperature data is published for two climatological stations in DuPage County, Wheaton, and Argonne National Laboratories. The average annual temperature of Wheaton, which is typical for these stations, and for the county as well, is 49.8 degrees Fahrenheit (°F) with an annual monthly high in July of 76.5°F and monthly low in January of 9.2°F. The annual average precipitation at Wheaton is 39.26 inches. The highest monthly average precipitation occurs in August with a value of 7.65 inches (U.S. Department of Commerce, 1975).

There are seven major drainage basins in DuPage County. These are: the Des Plaines River, the DuPage River, the East Branch DuPage River, the Fox River, Salt Creek, Sawmill Creek and the West Branch DuPage River.

2.3 Watershed Description

The following seven major watersheds within DuPage County are discussed in general detail in the following subsections. These subsections include a geographical description of the watershed, historical recorded flooding problems, and proposed and completed flood protection measures.

2.3.1 DesPlaines River (DP)

2.3.1.1 Geographical Description

The Des Plaines River includes all the easternmost tributaries located in DuPage County that are not within the Salt Creek Watershed. The general flow of the watershed is southeasterly in the headwaters and southwesterly at the Des Plaines River. Waters that enter such areas as Willow Creek, Bensenville Ditch or Addison Creek, found in the northeastern section of DuPage County, will flow east into Cook County, forming the Des Plaines River. As the Des Plaines River begins its turn to the southwest, it joins with Salt Creek, and then forms the southwest border between DuPage and Will Counties. The Des Plaines continues on a southwest course where it confluences with the Illinois River in Joliet.

Additional DuPage County tributaries that join the Des Plaines are Flagg Creek, Black Partridge Creek, and various ditches. Sawmill Creek, and associated Wards Creek; the East Branch DuPage River; West Branch DuPage River; and the DuPage River are also tributary to the Des Plaines, but are considered in greater detail in subsequent sections.

2.3.1.2 Principal Flood Problems

Addison Creek Within the Village of Bensenville, the three tributaries to Addison Creek do not experience severe flooding. The steep channel gradients help to convey high flows; therefore, overbank flooding is uncommon in most segments.

Bensenville Ditch Bensenville Ditch is a small stream that flows from its headwaters in Bensenville for 3.7 miles to where it becomes Silver Creek. Flood events have occurred in March 1948, October 1954, August 1968, September 1972, March 1976, June 1978, March 1979, March 1982, May 1983 and October 1986. Overbank flooding is cause by the inability of the channel to convey and store large peak flows.

Willow Creek The Willow Creek basin has recently become highly developed. Overbank flooding of this stream is caused by the inability of the channel to convey and store large peak flows.

Flagg Creek

The past history of flooding on Flagg Creek within the Village of Clarendon Hills indicates that flooding may occur during any season of the year. The majority of floods have occurred during March, April, and May; they are usually the result of spring rains and/or snowmelt. The 100-year discharge varies from 380 cfs at the downstream corporate limit to 190 cfs at the Eastern Avenue bridge.

Damaging floods on Flagg Creek can be documented from discharge records for the USGS gage on Flagg Creek at Willow Springs (U.S. Department of the Interior, 1975). This gage (no. 05533000, drainage area 16.5 square miles) was established in 1949, and records are continuous to the present. The most severe floods in the Flagg Creek basin are listed below.

Table 3: Flagg Creek Recorded Flood Discharges at Gage 05533000 Approximate Recurrence Water Discharge Interval Year (cfs) (years)

1961 2,680 85 1976 2,230 40 1975 1,630 15 1959 1,550 12 1957 1,350 8 1955 1,300 7

The portion of Flagg Creek flowing within the Village of Hinsdale flows through an underground culvert. For small flood events, the flow is contained in the culvert. For large floods, the culvert becomes surcharged and ponding occurs in the low-lying areas above the underground culvert. For a portion of 59th Street Ditch, the culvert is incapable of containing the 100-year storm, thus causing overland flow.

Plainfield Road Ditch Flooding at Plainfield Road Ditch occurs on farmland just west of the Tri-State Tollway and, in a milder form, at the International Harvester Company. No buildings are flooded. In both cases, shallow channels contribute to the flooding.

59th Street Ditch Flooding occurs on the 59th Street Ditch when flow from upstream exceeds the capacity of the underground conduit system. Floodwaters flow through the subdivision known as Wood View Estates. On the east side of the subdivision, the water flows into a

drainage ditch along the Tri-State Tollway. The water then flows south into 63rd Street Ditch, then east into Flagg Creek.

63rd Street Ditch The entire reach of 63rd Street Ditch east of State Route 83 in the Village of Willowbrook is subject to overbank flooding as described in the Hydrologic Atlases (U.S. Department of the Interior, HA-86, 1963; U.S. Department of the Interior, HA-149, 1963) and the report of the Des Plaines River Steering Committee (Des Plaines River Watershed Steering Committee, 1975). In addition, Wight and Company, in their Stormwater Management Study for Willowbrook, describes two areas draining to the 63rd Street Ditch which have been flooded (Wight and Company, 1977). One of these is at the corner of 59th Street and Clarendon Hills Road where flooding is due to inadequate drainage. This area flows into Marion Hills Ditch. The other is an area of overbank flooding along 63rd Street Ditch downstream from Lake Hinsdale to 63rd Street Ditch near Ridgemoor Drive and Quincy Drive.

79th Street Ditch Frequent residential damage occurs in one area in the Village of Burr Ridge. Flooding problems principally are caused by development in low lands that formerly served as natural drains. Overflow of the 79th Street Ditch causes damage to a residence on Hamilton Avenue south of 77th Street. The channel of this stream is not well defined in many places. This results in flooding of streets and yards in the area south of the intersection of 79th Street and Drew Avenue.

2.3.1.3 Flood Protection Measures

Addison Creek A major storm occurred in March 1948 that caused substantial flooding on Addison Creek. Following the flood, the channel was deepened and widened. To alleviate serious flooding of the headwaters of Addison Creek, a 685-acre-ft stormwater retention reservoir (the George Street Reservoir) was constructed in Bensenville. The reservoir provides a reduction on the 100-yr flows for Addison Creek. All studied tributaries of Addison flow into the George Street Reservoir, where the water is stored to reduce the flooding on Addison Creek. Pumping the reservoir can control outflow from the tributaries.

Flagg Creek There are no dams or reservoirs within the Flagg Creek. The main channel of Flagg Creek was improved in the past by paving a part of the channel between State Route 83 and Harris Avenue. Within the watershed, there are three facilities that provide some flood relief for local areas. These include the two interconnected detention ponds in Prospect Park, the Blue Lake detention area, and a grassed detention area in Hudson Park. These ponds do not have storage capacity for severe flooding events. The stream is not regulated by any floodplain management ordinance.

59th Street Ditch All of 59th Street Ditch within the Village of Hinsdale flows through an underground culvert. For small flood events, the flow is contained in a culvert. For large floods, the culvert becomes surcharged and ponding occurs in the low-lying areas above the underground culvert. The culvert is incapable of containing the 100-year storm, thus causing overland flow. There are no existing dams and reservoirs for the portion of the 59th Street Ditch flowing within the corporate limits of the Village of Hinsdale.

63rd Street Ditch The retention pond near the mouth of 63rd Street Ditch has been designed to retain 100-year flood flows for a short period of time without affecting the surrounding homes. For the portion of the stream flowing through the Village of Willowbrook, the community has previously completed several projects, including improving culverts and channels to reduce flood peaks. Lake Hinsdale, with a storage volume of about 35 acre-feet, controls discharges to 63rd Street Ditch from portions of the watershed west of Kingery Highway.

Plainfield Road Ditch There is a small lake on the International Harvester Company property along Plainfield Road Ditch. Some flood runoff will spill into this lake, but the lake is too small to reduce the peak flood discharge.

Bensenville Ditch, Willow Creek, and various ditches No information regarding flood protection measures for these tributaries is available.

2.3.2 DuPage River (DU)

2.3.2.1 Geographical Description

In DuPage County only small portions of watershed areas are attributed to the DuPage River: Spring Brook #2 and Lily Cache. Spring Brook #2 tributary drains to the south, while Lily Cache drains to the west into Will County, where they confluence with the DuPage River. Just upstream of the Spring Brook #2 confluence is the junction of the East and West Branches of the DuPage River. The DuPage River continues on a southerly course where it intersects Lily Cache and eventually the Des Plaines River in Joliet.

2.3.2.2 Principal Flood Problems

Lily Cache – DuPage River Watershed No information regarding flooding problems for this tributary is available.

Spring Brook #2 – DuPage River Watershed No information regarding flooding problems for this tributary is available.

2.3.2.3 Flood Protection Measures

Lily Cache – DuPage River Watershed No information regarding flood protection measures for this tributary is available.

Spring Brook #2 – DuPage River Watershed No information regarding flood protection measures for this tributary is available.

2.3.3 East Branch DuPage River (EB)

2.3.3.1 Geographical Description

The East Branch DuPage River flows southward in the central portion of DuPage County. Communities that are adjacent to this river are Bloomingdale, Glendale Heights, Lombard, Glen Ellyn, Downers Grove, Lisle and Woodridge. Other communities that contribute watershed area to the East Branch are Addison, Carol Stream, Darien, Oak Brook, Naperville, Wheaton and Westmont. The headwaters of the East Branch DuPage River begin in the Village of Bloomingdale and proceed to the south, not greatly altering course. Much of the river in the northern to central portions of the watershed is the result of channelization work from the early part of the 20th century.

The major tributaries studied in this drainage basin are Prentiss Creek, St. Joseph Creek, Lacey Creek, Rott Creek, Willoway Tributary, Glen Crest Creek, Glen Park, Armitage Creek, 22nd Street, East Branch Tributary #2, Swift Meadows and Army Trail.

2.3.3.2 Principal Flood Problems

Main Stem East Branch DuPage River

Flooding along the East Branch DuPage River is minimal due to the construction of Westlake Lake in the Village of Bloomingdale, which is designed for a 100-year event. The total drainage area is 1,350 acres, most of which is residential. Lake Illini, the retention lake for the Indian Lakes subdivision, drains to the East Branch DuPage River. This development is built on a broad, shallow, perched valley. During intense rainfalls, standing water occurs in areas of equal elevation to Lake Illini. Because of a high water table of roughly 778 feet, only two feet of storage is available before the designed 100-year level of 780 feet is exceeded.

Flood stages on the East Branch DuPage River are monitored by USGS gage no. 5540140. The three highest recorded floods for the stream are summarized in the following tabulation (U.S. Department of the Interior, 1978):

Table 4: East Branch DuPage River Flood Stages at Army Trail Road (Gage No. 5540140) Water Return Surface Discharge Period DATE (Elev) (cfs) (years) 8/26/72 707.93 204 10 4/18/75 706.97 105 9/26/77 706.78 91

The portion of the East Branch DuPage River flowing through the Village of Glen Ellyn presents the most severe flood hazard within Glen Ellyn. Recent floods along the East Branch DuPage River have occurred in April 1950, October 1954, September 1961, and August 1972. The August 1972 flood produced a discharge approximately equal to the computed 50-year discharge at Maple Avenue in the Village of Lisle. Recorded crests for this flood at two Illinois Division of Water Resources crest-stage gages near Glen Ellyn are as follows (U.S. Department of the Interior, 1973):

Table 5: East Branch DuPage River August 1972 Recorded Flood Crests

Location Elevation (feet NGVD)

Butterfield Road 676.44 St. Charles Road 691.24

Damages in the Village of Glen Ellyn from overflow of the East Branch DuPage River and accompanying storm sewer back-up problems during the 1972 flood totaled approximately $500,000 for private homeowners and $40,000 for the Village of Glen Ellyn (Glen Ellyn News, 1972). Since discharge data are not available for the 1950, 1954, and 1961 floods, it is not possible to give an accurate estimate of their frequency. High water marks for these floods are indicated in (U.S. Department of the Interior, 1964; U.S. Department of the Interior, 1965).

22nd Street Tributary The principal cause of flooding in the area is the inadequate capacity of the natural channel to contain the runoff resulting from intense thunderstorm precipitation over the basin. Inundation of lands adjoining the river channel has been aggravated over the years by the gradual accumulation of silt. Buildup of sand bars and islands in the channel has resulted in the loss of channel capacity. Another factor lending itself to the poor flow characteristics of the channel in some reaches is the excessive growth of brush, light timber, and aquatic vegetation.

In the past, the watershed has experienced almost none of the flood problems associated with the overflow of streams from their natural channels. As discussed above, the reason for this can be attributed to the undeveloped nature of the floodplain areas. However, the watershed has experienced flood damages as a result of the ponding of runoff compounded by the inability of the storm sewer system to convey the storm waters away in a timely manner.

Armitage Creek Along the Armitage Ditch drainage system flooding conditions are aggravated by inadequate culverts. As more of the upstream reaches become developed, the downstream flood problems are intensified. Shallow flooding caused by ponding of runoff during heavy rains also occurs in several low-lying areas. The Village of Glendale Heights has experienced flooding on several occasions in the past, such as October 1954, July 1957, September 1961, June 1967 and August 1972. It is not possible to estimate the frequency of these events, as discharge data is not available for Armitage Creek. Monetary estimates of the resulting damages are also unavailable.

Crabtree Creek Flooding has occurred along Crabtree Creek, although most of the damages incurred during high stages of this stream result from basement flooding caused by sewer back-up. Signs of stream bank and bed erosion, caused by high water velocities, are evident along Crabtree Creek.

East Branch DuPage River Tributary No. 2 Flooding problems have occurred at several locations in the Tributary No. 2 watershed, although these problems have generally been limited to yard flooding and road overtopping. Flooding has been reported by residents on Main Street, 2nd Street west of Forest Avenue, and along Park Avenue. Road overtopping has been reported on Main Street and Glenrise Avenue.

Lacey Creek Low-lying areas of the watershed are subject to periodic flooding caused by overflow of the various watercourses within the community. The most severe flooding occurs in late summer as a result of heavy thunderstorms following periods of prolonged rainfall that have saturated the ground. Flooding during the winter months has usually been a result of heavy rainfall on frozen ground. Repeated damage to structures has occurred during past floods, especially those of October 1954, July 1957, and August 1972.

Prentiss Creek Prentiss Creek presents the most severe flood hazard within the Village of Woodridge. Floods along Prentiss Creek, as well as along the village’s other streams, are usually highest in early spring, resulting from heavy rainfall and rapid snowmelt. Flooding along the creek is often aggravated by debris accumulation. Although just outside of the village limits, the constrictive culvert under State Route 53 causes substantial flooding of lands located just upstream of the bridge. Overbank flooding along Prentiss Creek is usually accompanied by back-up of street storm sewers and basement drains, two problems not specifically addressed by this study. Another major cause of flooding along 63rd Street is the inadequate capacity of the underground pipe that carries a small tributary stream from just upstream of 63rd Street at Winston Street to Prentiss Creek.

A profile of the July 1963 flood, Prentiss Creek’s flood of record, is available. Recorded flood crest elevations for the USGS crest- stage gage at State Highway 53 are as follows:

Table 6: Prentiss Creek Flood of Record (July 1963) Recorded Flood Crests at Illinois State Highway 53 (Downstream) Flood Flood Crest Elevation (NGVD)

July 1963 663.94 August 1972 663.81

Accurate estimates of the recurrence intervals for these floods cannot be made since the above flood crest elevations were affected by backwaters from the East Branch DuPage River, and corresponding discharges are not available.

St. Joseph’s Creek and the East Branch DuPage River The East Branch DuPage River and St. Joseph Creek have been sources of greatest concern in the Village of Lisle. Flooding has been reported on the East Branch DuPage River in 1948, 1950, 1954, 1957, and 1972. Flooding on St. Joseph Creek and the East Branch DuPage River in October 1954 caused the evacuation of many people. Water covered parts of Ogden Avenue, State Highway 53, Burlington Street, McKinley Avenue, Dumoulin Street, and River Drive. Flood waters reached the top of the Burlington Northern Railroad overpass on Main Street. A severe thunderstorm in July 1957 reportedly dropped 7.7 inches of rain in six hours in nearby Downers Grove, causing flooding along St. Joseph Creek in Lisle. The August 1972 flood, however, proved to be the flood of record on the East Branch DuPage River and the most damaging in the area. The 1972 flood is estimated to have a recurrence interval of about 50 years and resulted in a peak

discharge on the East Branch DuPage River at village of Lisle of 2,500 cubic feet per second. Torrential rains were reported in excess of 7 inches in three hours in localized measurements.

St. Joseph’s Creek The most severe flood of recent record occurred in August 1972, when flood waters rose near Belmont Avenue to an elevation of 691.13 feet on St. Joseph Creek (Downers Grove Reporter, 1954, et cetera). Based on the past history of floods within the area, this flood had a recurrence interval of 10 years.

Rott Creek, Willoway Brook, Glen Crest Creek, Glen Park Tributary, Swift Meadows and Army Trail No flooding information particular to these tributaries is available.

2.3.3.3 Flood Protection Measures

Main Stem – East Branch DuPage River Following the floods of 1954 and 1957 in the Village of Lisle, new emphasis was given to studies for the East Branch DuPage River. A Survey Report for Flood Control was completed in 1962 by the Department of Public Works and Buildings, Division of Waterways, covering this stream (State of Illinois, 1962). Subsequently, the East Branch DuPage River channel has been enlarged and levees built on both sides of the channel in the area from the Burlington Northern Railroad crossing to Middleton Avenue. From Maple Avenue to the Burlington Northern Railroad crossing, a levee was constructed on the east bank only. The levees along the East Branch DuPage River at Lisle will be overtopped by the 100-year flood.

For the portion of East Branch DuPage River flowing through the Village of Glen Ellyn, in the past, damages associated with storm sewer back-up have been significant during periods of intense rainfall. In order to avoid these street and basement flooding problems, several detention and retention ponds have been constructed within the Village of Glen Ellyn.

There are two low-flow dams located on the East Branch DuPage River. One is located in the Morton Arboretum near the Village of Lisle and the other is a controlling structure for the Churchill Woods Lagoon. There are no Federal flood control structures on the East Branch DuPage River or its tributaries within the unincorporated areas of DuPage County.

Armitage Creek The Village of Glendale Heights initiated a comprehensive drainage study (Ralph F. Gross and Son, Associates, Inc, Village

of Glendale Heights Comprehensive Storm Drainage Report, Nov. 1973) which highlighted flood problem areas and recommended corrective action including the installation of storm sewers, construction of retention ponds, channel dredging, the modification of existing drainage ordinances, and the adopting of new ordinances to preserve and control the natural flood plain. Many of the structural improvements recommended in this report have been constructed by the village. These measures have served to reduce and in some cases alleviate the flood problem in their vicinity. Such was the case on Armitage Fork, where channel paving and culvert enlargement significantly reduced the flood potential along this watercourse.

East Branch Tributary No. 2 One of the flood protection measures that has been implemented in East Branch Tributary No. 2 is an overflow channel to handle high flow between Main Street and Park Boulevard. Low flows are carried in a corrugated metal storm sewer, and an overflow channel is provided for high flows. A crossover structure just east of Main Street is designed to assure full flow in the storm sewer before flow enters the overflow channel. There is also an overflow basin located between Forest and Park Street in the south side of Second Street, which detains flow when the capacity of the Second Street storm sewer is reached. Stream bank stabilization was completed by DuPage County on the overflow channel in 1994 for the reach between Main Street and Forest Avenue, and the reach between Park Boulevard and Goodrich Avenue. Between Forest Avenue and Park Boulevard, the overflow passes through a wide grassy area that may have been designed for flood storage.

Glen Crest Creek Retention facilities were constructed in Glen Ellyn to reduce sewer back-up during intense rain events. These include the retention pond system at the Village Links golf course and the detention ponds at Panfish Park and Glen Ellyn Manor. During the August 1972 storm, no significant flooding was reported by areas serviced by the Village Links storm retention system.

Prentiss Creek As the areas near Prentiss Creek have been residentially developed, substantial filling has occurred, and portions of the stream have been realigned. This is particularly true in that reach of the stream between State Route 53rd and 63rd Street. An independent citizens’ committee, the Prentiss Creek Flood Committee, has been formed to investigate solutions to flooding along Prentiss Creek. Additionally, the Village of Woodridge has recently begun discussions with neighboring communities to consider the regulation of storm runoff into Prentiss Creek.

St. Joseph Creek Following the floods of 1954 and 1957, new emphasis was given to study St. Joseph Creek. A Survey Report for Flood Control was completed in 1962 by the Department of Public Works and Buildings, Division of Waterways, covering this stream (State of Illinois, 1962). St. Joseph Creek has been straightened and enlarged from its mouth to Curtiss Street in the portion flowing through the Village of Downers Grove. Channel and culvert improvements along St. Joseph Creek have significantly reduced the flood potential in some areas. During the flood of October 1954, extensive damage occurred in the downtown business area of the Village of Downers Grove. The village subsequently dredged a portion of St. Joseph Creek and that, together with clearing of debris from the channel, eliminated the flooding in the downtown area during the July 1957 flood. At the present time, a culvert from Mackie Avenue to Carpenter Street prevents the 100-year floodwaters from reaching the downtown business area. An earthen berm has been constructed just upstream of 55th Street to further reduce the flooding of downstream areas.

22nd Street Tributary There are no flood protection works on streams in the area. However, the area has an active storm water management program to alleviate some of the problems attributed to the ponding of runoff.

Crabtree Creek, Lacey Creek, Rott Creek, Glen Park Tributary, Willoway Creek, Swift Meadows and Army Trail Tributaries No information regarding flood protection measures for these tributaries is available.

2.3.4 Fox River (FR)

2.3.4.1 Geographical Description

The Fox River flows from the State of Wisconsin through the Illinois Counties of Lake, McHenry, Kane, Kendall and LaSalle confluencing with the Illinois River at Ottawa, Illinois. DuPage County contributes watershed area to the Fox River from all tributaries bordering the west side of the County, with the exception of tributaries that drain to the West Branch DuPage River.

The DuPage County tributaries that drain to the west, into Kane and Kendall Counties towards the Fox River, are: Brewster Creek, Norton Creek, Indian Creek and Waubansee Creek.

2.3.4.2 Principal Flood Problems

Indian Creek Indian Creek and its tributary Selmarten Creek, are subject to severe flooding resulting from the inadequacy of the natural channel and appurtenant drainage structures to accommodate the high rates of runoff resulting from intense thunderstorms. Channels are inadequate to handle the sudden surge of runoff, and discharges are retarded by the poor flow characteristics of the channels and by inadequate capacities of bridges, culverts, and sewers that cross the streams.

The major problem drainageway in Aurora is Indian Creek; it passes through a high-density development and urbanization is proceeding northward into the upper portions of the watershed.

Waubansee Creek The Waubansee Creek watershed has the potential for urban development and care should be taken to ensure reasonable growth. No specific flooding problems on Waubansee Creek have been identified.

Brewster and Norton Creeks The principal cause of flooding in the area is the inadequate capacity of the natural channel to contain the runoff resulting from intense thunderstorm precipitation over the basins. Inundation of lands adjoining the river channel has been aggravated over the years by the gradual accumulation of silt. Buildup of sand bars and islands in the channel has resulted in the loss of channel capacity. Another factor lending itself to the poor flow characteristics of some portions of channel is the excessive growth of brush, light timber and aquatic vegetation.

The flood of record occurred in June 1967 when areas along Brewster and Norton Creeks were inundated. Damage resulting from this flood generally occurred in small, localized, rural areas.

In the past, these tributaries experienced few problems associated with the overflow of streams from their natural channels. These watershed areas are comprised mostly of undeveloped or agricultural lands with very few structures in the flood plain. The flood hazards associated with the smaller streams are minor and again the flood plains are relatively undeveloped and are just now being developed. This, very little damage to structures has occurred in the past even during periods of extreme high water.

2.3.4.3 Flood Protections Measures

Waubansee Creek There are two on-channel surface reservoirs on Waubansee Creek just upstream of the crossing of the Elgin Joliet and Eastern railroad. Construction of the reservoirs meet the requirements of the Federal Insurance Administration developed by a private development company for flood control related to urbanization. In addition to reservoirs, on-site retention storage is being installed throughout the watershed wherever substantial residential or commercial construction is taking place.

Indian Creek, Norton Creek and Brewster Creek No information regarding flood protection measures for these tributaries is available.

2.3.5 Salt Creek (SC)

2.3.5.1 Geographical Description

Salt Creek is a tributary of the Des Plaines River, where a portion of the Creek flows through the eastern-central sections of DuPage County. Much of the watershed area in Salt Creek is densely developed, and has as a result suffered from significant flooding events (see 2.3.5.2 for more details). The communities of Roselle, Itasca, Wood Dale, Addison, Lombard, Villa Park, Elmhurst, Oak Brook, Oakbrook Terrace, Westmost, Clarendon Hills and Hinsdale all contribute watershed area to Salt Creek and its tributaries.

Oak Brook Tributary flows southward from the northern section of Cook County to Oak Brook, then eastward to its confluence with the Des Plaines River, at Lyons. The DuPage County Salt Creek tributaries involved are: Spring Brook, Devon Avenue, Westwood Creek, Sugar Creek, Oakbrook Tributary, Ginger Creek and Bronswood Tributary.

2.3.5.2 Principal Flood Problems

Main Stem Salt Creek Low-lying areas of Wood Dale, Itasca, Elmhurst, Addison, Oak Brook and Oakbrook Terrace are subject to periodic flooding caused by overflow of Salt Creek. As a result, storm drain outfalls become blocked and areas along small tributaries are flooded. The blocked storm runoff infiltrates the sanitary sewer system, creating sewer overloads and subsequent basement backup. Repeated damage to structures in the floodplain of Salt Creek has occurred during such floods as those in 1957, 1960, 1961, 1966, 1967, 1968, 1972, and 1973. The worst floods occurred in 1954, 1967, and 1972. The floods of 1954 and 1967 both have an estimated recurrence of 10 years as determined by SCS and the flood of 1972 has an estimated recurrence interval of 25 years as determined by the USGS.

In Addison, a USGS crest-stage recorder is located on Salt Creek at the Lake Street Bridge. The flood-of-record occurred on August 27, 1972. An official or published discharge value for Salt Creek at Addison is not available. Stage-discharge relationships developed by Harza indicates that this flood had a peak discharge of about 3,340 cubic feet per second (cfs), a 50-year event. A 1973 report (U.S. Department of Agriculture, 1976) indicated that about 700 homes were within the flooded area of which about 500 applied for Federal aid after the flood had receded. Major damage was attributed to basement flooding by direct overland flow

through windows or seepage through wall or foundation cracks. Additional damage occurred in some residences due to back-up through combined sewers. Dollar estimates of the damages are not available.

Spring Brook Creek and West Branch Tributary to Spring Brook Creek Spring Brook Creek drains the north sector of the Village of Bloomingdale. Flooding occurs because of inadequate channel capacities due to increased runoff from developing land within the Villages of Bloomingdale and Roselle. In the upper portion of the West Branch Tributary to Spring Brook Creek, flooding occurs because the land is flat, marshy, has considerable debris in the channel, and as such, has no well-defined course. After it crosses Lake Street, the West Branch Tributary to Spring Brook Creek flows northerly where the channel is well defined and flow is less obstructed. Flooding along the mainstem of Spring Brook Creek occurs downstream of the confluence with the West Branch Tributary to Spring Brook Creek. The creek is well defined but is usually clogged with debris. Flooding occurs because the gradient is much less than the upper reaches. Most flooding is confined along a narrow belt, paralleling the channel.

Flood stages on Spring Brook Creek are monitored by USGS gages no. 5531080. The three highest recorded floods for the stream are summarized in the following tabulation (USGS, 1978):

Table 7: Spring Brook (SC) Flood Stages – Gage No. 5531080

Water- Return Surface Discharge Period DATE (Elev) (cfs) (years) 8/26/72 714.10 645 50 1/27/74 710.25 263 4/18/75 710.16 256

Devon Avenue Tributary Devon Avenue Tributary overflow causes periodic flooding in the low-lying areas of the Village of Itasca. As a result, storm drain outfalls become blocked and areas along small tributaries are flooded. The blocked storm runoff infiltrates the sanitary sewer systems, creating sewer overloads and subsequent basement back- up. Repeated damage to structures in the floodplains have occurred during such floods as those in 1957, 1960, 1961, 1966, 1967, 1968, 1972, and 1973. Westwood Creek Principal flood problems in the Village of Addison are street flooding caused by inadequate storm sewers and out-of-bank

flooding along Salt and Westwood Creeks (U.S. Department of Agriculture, 1976). As stated previously, the flood-of-record occurred on August 27, 1972. It is unknown of the 700 impacted homes in the 1972 event, how many were affected by Westwood Creek alone.

Oak Brook Tributary Overflow of Oak Brook Tributary and Salt Creek also causes principal flood problems in the City of Oakbrook Terrace. Oak Brook Tributary is ungaged. The best historical data available for flooding in Oakbrook Terrace are from a USGS recorder gage on Salt Creek, just north of Western Springs at Wolf Road about 7,000 feet downstream of the eastern corporate limit (U.S. Department of the Interior, 1976). At this point, Salt Creek has a drainage area of 114 square miles, and there is 31 years of data from the Western Springs gage (U.S. Water Resources Council, 1976). The 5 most significant floods of record are tabulated below:

Table 8: USGS Recorder Gage of Salt Creek at Western Springs Gage Total Discharge Height Height Date (cfs) (ft) (ft)

March 20, 1948 1,920 8.06 632.99 August 28, 1972 1,790 8.55 633.48 October 10, 1954 1,710 8.27 633.20 April 19, 1975 1,600 8.14 633.07 May 12, 1966 1,460 7.63 632.56

Sugar Creek, Ginger Creek, Westwood Creek, and Bronswood Creek No flooding information particular to these tributaries is available.

2.3.5.3 Flood Protection Measures

Main Stem Salt Creek On Salt Creek, there is an existing low-flow dam at Oak Brook. There are a number of proposed reservoir projects in the Salt Creek watershed.

• A multipurpose flood control facility along Salt Creek referred to as the Elmhurst Quarry has been proposed for land directly north of the Chicago and Northwestern railroad, east of State Route 83 and west of Highland Avenue.

• One floodwater- retarding reservoir on Salt Creek (Busse Woods Reservoir) is under construction approximately one mile upstream of the Village of Itasca. Construction was

scheduled for completion in September 1976. This reservoir will reduce, but not eliminate, flooding in the Village of Itasca.

• The Kingery dike has been constructed on the east side of Salt Creek in the northern Village of Villa Park and it contains the 500-year flood. This dike is the eastern boundary of the floodway and is in extreme northern Villa Park. In addition, there is a local zoning ordinance in the Village of Villa Park which restricts development within the floodplain.

An Act in Regulation to the Rivers, Lakes, and Streams of the State of Illinois, approved June 10, 1911, as amended (Illinois Revised Statutes, Chapter 19, 52 et seq, 1975) authorizes the Department of Transportation to define floodplains and establish a permit procedure for regulating construction within such defined floodplains (Illinois Department of Transportation, 1973).

Spring Brook Creek and its Tributaries (Meacham Creek) Along Spring Brook in Roselle, the Centex Industrial Park provides 319.8 acre-feet of storage in a basin located just north of Irving Park Road. The Village of Roselle is planning another detention basin just south of the Chicago, Milwakee, St. Paul. and Pacific Railroad and north of Central Avenue.

Sugar Creek, Ginger Creek, Westwood Creek, Devon Avenue, Oak Brook Tributary and Bronswood Creek No information regarding flood protection measures for these tributaries is available.

2.3.6 Sawmill Creek (SW)

2.3.6.1 Geographical Description

Sawmill Creek (a Des Plaines River Tributary) is the smallest watershed identified within DuPage County. Sawmill Creek, found in the southeastern section of DuPage County, draws watershed area from the communities of Darien, Willowbrook, Woodridge, Burr Ridge and Downers Grove. As Sawmill Creek approaches the Des Plaines River, the characteristics of the watershed change from mild or moderately-sloped residential to steeply-sloped forested. It is this lower watershed area that is home to the Waterfall Glen Forest Preserve and Argonne National Laboratory.

Sawmill Creek’s one tributary, Wards Creek, joins Sawmill Creek on the south side of I-55, north of Argonne National Laboratory. Sawmill Creek confluences with the Des Plaines River approximately 7000 ft downstream of the Route 83 crossing of the Des Plaines River.

2.3.6.2 Principal Flood Problems

Inadequate storm sewers and out-of-bank flooding along Sawmill Creek and its tributaries, East Branch Sawmill Creek and West Branch Sawmill Creek cause principal flood problems in the City of Darien. Flooding from inadequate sewers occurs in the area bounded roughly by Plainfield Road and Willow Lane. Flood damages include residential damages, traffic disruptions, and associated neighborhood degradation caused by frequent flooding. There are no discharge gages located on Sawmill Creek, and peak discharges for past floods are not available.

East Branch Sawmill Creek Flooding occurs along the entire reach of East Branch Sawmill Creek in the Village of Willowbrook. The June 13, 1976, flood caused damage along Eleanor Place and Virginia Court south of 75th Street and north of 79th Street. Floods on East Branch Sawmill Creek generally occur at the same time as those on Flagg Creek. The Flagg Creek basin borders the Sawmill Creek basin on the north and west.

2.3.6.3 Flood Protection Measures

Sawmill Main Stem, Branches and Wards Creek Along the East Branch of Sawmill Creek, the Village of Willowbrook constructed Lake Hinsdale. With a storage volume of about 35 acre-feet, the facility controls discharges to both the

East Branch of Sawmill Creek and to the 63rd Street Ditch from portions of the watershed west of Kingery Highway. Other than this basin, there are no man-made flood protection measures on Sawmill Creek, the Branches of Sawmill Creek or Wards Creek. Sawmill Creek and the East Branch of Sawmill Creek are included in a floodwater management plan for the Des Plaines River watershed (“Des Plaines River Floodwater Management Plan and Environmental Assessment”, Des Plaines River Flood Plain Steering Committee, assisted by U.S. Department of Agriculture, January 1976). Measures recommended in that study have not been implemented.

2.3.7 West Branch DuPage River (WB)

2.3.7.1 Geographical Description

The West Branch DuPage River, the largest watershed in DuPage County, flows southward near the western edge of the county. The West Branch DuPage River flows through the communities of Hanover Park, Bartlett, Winfield, West Chicago, Warrenville, and Naperville. The communities of Roselle, Wayne, Bloomingdale, Carol Stream, Wheaton, Glendale Heights, St. Charles, Glen Ellyn, Lisle and Aurora also contribute watershed area to the West Branch DuPage River. The West Branch headwaters are found to the north of DuPage County in Cook County. The river enters DuPage County in the Village of Hanover Park where is winds its way west towards Bartlett. The river takes a slow serpentine approach, always to the south, changing bearing to the southeast through Warrenville and Naperville. Unlike the other more urbanized major river systems in DuPage County, the West Branch DuPage River has large forested buffers throughout its length. It is only when approaching the Warrenville and Naperville area where the river buffer decreases, also increasing the likelihood of flood impacts (please refer to section 2.3.7.2 for further information).

The major tributaries studied in this drainage basin are Tributary #1 (Keeneyville), Klein Creek, Kress Creek, Springbrook #1, Ferry Creek, Cress Creek and Steeple Run.

2.3.7.2 Principal Flood Problems

The West Branch DuPage River Main Stem Flooding along the West Branch DuPage River in the Village of Hanover Park is frequent and severe. Rapid urbanization in the drainage area since 1960 has led to increasing storm runoff, while at the same time, development in the floodplain in the north portion of the village has obstructed overbank flows during floods, raising water-surface elevations in the vicinity and generally worsening the damage conditions. A major storm in October 1954 caused record flooding in the Chicago area but Hanover Park was sparsely developed at that time. Other significant floods occurred on June 10, 1967, and on September 6, 1970, with an estimated 2.7 inches of rainfall in the drainage area. Peak discharges at the crest stage gage at Lake Street on the West Branch DuPage River reached 570 cfs in 1967 and 450 cfs in 1970. Damages in Hanover Park resulting from the 1970 flood were estimated at $470,000. In addition to flooding due to major storms, more frequent flooding occurs due to high waters in the river blocking storm sewer outlets and causing basement flooding (Harza Engineering Company, 1971).

West Branch DuPage River also causes flooding within the City of Naperville. The amount of land subject to inundation within the City of Naperville from the West Branch DuPage River was significantly reduced by the construction of the Fawell Dam, just north of Naperville, by the Illinois Division of Water Resources in July 1972. The natural topography of the City of Naperville, particularly in the north-central portion of the city, has always been inadequate for the removal of storm water without some degree of total surface ponding occurring. This problem has been aggravated, however, by the continued development within Naperville, which has decreased the amount of uncovered ground available for saturation by precipitation.

Major destructive floods along the West Branch DuPage River occurred in March 1948, April 1950, October 1954, July 1957, and August 1972. For the Illinois Division of Water Resources stream gage near Warrenville, the maximum recorded discharge occurred on August 26, 1972. Although records for this gage begin only in 1968, a high-water mark near the Warrenville gage indicates that the October 1954 flood conveyed even a greater discharge. Although the Warrenville stream gage crested on August 26 during the August 1972 flood, the majority of the damage within Naperville resulted from a storm occurring a few days later, on August 29, when an average of 5.9 inches of rain fell over the West Branch DuPage River Basin over a 5-hour period. Rain gages at two of Naperville’s sewage plants registered 4.75 and 5.25 inches of rainfall. As a result of the Fawell Dam’s recent construction, the West Branch DuPage River was reported to leave its banks only in the city’s southern portions. Property damage from the August 1972 flood was estimated in excess of $1.15 million for the Naperville area.

During the period of October 9-11, 1954, the West Branch DuPage River Basin received an average of approximately 7.5 inches of rain, while Naperville received in excess of 9 inches. The gage at Shorewood, on the DuPage River, registered its highest recorded discharge for this storm.

Klein Creek The principal causes of flooding in the area are the inadequate capacities of the natural channels to contain the runoff resulting from intense thunderstorm precipitation over the watershed. Additional flooding problems are created by the many channel and floodway constrictions resulting from inadequate waterway openings at bridges and the floodplain encroachments in urban areas. Many of the bridges, principally those along Klein Creek, have inadequate waterway openings which cause increased water

stages and flooding upstream of the bridge when discharges exceed their capacity.

A matter of serious concern has been the growth of urban development on the floodplain of the river. Houses, garages, fences, and related construction have been built on the immediate banks of the river without adequate consideration of their effect on flood flows on the river and are subject to early inundation in high water stages and also serve to block effective flow of the floodwaters.

Repeated damage to structures in the floodplains has occurred during such floods as those that occurred in 1942, 1947, 1948, 1949, 1950, 1951, 1953, 1954, 1957, 1959, 1961, 1962, 1966, 1967, 1972, and 1975. High water marks available along Klein Creek indicate elevations of approximately 743 feet in October 1954 and 743 feet in June 1962. Both of these storms have an estimated 10-year recurrence interval.

Klein Creek drains the southwest section of the Village of Bloomingdale. Construction commenced in this area in 1979 and converted 77 percent of the area north of Army Trail Road from agricultural to commercial/residential use. Flooding occurs here because of a naturally high water table and poorly draining soils. The worst flooding occurred during the August 1972 storm when a water-surface elevation of 765.5 feet was reached at Army Trial Road. This elevation correlated well with a predicted 767.7 100- year elevation from a USACE study (USACE, 1975). The flood areas shown on the Flood Boundary and Floodway Map were provided by Mackie Consultants, the engineer for the developer (Mackie Consultants, Inc., 1977).

Kress Creek Discussions with city representatives revealed that the major flood problems in West Chicago have been along Kress Creek. The greatest flood in the West Chicago area occurred in October 1954. Flood delineations for this event in West Chicago, taken from the Hydrologic Investigations Atlases (U.S. Department of the Interior, 1965, et cetera), indicate that areas adjacent to Kress Creek were flooded up to widths of 1,000 feet, while the Unnamed Tributary to Kress Creek was minimally affected. During the 1954 flood along the West Branch DuPage River, the portion of West Chicago upstream of State Highway 38 was flooded up to 250 feet from the channel on the right (west) bank, while downstream of the highway the left (east) bank was flooded for a distance of up to 350 feet from the channel. The peak discharge for the 1954 flood on the West Branch DuPage River in West Chicago had a recurrence probability of about 50 years. Specific damage

estimates in West Chicago during the 1954 or 1972 floods were not found in the newspaper accounts of the flooding.

Winfield Creek Principal flood problems in the City of Wheaton include overbank flooding from Winfield Creek, as well as local ponding of storm runoff at several locations. Major floods have occurred along Winfield Creek in May 1954, October 1954, and August 1972. Although the May 1954 flood caused only minor damage, substantial damages were sustained during the October flood of the same year. The following areas are among those hardest hit in the City of Wheaton during the October 1954 flood: areas surrounding Winfield Creek near North Side Park and Gary Avenue, the East Hawthorne subdivision, the area near Wheaton High School and the Wheaton Sanitary District plant on Weisbrook Road (Wheaton Experiences Much Loss, 1954).

The August 1972 flood was the flood of record for Winfield Creek. Several cars were washed into Winfield Creek at Main Street from streets and parking lots. Damages during the 1972 flood in Wheaton were set at $5,055,000 (“Damage Estimate Set,” 1972).

Gage readings for the August 26, 1972, flood along Winfield Creek are as follows (U.S. Department of the Interior, 1973):

Table 9: Winfield Creek Gage Readings for 1972 Flood Event Record Elevation Gage Location (NGVD) Winfield Creek Route 38 721.28 Gary Avenue 731.67

A discharge of 455 cfs was estimated at the Warrenville Road gage for Spring Brook Creek during the 1972 flood (U.S. Department of the Interior, 1973). This figure is slightly larger than the computed 100-year flood peak discharge of 430 cfs. No discharge data are available for Winfield Creek.

Steeple Run As stated previously, the most severe flooding event in the City of Naperville was the August 1972 event. Some of the most severe flooding within Naperville took place in the Steeple Run Watershed, that sits primarily in the historical east side of the city. Both Huffman and Porter Streets suffered from severe flooding due to storm sewer overflow and local ponding.

Cress Creek, Ferry Creek, Spring Brook #1 and Tributary #1 No significant flooding other than isolated drainage problems have been identified in these tributaries.

2.3.7.3 Flood Protection Measures

Main Stem West Branch DuPage River After the damaging floods in 1948 and 1950, the Illinois Division of Water Resources made flood control studies on the West Branch DuPage River and other streams. After the floods of 1954 and 1957, these studies were expanded and a report on the DuPage River completed in 1962. This report recommended a program of channel improvement, some levee and floodwall construction, and a detention reservoir on the West Branch DuPage River upstream from the City of Naperville. These flood control measures were intended to control flood flows with an expected recurrence frequency of about 50 years. Subsequently, Fawell Dam was constructed approximately 0.25 miles upstream of U.S. Highway 34 (Ogden Avenue). This dam was designed with a flood control storage reservoir of 2,900 acre-feet, adequate for a 50-year flood.

Three detention basins have been constructed by the City of Naperville since 1972, all of which have been designed to control runoff from the 100-year frequency rainfall. These basins are within the tributaries of Cress Creek and Steeple Run. In addition, another basin is proposed for the grounds of North Central College, and plans call for the expansion of an existing quarry, referred to as the Chicago Avenue Basin, to 100-year storm capacity.

The West Branch DuPage River is the major cause of flooding in the Village of Hanover Park, Illinois, downstream from the Village of Schaumburg. Flood control works on the West Branch DuPage River in Hanover Park include extensive channel improvements and two retention basins. Retention Basin “A” will be located along the West Branch DuPage River near the Hanover Park- Schaumburg corporate boundary, about 1,500 feet west of Springingsguth Road. This basin will provide about 110 acre-feet of flood control storage, but will not affect flood elevations on the West Branch DuPage River in Schaumburg.

Three dams have been built on the West Branch DuPage River. These are Warrenville Grove Dam, McDowell Forest Preserve Dam, and Fawell Dam. Warrenville Grove and McDowell Forest Preserve Dams are low-flow dams with no storage capacity. The other dam, Fawell Dam, lies north of Naperville and was constructed as a flood control dam. There are no new major flood

control projects proposed for the West Branch DuPage River for the near future.

Cress Creek Per a report performed by Lindley & Sons, Inc., Naperville- Northcentral Storm Drainage Report, a recommendation was made to build the Jefferson School Basin, at the intersection of Washington Street and Iroquois Avenue. This basin has since been completed.

Steeple Run Per a report performed by Lindley & Sons, Inc., Naperville- Northcentral Storm Drainage Report, a recommendation was made to construct the County Commons Basin, just east of Huffman Street at School Street; and the Pembroke Greens Basin, just south of Cheshire Road between Charles Street and Richard Road. These basins have been completed.

Creeks South of Foxcroft and South of 87th Street Earthen dikes with 1.0-foot diameter culverts are located along each of these tributaries to the West Branch DuPage River. These dikes were placed by private interests and cause an open field just southwest of the intersection of 87th Street and Washington Street to act as a detention pond. Because of their questionable construction, however, these dikes cannot be relied upon as flood control structures.

Winfield Creek Development of floodplains within the City of Wheaton is currently regulated by Chapter 12.5 of the Wheaton City Code. The problem of overbank flooding along Winfield Creek was recently studied for the City of Wheaton by the engineering firm of Baxter and Woodman, Inc. As a result of these studies (Baxter and Woodman, Inc., 1975; Baxter and Woodman, Inc., 1976), several suggestions were made to alleviate the flooding situation along the stream. These include construction of berms around properties near Gary Avenue, reconstruction of several culverts, debris clearance, and construction of a retention pond.

Klein Creek, Ferry Creek, Spring Brook #1, and Kress Creek No information regarding flood protection measures for these tributaries is available.

3.0 ENGINEERING METHODS & FLOOD PLAIN MANAGEMENT APPLICATIONS

For the flooding source studied in detail in the county, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this FIS. Flood events of a magnitude that are expected to be equaled or exceeded once on the average during any 10-, 50-, 100-, or 500-year period (recurrence interval) have been selected as having special significance for floodplain management and for flood insurance rates. These events, commonly termed the 10-, 50-, 100-, and 500-year floods, have a 10-, 2-, 1-, and 0.2-percent chance, respectively, of being equaled or exceeded during any year. Although the recurrence interval represents the long-term average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood that equals or exceeds the 100-year flood (1-percent chance of annual exceedence) in any 50-year period is approximately 40 percent (4 in 10), and, for any 90-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the county at the time of completion of this FIS. Maps and flood elevations will be amended periodically to reflect future changes.

General Benchmark Information

All elevations are referenced to National Geodetic Vertical Datum of 1929 (NGVD) formerly referred to as mean sea level with the 1929 General Adjustment; elevation reference marks used in the study are shown on the maps.

Qualifying bench marks within a given jurisdiction that are cataloged by the National Geodetic Survey (NGS) and entered into the National Spatial Reference System (NSRS) as First or Second Order Vertical and have a vertical stability classification of A, B, or C are shown and labeled on the FIRM with their 6- character NSRS Permanent Identifier.

Benchmarks cataloged by the NGS and entered into the NSRS vary widely in vertical stability classification. NSRS vertical stability classifications are as follows:

• Stability A: Monuments of the most reliable nature, expected to hold position/elevation well (e.g., mounted in bedrock)

• Stability B: Monuments which generally hold their position/elevation well (e.g., concrete bridge abutment)

• Stability C: Monuments which may be affected by surface ground movements (e.g., concrete monument below frost line)

• Stability D: Mark of questionable or unknown vertical stability (e.g., concrete monument above frost line, or steel witness post)

In addition to NSRS benchmarks, the FIRM may also show vertical control monuments established by a local jurisdiction; these monuments will be shown on the FIRM with the appropriate designations. Local monuments will only be placed on the FIRM if the community has requested that they be included, and if the monuments meet the aforementioned NSRS inclusion criteria.

To obtain current elevation, description, and/or location information for benchmarks shown on the FIRM for this jurisdiction, please contact the Information Services Branch of the NGS at (301) 713-3242, or visit their Web site at www.ngs.noaa.gov.

It is important to note that temporary vertical monuments are often established during the preparation of a flood hazard analysis for the purpose of establishing local vertical control. Although these monuments are not shown on the FIRM, they may be found in the Technical Support Data Notebook associated with this FIS and FIRM. Interested individuals may contact FEMA to access this data.

Vertical Datum Issues

All FISs and FIRMs are referenced to a specific vertical datum. The vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared. Until recently, the standard vertical datum in use for newly created or revised FISs and FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD 29). With the finalization of the North American Vertical Datum of 1988 (NAVD 88), many FIS reports and FIRMs are being prepared using NAVD 88 as the referenced vertical datum.

All flood elevations shown in this FIS report and on the FIRM are referenced to NGVD 29. Structure and ground elevations in the community must, therefore, be referenced to NGVD 29. It is important to note that adjacent communities may be referenced to NAVD 88. This may result in differences in base flood elevations across the corporate limits between the communities.

For more information on NAVD 88, see Converting the National Flood Insurance Program to the North American Vertical Datum of 1988, FEMA Publication FIA- 20/June 1992, or contact the Vertical Network Branch, National Geodetic Survey, Coast and Geodetic Survey, National Oceanic and Atmospheric Administration, Rockville, Maryland 20910 (Internet address http://www.ngs.noaa.gov).

Floodplain Management Applications

The NFIP encourages State and local governments to adopt sound floodplain management programs. To assist in this endeavor, each FIS provides 100-year floodplain data, which may include a combination of the following: 10-, 50-, 100-,

and 500-year flood elevations; delineations of the 100-year and 500-year floodplains; and 100-year floodway. This information is presented on the FIRM and in many components of the FIS, including Flood Profiles, Floodway Data tables, and Summary of Stillwater Elevation tables. Users should reference the data presented in the FIS as well as additional information that may be available at the local community map repository before making flood elevation and/or floodplain boundary determinations.

Floodplain Boundaries

To provide a national standard without regional discrimination, the 1-percent annual chance (100-year) flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2-percent annual chance (500-year) flood is employed to indicate additional areas of flood risk in the community. For the stream studied in detail, the 100- and 500-year floodplains have been delineated using the flood elevations determined at each cross section. Between cross sections, the boundaries were interpolated using topographic maps at a scale of 1:4,800, with contour intervals of 2 to 10 feet (State of Illinois, 1976; USGS, 1972, et cetera; State of Illinois, Floodplain Topographic Map for Salt Creek Watershed, 1975).

Approximate Methods

Flood boundaries for areas studied by approximate methods were delineated using USGS Flood Prone Area Maps, and Regulatory Flood Plain Maps (USGS, 1972, et cetera; USACE, 1975).

The 100- and 500-year floodplain boundaries are shown on the FIRM. On this map, the 100-year floodplain boundary corresponds to the boundary of the areas of special flood hazards (Zones A, AH, and AE), and the 500-year floodplain boundary corresponds to the boundary of areas of moderate flood hazards. In cases where the 100- and 500-year floodplain boundaries are close together, only the 100-year floodplain boundary has been shown. Small areas within the floodplain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data.

Floodways

Encroachment on floodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to assist local communities in this aspect of floodplain management. Under this concept, the area of the 100-year floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that the 100-year flood can be carried without substantial increases in flood heights. Minimum Federal

standards limit such increases to 1.0 foot, provided that hazardous velocities are not produced. The floodway in this FIS is presented to local agencies as a minimum standard that can be adopted directly or that can be used as a basis for additional floodway studies.

In Illinois though, under Revised Statutes, Section 65f, Chapter 19 as amended in 1973 (Illinois Department of Transportation, 1973), encroachment in the floodplain is limited to that which will cause only an insignificant increase in flood heights. Thus, at the recommendation of the Illinois Division of Water Resources, a floodway having no more than a 0.1-foot surcharge has been delineated for this study.

Unless specifically stated in the individual tributary write-ups, the floodways were computed on the basis of equal conveyance reduction from each side of the floodplain. The results of these computations are tabulated at selected cross sections for each stream segment for which a floodway is computed. The computed floodways are shown on the revised FIRM. In cases where the floodway and the 100-year floodplain boundaries are either close together or collinear, only the floodway boundary is shown.

The area between the floodway and 100-year floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the water-surface elevation of the 100-year flood by more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 1, “Floodway Schematic.”

FLOODWAY SCHEMATIC Figure 1

DuPage County Tributary Information

The following subsections discuss each tributary watershed in detail. Included in each subsection is a full tributary description, noting the major characteristics of the watershed. All hydrologic and hydraulic modeling used to generate discharge frequencies and subsequent recurrence interval elevations are included, followed by exhibits of the flood boundary, floodway data table and flood profile. Following approval by FEMA of updated models created through DuPage County, the tributary’s corresponding subfolder shall be updated as well. As such, the following subfolders shall be in a state of change until such time as all DuPage County tributaries have been updated. Even after this accomplishment, however, the subfolders are still subject to change based on LOMR requests. If there are particular questions related to this on-going process, please contact the DuPage County Department of Development and Environmental Concerns at 682-7230.

3.1 Des Plaines River (DP)

3.1.1 Main Stem (DPDP)

3.1.1.1 Tributary Description

In general, the Des Plaines River Main Stem begins its journey in the headwaters of urban / suburban Chicago, near to the Wisconsin / Illinois border. As the Main Stem winds its way to the southwest, joining Salt Creek in Lyons, Sawmill Creek near Lemont, and the DuPage River southwest of Joliet in Channahon, it eventually confluences with Illinois River at the Des Plaines Wildlife Conservation Area southwest of Joliet.

Specifically, the Van Patten Woods Forest Preserve found east of I-94 and north of Wadsworth is the starting location of the Des Plaines River in the state of Illinois. From this location, the Des Plaines takes a direct route to the south passing through buffered areas, but increasing the surrounding impervious areas, such as: the Wadsworth Savannah Forest Preserve, Gurnee Woods Forest Preserve, Independence Grove Forest Preserve, Old School Forest Preserve, MacArthur Woods Forest Preserve, the Grainger Woods Conservation Area, Half-Day Forest Preserve, the Marriot- Lincolnshire Golf Course, Ryerson Conservation Area, Potawatomi Woods Forest Preserve, Dam #1 Woods Forest Preserve, Lake Avenue Woods Forest Preserve, Camp Pine Woods Forest Preserve, Chippewa Woods Forest Preserve, Dam #4 Forest Preserve, Catherine Chevalier Forest Preserve, and Schiller Woods Forest Preserve. Once leaving this last forest preserve, the Des Plaines passes through the city of Chicago rarely encountering any buffered areas. After joining Salt Creek at Lyons, the Des Plaines changes course to the southwest, paralleling the Stevenson Expressway and the Chicago Sanitary and Ship Canal.

It is at this location where the Southeastern edge of DuPage County is formed. Though the County lines between Will and DuPage are not truly based on the Des Plaines River, it generally does follow the river for the greatest extent, until the river flows beyond the borders of DuPage County.

The Main Stem of the Des Plaines continues to the southwest, then turns to the south. In the area of Crest Hill, on the north side of Joliet, the Des Plaines and the Chicago Sanitary and Ship Canal intersect. The Des Plaines continues through the urban area of Joliet, and intersects with the Illinois southwest of Channahon.

3.1.1.2 Hydrologic Analysis

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Discharges for the 10-year, 50-year, and 100-year floods for the Des Plaines River Main Stem were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses of the Des Plaines River studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented in Table DPDP.1 below:

Table DPDP.1: USGS Stream Gages Used for Hydrologic Analysis of the Des Plaines River USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years) Des Plaines River at Lockport 05534050 700.0 7

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is presented in Table DPDP.2 below:

Table DPDP.2: Des Plaines River Drainage Area / Peak Discharge Relationship Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr Des Plaines River At River Mile 26.75 684 6,060 7,800 9,000 10,000

3.1.1.3 Hydraulic Analysis

Analyses of the hydraulic characteristics of flooding from the source studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. For construction and/or floodplain management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM.

Starting water-surface elevations for the streams studied in detail and limited detail were determined using corresponding flood elevations on

Section printed 29 April 2004

the main stem, flood profiles from previous studies by the State of Illinois and the SCS (State of Illinois, 1975; and Des Plaines River Watershed Steering Committee, January 1976), normal depth computations, and rating curves.

The water-surface elevations for the Des Plaines River were computed using the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program723-X6-L202A, 1973).

“Manning’s ‘n’ Values,” shows the channel and overbank “n” values for the streams studied by detailed methods. See Table DPDP.3. for further information.

Table DPDP.3: Des Plaines River Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Des Plaines River 0.030 0.060

The hydraulic analyses for this study are based only on the effects of unobstructed flow. The flood elevation as shown on the profiles are, therefore, considered valid only if hydraulic structures, in general, remain unobstructed and if channel and overbank conditions remain essentially the same as ascertained during this study.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.1.1.4 Flood Boundaries

To reference the flood boundaries for the Des Plaines River Main Stem, see Map Panels: 0908, 0909, 1001, 1002, 1003, 1004, 1005 and 1006

3.1.1.5 Floodways

Please reference attached Floodway Data Tables.

3.1.1.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above mouth TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS DES PLAINES RIVER (DPDP) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Sawmill Creek Tributary No. 3 (DPDP) DPDP0011 978 1 111 368 1.5 595.2 595.2 595.4 0.2 DPDP0012 2,208 1 31 100 5.6 603.1 603.1 603.1 0.0 DPDP0013 2,633 1 57 260 2.1 618.1 618.1 618.1 0.0 DPDP0014 4,775 1 111 337 1.7 637.4 637.4 637.5 0.1 DPDP0015 6,269 1 20 144 3.0 652.0 652.0 652.0 0.0 DPDP0016 6,436 1 180 775 0.7 652.4 652.4 652.4 0.0 DPDP0017 7,299 1 21 137 4.1 657.5 657.5 657.6 0.1 DPDP0018 8,464 1 53 136 3.1 670.3 670.3 670.4 0.1 DPDP0019 9,023 1 48 80 5.2 671.4 671.4 671.5 0.1 DPDP0020 10,911 1 67 116 3.6 688.4 688.4 688.5 0.1 DPDP0021 11,677 1 66 78 4.4 700.4 700.4 700.4 0.0 DPDP0022 12,411 1 228 459 0.9 703.5 703.5 703.5 0.0 DPDP0023 13,371 1 11 42 1.4 706.0 706.0 706.1 0.1 DPDP0024 13,630 1 32 56 1.1 706.4 706.4 706.5 0.1

1 In feet above confluence with Des Plaines River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SAWMILL CREEK TRIBUTARY NO. 3 (DPDP) 600 CONFLUENCE OF 600

COUNTY BOUNDARY

CONFLUENCE OF SAWMILL CREEK

SAWMILL CREEK TRIBUTARY NO. 3

595 595

FLOOD PROFILES

DES PLAINES RIVER (DPDP)

590 590

585 585

ELEVATION IN FEET (NGVD 29)

580 580

DPDP0005 575 575 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 570 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0001 DPDP0002 DPDP0003 DPDP0004 CROSS SECTION LOCATION 565 132000 133000 134000 135000 136000 137000 138000 139000 140000 141000 142000 143000 144000 145000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 08P 600 600

COUNTY BOUNDARY

595 595

FLOOD PROFILES

DES PLAINES RIVER (DPDP)

590 590

585 585

ELEVATION IN FEET (NGVD 29)

580 580

DPDP0010 575 575 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 570 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0006 DPDP0007 DPDP0008 DPDP0009 CROSS SECTION LOCATION 565 145000 146000 147000 148000 149000 150000 151000 152000 153000 154000 155000 156000 157000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 09P 100-YEAR BACKWATER FROM DES PLAINES RIVER

620 620

RAILROAD 615 615

610 610

CONFLUENCE WITH DES PLAINES RIVER

FLOOD PROFILES

605 605

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

600 600

FOREST PRESERVE ROAD

ELEVATION IN FEET (NGVD 29)

595 595

DPDP0012 590 590 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 585 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0011 CROSS SECTION LOCATION 580 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 10P 645 645

640 640

635 635

FLOOD PROFILES

630 630

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

625 625

ELEVATION IN FEET (NGVD 29)

620 620

DPDP0014 615 615 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 610 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0013 CROSS SECTION LOCATION 605 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 11P BLUFF ROAD

CASS AVENUE

FRONT STREET

665 EASTWOOD DRIVE 665

660 660

FLOOD PROFILES

655 655

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

650 650

ELEVATION IN FEET (NGVD 29)

645 645

DPDP0017 640 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 635 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0015 DPDP0016 CROSS SECTION LOCATION 630 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 12P 685 685

PARKING LOT ROAD

680 680

FLOOD PROFILES

675 675

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

670 670

ELEVATION IN FEET (NGVD 29)

665 665

660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0018 DPDP0019 CROSS SECTION LOCATION 650 7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 10000 10200 10400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 13P 710 QUARTER LANE 710

CLARENDON HILLS ROAD

705 705

FLOOD PROFILES

700 700

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

695 695

ELEVATION IN FEET (NGVD 29)

690 690

DPDP0022 685 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0020 DPDP0021 CROSS SECTION LOCATION 675 10400 10600 10800 11000 11200 11400 11600 11800 12000 12200 12400 12600 12800 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 14P 91ST STREET

LIMIT OF DETAILED STUDY

FLOOD PROFILES

SAWMILL CREEK TRIBUTARY NO. 3 (DPDP)

710 710

ELEVATION IN FEET (NGVD 29)

705 705

700 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPDP0023 DPDP0024 CROSS SECTION LOCATION 690 13000 13200 13400 13600 13800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 15P

3.1.2 Addison Creek (DPAC)

3.1.2.1 Tributary Description

Within the confines of DuPage County, Addison Creek has a total watershed area of 5815 acres. Situated on the northeastern edge of DuPage County, Addison Creek and its reaches flow from west to east, confluencing with the Des Plaines River in Cook County. Much of the watershed is found within the confines of the Village of Bensenville and Elmhurst, an area with older residential and commercial structures, and a good portion of the upper watershed is storm sewered.

The Main Stem of Addison Creek and its primary reach both start west of Illinois Route 83 (Kingery Highway) within residential subdivisions. The reaches travel to the east passing underneath Route 83 and eventually opening up within the White Pines Golf Course. Both reaches continue to the east passing under York Road, where they are joined at the George Street Reservoir. George Street Reservoir releases the flow to the south where it enters the River Forest Country Club, Mt. Emblem Cemetery and then a detention area. Flow then resumes to the east where it passes under I-294 and exits DuPage County.

3.1.2.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Addison Creek.

Peak discharges for Addison Creek and Addison Creek’s South Tributary, which does not have a streamflow gage, were determined using the HEC-1 computer program (USCOE, HEC-1 Hydrograph Package 723-X6-L2010) and the SCS hydrograph feature of the HEC-1 model (SCS, National Engineering Handbook, Section 4 “Hydrology”). Peak Discharges for the Addison Creek Tributaries were computed using the TR-20 computer program (SCS, Technical Release No. 20 – Computer Program for Project Formulation, Hydrology). The 500-year peak discharge was determined using a linear extrapolation preformed on probability paper.

Peak discharge-drainage area relationships for the 10-, 50-, 100-, and 500- year floods of each flooding source studied in detail are presented in Table DPAC.1.

Table DPAC.1: Addison Creek Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Addison Creek Tributary #1 – at George Street Reservoir 0.93 54 96 122 185

Addison Creek Tributary #2 - at York Road 1.18 56 88 106 146 - at Church Road 0.33 28 44 50 68

Addison Creek Tributary #3 - about 300 ft d/s George Street 1.20 50 62 86 115 - at Church Road 0.23 18 28 34 43

Addison Creek South Tributary - at York Road 1.68 426 736 915 1,421 - at Fairway Drive 1.12 202 346 429 693

Elevations for floods of the selected recurrence intervals of George Street Reservoir are presented in Table DPAC.2.

Table DPAC.2: Addison Creek Summary of Elevations (George Street Reservoir) Summary of Elevations

Flooding Source Peak Elevation (Ft – NGVD) And Location 10-yr 50-yr 100-yr 500-yr

George Street Reservoir 643.0 649.0 652.0 657.0

3.1.2.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

Roughness coefficients (Manning’s “n”) were assigned based on doled inspection, photographs, and engineering judgment (USGS, Roughness Characteristics of Natural Channels; Chow, Open Channel Hydraulics). Roughness values range from 0.030 to 0.075 for the channels and from 0.030 to 0.095 for the overbanks.

Water-surface elevations for floods of the selected recurrence intervals on Addison Creek’s South Tributary were computed using the HEC-2 step- backwater computer program (USCOE, HEC-2Water Surface Profiles 723-X6-L202A). Starting water-surface elevations for Bensenville Ditch were taken from the Flood Insurance Study for the City of Chicago, Illinois (FEMA, Flood Insurance Study – City of Chicago, Cook and DuPage Counties, Nov 1983).

Starting water-surface elevations on the Addison Creek tributaries were determined using the slope-area method. Water-surface profiles for present conditions on the Addison Creek tributaries were determined for the 10-, 50-, 100-, and 500-year floods using the WSP-2 computer program (USDA – SCS, Technical Release No. 61, WSP-2 Computer Program). Water Surface Profiles for present conditions on Addison Creek were determined for the 10-, 50-, and 100-year floods using the HEC-2 step-backwater computer program (USCOE, HEC-2Water Surface Profiles 723-X6-L202A).

Flood profiles were drawn showing the computed water-surface elevations for floods of the selected recurrence intervals. In cases where the 50- and 100-year flood elevations are close together, due to limitations of the profile scale, only the 100-year profile has been shown.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.1.2.4 Flood Boundaries

To reference the flood boundaries for Addison Creek, see Map Panels: 0305, 0306, 0308, 0309, 0603 and 0606

3.1.2.5 Floodways

Section printed 29 April 2004

Please reference attached Floodway Data Tables.

3.1.2.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above confluence with Des Plaines River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ADDISON CREEK (DPAC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Addison Creek Tributary No. 1 (DPAC) DPAC0010 71,096 1 121 2 271 0.4 656.5 656.5 656.6 0.1

1 In feet above confluence with Des Plaines River

1 In feet above confluence with Des Plaines River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ADDISON CREEK TRIBUTARY NO. 2 (DPAC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Addison Creek Tributary No. 3 (DPAC) DPAC0014 70,149 1 60 182 0.5 662.6 662.5 2 662.6 0.1 DPAC0015 70,640 1 50 193 0.4 663.1 663.1 663.2 0.1 DPAC0016 73,887 1 16 18 3.5 676.1 676.1 676.2 0.1 DPAC0017 75,994 1 249 1,265 0.0 682.5 682.5 682.5 0.0

1 In feet above confluence with Des Plaines River

2 Elevation computed without consideration of backwater effects from Addison Creek Tributary No. 2 TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ADDISON CREEK TRIBUTARY NO. 3 (DPAC) BRIDGE 2

GRAND AVENUE

GEORGE STREET

UNNAMED ROAD

CEMETERY ROAD 665 CEMETARY ROAD 665

COUNTY LINE ROAD

LIMIT OF DETAILED STUDY

GEORGE STREET RESERVOIR

LIMIT OF FLOODING AFFECTING COUNTY

660 660

FLOOD PROFILES

ADDISON CREEK (DPAC)

655 655 THE 50-YEAR FLOOD PROFILE UPSTREAM CULVERT OF STATION 66, 831 IS NOT AVAILABLE

CULVERT 650 650

ELEVATION IN FEET (NGVD 29)

645 645

DPAC0008 DPAC0009 640 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 635 COUNTY BOUNDARY 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPAC0001 DPAC0002 DPAC0003 DPAC0004 DPAC0005 DPAC0006 DPAC0007 CROSS SECTION LOCATION 630 61000 61500 62000 62500 63000 63500 64000 64500 65000 65500 66000 66500 67000 67500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 01P JEFFERSON AVENUE

LIMIT OF DETAILED STUDY

CONFLUENCE WITH GEORGE STREET RESERVOIR

FLOOD PROFILES

665 665

ADDISON CREEK TRIBUTARY NO. 1 (DPAC)

660 660

ELEVATION IN FEET (NGVD 29)

655 655

650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPAC0010 CROSS SECTION LOCATION 640 69000 69500 70000 70500 71000 71500 72000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 02P 690

685 685

YORK ROAD 680 680

CONFLUENCE AT GEORGE STREET RESERVOIR

675 CONFLUENCE OF ADDISON CREEK TRIBUTARY NO. 3 675

FLOOD PROFILES

SPILLWAY

670 CHURCH ROAD 670

ADDISON CREEK TRIBUTARY NO. 2 (DPAC)

LIMIT OF DETAILED STUDY

665 665

ELEVATION IN FEET (NGVD 29)

660 660

655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPAC0011 DPAC0012 DPAC0013 CROSS SECTION LOCATION 645 68500 69500 70500 71500 72500 73500 74500 75500 76500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 03P 100-YEAR BACKWATER FROM ADDISON CREEK NO 2

DENNIS DRIVE DENNIS DRIVE

S. YORK ROAD 685 GEORGE STREET 685

FOREST VIEW ROAD

APARTMENT DRIVEWAY APARTMENT DRIVEWAY

CONFLUENCE OF TRIBUTARY A

680 680

CONFLUENCE WITH ADDISON CREEK TRIBUTARY NO. 2

FLOOD PROFILES

675 675

ADDISON CREEK TRIBUTARY NO. 3 (DPAC)

670 670

ELEVATION IN FEET (NGVD 29)

665 665

CULVERTS 660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPAC0014 DPAC0015 DPAC0016 CROSS SECTION LOCATION 650 69000 69500 70000 70500 71000 71500 72000 72500 73000 73500 74000 74500 75000 75500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE FROM 2,047 FEET UPSTREAM OF STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER FOREST VIEW ROAD TO 4,099 FEET UPSTREAM OF FOREST 04P ARTHUR COURT

LIMIT OF DETAILED STUDY

690 690

FLOOD PROFILES

685 685

ADDISON CREEK TRIBUTARY NO. 3 (DPAC)

CULVERT 680 680

ELEVATION IN FEET (NGVD 29)

675 675

670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPAC0017 CROSS SECTION LOCATION 660 75500 76000 76500 77000 77500 78000

*DATA NOT AVAILABLE FROM 2,047 FEET UPSTREAM OF FEDERAL EMERGENCY MANAGEMENT AGENCY FOREST VIEW ROAD TO 4,099 FEET UPSTREAM OF FOREST STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER VIEW ROAD 05P

3.1.3 Bensenville Ditch (DPBD)

3.1.3.1 Tributary Description

Bensenville Ditch is a small, thin watershed tributary to the Des Plaines River. The total watershed area within DuPage County totals 1640 acres. The stream’s headwaters are found within unincorporated DuPage County, west of Wooddale Road just south of Irving Park Blvd in an older residential subdivision. Bensenville Ditch then proceeds to the east into the Village of Bensenville, hugging the south side of Irving Park Road. The stream passes underneath Irving Park Road and York Road, entering the Chicago – O’Hare Airport grounds, thus departing DuPage County.

Much of the tributary area to Bensenville Ditch is high-density residential and light commercial. Given the long, thin shape of the watershed, and the high imperviousness of the terrain, it would be expected to see some quick, high-peak, runoff events.

3.1.3.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Bensenville Ditch.

A generalized rainfall-runoff model was developed for Bensenville Ditch by the Illinois Department of Transportation using the HEC-1 computer program (USCOE, HEC-1 Hydrograph Package 723-X6-L2010). The model was based on SCS curve numbers (CN) and hydrograph lag times (TLAGs) for input. The relative imperviousness of each subarea was derived using the land cover, soil group, and average CN for each area. The resulting CN values for each subarea were used in the model for runoff loss and soil abstraction. The TLAG was derived using the modified curve number method outlined in SCS Technical Release No. 55 (SCS, Urban Hydrology for Small Watersheds).

The model was run to determine flows for recurrence intervals of 2 to 100 years with rainfall for 6, 12, and 24 hours. The rainfall values were obtained from a report titled “Effects of Basin Rainfall Estimates on Dam Safety Design in Illinois” (ISWS).

The results of the HEC-1 model run on Bensenville Ditch indicate that the 12-hour storm with a Huff 3 distribution (ISWS) will produce the maximum storm runoff from the watershed.

Peak discharge-drainage area relationships for the 10-, 50-, 100-, and 500- year floods of each flooding source studied in detail are presented in Table DPBD.1.

Section printed 29 April 2004

Table DPBD.1: Bensenville Ditch Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Bensenville Ditch - just d/s of Garden Ave 1.82 367 663 774 N/A - just d/s of York Road 1.56 296 527 610 N/A - just d/s of Mason Street 1.32 283 510 564 N/A - at Church Street 1.07 246 470 520 N/A

3.1.3.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface elevations for floods of the selected recurrence intervals on Bensenville Ditch were computed using the HEC-2 step-backwater computer program (USCOE, HEC-2Water Surface Profiles 723-X6- L202A). Starting water-surface elevations for Bensenville Ditch were taken from the Flood Insurance Study for the City of Chicago, Illinois (FEMA, Flood Insurance Study – City of Chicago, Cook and DuPage Counties, Nov 1983).

Section printed 29 April 2004

unobstructed and if channel and overbank conditions remain essentially the same as ascertained during this study.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.1.3.4 Flood Boundaries

To reference the flood boundaries for Bensenville Ditch, see Map Panels: 0302, 0303, 0305 and 0306

3.1.3.5 Floodways

Please reference attached Floodway Data Tables.

3.1.3.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above confluence with Des Plaines River

N. YORK ROAD

MASON STREET

GARDEN AVENUE

ORCHARD AVENUE

AUTO PARTS ROAD

IRVING PARK BOULEVARD

LIMIT OF DETAILED STUDY

670 670

FLOOD PROFILES

BENSENVILLE DITCH (DPBD) 665 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655

DPBD0008 650 650 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 645 10-YEAR FLOOD* STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

DPBD0001 DPBD0002 DPBD0003 DPBD0004 DPBD0005 DPBD0006 DPBD0007 640 43500 44000 44500 45000 45500 46000 46500 47000 47500 48000 48500 49000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 06P CHURCH ROAD

LIMIT OF DETAILED STUDY

670 670

FLOOD PROFILES

BENSENVILLE DITCH (DPBD) 665 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655

650 650 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 645 10-YEAR FLOOD* STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

DPBD0009 DPBD0010 640 49000 49500 50000 50500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 07P

3.1.4 Black Partridge Creek (DPBP)

3.1.4.1 Tributary Description

Black Partridge Creek is tributary to the Des Plaines River, and is adjacent to Argonne National Laboratories to the west. This watershed has a total area of 1750 acres, with low density residential and high open space / forest components. Black Partridge Creek begins within a residential section of the Village of Woodridge, east of Orchard Road, west of Lemont Road and north of I-55. The stream passes underneath Charing Cross Road twice and serpentines under Westminster Drive. Black Partridge takes a southern bearing and flows through a culvert at I-55. Upon exiting the I-55 culvert, Black Partridge continues to the south, collecting feeder ditches from both Unincorporated DuPage County and the Village of Woodridge. The Main Stem of Black Partridge Creek follows the east-side ditch of Orchard Road, passing underneath Orchard road near Internationale Drive. The creek enters a Forest Preserve Zone, exits DuPage County, and makes its way to the Des Plaines River.

3.1.4.2 Hydrologic Analysis

There is no information regarding the regulatory hydrologics of Black Partridge Creek within the confines of DuPage County.

3.1.4.3 Hydraulic Analysis

There is no information regarding the regulatory hydraulics of Black Partridge Creek within the confines of DuPage County.

3.1.4.4 Flood Boundaries

To reference the flood boundaries for Black Partridge Creek, see Map Panels: 1001 and 1004.

3.1.4.5 Floodways

No floodway information is currently available for this tributary.

3.1.4.6 Flood Profiles

No flood profile information is currently available for this tributary.

Section printed 29 April 2004

3.1.5 Crystal Creek (DPCT)

3.1.5.1 Tributary Description

Crystal Creek is tributary to the Des Plaines River, and is entirely within the extent of O’Hare International Airport, which itself is entirely within the City of Chicago. This watershed has a total area of 266 acres within its DuPage County portion. Crystal Creek begins near the northern end of O’Hare’s runway 14R/22L. It follows that runway toward the southeast, also collecting portions of the western side of the airport, before pausing in a large detention facility just south of the terminal area, which is in the Cook County portion of the watershed. It then drains to the Des Plaines River after crossing under Interstate 294 just north of its Irving Park Road interchange.

3.1.5.2 Hydrologic Analysis

There is no information regarding the regulatory hydrologics of Crystal Creek within the confines of DuPage County.

3.1.5.3 Hydraulic Analysis

There is no information regarding the regulatory hydraulics of Crsytal Creek within the confines of DuPage County.

3.1.5.4 Flood Boundaries

To reference the flood boundaries for Crystal Creek, see Map Panel: 0303.

3.1.5.5 Floodways

No floodway information is currently available for this tributary.

3.1.5.6 Flood Profiles

No flood profile information is currently available for this tributary.

Section printed 26 May 2004

3.1.6 Flagg Creek (DPFC)

3.1.6.1 Tributary Description

Flagg Creek is a tributary to the Des Plaines River. Within the confines of DuPage County, a total watershed area of 7608 acres flows to one of several feeder branches of Flagg Creek. The DuPage County communities that contribute watershed area to Flagg Creek are Burr Ridge, Willowbrook, Hinsdale, Clarendon Hills, Westmont, Darien and Unincorporated DuPage County. This southwestern region of DuPage County is a conglomeration of many different types of development; older construction and residential communities in the north (i.e. Hinsdale and Westmont), and fast-growing development to the south (i.e. Burr Ridge and Willowbrook). But as seemingly different as these communities may be, they share in some common geographical traits within the Flagg Creek Watershed.

All feeder branches modeled in DuPage County (79th Street Ditch, Plainfield Road Ditch, 63rd Street Ditch and 59th Street Ditch) flow from the west to the east. As all branches approach the county border between Cook and DuPage Counties, a steep gradient propels flow towards Flagg Creek.

The 79th Street Ditch finds its headwaters on the south side of I-55 within the Village of Burr Ridge. It flows northeast, parallel to I-55, until the ditch is to the east of Grant Street. The ditch turns to the southeast passing through residential subdivisions in Burr Ridge, passes underneath Hamilton Ave, and joins the ditch on 79th Street. The ditch flows to the south on Drew Avenue for a few hundred feet then turns to the east, exiting DuPage County as it passes underneath County Line Road.

The Plainfield Road Ditch is actually a ditch found somewhat to the south of Plainfield Road, but parallels Plainfield Road to a fair extent. This area of Burr Ridge is home to industrial / commercial properties. This is a simple branch that flows to the northeast, exiting DuPage County as it passes underneath County Line Road.

The 63rd Street Ditch is by far the most thoroughly explored and modeled tributary for Flagg Creek watershed within the DuPage County limits. This reach proceeds from the Villages of Westmont and Clarendon Hills, passing through such areas as Johnson Slough (58th Street) and under State Route 83. All feeder branches converge around 63rd Street within the Villages of Willowbrook and Burr Ridge. And like all Flagg Creek branches within DuPage County, 63rd Street eventually exits DuPage County as it passes underneath County Line Road.

Section printed 29 April 2004

The 59th Street Ditch is a small branch that causes some flooding difficulties around Charleston Road in Hinsdale as it attempts to flow through an older subdivision. Downstream of this subdivision, the 59th Street Ditch exits the County as it passes underneath County Line Road.

3.1.6.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Flagg Creek and all its associated ditches.

Harza prepared hydrologic analyses using the State Standard Method, and discharges for 10- and 100-year floods were estimated for Flagg Creek using the regional urbanized equations for Illinois (U.S. Department of the Interior, 1974). The 100-year discharges calculated by Harza were sent to the Illinois SWS for review. The discharges were approved by the SWS and certified by the DOWR. Data are located in a repository of flood- related data administered by the SWS. For each cross section of Flagg Creek, discharges for the 10- and 100-year floods were plotted on log- normal probability paper. The 50- and 500-year flood discharges were estimated by straight-line interpolation and extrapolation, respectively. The 500-year flood discharge is less reliable than the others because the period of record for discharge gages used to develop the regional urban equations is about 30 years.

Harza prepared the hydrologic analysis for the 59th Street Ditch. Discharges for the 2- and 100-year floods for this stream were computed using the Illinois State Standard Method Urbanized Equations (U.S. Department of the Interior, 1974). The 100-year discharges were sent to the SWS for review. The discharges were approved by the SWS and certified by the DOWR. These data are located in a repository of flood- related data administered by the SWS. For each cross section, discharges for the 2- and 100-year floods were plotted on log-normal probability paper. The 10-, 50-, and 500-year flood discharges were estimated by straight-line interpolation and extrapolation.

Discharges for the 10-, 50-, and 100-year floods for the 63rd Street Ditch were determined using regional equations developed by the Illinois SWS. The principal factors considered in this method were soil types, land uses, watershed slope, channel slope and dimensions, and rainfall distributions (Illinois Department of Transportation, Magnitude and Frequency of Floods in Illinois, 1973). The discharges were adjusted using factors recommended by the SWS that were developed from data for the USGS gage on Flagg Creek at Willow Springs, Illinois. The 100-year flood discharges for 63rd Street Ditch and East Branch Sawmill Creek in Willowbrook were sent to the SWS for review. These discharges were approved by the SWS and certified by the DOWR for use in the State’s

Section printed 29 April 2004

floodplain regulation program. Data are located in the Illinois Floodplain Repository which is administered by the SWS. Discharges for the 10-, 50- , 100-, and 500-year floods of each flooding source studied in detail in the community are shown in Table 1.

Discharges for the 10-, 50-, and 100-year floods on 79th Street Ditch and Plainfield Road Ditch were determined by Harza using regional flood- frequency equations. The parameters used were channel slope, drainage area, and the percent of urbanization and nearby gage records using methods recommended by the Illinois SWS. These methods were determined by the log-Pearson Type III analysis and the regional discharge equation at gage location (Baranecki, Vigilio, and Associates, 1977). The adjustment coefficients were developed from data for the USGS gage (No. 05533000, established in 1951), located at the 16.2-mile marker on Flagg Creek at Willow Springs, Illinois. The 100-year discharges for the streams were sent to the Illinois SWS for review. They were approved by the Illinois SWS and certified by the Illinois DWR for use in the state’s floodplain regulation program (Des Plaines River Watershed Steering Committee, 1975). Data are located in the State Floodplain Repository administered by the Illinois SWS. The flood discharges on Plainfield Road Ditch are much higher than the discharges of 79th Street Ditch because the slope of Plainfield Road Ditch is 30 percent greater than the slope of 79th Street Ditch, thereby increasing the rate of runoff.

Peak discharge-drainage area relationships for the 10-, 50-, 100-, and 500- year floods of each flooding source studied in detail are presented in Table DPFC.1.

Table DPFC.1: Flagg Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Flagg Creek - at mouth 18.1 1,660 2,650 3,180 4,500 - approx. 600 ft u/s 79th St Ditch 15.3 1,420 2,300 2,720 3,850 - at State Route 83 1.40 202 321 380 530 - at Eastern Ave. 0.40 101 160 190 265

Plainfield Road Ditch - at mouth 1.10 197 310 367 510 - at County Line Road 1.00 141 223 262 365

59th Street Ditch

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- at County Line Road 0.51 112 183 212 293

63rd Street Ditch - at mouth 4.90 710 1,130 1,330 1,850 - at County Line Rd. 3.70 565 900 1,070 1,490 - at Madison Street 2.20 390 620 729 1,010 - at Lake Hinsdale 0.60 185 295 349 490

79th Street Ditch - at County Line Road 1.00 91 141 165 226 - at 79th Street 0.90 77 118 140 190 - at Hamilton Street 0.80 57 90 105 145

3.1.6.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

All hydraulic information for Flagg Creek and Tributaries A, B and C (tributaries found in Cook County), was obtained from the Cook County Flood Insurance Study (FEMA, Flood Insurance Study – Cook County). Cross section data for the 63rd Street Ditch were obtained from the SCS (SCS / USDA etc., Flood Plain Information Maps and Profiles, 1975) and were supplemented with data from the Improvement Plan for Burr Ridge Meadows (Baranecki, Vigilio and Associates, December 1977). Land surveys provided cross section data for the other detained studied streams.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n” values” for these computations were assigned on the basis of field inspection. The range of “n” values for the streams are found in Table DPFC.2:

Table DPFC.2: Flagg Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

63rd Street Ditch 0.017 - 0.040 0.025 - 0.060 79th Street Ditch 0.048 - 0.055 0.032 - 0.085 Plainfield Rd Ditch 0.035 - 0.050 0.030 - 0.090 Flagg Creek 0.035 - 0.070 0.060 - 0.085

The starting water surface elevation for Flagg Creek was the 10-yr flood elevation for the Des Plaines River (SCS / USDA etc., Flood Plain

Section printed 29 April 2004

Information Maps and Profiles, 1975). Critical Depth was used for the starting water-surface elevation for 63rd Street Ditch. 79th street Ditch used the backwater for Tributary C. The starting water-surface elevation for Plainfield Road Ditch was obtained for the Indian Head Park Flood Insurance Study (HUD, Village of Indian Head Park, Illinois, December 1979). The starting water surface elevation for Tributary C were obtained from the Cook County Flood Insurance Study (FEMA, Flood Insurance Study – Cook County).

Water surface elevations for floods of selected recurrence intervals were computed using the SCS WSP-2 step-backwater program (SCS / USDA, TR-61: WSP-2 Computer Program, May 1976). Mathematical relationships used in the program include the standard step-backwater procedure that estimates total energy at each cross section and accounts for frictions losses between sections using Manning’s formula. The model requires discharge, cross-section geometry, bridge geometry, starting water surface elevation, and roughness data to simulate flood flow conditions.

For 59th Street Ditch studied by approximate methods, the elevation of the 100-yr flood was developed from normal depth calculations, consultation with the Village of Hinsdale Engineers, and the Hydrologic Investigation Atlas for Hinsdale (USGS, NIPC; 1964).

The hydraulic analyses for this study are based only on the effects of unobstructed flow. The flood elevations as shown on the profiles are, therefore, considered valid only if hydraulic structures, in general, remain unobstructed and if channel and overbank conditions remain essentially the same as ascertained during the study.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

Flood Profiles were drawn showing the computed water surface elevations to an accuracy of 0.5 foot for floods of the selected recurrence intervals. See sections 3.1.5.4 and 3.1.5.6 for further details.

3.1.6.4 Flood Boundaries

To reference the flood boundaries for Flagg Creek, see Map Panels: 0609, 0902, 0903, 0905, 0906, 0909 and 1003

3.1.6.5 Floodways

The floodways for 63rd Street Ditch were determined from the HUD-15 computer program (U.S. Department of Agriculture, 1977). Floodways

Section printed 29 April 2004

were computed without consideration of backwater from the receiving streams. Portions of the floodway for 63rd Street Ditch lies outside of the corporate limits for the Village of Willowbrook.

Please reference attached Floodway Data Tables for further information.

3.1.6.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above county boundary TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS 79TH STREET DITCH (DPFC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Plainfield Road Ditch (DPFC) DPFC0010 109 1 286 3,050 0.1 693.3 693.3 693.4 0.1 DPFC0011 1,119 1 53 245 0.8 693.3 693.3 693.4 0.1 DPFC0012 1,164 1 63 323 0.6 695.6 695.6 695.6 0.0 DPFC0013 1,799 1 64 404 0.4 695.6 695.6 695.6 0.0 DPFC0014 2,043 1 35 67 2.4 696.8 696.8 696.8 0.0 DPFC0015 2,123 1 65 102 1.6 696.9 696.9 697.0 0.1 DPFC0016 2,448 1 75 95 1.6 697.3 697.3 697.3 0.0 DPFC0017 2,808 1 34 39 2.9 698.7 698.7 698.7 0.0 DPFC0018 3,108 1 32 50 2.3 699.3 699.3 699.3 0.0 DPFC0019 3,398 1 27 61 1.8 699.5 699.5 699.5 0.0 DPFC0020 3,708 1 80 333 0.3 701.4 701.4 701.4 0.0 DPFC0021 3,958 1 34 101 1.0 701.4 701.4 701.4 0.0 DPFC0022 4,185 1 265 1,220 0.1 702.0 702.0 702.0 0.0 DPFC0023 4,351 1 159 846 0.1 704.5 704.5 704.5 0.0 DPFC0024 4,689 1 17 55 1.9 705.2 705.2 705.2 0.0 DPFC0025 4,904 1 23 71 1.2 705.3 705.3 705.3 0.0 DPFC0026 5,394 1 330 372 0.2 705.3 705.3 705.3 0.0

1 In feet above county boundary TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS PLAINFIELD ROAD DITCH (DPFC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) 63rd Street Ditch (DPFC) DPFC0029 1,037 1 110 253 3.2 670.6 670.6 670.6 0.0 DPFC0030 3,571 1 50 181 2.9 675.2 675.2 675.2 0.0 DPFC0031 4,762 1 100 546 1.9 683.3 683.3 683.3 0.0 DPFC0032 8,337 1 83 178 4.1 701.8 701.8 701.9 0.1 DPFC0033 9,755 1 67 242 3.0 712.0 712.0 712.1 0.1 DPFC0034 10,284 1 288 870 0.8 714.4 714.4 714.5 0.1 DPFC0035 12,650 1 200 709 0.5 723.8 723.8 723.9 0.1

1 In feet above county boundary TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS 63RD STREET DITCH (DPFC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Flagg Creek (DPFC) DPFC0036 48,845 1 83 314 1.2 712.3 712.3 712.4 0.1 DPFC0037 49,244 1 34 108 3.1 713.5 713.5 713.6 0.1 DPFC0038 49,796 1 26 102 2.8 715.7 715.7 715.8 0.1 DPFC0039 50,360 1 72 2 190 1.1 718.6 718.6 718.7 0.1

1 In feet above mouth

1 In feet above county boundary TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS 59TH STREET DITCH (DPFC) COUNTY BOUNDARY

79TH STREET

DREW AVENUE

700 HAMILTON AVENUE 700

LIMIT OF DETAILED STUDY

695 695

COUNTY LINE ROAD

FLOOD PROFILES

79TH STREET DITCH (DPFC) 690 690

685 685

ELEVATION IN FEET (NGVD 29)

680 680

675 675 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD DPFC0001 DPFC0005 DPFC0008 500-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0002 DPFC0003 DPFC0004 DPFC0006 DPFC0007 DPFC0009 CROSS SECTION LOCATION 665 0 500 1000 1500 2000 2500 3000 3500 4000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 16P 710 710

WEIR WEIR

705 FIELDSTONE DRIVE 705

COUNTY LINE ROAD

COUNTY BOUNDARY

CULVERTS

INTERNATIONAL HARVESTER ENTRANCE

700 700

FLOOD PROFILES

695 695 PLAINFIELD ROAD DITCH (DPFC)

CULVERT

UNNAMED ROAD UNNAMED ROAD

690 COMMERCE STREET 690

INTERNATIONAL STREET

ELEVATION IN FEET (NGVD 29)

50-YEAR PROFILE IS TOO CLOSE 685 TO THE 100-YEAR PROFILE 685 TO BE SHOWN SEPARATELY

DPFC0024 DPFC0025 680 680 LEGEND CULVERTS 500-YEAR FLOOD 100-YEAR FLOOD DPFC0012 DPFC0015 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0011 DPFC0013 DPFC0014 DPFC0016 DPFC0017 DPFC0018 DPFC0019 DPFC0020 DPFC0021 DPFC0022 DPFC0023 DPFC0010 CROSS SECTION LOCATION 670 -500 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 17P UNNAMED ROAD

LIMIT OF PROFILE*

FLOOD PROFILES

PLAINFIELD ROAD DITCH (DPFC)

ELEVATION IN FEET (NGVD 29)

710 710

705 705 LEGEND CULVERT 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0026 DPFC0027 DPFC0028 CROSS SECTION LOCATION 695 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY * PROFILE INFORMATION NOT AVAILABLE UPSTREAM OF THIS POINT STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 18P 700 700

695 695

ELM STREET

690 GARFIELD AVENUE 690

COUNTY LINE ROAD

WOODEN FOOTBRIDGE

685 685

CULVERT

FLOOD PROFILES

63RD STREET DITCH (DPFC)

680 COUNTY BOUNDARY 680

675 675

ELEVATION IN FEET (NGVD 29)

WEIR

670 CONFLUENCE OF 670

UNNAMED TRIBUTARY A

665 GRANT AVENUE 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0029 DPFC0030 DPFC0031 CROSS SECTION LOCATION 655 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY *DATA NOT AVAILABLE DOWNSTREAM OF 7,066 FEET 19P 725 725

720 720

LANE COURT

715 MADISON STREET 715

710 710

FLOOD PROFILES

63RD STREET DITCH (DPFC) 705 705

STATE ROUTE 83/

LAKE HINSDALE DRIVE

LIMIT OF DETAILED STUDY

ROBERT KINGERY HIGHWAY

700 700

ELEVATION IN FEET (NGVD 29)

695 695

DPFC0035 690 690 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 685 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0032 DPFC0033 DPFC0034 CROSS SECTION LOCATION 680 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE DOWNSTREAM OF 7,066 FEET STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 20P 720 720

718 718 THE 50- AND 100-YEAR FLOOD PROFILES ARE TOO CLOSE TO BE SHOWN SEPARATELY

ANN STREET FOOTBRIDGE FOOTBRIDGE

PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE

HARRIS AVENUE 716 STATE ROUTE 83/ 716

LIMIT OF DETAILED STUDY

ROBERT KINGERY HIGHWAY

714 714

FLAGG CREEK (DPFC)

FLOOD PROFILES

712 712

710 710

ELEVATION IN FEET (NGVD 29)

PRIVATE DRIVE PRIVATE DRIVE

PRIVATE DRIVE

PRIVATE DRIVE PRIVATE DRIVE 708 PRIVATE DRIVE PRIVATE DRIVE 708

LIMIT OF DETAILED STUDY

706 706 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 704 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0036 DPFC0037 DPFC0038 DPFC0039 CROSS SECTION LOCATION 702 48600 48800 49000 49200 49400 49600 49800 50000 50200 50400 50600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 21P COUNTY LINE ROAD

LIMIT OF DETAILED STUDY

CHARLESTON ROAD SOUTH

CHARLESTON ROAD NORTH

FLOOD PROFILES

59TH STREET DITCH (DPFC) 680 680

COUNTY BOUNDARY

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPFC0040 DPFC0041 DPFC0042 DPFC0043 CROSS SECTION LOCATION 655 0 250 500 750 1000 1250 1500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 22P

3.1.7 Willow Creek (DPWL)

3.1.7.1 Tributary Description

Willow Creek is a tributary to the Des Plaines River, which can be located as the watershed immediately to the north of Bensenville Ditch. Within the confines of DuPage County, the total watershed area for Willow Creek totals 3257 acres. The communities that feed watershed area into Willow Creek are Unincorporated DuPage County, Elk Grove Village, Bensenville and the City of Chicago.

Willow Creek drains from west to east, starting in an older residential section of DuPage County, west of Kingery Highway (Route 83). After passing under Kingery Highway, the stream enters the Village of Bensenville and an area of large commercial buildings used primarily for the storage of goods arriving and departing from O’Hare Airport. Once beyond these commercial zones, Willow Creek enters the confines of O’Hare Airport.

3.1.7.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Willow Creek.

Peak discharges for Willow Creek, which does not have a streamflow gage, were determined using the HEC-1 computer program (USCOE, HEC-1 Hydrograph Package 723-X6-L2010) and the SCS hydrograph feature of the HEC-1 model (SCS, National Engineering Handbook, Section 4 “Hydrology”). Peak Discharges for the Addison Creek Tributaries were computed using the TR-20 computer program (SCS, Technical Release No. 20 – Computer Program for Project Formulation, Hydrology). The 500-year peak discharge was determined using a linear extrapolation preformed on probability paper.

Peak discharge-drainage area relationships for the 10-, 50-, 100-, and 500- year floods of each flooding source studied in detail are presented in the Table DPWL.1.

Table DPWL.1: Willow Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Willow Creek

Section printed 9 September 2004

- at York Road 1.68 426 736 915 1,421 - at d/s end of culvert 1.12 202 346 429 693

3.1.7.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface elevations for floods of the selected recurrence intervals on Willow Creek were computed using the HEC-2 step-backwater computer program (USCOE, HEC-2Water Surface Profiles 723-X6-L202A). Starting water-surface elevations for those creeks were determined by performing a routing at restrictive culverts that cause ponding at York Road and the Chicago and North Western railroad embankment. The ponding area is just east of the study area.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.1.7.4 Flood Boundaries

Section printed 9 September 2004

To reference the flood boundaries for Willow Creek, see Map Panels: 0302, 0303, 0305 and 0306

3.1.7.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.1.7.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above confluence with Des Plaines River

680 680

RAILROAD

PRIVATE DRIVE PRIVATE DRIVE

THOMAS DRIVE 675 FAIRWAY DRIVE 675

THORNDALE AVENUE

LIMIT OF DETAILED STUDY LIMIT OF DETAILED STUDY

670 670

FLOOD PROFILES

665 665 SOUTH UNNAMED CREEK (DPWL)

660 660

ELEVATION IN FEET (NGVD 29)

655 655

DPWL0006 DPWL0007 650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPWL0001 DPWL0002 DPWL0003 DPWL0004 DPWL0005 CROSS SECTION LOCATION 640 33315 33815 34315 34815 35315 35815 36315 36815 37315 37815 38315 38815 39315 39815

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 23P LIMIT OF DETAILED STUDY

LIMIT OF DETAILED STUDY

670 670

FLOOD PROFILES

665 665 NORTH UNNAMED CREEK (DPWL)

660 660

ELEVATION IN FEET (NGVD 29)

655 655

650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DPWL0008 DPWL0009 DPWL0010 DPWL0011 CROSS SECTION LOCATION 640 33000 33500 34000 34500 35000 35500 36000 36500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 24P

3.2 DuPage River (DU)

3.2.1 Lily Cache (DULC)

3.2.1.1 Tributary Description

Lily Cache Creek has only a small watershed area (1180 acres) within the confines of DuPage County. Nearly the entire watershed area within DuPage County is residential, the primary branch starting in the headwaters within the Village of Darien on the west side of Lemont Road. This branch proceeds to the west in a serpentine motion, entering the Village of Woodridge and passing under Cambridge Road. The branch turns to the south and exits DuPage County.

A second Lily Cache Branch begins in a quickly developing part of Woodridge and Unincorporated DuPage County (found to the south of the first branch). Many of these lands are still in an open state and are likely to stay that way for some time as development is in the form of parks and schools. As this branch proceeds to the west, only one recently developed subdivision is encountered. The branch passes under Woodward Avenue and flows to the west exiting DuPage County.

3.2.1.2 Hydrologic Analysis

There is no information regarding the regulatory hydrologics of Lily Cache Creek within the confines of DuPage County.

3.2.1.3 Hydraulic Analysis

There is no information regarding the regulatory hydraulics of Lily Cache Creek within the confines of DuPage County.

3.2.1.4 Flood Boundaries

To reference the flood boundaries for Lily Cache, see Map Panels: 0809, 0907 and 1001.

3.2.1.5 Floodways

No floodway information is currently available for this tributary.

3.2.1.6 Flood Profiles

No flood profile information is currently available for this tributary.

Section printed 9 September 2004

3.2.2 Spring Brook #2 (DUSG)

3.2.2.1 Tributary Description

Spring Brook #2 is tributary to the DuPage River. The total watershed area found within DuPage County associated with Spring Brook #2 is 8033 acres. This area, comprised of the municipalities of Aurora and Naperville and unincorporated DuPage County, has undergone rapid developmental growth in recent decades, and is continuing to change land use characteristics.

There are three main feeder branches that make up the Spring Brook #2 Tributary. The first branch finds its headwater area in an older residential neighborhood within the City of Naperville, beginning near the Fox Valley Mall area. This branch winds its way west, eventually curving to the residential south passing under Route 34, Oswego Ave, Rickert Drive, and 75th Street where it meets the second Spring Brook #2 feeder branch.

Beginning in Aurora, approximately one mile west of Route 59 and about one mile south of 75th Street, the second feeder branch proceeds out of an older residential subdivision on a northeast bearing. It passes through a square mile area of unincorporated land that is still relatively undeveloped, and proceeds into the northwestern quadrant of the Springbrook Prairie. Still on this northeastern track, this branch joins the first feeder branch south of 75th Street and takes an abrupt turn to the south. The branch continues to wind its way through the prairie, crossing Book Road two times, when it joins the third feeder branch.

The third feeder, in many respects is very similar to the second feeder tributary in that the headwaters are found in older, residential Aurora, and that it proceeds on a northeast track. The starting location of this branch is one half mile south of Montgomery Road and one mile west of Route 59. As the branch proceeds east, it passes under Route 59 and through a newly developed piece of the City of Naperville. One mile downstream, this branch joins the second feeder branch within the Springbrook Prairie Forest Preserve.

Spring Brook #2 continues on a serpentine-like path through the forest preserve heading in a southerly bearing. The stream exits Springbrook Prairie Forest Preserve and DuPage County. Spring Brook #2 joins with the DuPage River in Will County just downstream of the East and West Branch DuPage River junction.

3.2.2.2 Hydrologic Analysis

Section printed 9 September 2004

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Spring Brook #2.

Discharges for the 10-year, 50-year, and 100-year floods for Spring Brook No. 2 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table DUSG.1

Table DUSG.1: Spring Brook #2 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Spring Brook #2 - at river mile 2.781 9.99 545 825 960 1,290 - approx. 1,660 ft u/s of 75th Street 3.30 190 330 400 600

3.2.2.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n” values” for these computations were assigned on the basis of field inspection. The range of “n” values for the streams are found in Table DUSG.2:

Table DUSG.2: Spring Brook #2 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Section printed 9 September 2004

Spring Brook #2 0.035 0.035

A small portion of Spring Brook #2 southwest of the City of Naperville between 87th and 95th Streets was also studied by approximate analysis. Depth of the 100-year flood at this location was calculated from a stage- frequency curve prepared for a USGS crest stage gage at 83rd Street.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.2.2.4 Flood Boundaries

To reference the flood boundaries for Spring Brook #2, see Map Panels: 0705, 0706, 0707, 0708, 0709 and 0807

3.2.2.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.2.2.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 9 September 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Brook No. 2 (DUSG) DUSG0001 17,272 1 133 679 1.4 657.0 657.0 657.1 0.1 DUSG0002 21,142 1 195 363 2.6 659.0 659.0 659.1 0.1 DUSG0003 25,700 1 133 946 1.0 668.5 668.5 668.6 0.1 DUSG0004 28,095 1 362 1,667 0.6 668.7 668.7 668.8 0.1 DUSG0005 31,715 1 227 448 1.6 671.5 671.5 671.6 0.1 DUSG0006 34,208 1 300 923 0.8 675.3 675.3 675.4 0.1 DUSG0007 39,330 1 855 3,064 0.1 681.8 681.8 681.9 0.1 DUSG0008 40,832 1 135 335 1.1 682.0 682.0 682.1 0.1 DUSG0009 42,286 1 87 286 1.3 682.3 682.3 682.4 0.1 DUSG0010 42,441 1 228 210 1.7 684.5 684.5 684.6 0.1 DUSG0011 44,308 1 120 376 0.5 684.9 684.9 685.0 0.1 DUSG0012 45,425 1 251 525 0.4 685.0 685.0 685.1 0.1 DUSG0013 45,578 1 256 1,256 0.2 687.1 687.1 687.2 0.1 DUSG0014 48,418 1 113 250 0.6 687.2 687.2 687.3 0.1

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SPRING BROOK NO. 2 (DUSG) 87TH STREET

COUNTY BOUNDARY

FLOOD PROFILES

SPRING BROOK NO. 2 (DUSG) 665 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655

650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DUSG0001 DUSG0002 CROSS SECTION LOCATION 640 17000 17500 18000 18500 19000 19500 20000 20500 21000 21500 22000 22500 23000 23500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 25P NAPERVILLE ROAD

FLOOD PROFILES

SPRING BROOK NO. 2 (DUSG)

670 670

ELEVATION IN FEET (NGVD 29)

665 665

660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DUSG0003 DUSG0004 CROSS SECTION LOCATION 650 23500 24000 24500 25000 25500 26000 26500 27000 27500 28000 28500 29000 29500 30000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 26P BOOK ROAD BOOK ROAD

83RD STREET 83RD STREET

FLOOD PROFILES

SPRING BROOK NO. 2 (DUSG) 680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DUSG0005 DUSG0006 CROSS SECTION LOCATION 655 30000 30500 31000 31500 32000 32500 33000 33500 34000 34500 35000 35500 36000 36500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 27P WEIR

75TH STREET

OAKTON LANE

RICKERT DRIVE

SPRING BROOK/ COUNTRYSIDE LAKE

FLOOD PROFILES

SPRING BROOK NO. 2 (DUSG) 690 690

DUSG0009 685 685

ELEVATION IN FEET (NGVD 29)

680 680 CULVERT

CULVERT

DUSG0010 675 675 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DUSG0007 DUSG0008 CROSS SECTION LOCATION 665 36500 37000 37500 38000 38500 39000 39500 40000 40500 41000 41500 42000 42500 43000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 28P OSWEGO ROAD

SEQUOIA ROAD

OGDEN AVENUE

WHISPERING HILLS DRIVE

SPRING BROOK/ LIMIT OF DETAILED STUDY COUNTRYSIDE LAKE LAKE OSBORNE

FLOOD PROFILES

SPRING BROOK NO. 2 (DUSG)

690 690

ELEVATION IN FEET (NGVD 29)

685 685

CULVERT CULVERT CULVERT

DUSG0014 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

DUSG0011 DUSG0012 DUSG0013 CROSS SECTION LOCATION 670 43000 43500 44000 44500 45000 45500 46000 46500 47000 47500 48000 48500 49000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 29P

3.3 East Branch DuPage River (EB)

3.3.1 Main Stem (EBEB)

3.3.1.1 Tributary Description

The Main Stem of the East Branch DuPage River has its headwaters in the Village of Bloomingdale, specifically Westlake Park. The East Branch takes a southern route passing through communities such as Bloomingdale, Glendale Heights, Glen Ellyn, Lombard, Lisle, Woodridge and Unincorporated DuPage County. Additional communities such as Addison, Wheaton, Naperville and Bolingbrook contribute watershed area to the East Branch DuPage River Main Stem. The total watershed area tributary to the East Branch DuPage River Main Stem is 21512 acres.

As the East Branch Main Stem proceeds from Westlake Park in Bloomingdale, it passes under Glen Ellyn Road, Brookdale Drive, Army Trail Road, the CCP Rail Road embankment, North Avenue, St. Charles Road, Crescent Boulevard, Hill Avenue, The Illinois Prairie Path, Route 53 (North), Roosevelt Road (Route 38), Butterfield Road (Route 56), Route 53 (South), Warrenville Road, I-88 (the East-West Tollway), Ogden Avenue, Burlington Avenue, the Burlington Northern Railroad bridge, Short Street, Maple Avenue, Four Lakes Avenue, Summerhill Drive, Hobson Avenue, and 75th Street within the confines of DuPage County. The East Branch proceeds through Royce Road before confluencing the West Branch DuPage River in Will County.

The East Branch DuPage River Main Stem watershed has some natural buffer areas to protect the floodplain area through the placement of Forest Preserves and parks. Such areas found on the main stem are: West Lake Park, Sunnyside Park, the East Branch Forest Preserve, Ackerman Park, Churchill Woods Forest Preserve, Glen Oak County Club, Western Acres Golf Course, Lisle Community Park, River Bend Golf Course, Seven Bridges Golf Course, and Green Valley Forest Preserve. Outside of these preserve areas, the primary land use is residential.

3.3.1.2 Hydrologic Analysis

Discharge-frequency data for East Branch DuPage River were developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC-1 rainfall- runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the

Section printed 29 April 2004

Armitage Creek 6.4 280 330 350 410

3.3.1.3 Hydraulic Analysis

Cross-section data for East Branch DuPage River were obtained by field measurement.

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Roughness coefficients (Manning’s “n”) for East Branch DuPage River were estimated by field inspection at the various cross sections. Table EBEB.3 shows the channel and overbank “n” values for the streams studied by detailed methods.

Table EBEB.3: East Branch DuPage River Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

East Branch DuPage River 0.035 - 0.055 0.055 - 0.090

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.1.4 Flood Boundaries

Section printed 29 April 2004

To reference the flood boundaries for East Branch DuPage River Main Stem, see Map Panels: 0205, 0206, 0208, 0209, 0307, 0502, 0503, 0505, 0506, 0508, 0509, 0601, 0602, 0604, 0605, 0607, 0802, 0803, 0805, 0806, 0808 and 0809

3.3.1.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.1.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch DuPage River (EBEB) EBEB0001 39,546 1 698 2,239 1.4 652.3 652.3 652.4 0.1 EBEB0002 42,553 1 140 876 3.4 655.1 655.1 655.2 0.1 EBEB0003 46,276 1 267 1,636 1.8 657.9 657.9 658.0 0.1 EBEB0004 51,841 1 530 3,001 1.0 660.2 660.2 660.2 0.0 EBEB0005 54,164 1 113 623 4.7 662.1 662.1 662.2 0.1 EBEB0006 55,725 1 110 694 4.2 663.3 663.3 663.3 0.0 EBEB0007 56,177 1 171 736 3.9 663.7 663.7 663.8 0.1 EBEB0008 58,385 1 857 2,852 1.0 664.5 664.5 664.6 0.1 EBEB0009 58,527 1 857 2,871 1.0 664.5 664.5 664.6 0.1 EBEB0010 59,387 1 296 3,884 0.6 665.0 665.0 665.1 0.1 EBEB0011 60,050 1 90 728 4.0 665.7 665.7 665.7 0.0 EBEB0012 60,231 1 135 487 6.0 665.8 665.8 665.8 0.0 EBEB0013 61,326 1 119 776 3.7 668.1 668.1 668.1 0.0 EBEB0014 62,802 1 106 787 3.7 669.2 669.2 669.2 0.0 EBEB0015 64,011 1 205 1,366 1.6 670.4 670.4 670.4 0.0 EBEB0016 64,347 1 531 2,323 0.9 670.5 670.5 670.6 0.1 EBEB0017 65,098 1 569 3,182 0.7 670.6 670.6 670.7 0.1

1 In feet above confluence with West Branch DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS EAST BRANCH DUPAGE RIVER (EBEB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch DuPage River (EBEB) EBEB0018 66,245 1 273 1,368 1.6 671.0 671.0 671.1 0.1 EBEB0019 67,569 1 535 2,234 1.0 671.6 671.6 671.7 0.1 EBEB0020 70,769 1 516 2,399 0.9 673.8 673.8 673.9 0.1 EBEB0021 72,500 1 122 653 3.4 674.3 674.3 674.4 0.1 EBEB0022 74,465 1 368 1,600 1.4 676.4 676.4 676.4 0.0 EBEB0023 76,235 1 1,030 2 1,667 1.3 676.7 676.7 676.8 0.1 EBEB0024 77,448 1 200 387 5.7 676.8 676.8 676.9 0.1 EBEB0025 77,785 1 160 797 2.0 677.3 677.3 677.4 0.1 EBEB0026 80,229 1 1,008 2,662 0.6 678.4 678.4 678.4 0.0 EBEB0027 83,043 1 55 273 5.3 680.3 680.3 680.4 0.1 EBEB0028 83,918 1 60 346 4.1 682.1 682.1 682.2 0.1 EBEB0029 85,337 1 743 2,597 0.6 682.8 682.8 682.9 0.1 EBEB0030 87,732 1 460 1,760 0.8 683.4 683.4 683.5 0.1 EBEB0031 89,169 1 117 605 2.4 684.5 684.5 684.6 0.1 EBEB0032 90,156 1 658 2,629 0.5 684.9 684.9 685.0 0.1 EBEB0033 91,769 1 790 770 1.9 686.7 686.7 686.8 0.1 EBEB0034 92,385 1 759 2,763 0.5 686.9 686.9 687.0 0.1

1 In feet above confluence with West Branch DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS EAST BRANCH DUPAGE RIVER (EBEB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch DuPage River (EBEB) EBEB0035 94,068 1 544 2,361 0.6 687.0 687.0 687.1 0.1 EBEB0036 97,486 1 128 481 3.0 687.6 687.6 687.7 0.1 EBEB0037 98,482 1 79 2 341 4.2 689.8 689.8 689.8 0.0 EBEB0038 99,487 1 840 642 2.2 691.6 691.6 691.7 0.1 EBEB0039 101,248 1 690 3,480 0.4 691.8 691.8 691.9 0.1 EBEB0040 106,067 1 329 928 1.1 692.5 692.5 692.6 0.1 EBEB0041 108,486 1 338 399 2.5 693.6 693.6 693.7 0.1 EBEB0042 113,097 1 62 133 2.6 697.7 697.7 697.8 0.1 EBEB0043 116,118 1 29 130 2.7 700.6 700.6 700.7 0.1 EBEB0044 117,099 1 57 91 3.9 702.0 702.0 702.1 0.1 EBEB0045 118,935 1 1,143 6,429 0.1 710.5 710.5 710.6 0.1 EBEB0046 122,553 1 692 3,198 0.1 712.2 712.2 712.3 0.1

1 In feet above confluence with West Branch DuPage River

1 In feet above confluence with East Branch DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain Actual f TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY

AND INCORPORATED AREAS EAST BRANCH TRIBUTARY NO. 3 (EBEB) [SCHWARTZ CREEK] 75TH STREET 660 CONFLUENCE OF 660

COUNTY BOUNDARY

EAST BRANCH TRIBUTARY NO. 7

CONFLUENCE OF CRABTREE CREEK

655 655

FLOOD PROFILES

650 650

EAST BRANCH DUPAGE RIVER (EBEB)

645 645

ELEVATION IN FEET (NGVD 29)

640 640

635 635 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 630 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0001 EBEB0002 CROSS SECTION LOCATION 625 33000 34000 35000 36000 37000 38000 39000 40000 41000 42000 43000 44000 45000 46000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 36P WEIR

SHORT STREET 670 MAPLE AVENUE 670

SUMMERHILL DRIVE

FOUR LAKES AVENUE

CONFLUENCE OF ROTT CREEK

CONFLUENCE OF ST. PROCOPIUS CREEK

665 665

HOBSON ROAD & CONFLUENCE WITH PRENTISS CREEK

FLOOD PROFILES

660 660

EAST BRANCH DUPAGE RIVER (EBEB)

655 655

ELEVATION IN FEET (NGVD 29)

650 EBEB0009 650

EBEB0007 EBEB0008 645 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0003 EBEB0004 EBEB0005 EBEB0006 CROSS SECTION LOCATION 635 46000 47000 48000 49000 50000 51000 52000 53000 54000 55000 56000 57000 58000 59000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 37P 685 685

LACEY AVENUE

STATE ROUTE 53

680 ARBORETUM ROAD ARBORETUM ROAD 680

WARRENVILLE ROAD

MIDDLETON AVENUE

BURLINGTON AVENUE

EAST - WEST TOLLWAY (I-88)

U.S. HIGHWAY 34 (OGDEN AVENUE)

CONFLUENCE OF ST. JOSEPH CREEK

CONFLUENCE OF EAST BRANCH TRIBUTARY NO. 3 675 CONFLUENCE OF EASH BRANCH TRIBUTARY NO. 5 675

FLOOD PROFILES

RAILROAD 670 670

EAST BRANCH DUPAGE RIVER (EBEB)

665 665

ELEVATION IN FEET (NGVD 29)

660 660

EBEB0020 655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD EBEB0012 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0010 EBEB0011 EBEB0013 EBEB0014 EBEB0015 EBEB0016 EBEB0017 EBEB0018 EBEB0019 CROSS SECTION LOCATION 645 59000 60000 61000 62000 63000 64000 65000 66000 67000 68000 69000 70000 71000 72000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 38P CONFLUENCE OF

685 (STATE ROUTE 56) 685

BUTTERFIELD ROAD

TREATMENT PLANT ROAD

CONFLUENCE OF UNNAMED

STREAM NORTH OF 22ND STREET

CONFLUENCE OF LACEY CREEK

EAST BRANCH TRIBUTARY NO. 4

680 680

FLOOD PROFILES

675 675

EAST BRANCH DUPAGE RIVER (EBEB)

670 670

ELEVATION IN FEET (NGVD 29)

665 665

EBEB0027 EBEB0028 660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD EBEB0024 50-YEAR FLOOD 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0021 EBEB0022 EBEB0023 EBEB0025 EBEB0026 CROSS SECTION LOCATION 650 72000 73000 74000 75000 76000 77000 78000 79000 80000 81000 82000 83000 84000 85000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 39P STATE ROUTE 53

ROOSEVELT ROAD

690 690

FLOOD PROFILES

685 685

EAST BRANCH DUPAGE RIVER (EBEB)

680 680

ELEVATION IN FEET (NGVD 29)

675 675

EBEB0036 670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0029 EBEB0030 EBEB0031 EBEB0032 EBEB0033 EBEB0034 EBEB0035 CROSS SECTION LOCATION 660 85000 86000 87000 88000 89000 90000 91000 92000 93000 94000 95000 96000 97000 98000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 40P 715 715

710 710

HILL AVENUE

NORTH AVENUE

705 ST. CHARLES ROAD 705

CRESCENT BOULEVARD

ILLINOIS PRAIRIE PATH (MAIN STEM)

700 CONFLUENCE OF EAST BRANCH TRIBUTARY NO. 2 CONFLUENCE OF EAST BRANCH TRIBUTARY NO. 1 700

FLOOD PROFILES

695 695

EAST BRANCH DUPAGE RIVER (EBEB)

ABANDONED RAILROAD

690 690

ELEVATION IN FEET (NGVD 29)

685 685

EBEB0041 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0037 EBBE0038 EBEB0039 EBEB0040 CROSS SECTION LOCATION 670 98000 99000 100000 101000 102000 103000 104000 105000 106000 107000 108000 109000 110000 111000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 41P RAILROAD

715 CONFLUENCE OF 715

TOP OF RAIL = 739.0 SWIFT MEADOWS TRIBUTARY

CONFLUENCE OF ARMITAGE DITCH

710 710

FLOOD PROFILES

705 705

EAST BRANCH DUPAGE RIVER (EBEB)

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0042 EBEB0043 EBEB0044 EBEB0045 CROSS SECTION LOCATION 680 111000 112000 113000 114000 115000 116000 117000 118000 119000 120000 121000 122000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 42P ARMY TRAIL ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

720 720

EAST BRANCH DUPAGE RIVER (EBEB)

715 715

ELEVATION IN FEET (NGVD 29)

710 710

705 705 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0046 CROSS SECTION LOCATION 695 122000 123000 124000 125000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 43P 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

695 695

RIVER DRIVE

PRIVATE DRIVE

DEVON AVENUE

PRIVATE DRIVE 690 SWARTZ AVENUE 690

PARKING LOT CROSSING

TWIN CULVERTS THROUGH LEVEE 685 685

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER

FLOOD PROFILES

680 680

EAST BRANCH. TRIBUTARY NO. 3 (EBEB)

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD

CULVERT 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

STREAM BED AND INCORPORATED AREAS

DUPAGE COUNTY, IL

EBEB0047 EBEB0048 EBEB0049 EBEB0050 EBEB0051 CROSS SECTION LOCATION 655 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 47P 715 715

MIDDLETON AVENUE

WINCHESTER AVENUE

LIMIT OF DETAILED STUDY

710 710

FLOOD PROFILES

705 705 EAST BRANCH. TRIBUTARY NO. 3 (EBEB)

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBEB0052 EBEB0053 CROSS SECTION LOCATION 680 2200 2400 2600 2800 3000 3200 3400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 48P

3.3.2 Armitage Creek (EBAR)

3.3.2.1 Tributary Description

Armitage Creek is located in DuPage County in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Armitage Creek Watershed covers approximately 2.13 square miles in Glendale Heights, Bloomingdale, and unincorporated Bloomingdale Township, as shown in Figures 2-1 and 2-2. Armitage Creek flows into the main channel of the East Branch DuPage River approximately 1,400 feet north of North Avenue (Illinois State Route 64).

The drainage system consists of 2.2 miles of the main stem of Armitage Creek and 0.8 miles of Armitage Fork tributary. The main stem of Armitage Creek originates at Glen Point Business Park detention ponds, located west of Bloomingdale Road, and flows generally to the southeast towards the East Branch DuPage River. The creek channel between Paul Avenue and Lincoln Avenue (approximately 1,400 feet) and the channel between Armitage Avenue and Wayne Avenue (approximately 2,070 feet) are enclosed.

The Armitage Fork tributary begins at the outfall east of Bloomingdale Road. This tributary travels westward and joins the mainstem of Armitage Creek just north of Winthrop Avenue. Downstream of Pearl Avenue, the in-bank creek channel is lined with concrete; this segment extends for approximately 1,500 feet to the confluence with the main stem.

3.3.2.2 Hydrologic Analysis

For Armitage Tributary, flood flow frequency data were developed through use of the State of Illinois multiple regression equations (IDOT, Magnitude and Frequency of Floods in Illinois, 1973). This method utilizes regional equations developed from known flood-frequency curves, which relate flood peak discharges to recurrence intervals of 1.25, 2, 5, 10, 25, 50, and 100 years using drainage area, main channel slope, rainfall intensity, and a regional factor as independent variables. For Armitage Fork and the upstream reach of Armitage Ditch, peak discharges were derived by comparison of drainage areas to the main stem.

The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Drainage area peak discharge relationships for Armitage Tributary are shown in Table EBAR.1.

Table EBAR.1 Armitage Creek Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

East Branch DuPage - above confluence w/ Armitage Creek 6.4 280 330 350 410

Armitage Creek - at Mouth 2.1 320 550 715 1,420 - above confluence w/ Armitage Fork 0.8 195 325 435 865 - at Ardmore Avenue 0.4 140 235 305 605 - above Placid Avenue 0.2 60 135 225 540

Armitage Fork - at Mouth 0.7 185 315 415 820

3.3.2.3 Hydraulic Analysis

Cross sections for he backwater analyses of the East Branch DuPage River were field surveyed; for Armitage Creek and Armitage Fork, channel sections were field surveyed, with the overbank sections taken from topographic maps at a scale of 1:9,600, with a contour interval of four feet (Ralph F. Gross and Son, Assoc., Inc., Village of Glendale Heights Comprehensive Storm Drainage Report, Nov 1973). In all cases, cross sections were located at close intervals above and below bridges and culverts in order to compute the significant backwater effects of these structures in the highly urbanized areas. Locations of selected cross sections used in the hydraulic analyses are shown on in the Flood Profiles section 3.3.2.6.

Channel roughness factors (Manning’s “n”) for these computations were assigned on the basis of field inspection of flood plain areas. Roughness values varied for each stream studied in detail as shown in the Table EBAR.2.

Section printed 29 April 2004

Table EBAR.2: Armitage Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

East Branch DuPage River 0.035 - 0.055 0.055 - 0.090 Armitage Creek 0.024 - 0.035 0.050 - 0.065 Armitage Fork 0.024 - 0.035 0.060 - 0.070

Flood profiles were drawn showing computed water-surface elevations to an accuracy of 0.5 foot for floods of the selected recurrence intervals. Water surface elevations of floods of the selected recurrence intervals were computed through use of the COE HEC-2 step-backwater computer program (USCOE, HEC-2 Water Surface Profiles, Generalized Computer Program, Oct. 1973).

Starting elevations for the East Branch DupPge River were developed by the slope-area method; for Armitage Creek, starting elevations were taken at its junctions with the East Branch DuPage River flowlines; and for Armitage Fork, starting elevations were taken at its junctions with the flowlines of the main stem. All elevations are referenced to the National Geodetic Vertical Datum of 1929 (NGVD).

3.3.2.4 Flood Boundaries

To reference the flood boundaries for Armitage Creek, see Map Panels: 0208 and 0209.

3.3.2.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.2.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Armitage Ditch (EBAR) EBAR0001 1,452 1 67 180 4.0 707.8 707.8 707.9 0.1 EBAR0002 2,006 1 24 83 8.6 710.9 710.9 710.9 0.0 EBAR0003 2,899 1 54 157 4.6 718.6 718.6 718.6 0.0 EBAR0004 3,501 1 81 316 2.3 720.8 720.8 720.8 0.0 EBAR0005 3,992 1 47 169 4.2 722.1 722.1 722.1 0.0 EBAR0006 4,499 1 127 516 1.4 725.9 725.9 726.0 0.1 EBAR0007 5,423 1 254 587 1.2 733.2 733.2 733.3 0.1 EBAR0008 5,940 1 260 979 0.4 733.5 733.5 733.6 0.1 EBAR0009 6,579 1 290 904 0.5 733.5 733.5 733.6 0.1 EBAR0010 7,455 1 40 192 2.3 737.6 737.6 737.7 0.1 EBAR0011 8,920 1 35 100 4.3 741.1 741.1 741.1 0.0 EBAR0012 10,225 1 12 53 5.7 752.4 752.4 752.5 0.1 EBAR0013 10,620 1 70 548 0.6 758.6 758.6 758.6 0.0 EBAR0014 11,200 1 303 1,074 0.3 760.0 760.0 760.1 0.1 EBAR0015 11,690 1 226 477 0.5 760.1 760.1 760.1 0.0

1 In feet above confluence with East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ARMITAGE DITCH (EBAR) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Armitage Fork (EBAR) EBAR0016 1,452 1 50 8 740.5 740.5 740.5 740.5 0.0 EBAR0017 2,101 1 191 2 758.2 758.2 758.2 758.2 0.0

1 In feet above confluence with Armitage Ditch TABLE5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ARMITAGE FORK (EBAR) 740 740

735 735

JILL COURT

LESLIE LANE

WAYNE AVENUE

GLEN ELLYN ROAD

730 ARMITAGE AVENUE 730

TREATMENT PLANT ROAD

LIMIT OF DETAILED STUDY

725 725

FLOOD PROFILES

ARMITAGE DITCH (EBAR)

720 720

715 HIGHLAND AVENUE 715

WINTHROP AVENUE

FULLERTON AVENUE

ELEVATION IN FEET (NGVD 29)

CONFLUENCE OF ARMITAGE FORK

710 710

EBAR0009 EBAR0010 705 705 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBAR0001 EBAR0002 EBAR0003 EBAR0004 EBAR0005 EBAR0006 EBAR0007 EBAR0008 CROSS SECTION LOCATION 695 1200 1700 2200 2700 3200 3700 4200 4700 5200 5700 6200 6700 7200 7700

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 30P 765 765

760 760

LINCOLN AVENUE

755 ARDMORE AVENUE 755

750 750

FLOOD PROFILES

ARMITAGE DITCH (EBAR)

PLACID AVENUE

745 POLO CLUB ROAD 745

LIMIT OF DETAILED STUDY

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBAR0011 EBAR0012 EBAR0013 EBAR0014 EBAR0015 CROSS SECTION LOCATION 720 7700 8200 8700 9200 9700 10200 10700 11200 11700

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 31P 765 765

760 760

755 755

CONFLUENCE WITH ARMITAGE DITCH

750 750

FLOOD PROFILES

ARMITAGE FORK (EBAR)

745 745

LIMIT OF DETAILED STUDY

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBAR0016 EBAR0017 CROSS SECTION LOCATION 720 0 250 500 750 1000 1250 1500 1750 2000 2250 2500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ARMITAGE DITCH 32P

3.3.3 Army Trail Road Tributary (EBAT)

3.3.3.1 Tributary Description

Army Trail Road Tributary is tributary to the East Branch DuPage River. The tributary watershed is found in the headwater region of the East Branch DuPage River watershed. The 282-acre watershed is centered over Army Trail Road in the Villages of Addison and Bloomingdale, flowing west from Route 53 to the East Branch DuPage River.

Much of the watershed in the headwaters is impervious due to such highway surfaces as Army Trail Road, Swift Road and I-355. As the watershed nears the confluence with the East Branch DuPage River, the land use changes dramatically to one of high prairie grasses and marshes. In recent years, the land use has changed to a more commercial use throughout the watershed, yet the downstream–most sections remain unaffected.

On the northwest side of the intersection of Swift Road and Army Trail Road, evidence of the Army Trail Tributary channel begins. This older residential area dumps storm water runoff into a depression on the north side of Army Trail Road, opposite to Meadow Lane. Conduits pass these waters to the south side of Army Trail Road. The channel takes a westerly track through thick brush and marshes. As the bearing turns more to the south, the channel is more exposed as it goes through a large nursery and agricultural area. The channel turns to the west once more, passing through the Valley View Road culvert and a ComEd Access Road culvert until it reaches the confluence with the East Branch DuPage River.

3.3.3.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge frequency relationships for floods of the selected recurrence intervals for each flooding source studies in detail affecting the community.

Section printed 29 April 2004

3.3.3.3 Hydraulic Analysis

Analyses of the hydraulic characteristics of flooding from the East Branch DuPage River were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. For construction and/or floodplain management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM.

Cross-section data for East Branch DuPage River were obtained by field measurement.

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Since no formal study was completed on Army Trail Tributary, the East Branch DuPage River 100-yr elevation information, determined through the above methods, at the location of the junction between the East Branch DuPage River and Army Trail Road Tributary is used for backwater effects on Army Trail Tributary. In addition to the determined backwater zone information, the unnumbered A-zone boundary was further formed through local studies and the USGS Flood of Record Maps.

3.3.3.4 Flood Boundaries

To reference the flood boundaries for Army Trail Road Tributary, see Map Panels: 0206 and 0209.

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3.3.4 Crabtree Creek (EBCR)

3.3.4.1 Tributary Description

Crabtree Creek is the southern-most watershed tributary to the East Branch DuPage River within DuPage County. With the exception of a very small area, the entirety of Crabtree Creek can be found within the Village of Woodridge. The total watershed area contributing to Crabtree Creek is 983 acres.

Crabtree Creek begins on the west side of I-355 and flows in an easterly manner towards the East Branch DuPage River. A branch of Crabtree, joining at midway point of the watershed, proceeds to the northern reaches of the watershed, also ending on the west side of I-355.

The modeled section of Crabtree begins upstream of Janes, where it flows east passing underneath such streets as Larchwood Lane, Woodridge Drive, Westview Lane, and Route 53. Crabtree then flows underneath the DuPage County Greene Valley Wastewater Treatment Facility and the Sewage Plant Drive to join the East Branch DuPage River.

3.3.4.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Crabtree Creek.

For Crabtree Creek, flood peak discharges were computed using the multiple regression equations stated in “Magnitude and Frequency of Floods in Illinois” (IDOT, 1973).

Discharges for the 500-year flood were determined by straight-line extrapolation of a log-probability curve of flood discharges computed for frequencies up to 100 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBCR.1

Table EBCR.1: Crabtree Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Crabtree Creek - within Woodridge

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corporate limits 1.45 325 575 740 1,430

East Branch DuPage River - just d/s of Crabtree Creek 75.3 1,850 2,630 3,080 4,270

Discharges for stream studies by approximate methods were determined from a regional curve that indicated the 100-yr peak discharge, in cubic feet per second (cfs), as a function of acreage stream-bed slope. This curve was determined by solving and plotting solutions to the multiple regression equation adopted by the State of Illinois (IDOT, 1973), for several streams within DuPage County.

3.3.4.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Roughness coefficients (Manning’s “n”) for Crabtree Creek were estimated from field inspection at cross-section locations, and from model calibration based on high water marks. The range of “n” values for the streams are found in Table EBCR.2:

Table EBCR.2: Crabtree Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Crabtree Creek 0.035 0.065

Water-surface profiles for Crabtree Creek were computed through use of the USACE’s HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973). Profiles were determined for the 10-, 50-, 100-, and 500-year floods.

Starting elevations at the downstream corporate limits for Crabtree Creek were determined from profiles of these streams computed for the FIS of the unincorporated areas of DuPage County (FEMA, 1982).

Section printed 29 April 2004

unobstructed and if channel and overbank conditions remain essentially the same as ascertained during this study.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.4.4 Flood Boundaries

To reference the flood boundaries for Crabtree Creek, see Map Panels: 0806, 0809 and 0907.

3.3.4.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.4.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above confluence with East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS CRABTREE CREEK (EBCR) STATE HIGHWAY 53

SEWAGE DISPOSAL ROAD

680 CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 680

FLOOD PROFILES

CRABTREE CREEK (EBCR)

670 670

660 660

ELEVATION IN FEET (NGVD 29)

650 650

640 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 630 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBCR0001 CROSS SECTION LOCATION 620 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 33P 710 WESTVIEW LANE 710

700 700

FLOOD PROFILES

CRABTREE CREEK (EBCR)

690 690

680 680

ELEVATION IN FEET (NGVD 29)

670 670

EBCR0003 660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBCR0002 CROSS SECTION LOCATION 640 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 34P WOODRIDGE DRIVE

LIMIT OF DETAILED STUDY

FLOOD PROFILES

CRABTREE CREEK (EBCR)

720 720

710 710

ELEVATION IN FEET (NGVD 29)

700 700

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBCR0004 CROSS SECTION LOCATION 670 5200 5400 5600 5800 6000 6200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 35P

3.3.5 East Branch Tributary No. 1 (EBE1)

3.3.5.1 Tributary Description

Tributary No. 1 to the East Branch DuPage River is a relatively small tributary with a watershed area of 431 acres. The communities of Addison, Lombard and Unincorporated DuPage County all contribute watershed area to this tributary. The land use of Tributary No. 1 is somewhat divided between impervious areas and vacant prairie.

Tributary No. 1 begins its flow one half mile north of North Avenue at Route 53. The tributary proceeds to the west where it runs into I-355. The tributary follows the eastern ditch of I-355 to North Avenue where flow is channeled under I-355. Once flow emerges on the west side of I- 355, the channel resumes a westerly course, passes under Swift Road, enters the East Branch Forest Preserve and joins the East Branch DuPage River.

3.3.5.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Tributary No. 1.

Discharges for the 10-year, 50-year, and 100-year floods for East Branch Tributary No. 1 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBE1.1.

Table EBE1.1: East Branch Tributary No. 1 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

East Branch Tributary No. 1 - at mouth 0.44 85 155 210 330

3.3.5.3 Hydraulic Analysis

Section printed 29 April 2004

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n”) for East Branch Tributary No. 1 were estimated from field inspection at cross-section locations, and from model calibration based on high water marks.

Table EBE1.2: East Branch Tributary No. 1 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

E.B. Tributary No.1 0.045 - 0.070 0.045 - 0.080

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.5.4 Flood Boundaries

To reference the flood boundaries for East Branch Tributary No. 1, see Map Panels: 0209, 0307, 0503 and 0601.

3.3.5.5 Floodways

Section printed 29 April 2004

No floodway information is available for this tributary.

3.3.5.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 725

100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

720

SWIFT ROAD

715 UNNAMED ROAD

710 710

FLOOD PROFILES

705 705

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER

EAST BRANCH TRIBUTARY NO. 1 (EBE1)

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBE10001 CROSS SECTION LOCATION 680 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER *DATA NOT AVAILABLE 44P NORTH AVENUE

LIMIT OF DETAILED STUDY

720 720

FLOOD PROFILES

715 715

EAST BRANCH TRIBUTARY NO. 1 (EBE1)

710 710

ELEVATION IN FEET (NGVD 29)

705 705

EBE10002 EBE10003 700 700 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 690 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER *DATA NOT AVAILABLE 45P

3.3.6 East Branch Tributary No. 2 (EBE2)

3.3.6.1 Tributary Description

East Branch Tributary No. 2 is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The watershed location within the County is shown in Figure 1. The East Branch Tributary No. 2 Watershed covers approximately 1.2 square miles (768 acres). This watershed includes parts of the Villages of Glen Ellyn and Glendale Heights, and areas in unincorporated Milton and Bloomingdale Townships. Tributary No. 2 flows into the main channel of the East Branch of the DuPage River 3,500 feet south of North Avenue (Illinois State Route 64), just upstream of the Great Western Trail.

The mainstem of Tributary No. 2 begins at a detention pond on the north side of James Court serving a subdivision in Glendale Heights north of North Avenue. The tributary then proceeds through a series of closed conduits leading to an outfall located 900 feet south of North Avenue behind the site of a vacant strip mall. The flow continues in a channel through a wooded wetland to just upstream of Main Street. Tributary No. 2 flows from west to east between Main Street and the East Branch of the DuPage River. At Main Street, a small tributary draining from the southwest joins the mainstem of Tributary No. 2.

Between Main Street and Park Boulevard, low flows are carried in a corrugated metal storm sewer, and an overflow channel is provided for high flows. A crossover structure just east of Glen Ellyn Road is designed to assure full flow in the storm sewer before flow enters the overflow channel. Streambank stabilization was completed by DuPage County on the overflow channel in 1994 for the reach between Main Street and Forest Avenue. Between Forest Avenue and Park Boulevard, the overflow passes through a wide grassy area that may have been designed for flood storage. The culverts at both Forest Avenue and Park Boulevard consist of one circular pipe and one arch-shaped corrugated metal pipe (CMP).

Approximately 450 feet downstream of Park Boulevard, the flow is confined in two 400-foot long corrugated metal pipes, which carry the flow under Second Street and Goodrich Avenue. Downstream of the outlets of these pipes, the County has constructed channel improvements and erosion protection for a distance of 400 feet. Just downstream of this channel improvement, there is a 200-foot long, corrugated metal culvert that was installed by the owner of parcel number 05-02-215-013. The fill over the culvert has completely eliminated the channel across most of the parcel. The culvert outlet is approximately 120 feet upstream of Glenrise Avenue. There are three CMP arch culverts at both Glenrise and Eastern Avenues. Both sets of culverts exhibit poor alignment and accumulation

Section printed 29 April 2004

of sediment. A fourth circular pipe at Eastern Avenue is completely blocked by sediment and debris. The area from downstream of Goodrich Avenue to just upstream of Eastern Avenue also has experienced erosion problems. Downstream of Eastern Avenue, portions of the channel banks and floodplain are heavily wooded with areas of both wooded and open wetland. Approximately 500 feet downstream of Eastern Avenue, the Tributary No. 2 channel splits into two distributaries for the remaining 700 feet to the East Branch. The south distributary channel is dry during low flow periods.

Just south of the Great Western Trail, the southwest tributary begins in the area between Pleasant and Prairie Avenues. This area drains through a storm sewer system to a 54-inch culvert under the trail. Then the flow travels through a series of culverts and constructed channels past the Center Ice of DuPage Ice Arena north of Poss Street. From the ice arena, the southwest branch flows due east under Highland Avenue and past the Seventh Day Adventist Church School to Main Street. Storm sewers carry flow north along Main Street to the Tributary No. 2 main channel.

Single-family residential subdivisions are the primary development in the watershed. A vacant strip mall formerly anchored by a Venture store is located along the south side of North Avenue, west of Main Street. A large wetland area behind this strip mall and an area known as Stacey Park are some of the undeveloped areas. The watershed includes about 1 mile of both North Avenue and Glen Ellyn Road/Main Street and smaller segments of St. Charles Road and Geneva Road. Main Street is known as Glen Ellyn Road north of North Avenue.

3.3.6.2 Hydrologic Analysis

The DuPage County Department of Development and Environmental Concerns have been working with the Northeastern Illinois Planning Commission (NIPC) to perform the regional hydrologic analysis for various watersheds since early 1980. A continuous hydrologic model, Hydrologic Simulation Program, FORTRAN (HSPF), was used to simulate the hydrologic characteristics of the watershed. HSPF uses a Watershed Data Management (WDM) file for storing input and output data. The current WDM file contains detailed precipitation data, other meteorologic data, recorded stream flow data, and simulated runoff and streamflow throughout DuPage County. Data is available back to 1948. The precipitation, meteorologic, and recorded streamflow data, along with land cover data are used to develop and calibrate the HSPF model to produce the simulated runoff for six land cover types. The land cover areas for each of the six land covers are generated by County's Geographic Information Systems (GIS) for each watershed. The six land cover types are impervious: flat, medium, and steep grass; forestland; and

Section printed 29 April 2004

agricultural/cropland. The procedures used for hydrologic analysis are discussed in Application Guide for Hydrologic Modeling in DuPage County using Hydrologic Simulation Program – Fortran (HSPF), (Price, 1996). HSPF simulates continuous hourly runoff from continuous precipitation and meteorologic data. Both surface and subsurface runoff are simulated. Thus, both stormflow and baseflow are simulated.

Hydrologic modeling for the entire East Branch DuPage River watershed including Tributary No. 2 is documented in Hydraulic Evaluation of HSPF Model for East Branch DuPage River Watershed (Price and Chang, 2001). This document describes the development and calibration of an HSPF model used to represent runoff from land covers throughout the East Branch watershed. The calibrated HSPF model generates unit runoff in inches per hour for six typical land covers. The land covers were developed for soil and vegetative conditions typically found in DuPage County. These land covers represent impervious area, flat, medium and steep sloped grassed areas, forest and agricultural land. Land segments in each tributary subbasin are assigned to one of these land covers within the hydraulic model. Within the hydraulic model, the area is associated with the appropriate HSPF runoff.

Hydrologic Calibration HSPF was regionally calibrated to five streamflow gages in the three primary watersheds in DuPage County (Salt Creek, East Branch of the DuPage River, and West Branch of the DuPage River) and then verified using a separate period of record and additional streamflow gates (ten total gages). The model was later applied in two smaller watersheds at the edge of the County, Sawmill Creek and Springbrook #2 to the DuPage River. The calibration and verification are described in "Hydrologic Calibration of HSPF Model for DuPage County" (NIPC, 1994) and in "Meteorologic Database Extension and Hydrologic Calibration and Hydraulic Evaluation of HSPF Model for Sawmill Creek Watershed" (NIPC, 1996). During the regional calibration and verification of the three primary watersheds and application in Sawmill Creek, it was found that a single set of HSPF model parameters (for each of the six land cover types) was applicable throughout each of the watersheds.

During calibration of the HSPF model, only unrouted runoff volumes were compared to annual, monthly, and event streamflow volumes. Thus, the model was not calibrated in terms of matching peak flows or timing of runoff within events. That portion of the hydrologic calibration occurs during the hydraulic modeling of specific watersheds and is termed "hydraulic evaluation". After hydraulic routing, the runoff through the stream network system, a final adjustment of HSPF model parameters can occur to produce appropriate timing of runoff within events.

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Relationship between Hydrologic Simulation and Hydraulic Simulation After the HSPF model is calibrated, the simulated runoff is routed through the stream network using a separate hydraulic model called FEQ. The simulated runoff stored in the WDM (HSPF) is with a format that is incompatible with the FEQ. Thus, a utility program called "WDMUTL" is used to export runoff from the WDM into a time series file (TSF) to be used in the FEQ model. The TSF contains runoff for each of the six land cover types and for each precipitation gage used to generate the runoff.

A number of TSFs are created for various purposes. Most of the files are used in hydraulic calibration and are created for specific portions of the County or for specific watersheds. This type of TSFs use a detail network of long-term or short-term precipitation gages to better define the temporal and spatial distribution of the calibration storm. The other type of TSFs are created for Countywide use in flood plain studies and alternative analysis. They are TSFLONG and TSFBIG. TSFLONG is based on precipitation data from the O'Hare and Wheaton long-term gages from water years 1949 through 1993. Instead of simulating the entire 45 years of record, DuPage County selected 115 discrete storms, which generated significant runoff volumes. The results from TSFLONG are used to perform frequency analysis. TSFBIG contains runoff based on very large precipitation events that have occurred in the Midwest. These events are used to assess performance of the stream system and hydraulic features under very extreme conditions.

3.3.6.3 Hydraulic Analysis

Hydraulic analysis was conducted using the continuous simulation hydraulic analysis software FEQ. Using FEQ, a detailed model of the Tributary No. 2 drainage network was developed. The model simulates flow storage in detention ponds, natural storage areas and floodplains. It also calculates the depth and discharge of flow through open channels, storm sewers and overflow paths.

Overview of FEQ Software Program FEQ, or Full Equations Model, was developed by Dr. Delbert Franz of Linsley, Kraeger Associates, Ltd. (Franz, 2001) FEQ is used to simulate flow in a stream system by solving numerically the equations for unsteady flow in open channels and through control structures. The program separates the flows into three broad classes: stream reaches, dummy reaches, and level-pool reservoirs. These three parts are then combined using different control structures, such as junctions, bridges, culverts, dams, waterfalls, spillways, weirs, side weirs, pumps, and others. FEQ determines the flow and depth throughout the stream system given initial and boundary conditions. FEQ can also be applied in the simulation of a wide-range of stream configurations, such as loops, lateral-inflow

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conditions, and special features. The boundary conditions can be values such as the water-surface stage, discharge, or the stage-discharge relationship at a node. Wind stress may also be included in the analysis, as well as the effects of lateral inflows, when given local runoff intensity data.

FEQ model input consists of the following elements:

83. Run Control – specifies the simulation length and model execution options.

84. Branch Description – defines channel stationing, flow line elevations and cross-section locations.

85. Tributary Area – defines drainage area and land cover proportions draining to each branch and reservoir represented in the model.

86. Network Control Input – describes how the system is connected together and specifies the function tables used to represent hydraulic structures.

87. Operation of Control Structures – there are no operable structures in the Tributary No. 2 drainage network.

88. Input Files – files containing time series of external flow inputs to the system.

89. Output Files – files written by FEQ to be used as flow input to another FEQ model.

90. Special Output – text file output of flow and stage at each time step for a set of specific modeled locations.

91. Function Tables – all cross-section and hydraulic structure information is stored in tables, which must be read into the model.

92. Initial Condition – provides information FEQ needs to determine an initial network solution that can be used as a model boundary condition.

FEQ Model of Tributary No. 2 Detailed FEQ modeling was developed for 6,300 feet of the main channel of Tributary No. 2 and for 3,470 feet of its southwest tributary. Modeling of the mainstem continues an additional 1,800 feet through storm sewers north to the James Court detention pond in Glendale Heights.

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The model consists of 26 branches representing reaches of open channel and storm sewers in the Tributary No. 2 drainage system, and 12 branches in the portion of the model taken from the FEQ model of the East Branch main channel. Function tables were used to represent additional hydraulic features such as culverts, expansions, contractions, inlet structures, and weirs. Four linear reservoirs and two detention ponds are represented in the model. Five additional surface ponding areas are also modeled as level pool reservoirs. The wetland area west of Main Street is represented in FEQ as a channel-routed reservoir.

The hydraulic characteristics of the stream system were obtained from field surveys performed in 1987 and 1995. Additional data was collected from DuPage County aerial photo and topographic maps and from IDOT plans for North Avenue. Hydrologic inputs and East Branch main channel data were provided by DuPage DEC. Watershed subbasin delineations were conducted on DuPage DEC 2-foot contour interval topographic maps and verified during field inspection. The watershed boundaries for Tributary No. 2 were previously established by the DEC and were verified to be correct. Field survey data collected includes cross-sections of the stream and floodplain, hydraulic structures such as bridges, culverts, dams, weirs, and other hydraulic controls.

Existing (1990) as well as future conditions (ultimate development) land cover data for the Tributary No. 2 watershed were obtained from DuPage County’s GIS system. The future conditions land use was used for economic and project analysis and for floodplain mapping. Existing conditions land use was used for hydraulic calibration. The land cover data for the Tributary No. 2 input to the FEQ program represents the tributary area characteristics of the Tributary No. 2 Watershed. This data is combined with the individual land cover runoff series obtained from the HSPF simulation. This process is further described in the "Hydrologic and Hydraulic Methods Report" (DuPage DEC, 1994), and the "East Branch Hydraulic Evaluation" (Price and Chang, 2001). Approximately 28 percent of the watershed was found to have impervious land cover under current land use conditions. Impervious area is estimated to increase to 36 percent under future land use conditions.

Streams Modeled The East Branch Tributary No. 2 model contains detailed modeling of the mainstem contains 6334 feet of open channel up to an outfall which is located in the former site of the Venture strip mall. There is also 1769 feet of storm sewer between the James Court detention pond and the outfall. The second stream is the Southwest Tributary. This tributary has 400 feet of parallel storm sewers running along Main Street. The Southwest Tributary has an additional 700 feet of open channel extending up to the parking lot on the north side of Poss Street. The Southwest Tributary also

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receives water from ponding areas south of the Great Western Trail. The total lengths and stationing of the storm sewers and detention areas were determined using the DuPage GIS system.

Cross-Section Data All model cross-sections must be portrayed in the DuPage County GIS. An ArcInfo script program, known as XDI was used to input and manipulate model cross-sections. The following functions were performed using XDI:

93. Entering the survey data into the County GIS

94. Extension of cross-sections that do not cover the full extent of the flood plain

95. Review and editing of cross-sections to screen out inappropriate survey points

96. Fabrication of cross-sections at additional locations needed for modeling

XDI generates text output in FEQUTL format for processing using the FEQX command. XDI also calculates the stream station of each cross- section.

The channel cross-sections were surveyed in 1987 and 1994 by Donohue and Associates. Twenty-six channel and floodplain cross-sections were surveyed. As they were surveyed, State Plane Coordinates were determined for each surveyed elevation location. Where possible, all of the surveyed cross-section points were used in the analysis. If any extra information was needed, such as horizontal extensions, the County’s XDI software and digital topography were used as needed.

In addition to the surveyed cross-sections, there were also fabricated cross-sections used in the analysis. The fabricated cross-sections were created for various reasons. Some of the surveyed cross-sections were surveyed with no state plane coordinates. For this situation, the approximate location is determined and the State Plane Coordinates were assumed. This data was then used along with the surveyed elevations. There were also fabricated sections generated from existing surveyed sections. Overland flow sections were fabricated sections was well. All of the fabricated sections were extended using XDI.

Table EBE2.1 lists the cross-section ID, the table number, the low point (flow line elevation) and station.

Table EBE2.1. Surveyed Channel Cross Sections

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FEQ Table Cross Section Description Number 0 Janus Wetland 100 1 Janus Wetland 101 2 D/S of Eastern Ave 102 3 U/S of Eastern Ave 103 4 Between Eastern Ave and Glenrise Ave 104 5 D/S of Glenrise Ave 105 6 U/S of Glenrise Ave 106 7 Between Glenrise Ave and Goodrich Ave 107 8 Between Glenrise Ave and Goodrich Ave 108 9 Between Goodrich Ave and Park St 109 10 D/S of Park St 110 11 U/S of Park St 111 12 Between Park St and Forest Ave 112 13 D/S of Forest Ave 113 14 U/S of Forest Ave 114 15 D/S of Main St (Glen Ellyn Rd) 115 16 U/S of Main St (Glen Ellyn Rd) 116 17 Through wetland west of Main St 117 18 Through wetland west of Main St 118 19 Through wetland west of Main St 119 20 U/S of Glen Ellyn Rd 120 21 Between Highland Ave and Main St 121 22 20' D/S of Highland Ave structure 122 23 Constructed channel around Ice Areana 123 24 U/S 3.5 ft drop 124 25 U/S of Great Western Trail bike path 125

Another group of cross-sections are classified as closed conduits. Closed conduits of significant length were modeled as branches. A list of the closed conduits represented in the Trib 2 FEQ model is in Table EBE2.2.

Table EBE2.2. Closed Conduits Table Description Location Number FEQ Branch 65 by 40 CMP Arch Main St to Park Ave and Private Pipe 665 9, 8, 4 Twin 87 by 63 CMP Arch Under 2nd St and Goodrich Ave 687 6 48 by 84 RCP Elliptical Under vacant strip mall 684 12 18" Circular RCP Under Main St 618 14 24" Circular RCP Under Main St 624 26 36" Circular RCP Under Poss St, Main St, and Ice Arena 636 18, 22, 24 Twin 34 by 18 CMP Culvert Under Highland Ave 634 21

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42" Circular RCP North of North Ave 642 13 78 by 54" CMP Arch Main St culvert 678 100

Manning n-values were assigned to the horizontal segments of each cross- section. Each n-value was determined from the characteristics of the channel cross-section, using values determined from Chow, 1959. The channel n-values as well as the overbank n-values were determined.

Tributary Area East Branch Tributary No. 2 was delineated into 35 subbasins. These subbasins generally correspond to the areas draining to each branch and reservoir node represented in the FEQ model. Several “extra” subbasins were created for possible future use, while some branches, such as short closed conduits were not assigned any tributary area. The areas from the 35 subbasins are allocated to 29 branches and nodes. One subbasin (11B) is not assigned because it does not appear to discharge to the Tributary No. 2 stream network. A total of 1.176 square miles of area was assigned to FEQ branches and reservoirs.

The DuPage County GIS was used to determine land cover areas within each subbasin. There are GIS coverages available for calculating both current and future land cover.

Hydraulic Structures Nineteen major hydraulic structures were modeled explicitly in the Tributary 2 FEQ model not counting the storage area outlets discussed in Section 3.2.2.6. These structures are mostly road crossing culverts and storm sewers but there are also a few channel transitions and unusual inlet structures. These structures are listed in Table EBE2.3 along with the FEQ modeling approach employed for each structure. FEQ provides many tools for use in representing hydraulic structures. Some typical approaches are described below.

Roadway culverts are represented using a combination of FEQUTL commands. One or more CULVERT commands are used to compute tables for flows through the culvert barrels. The EMBANKQ command is used to calculate flow over the roadway within the channel banks and a CHANRAT table is used for flow over the road that occurs in each overbank. This approach was used to model five Tributary 2 structures.

Long culverts and storm sewers are represented in FEQ as regular branches. This approach has the advantages of applying the full unsteady flow solution to the structure and assures that stored flow within the structure is accounted for. The EXPCON command in FEQUTL is used to calculate entrance and exit losses for the transitions between open

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channel and storm sewers. Ten sewers and culverts are represented as branches in the Tributary No. 2 model.

Unusual structures such as slope box inlets are typically modeled using a combination of FEQUTL commands and manual modifications to the computed table. There are four inlet structures that employ manually adjusted 2-D tables in the Tributary No. 2 FEQ model.

There are two major channel transitions in the Tributary 2 watershed where there are sudden expansions in channel dimensions. These transitions are modeled using the EXPCON command.

Table EBE2.3. Hydraulic Structures Stream Structure Structure Modeling Approach Number Main Confluence with East Branch EXPCON Channel S-1 Eastern Ave CULVERT, EMBANKQ, CHANRAT S-2 Glenrise Ave CULVERT, EMBANKQ, CHANRAT Private Pipe FEQ Branch, EXPCON S-3 Culvert under Second Street and FEQ Branch, EXPCON Goodrich S-4 Park Blvd CULVERT, EMBANKQ, CHANRAT S-5 Forest Ave CULVERT, EMBANKQ, CHANRAT Storm Sewer from Main St. to FEQ Branch, EXPCON Park St. S-6 Box Inlet D/S of Main St Fabricated 2D Table S-6 Main St. Culvert FEQ Branch, EXPCON S-7 Storm Sewer under Venture FEQ Branch, EXPCON SW Storm sewers under Main St. FEQ Branch, EXPCON Tributary S-9 Inlet structure on W. side of Main Fabricated 2D Tables S-12 Storm Sewer under Ice Arena FEQ Branch, EXPCON S-11 Culvert under Highland FEQ Branch, EXPCON Sudden Drops in Channel Invert EXPCON U/S of Ice Arena S-13 Storm Sewer under parking lot FEQ Branch, EXPCON S-16 Great Western Trail CULVERT Pleasant-Prairie Storm Sewers FEQ Branch Pleasant-Prairie Inlets Fabricated 2D Tables

Storage Areas and Detention Basins Storage areas and detention basins typically are modeled in FEQ as level- pool reservoirs although it is also possible to model in-line storage as a branch. Outlet flows can be modeled either as simple rating curves or as 2-dimensional ratings that account for submergence. The Tributary No. 2 FEQ model includes eleven level pool reservoirs. These included four

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linear reservoirs, two detention ponds, and five surface ponding areas as listed in Table EBE2.4.

Linear reservoirs are a modeling device used to simulate the effect of diffuse storage and overland flow on the runoff from a subbasin. No real storage pond exists in the subbasin, (or if one does, it is not modeled explicitly). The linear reservoir is used to replicate the attenuation of the runoff hydrograph that is observed in large subbasins with significant overland flow. Four remote subbasins are modeled using linear reservoirs.

Table EBE2.4. Level Pool Reservoirs in the Tributary No. 2 Model Description Type Model Node Outlet Subbasin F3 Linear F3 1-D Linear Relation Wetland Northeast of Ponding Area F5 EMBANKQ North Avenue and Glen Ellyn Road James Court Detention Detention Pond F7 CULVERT Subbasin F9 Linear F9 1-D Linear Relation Subbasin F19N and F19S Linear F19 1-D Linear Relation Ponding between Poss Ponding Area F15 EXPCON Street and the Great Western Trail Ponding U/S of Great Ponding Area F17 CULVERT Western Trail Ponding Area on Prairie Ponding Area F53 ORIFICE and Avenue EMBANKQ Ponding Area on Pleasant Ponding Area F55 ORIFICE and Avenue EMBANKQ Denby Woods Pond Detention Pond F57 ORIFICE Subbasin 17C and 17D Linear F59 1-D Linear Relation

Seven additional ponding areas are modeled as real reservoirs. For these, storage-area-elevation data was derived using DuPage DEC topographic maps and outlet conditions were modeled using appropriate FEQUTL commands.

3.3.6.4 Flood Boundaries

To reference the flood boundaries for East Branch Tributary No. 2, see Map Panels: 0208, 0209, 0502 and 0503.

3.3.6.5 Floodways

Conveyance floodways were determined for each modeled open channel cross section for East Branch Tributary No. 2 using the FEQUTL FLOODWAY command using the PVSTATS computer program. The equal conveyance option was employed in the command. This command

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calculates cross-section encroachments that result in equal losses of conveyance from each side of the floodplain. Encroachments are increased until either the water-surface elevation rises 0.1 foot or the total conveyance loss reaches 10 percent.

Please reference attached Floodway Data Tables for further information.

3.3.6.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch Tributary No. 2 (EBE2) EBE20100 494 1 476 2,255 2.3 699.0 699.0 699.1 0.1 EBE20101 1,073 1 323 518 2.8 699.4 699.4 699.5 0.1 EBE20102 1,501 1 220 321 7.5 702.1 702.1 702.2 0.1 EBE20103 1,564 1 548 913 2.1 705.1 705.1 705.2 0.1 EBE20104 1,953 1 110 279 3.4 705.7 705.7 705.8 0.1 EBE20105 2,315 1 73 201 11.4 707.4 707.4 707.5 0.1 EBE20106 2,379 1 144 550 1.8 709.7 709.7 709.8 0.1 EBE20107 2,834 1 126 410 2.5 710.2 710.2 710.3 0.1 EBE20108 3,077 1 89 326 2.8 710.6 710.6 710.7 0.1 EBE20109 3,677 1 96 404 1.8 714.6 714.6 714.7 0.1 EBE20110 3,925 1 54 245 12.8 714.7 714.7 714.8 0.1 EBE20111 4,024 1 154 717 0.9 716.9 716.9 717.0 0.1 EBE20112 4,207 1 144 524 1.1 716.9 716.9 717.0 0.1 EBE20113 4,376 1 97 294 16.7 717.0 717.0 717.1 0.1 EBE20114 4,469 1 135 543 2.8 719.9 719.9 720.0 0.1 EBE20115 4,851 1 30 59 5.6 720.4 720.4 720.5 0.1 EBE20116 4,998 1 93 220 1.8 722.6 722.6 722.7 0.1

1 In feet above Confluence with East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS EAST BRANCH TRIBUTARY NO. 2 (EBE2) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch Tributary No. 2 (EBE2) EBE20117 5,331 1 128 260 1.0 722.9 722.9 723.0 0.1 EBE20118 5,576 1 151 272 1.1 723.0 723.0 723.1 0.1 EBE20119 6,049 1 194 344 1.1 723.2 723.2 723.3 0.1

1 In feet above Confluence with East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS EAST BRANCH TRIBUTARY NO. 2 (EBE2) 730 730

725 725

FOREST AVENUE

PRIVATE CULVERT

EASTERN AVENUE

PARK BOULEVARD

PRIVATE CULVERT

GLENRISE AVENUE

720 CONFLUENCE WITH 720

EAST BRANCH DUPAGE RIVER CULVERTS

715 715

CULVERTS FLOOD PROFILES

MAIN STREET 710 710

EAST BRANCH TRIBUTARY NO. 2 (EBE2)

LIMIT OF DETAILED STUDY

705 CULVERTS 705

ELEVATION IN FEET (NGVD 29) CULVERT

700 EBE20116 700

EBE20117 EBE20118 EBE20119 695 695 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD EBE20103 EBE20106 EBE20111 EBE20114 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBE20100 EBE20101 EBE20102 EBE20104 EBE20105 EBE20107 EBE20108 EBE20109 EBE20110 EBE20112 EBE20113 EBE20115 CROSS SECTION LOCATION 685 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 46P

3.3.7 East Branch Tributary No. 3 (EBE3)

3.3.7.1 Tributary Description

The East Branch Tributary No. 3 is a 312-acre watershed that lies primarily in the Village of Lombard. The watershed is residential in nature, with such road features as I-355 near the mouth of the tributary and Finley Road bisecting the watershed from north to south.

East Branch Tributary No. 3 begins at Four Seasons Park in Lombard, on the east side of Finley Road approximately one half mile south of Roosevelt Road. The tributary curves to the north, then west, passing underneath Finley Road and Aspen Drive. The tributary proceeds west behind several dead-end streets and housing complexes until it crosses Aspen Road again. The reach passes underneath S. Lloyd Avenue, enters a marshy area on the east side of I-355, proceeds underneath I-355 and immediately joins the East Branch DuPage River on the west side of the highway.

3.3.7.2 Hydrologic Analysis

3.3.7.3 Hydraulic Analysis

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management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM.

Cross-section data for East Branch DuPage River were obtained by field measurement.

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Since no formal study was completed on East Branch Tributary No. 3, the East Branch DuPage River 100-yr elevation information, determined through the above methods, at the location of the junction between the East Branch DuPage River and the East Branch Tributary No. 3 is used for backwater effects on East Branch Tributary No. 3. In addition to the determined backwater zone information, the unnumbered A-zone boundary was further formed through local studies and the USGS Flood of Record Maps.

3.3.7.4 Flood Boundaries

To reference the flood boundaries for East Branch Tributary No. 3, see Map Panels: 0506 and 0604

3.3.7.5 Floodways

No floodway information is available.

3.3.7.6 Flood Profiles

No flood profile information is available.

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3.3.8 East Branch Tributary No. 6 (EBE6)

3.3.8.1 Tributary Description

East Branch Tributary No. 6 (previously known as St. Procopius Creek) is a relatively large watershed consisting of approximately 1183 acres. This watershed flowing primarily from west to east is within the communities of Lisle, Naperville and Unincorporated DuPage County. The overall land use of the watershed is divided into three parts: institutional / commercial, medium-high density residential and low density residential. Both the institutional grounds (Benedictine University) and the low density residential are within Unincorporated DuPage County and Woodridge, where the high density residential is primarily found in the community of Lisle.

Three branches of East Branch Tributary No. 6 exist. This first, northernmost branch begins at Benedictine University and flows the to southeast. The branch passes underneath College Road and Millridge Lane, until it confluences with the second branch at Seven Bridges Golf Course.

The second branch begins in Naperville, where it quickly passes into Lisle – both areas being of higher density residential. Much of this second branch appears to be submerged in pipe, but emerges from the pipe upstream of College Road, just south of Abbeywood Drive. The second branch passes east underneath College Road, proceeds behind several townhouses, and passes underneath Golf View Drive. This second branch joins the first branch on the northwestern edge of the Seven Bridges Golf Course. The joined branch continues to the south, passing under Greene Road and Greene Trails Drive through higher density residential areas in the Village of Woodridge. On the south side of Greene Trails Drive, the second branch encounters the third, and final, East Branch Tributary No. 6 branch.

The third branch begins in low-density residential areas in the southern part of the watershed. The branch, starting in Eggerman Woods Forest Preserve (at the NE corner of Hobson and College Roads) proceeds on a Northeast bearing through upscale residential areas, passing underneath Donwood Drive West and Donwood Drive East. Traveling east, the third branch passes through Donwood Trails Drive and Oak Trails Drive. On the east side of Oak Trails Drive, the third branch converges with branch two. The joined tributary continues to the east where it passes underneath Greene Trails Drive and Greene Road to join the East Branch DuPage River at the Seven Bridges Golf Course.

3.3.8.2 Hydrologic Analysis

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Discharges for East Branch Tributary No. 6 (St. Procopius Creek) were computed by using the square root of the drainage areas ratio applied to the results for Lacey Creek. Lacey Creek is a local area tributary of the East Branch DuPage River considered to have similar drainage characteristics to East Branch Tributary No. 6.

Discharges for the 500-yr floods of all stream were determined by linear extrapolation of a log-probability graph plotted for calculated peak discharges.

Peak discharges for the 10-, 50-, 100-, and 500-year floods are shown in Table EBE6.1.

Table EBE6.1: East Branch Tributary No. 6 (St. Procopius Creek) Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

East Branch Tributary No. 6 - approx. 600 feet d/s of Mill Bridge Lane 0.68 170 265 320 440

3.3.8.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The 100-year flood stage for streams studied by approximate methods was determined by solving Manning’s equation for depth of flow in the channel.

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These streams were field surveyed to obtain typical stream cross sections, average stream channel slope, and Manning’s “n” values.

Roughness coefficients (Manning’s “n”) for East Branch Tributary No. 6 were estimated from field inspection at cross-section locations, and from model calibration based on high water marks. Please see table EBE6.2 for further information.

Table EBE6.2: East Branch Tributary No.6 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

East Branch Tributary No. 6 0.035 - 0.040 0.060 - 0.080

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.8.4 Flood Boundaries

To reference the flood boundaries for East Branch Tributary No. 6, see Map Panels: 0804, 0805 and 0808.

3.3.8.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.8.6 Flood Profiles

Please reference attached Flood Profile Sheets

1 In feet above confluence with East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ST. PROCOPIUS CREEK (EBE6) 715 715

710 710

705 705

LIMIT OF DETAILED STUDY CULVERT

700 700 CULVERT

FLOOD PROFILES

ST. PROCOPIUS CREEK (EBE6)

695 MILL BRIDGE LANE 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

EBE60002 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBE60001 CROSS SECTION LOCATION 670 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 54P 720 720

715 PRIVATE ROAD 715

710 710

THE 50- AND 500-YEAR FLOOD PROFILES ARE TOO CLOSE TO BE SHOWN SEPARATELY FLOOD PROFILES

ST. PROCOPIUS CREEK (EBE6)

705 COLLEGE ROAD 705

LIMIT OF DETAILED STUDY

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBE60003 EBE60004 CROSS SECTION LOCATION 680 9400 9600 9800 10000 10200 10400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 55P

3.3.9 East Branch Tributary No. 7 (EBE7)

3.3.9.1 Tributary Description

East Branch Tributary No. 7 is a 533 acre tributary watershed to the East Branch DuPage River, found in the south-central section of DuPage County. Though containing some watershed area in the City of Naperville, East Branch Tributary No. 7 is almost entirely unincorporated. This area has undergone much recent development in the form of single and multi-family dwellings.

Two branches make up the stream length of East Branch Tributary No. 7. The northern, or first branch starts west of Brenwood Drive and south of Hobson Road. The branch flows directly east, passing under Brenwood Drive. The branch turns to the south and follows the backyard lot lines of a residential subdivision, eventually turning to the east encountering the second branch.

The second branch of the East Branch Tributary No. 7 begins on the west side of Palomino Road and north of 75th Street. The second branch flows to the east passing beneath Palomino Road. The branch continues to the northeast, following the back lot lines of residential subdivisions until it eventually joins the first branch. The joined branch continues directly east, passes under Greene Road and confluences with the East Branch DuPage River in the Green Valley Forest Preserve.

3.3.9.2 Hydrologic Analysis

Discharges for the 10-year, 50-year, and 100-year floods for East Branch Tributary No. 7 studied by the limited detail method were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight- line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBE7.1.

Section printed 29 April 2004

Table EBE7.1: East Branch Tributary No. 7 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

East Branch Tributary No. 7 - at mouth 0.71 180 330 425 650

3.3.9.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Starting water-surface elevations for the streams studied in detail and limited detail were determined using corresponding flood elevations on the main stem, flood profiles from previous studies by the State of Illinois and the SCS (State of Illinois, 1975; and Des Plaines River Watershed Steering Committee, January 1976), normal depth computations, and rating curves. Backwater effects at confluences with larger stream systems are reflected on the flood profiles.

The water-surface elevations for the East Branch Tributary No. 7 studied in detail and limited detail were computed using either the SCS WSP-2 backwater computer program or the USACE HEC-2 step-backwater computer program (U.S. Department of Agriculture, 1974; USACE, HEC- 2 Water-Surface Profiles, Computer Program723-X6-L202A, 1973.

Roughness coefficients (Manning’s “n”) for East Branch Tributary No. 7 were estimated from field inspection at cross-section locations, and from model calibration based on high water marks.

Table EBE7.2: East Branch Tributary No. 7 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Section printed 29 April 2004

East Branch Tributary No. 7 0.055 - 0.080 0.080 - 0.100

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

The 100-year flood stage for streams studied by approximate methods was determined by solving Manning’s equation for depth of flow in the channel. These streams were inspected in the field to obtain stream cross-sections, and measurements at bridges and culverts.

3.3.9.4 Flood Boundaries

To reference the flood boundaries for East Branch Tributary No. 7, see Map Panels: 0805, 0808 and 0809.

3.3.9.5 Floodways

No floodway information is available for this tributary.

3.3.9.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

700 700

FOOTBRIDGE 690 GREENE ROAD 690

DRIVEWAY TO DERBY DRIVE

680 680

FLOOD PROFILES

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 670 670

EAST BRANCH TRIBUTARY NO. 7 (EBE7)

660 660

ELEVATION IN FEET (NGVD 29)

650 650

EBE70002 EBE70003 640 640 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 630 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

EBE70001

620 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER * DATA NOT AVAILABLE 56P FOOTBRIDGE

MURRAY DRIVE 730 PALOMINO DRIVE 730

LIMIT OF DETAILED STUDY

PRIVATE ROAD TO 75TH STREET

720 720

FLOOD PROFILES

710 710

EAST BRANCH TRIBUTARY NO. 7 (EBE7)

700 700

ELEVATION IN FEET (NGVD 29)

690 690

680 680 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD

EBE70005 50-YEAR FLOOD* 670 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

EBE70004 EBE70006 EBE70007

660 5200 5600 6000 6400 6800 7200 7600 8000 * DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 57P

3.3.10 Glen Crest Creek (EBGL)

3.3.10.1 Tributary Description

Glen Crest Creek (previously known as East Branch Tributary No. 4) is a 1739-acre watershed that is tributary to the East Branch DuPage River. Primarily draining the Village of Glen Ellyn, Glen Crest Creek has contributing watershed area from the Villages of Wheaton and Lombard, and Unincorporated DuPage County. The bulk of the land use is suburban residential, with a rather large recreational area / golf course centered in the middle of the watershed. Much of the watershed, especially in the headwaters, has been placed in conduit.

There are two branches of Glen Crest Creek that deserve attention. The first is a short branch that starts at the reservoir created at Glen Ellyn’s Panfish Park, located a few hundred feet to the south of Roosevelt Road and bounded on the east and west by Route 53 and Park Boulevard respectively. Storm waters enter the site from the northeastern section of the watershed, and exit through a conduit to the southwest. The conduit opens up at The Links Golf Course where branch one encounters branch two.

Branch two begins in the northern section of the Links Golf Course. Branch two drains all waters from the northcentral and northwestern parts of the watershed. After joining branch one, branch two enters another conduit system that proceeds to the southeast. The channel opens up upon entering the Willowbrook Forest Preserve Wildlife Haven, and remains in an open state until the confluence with the East Branch DuPage River. The branch takes a northeasterly course and passes under Sheffield Road, 22nd Street and Route 53. The bearing changes to the southeast where the branch continues under Bemis Road and Glen Crest Drive before encountering the East Branch DuPage River.

3.3.10.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Glen Crest Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Glen Crest Creek studied in detail and for the 10-year and 100-year events for streams studied by the limited detail method were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Section printed 29 April 2004

Hydrologic computations for the Village of Glen Ellyn Links storm retention system, as well as other areas in the village which experience shallow flooding, were based on the SCS Technical Release No. 55 (U.S. Department of Agriculture, 1975). The drainage basin of the Village Links system was first subdivided into those areas that drain directly into the golf course ponds, and those that first drain into other ponds and eventually discharge into the golf course ponds through storm sewers. For all areas, storage volumes and release rates applicable to a 100-year flood were then determined. The discharge rate available to direct runoff to the golf course was reduced to account for release rates of upstream ponding areas and storm sewers. The final required detention volume and corresponding 100-year flood elevation for the golf course was then determined.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBGL.1.

Table EBGL.1: Glen Crest Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Glen Crest Creek - at Leask Lane 4.34 455 730 870 1,200 - at mouth 2.60 370 485 550 750

3.3.10.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface profiles of Glen Crest Creek were computed through use of the USACE’s HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973). Profiles were determined for the 10-, 50-, 100-, and 500-year floods.

Section printed 29 April 2004

Starting elevations at the downstream corporate limits for Glen Crest Creek were determined from profiles of these streams computed for the FIS of the unincorporated areas of DuPage County (FEMA, 1982).

100-year flood elevations along the Village Links storm water retention system were computed from discharge-storage relationships developed for each drainage sub-area. Storm sewer head losses were calculated from standard equations for closed pipe and orifice flows. The 100-year starting water-surface elevation at the stream east of Park Boulevard into which this retention system empties was determined from a slope-area analysis.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

Roughness coefficients (Manning’s “n”) for Glen Crest Creek were estimated from field inspection at cross-section locations, and from model calibration based on high water marks.

Table EBGL.2: Glen Crest Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Glen Crest Creek 0.065 - 0.085 0.055 - 0.070

3.3.10.4 Flood Boundaries

To reference the flood boundaries for Glen Crest Creek, see Map Panels: 0505, 0506, 0508 and 0509.

3.3.10.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.10.6 Flood Profiles

Section printed 29 April 2004

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch DuPage River Tributary No. 4 (EBGL) EBGL0001 557 1 28 94 5.9 684.5 684.5 684.5 0.0 EBGL0002 2,362 1 93 267 2.1 700.4 700.4 700.5 0.1 EBGL0003 3,293 1 125 367 1.3 709.9 709.9 709.9 0.0 EBGL0004 4,398 1 58 181 2.7 715.9 715.9 715.9 0.0 EBGL0005 4,684 1 110 2 327 1.5 728.2 728.2 728.2 0.0 EBGL0006 5,712 1 82 178 2.8 729.9 729.9 729.9 0.0

1 In feet above confluence with East Branch DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY

AND INCORPORATED AREAS EAST BRANCH TRIBUTARY NO. 4 (EBGL) [GLEN CREST CREEK] 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

BEMIS ROAD

705 GLEN CREST DRIVE 705

SUNNYBROOK ROAD

700 700

FLOOD PROFILES

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER

695 695

EAST BRANCH TRIBUTARY NO. 4 (EBGL)

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBGL0001 EBGL0002 CROSS SECTION LOCATION 670 0 500 1000 1500 2000 2500 3000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 49P 740 740

735 735

FOOTBRIDGE

22ND STREET

STATE ROUTE 53

730 (BRYANT AVENUE) 730

725 725

FLOOD PROFILES

720 720

EAST BRANCH TRIBUTARY NO. 4 (EBGL)

LIMIT OF DETAILED STUDY

715 SHEFFIELD ROAD 715

ELEVATION IN FEET (NGVD 29)

710 710

705 705 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBGL0003 EBGL0004 EBGL0005 EBGL0006 CROSS SECTION LOCATION 695 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 8000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DU PAGE RIVER 50P

3.3.11 Glen Park (EBGP)

3.3.11.1 Tributary Description

Glen Park Tributary is a 455-acre tributary to the East Branch DuPage River. This rather small tributary has contributing watershed area from the Village of Lombard, the Village of Downers Grove and Unincorporated DuPage County.

Glen Park begins on the north side of Butterfield Road (Route 56) in the Village of Downers Grove, just east of I-355. The channel passes west underneath I-355, Glen Park Road, Hampton Road and Valley Road until confluencing with the East Branch DuPage River.

3.3.11.2 Hydrologic Analysis

3.3.11.3 Hydraulic Analysis

Cross-section data for East Branch DuPage River were obtained by field measurement.

Section printed 29 April 2004

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Since no formal study was completed on Glen Park Tributary, the East Branch DuPage River 100-yr elevation information, determined through the above methods, at the location of the junction between the East Branch DuPage River and Glen Park Road Tributary is used for backwater effects on Glen Park Tributary. In addition to the determined backwater zone information, the unnumbered A-zone boundary was further formed through local studies and the USGS Flood of Record Maps.

3.3.11.4 Flood Boundaries

To reference the flood boundaries for Glen Park Tributary, see Map Panels: 0509 and 0607.

3.3.11.5 Floodways

No floodway information is available.

3.3.11.6 Flood Profiles

No flood profile information is available.

Section printed 29 April 2004

3.3.12 Lacey Creek (EBLA)

3.3.12.1 Tributary Description

Lacey Creek is a 2955-acre watershed tributary to the East Branch DuPage River. Communities contributing watershed area to Lacey Creek are primarily Downers Grove and Unincorporated DuPage County, but a very small portion of Oak Brook contributes on the very eastern edge of the watershed. The land use for Lacey Creek is extremely diverse. The northeastern and western sections of the watershed are open areas consisting of golf courses, forest preserves and the Morton Arboretum. The south-central section is comprised of residential subdivisions and commercial enterprises. And the north-central section of the Lacey Creek watershed includes large highway junctions of Butterfield Road, I-355 and I-88.

The Lacey Creek main stem has its origins at Fairview Avenue in Downers Grove, just east of Williams College. Flow proceeds to the west, passing through the Williams College campus, Lyman Woods Forest Preserve, and Highland Avenue. On the west side of Highland Avenue, Lacey Creek enters a single-family residential area and passes under such roads as Barneswood Drive, Saratoga Avenue, Venard Drive, Downers Drive, and Finley Road. The creek enters a conduit that passes under the I-88 / I-355 corridor, opening up on the west side in the Morton Arboretum. Lacey Creek passes from the Arboretum into the Hidden Lake Forest Preserve. Lacey Creek confluences with the East Branch DuPage River within the Hidden Lake Forest Preserve.

3.3.12.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Lacey Creek.

Discharge-frequency data for the mouth of Lacey Creekwere developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC-1 rainfall- runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the HEC-1 model of the DuPage River Basin to determine the 10-year, 50- year, and 100-year peak discharges (U.S. Department of Commerce, 1963).

Section printed 29 April 2004

Discharges for the 10-year, 50-year, and 100-year floods for Lacey Creek, studied by the limited detail method were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Much of Lacey Creek was determined by linear extrapolation of a log- probability graph of flood discharges computed for frequencies up to 100 years. Peak discharges for the upstream reaches of Lacey Creek were obtained by applying the square root of the drainage area ratio method to discharge values obtained from the HEC-1 computer model. This method consists of calculating upstream discharges from a known downstream station by multiplying the discharge values from that downstream station by the square root of the ratio of the drainage area of the upstream station in question to the drainage area of the downstream station.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBLA.1.

Table EBLA.1: Lacey Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Lacey Creek - at mouth 4.80 450 720 860 1,180

3.3.12.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater

Section printed 29 April 2004

computer program (USACE, HEC-2 Water-Surface Profiles, 1976). Water-surface profiles for Lacey Creek were developed using the USACE HEC-2 step-backwater computer model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973).

Roughness coefficients (Manning’s “n”) for Lacey Creek were estimated by field inspection at the various cross sections.

Table EBLA.2: Lacey Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Lacey Creek 0.040 - 0.060 0.040 - 0.080

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.12.4 Flood Boundaries

To reference the flood boundaries for Lacey Creek, see Map Panels: 0509, 0607, 0608, 0803, 0901 and 0902.

3.3.12.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.12.6 Flood Profiles

Please reference attached Flood Profile Sheets

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Lacey Creek (EBLA) EBLA0001 686 1 285 3 873 1.0 676.7 676.0 2 676.1 0.1 EBLA0002 2,483 1 185 623 1.4 677.0 677.0 677.1 0.1 EBLA0003 4,382 1 285 3 1,597 0.5 680.5 680.5 680.6 0.1 EBLA0004 4,804 1 700 3 956 0.9 680.7 680.7 680.8 0.1 EBLA0005 5,068 1 445 3 584 1.5 681.7 681.7 681.8 0.1 EBLA0006 6,109 1 450 465 1.9 683.5 683.5 683.6 0.1 EBLA0007 7,579 1 280 582 1.5 689.2 689.2 689.3 0.1 EBLA0008 8,760 1 215 1,641 0.4 691.5 691.5 691.5 0.0 EBLA0009 9,217 1 90 638 1.1 691.9 691.9 691.9 0.0 EBLA0010 10,165 1 60 135 5.1 692.0 692.0 692.0 0.0 EBLA0011 10,894 1 70 427 1.6 695.1 695.1 695.1 0.0 EBLA0012 11,989 1 85 439 1.6 696.5 696.5 696.5 0.0 EBLA0013 12,972 1 210 1,477 0.5 696.7 696.7 696.7 0.0 EBLA0014 14,000 1 1,020 3,412 0.2 696.8 696.8 696.8 0.0 EBLA0015 15,166 1 675 4,703 0.1 696.8 696.8 696.8 0.0 EBLA0016 16,831 1 125 540 1.0 697.2 697.2 697.3 0.1 EBLA0017 17,362 1 100 381 1.4 698.1 698.1 698.2 0.1 EBLA0018 17,785 1 155 373 1.4 699.0 699.0 699.1 0.1

1 In feet above confluence with East Branch DuPage River

2 Elevation computed without consideration of backwater effects from East Branch DuPage River

1 In feet above confluence with East Branch DuPage River

2 Elevation computed without consideration of backwater effects from East Branch DuPage River

690 690

PRIVATE ROAD PRIVATE ROAD PRIVATE ROAD PRIVATE ROAD

685 685

LACEY CREEK (EBLA)

FLOOD PROFILES

680 CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 EBLA0005 EBLA0006 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

EBLA0001 EBLA0002 EBLA0003 EBLA0004

AND INCORPORATED AREAS

DUPAGE COUNTY, IL 655

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 58P 700 FINLEY ROAD 700

VENARD DRIVE

DOWNERS DRIVE

SARATOGA AVENUE

BARNESWOOD DRIVE

695 695

LACEY CREEK (EBLA)

FLOOD PROFILES 690 690

685 685

ELEVATION IN FEET (NGVD 29)

680 680

675 EBLA0012 EBLA0013 675 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

EBLA0007 EBLA0008 EBLA0009 EBLA0010 EBLA0011

AND INCORPORATED AREAS

DUPAGE COUNTY, IL 665

6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000 FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 59P 715 715

710 710

PRIVATE ROAD

HIGHLAND AVENUE

WILLIAMS COLLEGE

705 705

LACEY CREEK (EBLA)

FLOOD PROFILES 700 700

695 695

ELEVATION IN FEET (NGVD 29)

690 690

FAIRVIEW AVENUE

LIMIT OF DETAILED STUDY

685 EBLA0019 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

EBLA0014 EBLA0015 EBLA0016 EBLA0017 EBLA0018

AND INCORPORATED AREAS

DUPAGE COUNTY, IL 675 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 60P

3.3.13 Prentiss Creek (EBPR)

3.3.13.1 Tributary Description

Prentiss Creek is tributary to the East Branch DuPage River, joining the river in Woodridge at the Seven Bridges Golf Course. The Prentiss Creek watershed area, shared by the communities of Woodridge, Downers Grove, Lisle, Darien and Unincorporated DuPage County, totals 4507 acres. Much of Prentiss Creek watershed has a land use of suburban residential and commercial.

The main stem of Prentiss Creek begins in Downers Grove in the residential area just east of Dunham Road. The main stem proceeds to the west primarily, passing through Dunham Road, Ruth Power’s Park, Springside Avenue, and Prentiss Avenue. A couple hundred feet downstream of Prentiss Avenue, the main stem is joined with the first Prentiss Creek branch traveling from the northeastern reaches of the watershed. The main stem continues to the west passing under Woodward Avenue, Puffer Road, I-355 (which is not included in the current FEMA FIS model), a few private roads, 63rd Street, Hobson Road, and a weir near 63rd Street. Shortly after this weir, the main stem joins the second Prentiss Creek Branch that drains the northern part of the watershed. The main stem proceeds to the west, sandwiched between subdivisions until it crosses under Route 53. After passing a few gabion weirs, Prentiss Creek main stem joins the East Branch DuPage River.

The first branch, which drains the northeastern section of the watershed, begins in the Village of Downers Grove upstream of Springside Avenue. The branch proceeds to the west, on an intersecting course with the main stem, through such streets as Wells Drive, Priden Drive and Loomis Drive.

The second, much smaller branch drains the north-central portions of the Prentiss watershed. The branch begins at the Meadows School in Woodridge and proceeds south through 59th Street. A mile beyond 59th Street, the second branch joins main stem Prentiss Creek.

3.3.13.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Prentiss Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Prentiss Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973).

Section printed 29 April 2004

The USGS stream gages used for the hydrologic analyses for the streams studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented below:

Table EBPR.1: USGS Stream Gages Used for Hydrologic Analysis of the Prentiss Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Prentiss Creek near Lisle 05540240 6.48 15

The results of the hydrologic analyses were submitted to the Illinois State Water Survey for review. The 100-year flood discharges computed for the streams studied in detail and the streams studied by limited detail in the unincorporated areas of DuPage County were approved by the SWS and were certified by the DWR.

The discharges for Prentiss Creek were derived from a regional frequency analysis using two Illinois Division of Water Resources stage recording gages located on the East Branch DuPage River, and five damage index stations used in the above Chicago Metro Study. Of these damage index stations, three were located along St. Joseph Creek, and one each along the East Branch DuPage River and Armitage Ditch. The analysis of the two Division of Water Resources gages, no. D W-C-3 at Naperville in Will County and No. D W-C-4 near Lisle in DuPage County, with individual recording periods of 14 and 15 years, respectively, followed the standard log-Pearson Type III method as outlined by the Water Resources Council (U.S. Water Resources Council, 1967). For the damage index stations, synthetic frequency-discharge curves were derived using regionalized statistics developed in the Chicago Metro Study. Flood peak discharges were obtained from regional drainage area-peak discharge curves computed from the results of the above gage and station analyses. Discharges for the 500-year floods were determined by straight-line extrapolation of a log-probability curve of flood discharges computed for frequencies up to 100 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBPR.2.

Table EBPR.2: Prentiss Creek Summary of Discharges

Section printed 29 April 2004

Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Prentiss Creek - at mouth 6.60 540 850 1,020 1,410 - at 63rd Street Bridge 3.97 420 665 795 1,100

3.3.13.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface profiles of Prentiss Creek were computed through use of the USACE’s HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973). Profiles were determined for the 10-, 50-, 100-, and 500-year floods.

Starting elevations at the downstream corporate limits for Prentiss Creek were determined from profiles of these streams computed for the FIS of the unincorporated areas of DuPage County (FEMA, 1982).

Roughness coefficients (Manning’s “n”) for Prentiss Creek were estimated from field inspection at cross-section locations, and from model calibration based on high water marks. Refer to Table EBPR.3 for further information.

Table EBPR.3: Prentiss Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Prentiss Creek 0.045 - 0.050 0.070 - 0.100

Section printed 29 April 2004

unobstructed and if channel and overbank conditions remain essentially the same as ascertained during this study.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.13.4 Flood Boundaries

To reference the flood boundaries for Prentiss Creek, see Map Panels: 0803, 0805, 0806, 0809, 0904, 0905, 0907 and 0908.

3.3.13.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.13.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above East Branch DuPage River

CONFLUENCE WITH

EAST BRANCH DUPAGE RIVER

665 665

FLOOD PROFILES

PRENTISS CREEK (EBPR)

HOBSON ROAD 660 660

655 655

ELEVATION IN FEET (NGVD 29)

650 650

CULVERTS

645 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 635 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 61P 690 690

685 685

680 STATE ROUTE 53 680

675 675

FLOOD PROFILES

PRENTISS CREEK (EBPR)

670 670

665 665

ELEVATION IN FEET (NGVD 29)

660 660

655 655 LEGEND 500-YEAR FLOOD CULVERT 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBPR0001 CROSS SECTION LOCATION 645 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 62P 725 725

720 720

HOBSON ROAD 715 PRIVATE DRIVE 715

710 710

FLOOD PROFILES

PRENTISS CREEK (EBPR)

705 705

PUFFER ROAD 700 700

ELEVATION IN FEET (NGVD 29)

695 695

EBPR0005 690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBPR0002 EBPR0003 EBPR0004 CROSS SECTION LOCATION 680 12000 12500 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 63P 745 745

740 PRENTISS DRIVE 740

WOODWARE AVENUE SPRINGSIDE AVENUE

735 735

FLOOD PROFILES

PRENTISS CREEK (EBPR)

730 DUNHAM ROAD 730

725 725

ELEVATION IN FEET (NGVD 29)

720 720

EBPR0010 EBPR0011 715 715 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBPR0006 EBPR0007 EBPR0008 EBPR0009 CROSS SECTION LOCATION 705 17500 18000 18500 19000 19500 20000 20500 21000 21500 22000 22500 23000 23500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 64P

3.3.14 Rott Creek (EBRC)

3.3.14.1 Tributary Description

Rott Creek is a 3832-acre watershed that is tributary to the East Branch DuPage River. The communities that contribute watershed area to Rott Creek are: Naperville, Lisle, Wheaton and Unincorporated DuPage County. Rott Creek is located in the central section of DuPage County, and has varied land use characteristics. The headwater portion of Rott Creek shares equal land uses between undeveloped and residentially developed areas. The central section of the watershed has experienced booming growth with large commercial ventures such as Lucent Technologies and numerous hotels. The southern section of the watershed changes land use between high and low density residential, but as the watershed nears the East Branch River the land use changes to light commercial and park land.

Rott Creek is a relatively long, single-branched tributary. The headwaters of Rott Creek can be found in Herrick Lake Forest Preserve. As Rott Creek proceeds to the south, it encounters newly developed sites upstream of Warrenville and Naperville Roads (Lucent Technologies). The creek passes east under Naperville Road and enters a series of detention ponds. Rott Creek turns to the south, passing under Warrenville Road, I-88, Old Tavern Road, Ogden Avenue, and Wellington Avenue. Rott Creek turn abruptly to the east and continues to pass under Keller Street, Beaubien Boulevard, Arlington Avenue, the Burlington Northern Railroad, Yackley Avenue, and Varsity Drive before confluencing with the East Branch DuPage River at the Lisle Community Park.

3.3.14.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Rott Creek.

For Rott Creek, synthetic frequency-discharge curves were derived for three stations used in the Chicago Metropolitan study using regionalized statistics developed in that study and assuming zero skew. Discharges for the 500-year floods of all streams were determined by linear extrapolation of a log-probability graph plotted for calculated peak discharges.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBRC.1.

Table EBRC.1: Rott Creek Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Rott Creek - at mouth 5.06 405 640 745 1,025 - at Yackley Avenue 4.94 395 620 725 995 - below Old Tavern Rd 3.91 275 430 505 695 - below I-88 3.44 188 269 306 382

3.3.14.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface elevations of floods of the selected recurrence intervals were computed through use of the COE HEC-2 step-backwater computer model. Starting water-surface elevations for Rott Creek were determined using the slope/area method.

For the areas studied by approximate methods, 100-year flood water- surface elevations were determined by solving Manning’s equation for depth of flow in the channel. These streams were field surveyed to obtain typical stream cross-sections, average stream channel slope, and Manning’s “n” values.

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.14.4 Flood Boundaries

Section printed 29 April 2004

To reference the flood boundaries for Rott Creek, see Map Panels: 0409, 0507, 0508, 0703, 0801, 0802 and 0805.

3.3.14.5 Floodways

No floodway was delineated on Rott Creek above the East-West Tollway, as the recent channel improvements in this area contain the 100-year flood.

Please reference attached Floodway Data Tables for further information.

3.3.14.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Rott Creek (EBRC) EBRC0001 1,731 1 256 158 4.7 664.5 658.9 2 659.0 2 0.1 EBRC0002 2,505 1 108 305 2.4 668.4 668.4 668.4 0.0 EBRC0003 3,206 1 47 135 5.5 670.0 670.0 670.1 0.1 EBRC0004 4,108 1 44 121 6.0 675.5 675.5 675.5 0.0 EBRC0005 4,330 1 37 124 5.8 677.1 677.1 677.1 0.0 EBRC0006 6,390 1 59 151 4.8 687.2 687.2 687.3 0.1 EBRC0007 7,204 1 65 185 3.9 692.1 692.1 692.2 0.1 EBRC0008 7,743 1 94 249 2.9 694.2 694.2 694.3 0.1 EBRC0009 11,200 1 195 513 1.4 711.4 711.4 711.5 0.1 EBRC0010 12,215 1 50 133 5.4 717.7 717.7 717.7 0.0 EBRC0011 12,425 1 154 425 1.7 720.8 720.8 720.8 0.0 EBRC0012 13,190 1 120 333 2.2 722.2 722.2 722.3 0.1 EBRC0013 13,407 1 120 399 1.8 722.5 722.5 722.6 0.1 EBRC0014 13,978 1 83 245 2.1 722.8 722.8 722.8 0.0 EBRC0015 14,215 1 186 585 0.9 724.6 724.6 724.6 0.0 EBRC0016 14,465 1 278 1,205 0.4 724.6 724.6 724.6 0.0 EBRC0017 15,498 1 354 1,068 0.5 724.6 724.6 724.6 0.0 EBRC0018 16,162 1 195 532 0.9 724.7 724.7 724.7 0.0

1 In feet above confluence with East Branch DuPage River

2 Elevations computed without consideration of backwater effects from East Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ROTT CREEK (EBRC) 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

710 710

700 700

PRIVATE DRIVE VARSITY DRIVE

YACKLEY AVENUE

690 690

ROTT CREEK (EBRC)

FLOOD PROFILES

680 CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 680

RAILROAD 670 670 CULVERT

CULVERT

ELEVATION IN FEET (NGVD 29)

660 660

650 EBRC0006 650

YACKLEY AVENUE LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

AND INCORPORATED AREAS

EBRC0001 EBRC0002 EBRC0003 EBRC0004 EBRC0005

DUPAGE COUNTY, IL 630 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 65P 730 FOOTBRIDGE 730

KELLER STREET OGDEN AVENUE

BEAU BIEN ROAD FENDER AVENUE FENDER AVENUE

BURLINGTON AVENUE BURLINGTON AVENUE

720 720

ROTT CREEK (EBRC)

FLOOD PROFILES 710 710

700 700

ELEVATION IN FEET (NGVD 29)

690 690

680 EBRC0010 EBRC0011 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

AND INCORPORATED AREAS

EBRC0007 EBRC0008 EBRC0009

DUPAGE COUNTY, IL 660 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 66P FOOT BRIDGE

OLD TAVERN ROAD

EAST-WEST TOLLWAY (I-88)

ROTT CREEK (EBRC)

FLOOD PROFILES 740 740

730 730

ELEVATION IN FEET (NGVD 29) CULVERT 720 720

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

AND INCORPORATED AREAS

EBRC0012 EBRC0013 EBRC0014 EBRC0015 EBRC0016 EBRC0017 EBRC0018

DUPAGE COUNTY, IL 690

13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 67P PRIVATE ROAD

NAPERVILLE ROAD

WARRENVILLE ROAD

LIMIT OF DETAILED STUDY

ROTT CREEK (EBRC)

FLOOD PROFILES 740 740

730 730

ELEVATION IN FEET (NGVD 29)

720 720

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD STREAM BED

CROSS SECTION LOCATION

AND INCORPORATED AREAS

DUPAGE COUNTY, IL 690

18000 18500 19000 19500 20000 FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 68P

3.3.15 St. Joseph’s Creek (EBSJ)

3.3.15.1 Tributary Description

St. Joseph’s Creek is a 7203-acre watershed tributary to the East Branch DuPage River. The communities that contribute watershed area to the St. Joseph Creek watershed are: Lisle, Downers Grove, Westmont, Darien and Unincorporated DuPage County. This large watershed has a primary land use of suburban residential, but there are more open areas found in the upper reaches of the watershed, and along the I-355 corridor.

St. Joseph Creek is broken down into several segments: St. Joseph Creek (Main Stem), the St. Joseph Creek North Branch, St. Joseph Creek South Branch, St. Joseph Creek Tributary, St. Joseph Creek Tributary 1 (A), and St. Joseph Creek Tributary 2 (B). Each segment shall be described in detail.

St. Joseph Creek headwaters are found on the southeast corner of 63rd Street and Williams Street in the Village of Westmont. The Creek proceeds on a northwesterly course passing under such roads as Williams Street, 63rd Street, and 61st Street. St. Joseph changes bearing to the northeast passing under 60th Street and 59th Street. It is north of 59th Street that St. Joseph Creek enters Westmont’s Twin Lakes Park, and confluences with St. Joseph Tributary. St. Joseph Creek exits the park to the northwest, entering the Twin Lakes Golf Course and the King Arthur Court apartment complex detention system. The creek emerges on the west side of Cumnor Avenue, and runs parallel to 56th Street to Fairview Avenue. After passing under Fairview, St. Joseph Creek enters Patriot Park where the creek confluences with the St. Joseph Creek South Branch. The Main Stem continues to the north passing under 55th Street and enters a long conduit at Hill Street that passes underneath an elementary school and parking lot, which exits on the east side of Blodgett Avenue. Main Stem St. Joe enters another conduit at Blodgett Avenue that exits on the north side of Maple Avenue. The Main Stem confluences with St. Joseph Creek North Branch and enters a 16-ft diameter conduit that passes underneath the Downers Grove business district. This large conduit exits on the west side of Carpenter Street. The Main Stem continues to the west through less dense residential areas, passing under such roads as Brookbank Road and Jacqueline Drive before entering the Maple Grove Forest Preserve. Upon exiting the Forest Preserve, St. Joe passes under Lee Avenue, Belmont Road, Curtiss Avenue and Walnut Avenue. After passing by the Downers Grove Wastewater Treatment Plant, on the west side of Walnut Avenue, the Main Stem winds its way through relatively untouched terrain until it passes underneath I-355. The Main Stem confluences with St. Joseph Creek Tributary 2 (B), continues west for about one half mile, where it changes bearing to the northwest, passing

Section printed 29 April 2004

under the Burlington Northern Railroad, Ogden Avenue and Center Street. On the downstream side of Center Street, St. Joseph Creek confluences with the St. Joseph Creek Tributary 1 (A). The Main Stem continues to the west passing under Main Street (Lisle), Route 53 and Dumoulin Avenue. Just west of this location, St. Joseph Creek joins the East Branch DuPage River.

St. Joseph Creek Tributary 1 (A) begins in corporate ponds located on the north side of Warrenville Road. The branch flows south passing under Warrenville Road, entering another corporate pond area. Tributary 1 (A) exits the pond under Oldham Avenue, passes closely alongside some residential houses, flows under Buckley Avenue and the Middleton/Center intersection, on the downstream side of which the branch confluences with Main Stem St. Joseph Creek.

St. Joseph Creek Tributary 2 (B) begins in a relatively open area on the east side of I-355, south of Ogden Avenue. The branch flows to the southwest, passing underneath I-355 and the Burlington Northern Railroad, on the downstream side of which the branch confluences with Main Stem St. Joseph Creek.

St. Joseph Creek North Branch begins on the east side of Cumnor Road (north of the Burlington Northern Railroad tracks). The branch proceeds to the southwest passing under such roads as Florence Avenue, Hummer Park Drive, Fairview Avenue, Austin Street, Rogers Street, and Douglas Road. The branch passes under the Burlington Northern Railroad and on the downstream side confluences with the St. Joseph Creek Main Stem.

St. Joseph Creek South Branch begins in a depressional area on the south side of 59th Street, east of Middaugh Street in Downers Grove. The overall flow of the South Branch is to the northeast, passing under such roads as 59th Street, Brookbank Road, Carpenter Street, Main Street, Webster Street, Washington Street, Lyman Avenue and Fairmount Avenue. The South Branch then enters Patriot Park and confluences with St. Joseph Creek Main Stem.

St. Joseph Creek Tributary is a short branch that begins on the south side of 60th Street in a residential detention pond. The branch flows to the north, under 60th Street, into a residential/corporate pond. The branch continues north underneath 59th Street into Twin Lakes Park where it encounters the Main Stem of St. Joseph Creek.

3.3.15.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for St. Joseph’s Creek.

Section printed 29 April 2004

Discharges for the 10-year, 50-year, and 100-year floods for St. Joseph Creek studied by the limited detail method were computed using the log- Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses for the streams studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented below in Table EBSJ.1.

Table EBSJ.1: USGS Stream Gages Used for Hydrologic Analysis of St. Joseph’s Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

St. Joseph’s Creek at Lisle 05540200 11.80 15

Discharges for the 500-year flood for South Branch St. Joseph Creek were determined by linear extrapolation of a log-probability graph of flood discharges computed for frequencies up to 100 years.

For St. Joseph Creek, synthetic frequency-discharge curves were derived for three stations used in the Chicago Metropolitan study using regionalized statistics developed in that study and assuming zero skew. Discharges for the 10-, 50-, 100-, and 500-year floods on St. Joseph Creek in the Village of Westmont were derived by extrapolation of discharge- drainage area relationship for the creek in Downers Grove. Discharges for Tributaries 1, 2, and 3 in Lisle were derived from DWR multiple regression equations (State of Illinois, 1973).

The discharges for St. Joseph Creek Tributary were derived using the State Standard Method. Discharges for the 10- and 100-year floods were computed using regional equations for Illinois (U.S. Department of the Interior, 1974). Hydrologic and hydraulic analysis of the detention ponds on the stream showed that their effect on floods greater than or equal to the 10-year event is minimal. Therefore, no adjustments were applied to the discharges developed from the regional equations. Discharges for the 10- and 100-year floods were plotted on log-normal probability paper. The 50- and 500-year flood discharges were estimated by straight line interpolation and extrapolation, respectively. The 100-year discharges estimated for the two detailed study streams were sent to the SWS for

Section printed 29 April 2004

review. The discharges were approved by the SWS and certified by the DOWR. Data are located in a repository of flood-related data administered by the SWS.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBSJ.2.

Table EBSJ.2: St Joseph Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

St. Joseph Creek - North Branch - at confluence with St. Joseph Creek 2.05 250 395 465 650

St Joseph Creek - South Branch - at confluence with St. Joseph Creek 0.75 180 285 335 465

St Joseph Creek - Tributary - at confluence with St. Joseph Creek 0.30 54 87 101 140

St Joseph Creek - Tributary 1(a) - at mouth 0.50 125 195 230 320 - above Warrenville Rd 0.20 55 90 105 145

St Joseph Creek - Tributary 2(b) - at Burlington Northern Railroad 0.47 145 230 275 385 - at Ogden Avenue 0.19 90 145 175 245

St. Joseph Creek - at mouth 11.80 730 1,160 1,365 1,900 - at Main Street 11.10 710 1,125 1,320 1,830 - at Burlington Northern Railroad 10.40 690 1,090 1,290 1,770 - d/s of Maple Avenue 3.28 405 645 760 1,055 - at Cumnor Avenue 1.65 290 460 540 750 - at 63rd Street 0.80 205 330 390 515 - d/s of 55th Street 2.83 155 250 295 405

Section printed 29 April 2004

3.3.15.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface profiles for North Branch St. Joseph Creek and South Branch St. Joseph Creek were developed using the USACE HEC-2 step- backwater computer model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973).

For North Branch and South Branch of St. Joseph Creek, starting elevations were determined from concurrent flowlines with the main stem.

Roughness coefficients (Manning’s “n”) for North Branch St. Joseph Creek and South Branch St. Joseph Creek were estimated by field inspection at the various cross sections.

Cross sections for St. Joseph Creek, Tributary 1 (A) and Tributary 2 (B) were field surveyed. For St. Joseph Creek, the below water sections were obtained by field measurement and the overbank sections were obtained from aerial photographs (Northeastern Illinois Planning Commission, 1975). In all cases, cross sections were located at close intervals above and below bridges and culverts in order to compute the significant backwater effects of these structures.

Water-surface elevations of floods of the selected recurrence intervals were computed for St. Joseph Creek, Tributary 1 (A) and Tributary 2 (B) through use of the USACE HEC-2 step-backwater computer model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6- L202A, 1973).

Starting water-surface elevations for St. Joseph Creek were calculated using the slope/area method.

Section printed 29 April 2004

Roughness coefficients for St. Joseph Creek, Tributary 1 (A) and Tributary 2 (B) were estimated by field inspection of the streams and floodplains.

Cross-section data for St. Joseph Creek Tributary were obtained from field measurements.

Hydraulic analyses for the St. Joseph Creek Tributary were made using the backwater program WSP-2 of the U.S. Department of Agriculture, Soil Conservation Service (SCS) (U.S. Department of Agriculture, 1976). Mathematical relationships used in the model include the standard step method for backwater computations which estimates total energy at each cross section and accounts for friction losses between sections using Manning’s formula. The model requires discharge, cross-section geometry, bridge geometry, starting water-surface elevations, and roughness data to simulate flood flow conditions.

The starting water-surface elevations for St. Joseph Creek Tributary are the water-surface elevations on St. Joseph Creek at the confluence of the two streams.

Roughness coefficients (Manning’s “n”) for St. Joseph Creek were estimated from field inspection at cross-section locations, and from model calibration based on high water marks. Refer to Table EBSJ.3 for further details.

Table EBSJ.3: St. Joseph Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

St. Joseph Creek - North Branch 0.035 0.070 St. Joseph Creek - South Branch 0.035 0.060 St. Joseph Creek 0.028 - 0.038 0.035 - 0.050 St. Joseph Creek Tributary 0.028 - 0.038 0.035 - 0.050 Tributary 1 (A) 0.035 - 0.040 0.060 - 0.080 Tributary 2 (B) 0.035 - 0.040 0.060 - 0.080

Section printed 29 April 2004

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.15.4 Flood Boundaries

To reference the flood boundaries for St. Joseph Creek, see Map Panels: 0608, 0802, 0803, 0806, 0901, 0902, 0904 and 0905.

3.3.15.5 Floodways

The St. Joseph Creek floodway was determined using the HUD-15 computer program.

Please reference attached Floodway Data Tables for further information.

3.3.15.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) St. Joseph Creek (EBSJ) EBSJ0001 897 1 80 441 3.1 668.6 667.8 2 667.9 0.1 EBSJ0002 1,256 1 167 623 2.2 669.2 669.2 669.2 0.0 EBSJ0003 1,419 1 114 390 3.5 669.2 669.2 669.2 0.0 EBSJ0004 1,736 1 114 435 3.1 669.6 669.6 669.6 0.0 EBSJ0005 2,142 1 54 398 3.4 670.0 670.0 670.0 0.0 EBSJ0006 3,173 1 47 558 2.4 671.0 671.0 671.1 0.1 EBSJ0007 3,537 1 83 376 3.5 671.0 671.0 671.0 EBSJ0008 3,960 1 64 387 3.4 671.6 671.6 671.7 0.1 EBSJ0009 4,488 1 120 479 2.8 673.7 673.7 673.8 0.1 EBSJ0010 5,016 1 149 4 452 2.9 674.1 674.1 674.2 0.1 EBSJ0011 5,334 1 47 181 7.3 674.4 674.4 674.4 0.0 EBSJ0012 5,492 1 152 4 1,050 1.3 675.6 675.6 675.6 0.0 EBSJ0013 5,702 1 103 4 595 2.2 676.4 676.4 676.5 0.1 EBSJ0014 6,547 1 127 479 2.7 676.5 676.5 676.6 0.1 EBSJ0015 6,969 1 47 267 4.8 676.7 676.7 676.8 0.1 EBSJ0016 7,920 1 69 332 3.9 678.4 678.4 678.5 0.1 EBSJ0017 8,923 1 70 375 3.4 680.0 680.0 680.1 0.1

1 In feet above confluence with East Branch DuPage River

2 Elevation considered without backwater effects from East Branch DuPage River

3 Floodway coincident with channel banks 4 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) St. Joseph Creek (EBSJ) EBSJ0018 9,291 1 52 329 3.9 680.5 680.5 680.6 0.1 EBSJ0019 10,021 1 50 310 4.2 681.5 681.5 681.5 0.0 EBSJ0020 10,400 1 50 310 4.2 681.9 681.9 681.9 0.0 EBSJ0021 12,159 1 50 450 2.9 684.0 684.0 684.0 0.0 EBSJ0022 12,828 1 40 1,113 1.2 688.0 688.0 688.1 0.1 EBSJ0023 14,159 1 60 464 2.7 690.8 690.8 690.9 0.1 EBSJ0024 15,054 1 170 446 2.8 692.7 692.7 692.8 0.1 EBSJ0025 16,016 1 148 745 1.7 694.7 694.7 694.8 0.1 EBSJ0026 18,304 1 85 844 1.5 696.8 696.8 696.9 0.1 EBSJ0027 19,142 1 105 876 1.4 697.4 697.4 697.5 0.1 EBSJ0028 19,834 1 140 730 1.7 697.9 697.9 698.0 0.1 EBSJ0029 20,362 1 190 1,017 1.2 698.4 698.4 698.5 0.1 EBSJ0030 21,589 1 110 504 2.5 699.7 699.7 699.8 0.1 EBSJ0031 22,223 1 105 239 5.2 700.2 700.2 700.3 0.1 EBSJ0032 22,440 1 45 718 1.7 701.3 701.3 701.4 0.1 EBSJ0035 27,625 1 3 89 3.3 709.8 709.8 709.8 0.0 EBSJ0036 27,998 1 3 98 3.0 710.1 710.1 710.1 0.0

1 In feet above confluence with East Branch DuPage River

2 Elevation considered without backwater effects from East Branch DuPage River

3 Floodway coincident with channel banks 4 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) St. Joseph Creek (EBSJ) EBSJ0037 28,689 1 3 93 3.2 715.0 715.0 715.0 0.0 EBSJ0038 29,581 1 51 228 1.3 715.3 715.3 715.4 0.1 EBSJ0039 30,741 1 146 342 1.9 718.1 718.1 718.2 0.1 EBSJ0040 31,582 1 118 352 1.9 719.5 719.5 719.6 0.1 EBSJ0041 32,253 1 98 298 2.2 719.8 719.8 719.9 0.1 EBSJ0042 33,189 1 83 564 1.2 721.0 721.0 721.1 0.1 EBSJ0043 35,047 1 301 1,435 0.4 726.1 726.1 726.2 0.1 EBSJ0044 35,772 1 170 198 2.5 727.6 727.6 727.7 0.1 EBSJ0045 36,474 1 124 361 1.3 730.6 730.6 730.7 0.1 EBSJ0046 38,687 1 53 185 2.2 734.1 734.1 734.2 0.1

1 In feet above confluence with East Branch DuPage River

2 Elevation considered without backwater effects from East Branch DuPage River

3 Floodway coincident with channel banks 4 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Tributary 1 (A) (EBSJ) EBSJ0047 97 1 7 22 10.2 670.8 670.5 2 670.5 0.0 EBSJ0048 265 1 89 145 1.6 674.3 674.3 674.3 0.0 EBSJ0049 355 1 13 33 7.1 675.3 675.3 675.3 0.0 EBSJ0050 476 1 15 264 0.9 678.6 678.6 678.6 0.0 EBSJ0051 775 1 15 29 7.9 679.6 679.6 679.6 0.0 EBSJ0052 1,227 1 65 122 1.9 682.5 682.5 682.5 0.0 EBSJ0053 1,484 1 59 217 1.1 684.3 684.3 684.3 0.0 EBSJ0054 2,139 1 51 65 3.5 689.5 689.5 689.5 0.0 EBSJ0055 2,566 1 180 3 512 0.4 696.1 696.1 696.2 0.1 EBSJ0056 3,156 1 88 32 3.3 699.4 699.4 699.5 0.1 EBSJ0057 4,030 1 210 3 65 1.6 710.8 710.8 710.8 0.0 EBSJ0058 5,302 1 50 29 3.6 728.1 728.1 728.1 0.0

1 In feet above confluence with St. Joseph Creek

2 Elevation computed without consideration of backwater effects from St. Joseph Creek

3 Actual floodway width cannot be shown on the FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS TRIBUTARY 1 (A) (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Tributary 2 (B) (EBSJ) EBSJ0059 195 1 65 530 0.5 685.2 685.2 685.3 0.1 EBSJ0060 935 1 70 321 0.9 685.2 685.2 685.3 0.1 EBSJ0061 1,662 1 104 2 186 1.5 685.4 685.4 685.5 0.1 EBSJ0062 1,780 1 75 2 68 4.1 687.3 687.3 687.4 0.1 EBSJ0063 2,012 1 13 31 9.0 695.0 695.0 695.0 0.0 EBSJ0064 2,158 1 25 66 4.2 697.2 697.2 697.2 0.0 EBSJ0065 2,421 1 19 50 5.5 699.8 699.8 699.8 0.0

1 In feet above confluence with St. Joseph Creek

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain. TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS TRIBUTARY 2 (B) (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) North Branch St. Joseph Creek (EBSJ) EBSJ0066 264 1 23 95 4.9 713.1 713.1 713.2 0.1 EBSJ0067 898 1 21 69 6.7 715.6 715.6 715.6 0.0 EBSJ0068 1,636 1 60 232 2.0 721.9 721.9 721.9 0.0 EBSJ0069 2,265 1 121 267 1.7 722.3 722.3 722.3 0.0 EBSJ0070 2,497 1 224 437 1.1 722.5 722.5 722.6 0.1 EBSJ0071 2,957 1 139 353 1.3 723.2 723.2 723.3 0.1 EBSJ0072 3,432 1 27 76 6.1 723.9 723.9 724.0 0.1 EBSJ0073 3,749 1 100 2 832 0.6 725.9 725.9 725.9 0.0

1 In Feet above confluence with St. Joseph Creek

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS NORTH BRANCH ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) South Branch St. Joseph Creek (EBSJ) EBSJ0074 211 1 288 1,528 0.2 718.2 2 718.2 718.3 0.1 EBSJ0075 581 1 438 2,294 0.2 718.2 2 718.2 718.3 0.1 EBSJ0076 986 1 177 1,080 0.3 718.2 2 718.2 718.3 0.1 EBSJ0077 1,320 1 231 924 0.4 718.3 718.3 718.4 0.1 EBSJ0078 1,465 1 305 1,441 0.2 718.3 718.3 718.4 0.1 EBSJ0079 1,810 1 139 265 1.3 718.9 718.9 719.0 0.1 EBSJ0080 2,474 1 80 147 2.3 723.8 723.8 723.8 0.0 EBSJ0081 3,050 1 39 52 6.4 726.9 726.9 726.9 0.0 EBSJ0082 3,684 1 121 119 2.8 731.3 731.3 731.4 0.1 EBSJ0083 4,328 1 88 296 1.1 739.2 739.2 739.3 0.1 EBSJ0084 4,380 1 93 199 1.7 739.3 739.3 739.4 0.1 EBSJ0085 4,481 1 87 317 1.0 739.4 739.4 739.5 0.1 EBSJ0086 5,016 1 43 108 3.1 743.4 743.4 743.5 0.1 EBSJ0087 5,069 1 64 142 2.4 744.0 744.0 744.1 0.1 EBSJ0088 5,122 1 84 194 1.7 744.4 744.4 744.5 0.1 EBSJ0089 5,388 1 102 209 1.6 745.7 745.7 745.8 0.1 EBSJ0090 6,766 1 100 969 0.3 747.8 747.8 747.9 0.1

1 In feet above confluence with St. Joseph Creek

2 Backwater from St. Joseph Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SOUTH BRANCH ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) South Branch St. Joseph Creek (EBSJ) EBSJ0091 7,117 1 204 330 1.0 747.8 747.8 747.9 0.1 EBSJ0092 7,595 1 179 416 0.8 748.0 748.0 748.1 0.1

1 In feet above confluence with St. Joseph Creek

2 Backwater from St. Joseph Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SOUTH BRANCH ST. JOSEPH CREEK (EBSJ) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) St. Joseph Creek Tributary (EBSJ) EBSJ0093 744 1 39 52 1.9 728.4 728.4 728.5 0.1 EBSJ0094 2,804 1 51 44 1.3 731.3 731.3 731.4 0.1

1 In feet above confluence with St. Joseph Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS ST. JOSEPH CREEK TRIBUTARY (EBSJ) 690 690 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

685 685

MAIN STREET

OGDEN AVENUE

CENTER STREET

LINCOLN AVENUE

680 (U.S. HIGHWAY 34) 680

DUMOULIN AVENUE

(STATE HIGHWAY 53)

CONFLUENCE OF TRIBUTARY 1 (A)

675 675

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER

FLOOD PROFILES

CULVERT ST. JOSEPH CREEK (EBSJ) 670 670

RAILROAD 665 665

ELEVATION IN FEET (NGVD 29)

660 660

EBSJ0010 EBSJ0011 EBSJ0012 EBSJ0013 655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0001 EBSJ0002 EBSJ0003 EBSJ0004 EBSJ0005 EBSJ0006 EBSJ0007 EBSJ0008 EBSJ0009 CROSS SECTION LOCATION 645 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 69P 695 695

690 WALNUT AVENUE 690

CONFLUENCE OF TRIBUTARY 2 (B)

685 685

FLOOD PROFILES

ST. JOSEPH CREEK (EBSJ)

680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 CURTISS STREET 670

EBSJ0021 EBSJ0022 665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0014 EBSJ0015 EBSJ0016 EBSJ0017 EBSJ0018 EBSJ0019 EBSJ0020 CROSS SECTION LOCATION 655 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 70P LEE AVENUE

PRIVATE DRIVE

BELMONT ROAD

700 700

FLOOD PROFILES

ST. JOSEPH CREEK (EBSJ)

695 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

EBSJ0026 EBSJ0027 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0023 EBSJ0024 EBSJ0025 CROSS SECTION LOCATION 670 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 71P JACQUELINE DRIVE 705 BROOKBANK ROAD 705

LIMIT OF DETAILED STUDY

700 700

FLOOD PROFILES

ST. JOSEPH CREEK (EBSJ)

695 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0028 EBSJ0029 EBSJ0030 EBSJ0031 EBSJ0032 CROSS SECTION LOCATION 670 19500 20000 20500 21000 21500 22000 22500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 72P 725 725

HILL STREET

55TH STREET

GRAND AVENUE

MAPLE AVENUE

GRAND AVENUE

MACKIE AVENUE CONFLUENCE OF

DEERPATH ROAD

FAIRVIEW AVENUE

720 BLODGETT AVENUE 720

LIMIT OF DETAILED STUDY

NORTH BRANCH ST. JOSEPH CREEK

715 715

CULVERT FLOOD PROFILES

CULVERT ST. JOSEPH CREEK (EBSJ)

710 710 CULVERT

CULVERT 705 705

ELEVATION IN FEET (NGVD 29)

700 700

BERM

EBSJ0040 EBSJ0041

695 CONFLUENCE OF 695 LEGEND 500-YEAR FLOOD

SOUTH BRANCH ST. JOSEPH CREEK 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0035 EBSJ0036 EBSJ0037 EBSJ0038 EBSJ0039 CROSS SECTION LOCATION 685 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 73P JAMES DRIVE

59TH STREET

CUMNOR ROAD 735 WILLIAM STREET 735

KING ARTHUR COURT CROSSING

57TH STREET/ WILLIAMS STREET

EASY ACRES GOLF COURSE CULVERT

730 CONFLUENCE OF ST. JOSPEH CREEK TRIBUTARY 730

FLOOD PROFILES

ST. JOSEPH CREEK (EBSJ)

725 725

720 720

ELEVATION IN FEET (NGVD 29) CULVERT CULVERT

715 715

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0042 EBSJ0043 EBSJ0044 EBSJ0045 CROSS SECTION LOCATION 700 32500 33000 33500 34000 34500 35000 35500 36000 36500 37000 37500 38000 38500 39000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 74P 61ST STREET

63RD STREET

LIMIT OF DETAILED STUDY

FLOOD PROFILES

ST. JOSEPH CREEK (EBSJ)

740 740

735 735

ELEVATION IN FEET (NGVD 29)

730 730

725 725 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 720 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0046 CROSS SECTION LOCATION 715 38000 38500 39000 39500 40000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 75P 700 700 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

695 695

FOOTBRIDGE FOOTBRIDGE

CENTER STREET 690 BUCKLEY AVENUE 690

MIDDLETON AVENUE

CONFLUENCE WITH ST. JOSEPH CREEK

685 685

FLOOD PROFILES

TRIBUTARY 1 (A) (EBSJ)

680 680

WARRENVILLE ROAD

675 675

ELEVATION IN FEET (NGVD 29)

670 670

EBSJ0054 EBSJ0055 665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0047 EBSJ0048 EBSJ0049 EBSJ0050 EBSJ0051 EBSJ0052 EBSJ0053 CROSS SECTION LOCATION 655 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 76P 720 720

715 715

710 710

THE 50- AND 500-YEAR PROFILES FLOOD PROFILES

ARE TOO CLOSE TO THE 100-YEAR TRIBUTARY 1 (A) (EBSJ) ELEVATIONS TO BE SHOWN SEPARATELY 705 705

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0056 EBSJ0057 CROSS SECTION LOCATION 680 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 77P LIMIT OF DETAILED STUDY

730 730

THE 50- AND 500-YEAR PROFILES FLOOD PROFILES ARE TOO CLOSE TO THE 100-YEAR TRIBUTARY 1 (A) (EBSJ) ELEVATIONS TO BE SHOWN SEPARATELY 725 725

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0058 CROSS SECTION LOCATION 700 4500 4700 4900 5100 5300 5500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 78P 705 705 100-YEAR BACKWATER FROM ST. JOSEPH CREEK

700 700

RAILROAD 695 695

690 690

CONFLUENCE WITH ST. JOSEPH CREEK

FLOOD PROFILES

TRIBUTARY 2 (B) (EBSJ)

FOOTBRIDGE 685 685

LIMIT OF DETAILED STUDY

680 680

ELEVATION IN FEET (NGVD 29)

675 675

EBSJ0063 EBSJ0064 EBSJ0065 670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0059 EBSJ0060 EBSJ0061 EBSJ0062 CROSS SECTION LOCATION 660 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 79P RAILROAD 730 730

ROGER STREET

DOUGLAS ROAD

AUSTIN STREET

WILCOX AVENUE

725 FAIRVIEW AVENUE 725

LIMIT OF DETAILED STUDY

CONFLUENCE WITH ST. JOSEPH CREEK

720 720

FLOOD PROFILES

CULVERT 715 715

THE 50-YEAR FLOOD PROFILE IS NORTH BRANCH ST. JOSEPH CREEK (EBSJ) TOO CLOSE TO THE 100-YEAR ELEVATION TO BE SHOWN SEPARATELY

CULVERT 710 CUMNOR ROAD 710

FLORENCE AVENUE

ELEVATION IN FEET (NGVD 29)

705 705 CONCRETE VERTICAL DROP INTO CULVERT UNDER RAILROAD

700 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0066 EBSJ0067 EBSJ0068 EBSJ0069 EBSJ0070 EBSJ0071 EBSJ0072 EBSJ0073 CROSS SECTION LOCATION 690 0 500 1000 1500 2000 2500 3000 3500 4000 4500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 80P 100-YEAR BACKWATER FROM ST. JOSEPH CREEK

735 735

730 LYMAN AVENUE 730

FAIRMOUNT AVENUE

WASHINGTON STREET

CONFLUENCE WITH ST. JOSEPH CREEK

725 725

FLOOD PROFILES

720 WEBSTER STREET 720

THE 50-YEAR PROFILE IS TOO CLOSE SOUTH BRANCH ST. JOSEPH CREEK (EBSJ) TO THE 100-YEAR ELEVATION TO BE SHOWN SEPARATELY

715 715

ELEVATION IN FEET (NGVD 29)

710 710

705 705 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD EBSJ0078 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0074 EBSJ0075 EBSJ0076 EBSJ0077 EBSJ0079 EBSJ0080 EBSJ0081 EBSJ0082 CROSS SECTION LOCATION 695 0 500 1000 1500 2000 2500 3000 3500 4000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 81P 59TH STREET

MAIN STREET

PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE PRIVATE DRIVE

MIDDAUGH ROAD

CARPENTER STREET

BROOKBANK AVENUE

LIMIT OF DETAILED STUDY

THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR ELEVATION TO BE SHOWN SEPARATELY 750 750

FLOOD PROFILES

745 745

SOUTH BRANCH ST. JOSEPH CREEK (EBSJ)

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 EBSJ0085 EBSJ0088 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD EBSJ0084 EBSJ0087 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0083 EBSJ0086 EBSJ0089 EBSJ0090 EBSJ0091 EBSJ0092 CROSS SECTION LOCATION 720 4000 4500 5000 5500 6000 6500 7000 7500 8000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 82P 61ST STREET

59TH STREET 60TH STREET

LIMIT OF DETAILED STUDY

CONFLUENCE WITH ST. JOSEPH CREEK

FLOOD PROFILES

735 735

ST. JOSEPH CREEK TRIBUTARY (EBSJ)

730 730 CULVERT

ELEVATION IN FEET (NGVD 29)

725 725

720 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBSJ0093 EBSJ0094 CROSS SECTION LOCATION 710 0 500 1000 1500 2000 2500 3000 3500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH ST. JOSEPH CREEK 83P

3.3.16 Swift Meadows (EBSM)

3.3.16.1 Tributary Description

Swift Meadows is a 600-acre watershed tributary to the East Branch DuPage River. The communities that contribute watershed area to this tributary are Bloomingdale, Addison and Unincorporated DuPage County. The land use of the tributary is commercial / industrial in the headwaters, open prairie in the central sections and low density residential near the confluence with the East Branch DuPage River.

Swift Meadows Main Stem begins within the Swift Meadows Forest Preserve, found on the north side of Army Trail Road, west of Walter Drive. The Main Stem flows to the southwest where it confluences with the Walter Drive West Ditch. The Main Stem flows to the south, passes underneath Army Trail Road, eventually confluencing with the East Branch DuPage River.

The Walter Drive West Ditch starts on the north side of Byron Avenue. The ditch passes under Byron, flows on the west side of Walter Avenue for on quarter mile where it confluences with the Swift Meadows Main Stem.

3.3.16.2 Hydrologic Analysis

3.3.16.3 Hydraulic Analysis

Section printed 29 April 2004

elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. For construction and/or floodplain management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM.

Cross-section data for East Branch DuPage River were obtained by field measurement.

The 100-year water-surface elevation on the East Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Since no formal study was completed on Swift Meadows Tributary, the East Branch DuPage River 100-yr elevation information, determined through the above methods, at the location of the junction between the East Branch DuPage River and Swift Meadows Tributary is used for backwater effects on Swift Meadows Tributary. In addition to the determined backwater zone information, the unnumbered A-zone boundary was further formed through local studies and the USGS Flood of Record Maps.

3.3.16.4 Flood Boundaries

To reference the flood boundaries for Swift Meadows Tributary, see Map Panels: 0206 and 0209.

3.3.16.5 Floodways

No floodway information is available.

3.3.16.6 Flood Profiles

No flood profile information is available.

Section printed 29 April 2004

3.3.17 22nd Street (EBTS)

3.3.17.1 Tributary Description

22nd Street Tributary is a 494-acre watershed tributary to the East Branch DuPage River. Lombard and Unincorporated DuPage County contribute watershed area to the 22nd Street Tributary. The overall land use of the watershed is highly urbanized with a large amount of impervious area.

22nd Street Tributary begins at Main Street, just north of 22nd Street in Downers Grove. The stream travels to the east passing under such roads as Finley Road, I-355, and twice under Foxworth Boulevard before confluencing with the East Branch DuPage River.

3.3.17.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for 22nd Street Tributary.

Discharges for the 10-year, 50-year, and 100-year floods for 22nd Street Tributary were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Frequency-discharge data for the 22nd Street Tributary were developed through the use of the SCS Urban Hydrology for Small Watersheds, Technical Release No. 55 (U.S. Department of Agriculture, 1975). This method was considered the most appropriate because the drainage areas were small, and the method accounted for the diversity and irregularity of the land use within the basin.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBTS.1.

Table EBTS.1: 22nd Street Tributary Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

22nd Street Tributary - at mouth 0.88 235 340 390 605 - at Finley Road 0.49 175 254 291 451

Section printed 29 April 2004

3.3.17.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface profiles for 22nd Street Tributary were developed using a HEC-2 computer step-backwater model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973). Profiles were determined for the 10-, 50-, 100-, and 500-year floods. Flood elevations for the 22nd Street Tributary may be raised by debris blockage of bridges or culverts.

Starting water-surface elevations 22nd Street Tributary were calculated using the slope/area method.

Roughness coefficients for 22nd Street Tributary were estimated by field inspection at the various cross section locations. Refer to EBTS.2 for further information.

Table EBTS.2: 22nd Street Tributary Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

22nd Street 0.045 - 0.080 0.050 - 0.070

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

Section printed 29 April 2004

3.3.17.4 Flood Boundaries

To reference the flood boundaries for 22nd Street Tributary, see Map Panels: 0506, 0509, 0604 and 0607.

3.3.17.5 Floodways

The floodway along the unnamed tributary north of 22nd Street was computed without consideration of backwater flooding near its mouth. Floodway surcharge elevations along the lower portion of the unnamed stream, therefore, are below rather than above the 100-year flood elevations as determined by backwater flooding.

Please reference attached Floodway Data Tables for further information.

3.3.17.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with East Branch DuPage River

710 710

705 705

700 700

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER THE 50-YEAR FLOOD PROFILE IS TO CLOSE TO THE 100-YEAR PROFILE FLOOD PROFILES TO BE SHOWN SEPARATELY 695 695

UNNAMED STREAM NORTH OF 22ND STREET (EBTS)

FINLEY ROAD 690 690

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

685 685

EBTS0008 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBTS0001 EBTS0002 EBTS0003 EBTS0004 EBTS0005 EBTS0006 EBTS0007 CROSS SECTION LOCATION 670 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 84P

3.3.18 Willoway Brook (EBWI)

3.3.18.1 Tributary Description

Willoway Brook, previously known as East Branch Tributary No.5, is a 2879-acre watershed that is tributary to the East Branch DuPage River. The communities that contribute watershed area to Willoway Brook are Wheaton, Glen Ellyn, Lisle and Unincorporated DuPage County. The land use characteristic in the headwaters of Wheaton and Glen Ellyn is largely dense residential and commercial. The central and southern, or downstreammost areas, are classified as less-dense residential and open prairie / forested.

Willoway Brook begins in the Danada section of Wheaton, on the north side of Butterfield Road, east of East Loop Road. Willoway Brook flows to the south, passing under Butterfield Road, and entering the Danada Forest Preserve. The brook flows into Rice Lake and must flow over a weir /culvert system to exit the lake. Downstream and to the south of Rice Lake, the stream passes under several roads; Robinwood Lane, North Arboretum Circle, Regency Woods Drive, Edgebrooke Drive and Pebble Creek Drive. The stream’s bearing turns to the east, passing under Leask Lane. On the east side of Leask Lane, Willoway Brook enters the Morton Arboretum Property. There are a few service roads and pedestrian bridges in this area, but the primary hydraulic features are the crossing under Main Route (West Side), Sterling Pond and its outlet, and Lake Marmo and outlet. Once through all these features, Willoway Brook winds its way through further marshes until it encounters the East Branch DuPage River.

3.3.18.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Willoway Brook.

Discharges for the 10-year, 50-year, and 100-year floods for Willoway Brook were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table EBWI.1.

Table EBWI.1: Willoway Brook Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Willoway Brook - at mouth 4.95 455 730 870 1,200

3.3.18.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The water-surface elevations for the streams studied in detail and limited detail, including Willoway Brook, were computed using either the SCS WSP-2 backwater computer program or the USACE HEC-2 step- backwater computer program (U.S. Department of Agriculture, 1974; USACE, HEC-2 Water-Surface Profiles, Computer Program723-X6- L202A, 1973).

Roughness coefficients for Willoway Brook were estimated by field inspection at the various cross section locations. Refer to Table EBWI.2 for further information.

Table EBWI.2: Willoway Brook Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Willoway Brook 0.035 - 0.040 0.060 - 0.080

Section printed 29 April 2004

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.3.18.4 Flood Boundaries

To reference the flood boundaries for Willoway Brook, see Map Panels: 0505, 0507, 0508, 0509 and 0802.

3.3.18.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.3.18.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with East Branch DuPage River

2 Data not available TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS EAST BRANCH TRIBUTARY NO. 5 (EBWI) 705 705 100-YEAR BACKWATER FROM EAST BRANCH DUPAGE RIVER

700 700

DAM DAM CULVERT

UNNAMED ROAD UNNAMED ROAD UNNAMED ROAD UNNAMED ROAD

695 ARBORETUM ROAD 695

690 690

CONFLUENCE WITH EAST BRANCH DUPAGE RIVER

FLOOD PROFILES

LEASK LANE 685 685

EAST BRANCH TRIBUTARY NO. 5 (EBWI)

680 LIMIT OF FLOODING 680

ELEVATION IN FEET (NGVD 29)

675 675

EBWI0005 670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBWI0001 EBWI0002 EBWI0003 EBWI0004 CROSS SECTION LOCATION 660 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 51P 725 725

720 PRIVATE ROAD PRIVATE ROAD 720

LIMIT OF FLOODWAY

REGENCY WOODS DRIVE

715 715

FLOOD PROFILES

710 710

EAST BRANCH TRIBUTARY NO. 5 (EBWI)

705 ROBINWOOD LANE 705

ELEVATION IN FEET (NGVD 29)

NORTH ARBORETUM CIRCLE

700 700

695 695 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBWI0006 EBWI0007 EBWI0008 EBWI0009 EBWI0010 EBWI0011 CROSS SECTION LOCATION 685 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 52P LIMIT OF DETAILED STUDY

FLOOD PROFILES

735 735

EAST BRANCH TRIBUTARY NO. 5 (EBWI)

THE 50-YEAR FLOOD PROFILE IS TOO CLOSE 730 TO THE 100-YEAR PROFILE TO BE 730 SHOWN SEPARATELY

ELEVATION IN FEET (NGVD 29)

725 725

720 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

EBWI0012 CROSS SECTION LOCATION 710 11500 12000 12500 13000 13500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH EAST BRANCH DUPAGE RIVER 53P

3.4 Fox River (FR)

3.4.1 Brewster Creek (FRBC)

3.4.1.1 Tributary Description

Brewster Creek watershed is tributary to the Fox River. The total DuPage County watershed area for Brewster Creek is 4483 acres. The DuPage County communities contributing to the Brewster Creek watershed area are: Bartlett, Wayne and Unincorporated DuPage County. The headwaters found within DuPage County are the only area of development within the watershed. The central and downstream most portions are virtually untouched in the Pratt Wayne Woods Forest Preserve.

Brewster Creek begins in the headwaters of Bartlett but are not in a particularly well-formed state until the waters pass from east to west under Route 59. Brewster Creek continues to the west through Pratt Wayne Woods Forest Preserve. Brewster Creek passes under Munger and Powis Roads while within the Forest Preserve, and exits the Forest Preserve and DuPage County simultaneously. Brewster Creek continues through Kane County and confluences with the Fox River in South Elgin.

3.4.1.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Brewster Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Brewster Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses for the streams studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented below in Table FRBC.1.

Table FRBC.1: USGS Stream Gages Used for Hydrologic Analysis of Brewster Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Section printed 29 April 2004

Brewster Creek at Valleyview 05551030 14.00 14

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table FRBC.2.

Table FRBC.2: Brewster Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Brewster Creek - at river mile 4.16 2.90 94 111 119 393

3.4.1.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The water-surface elevations for the streams studied in detail and limited detail, including Brewster Creek, were computed using either the SCS WSP-2 backwater computer program or the USACE HEC-2 step- backwater computer program (U.S. Department of Agriculture, 1974; USACE, HEC-2 Water-Surface Profiles, Computer Program723-X6- L202A, 1973).

Roughness coefficients for Brewster Creek were estimated by field inspection at the various cross section locations. Refer to table FRBC.3 for further details.

Table FRBC.3: Brewster Creek Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

Brewster Creek 0.035 0.060 - 0.070

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.4.1.4 Flood Boundaries

To reference the flood boundaries for Brewster Creek, see Map Panels: 0101, 0102, 0104 and 0105.

3.4.1.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.4.1.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS BREWSTER CREEK (FRBC) 795 795

790 790

785 MUNGER ROAD 785

LIMIT OF DETAILED STUDY

780 780

FLOOD PROFILES

BREWSTER CREEK (FRBC)

775 775

770 770

ELEVATION IN FEET (NGVD 29)

765 765

760 760 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 755 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRBC0001 FRBC0002 CROSS SECTION LOCATION 750 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000 26500 27000 27500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DU PAGE RIVER 85P STATE ROUTE 59

HIGH LEVEL BRIDGE

LIMIT OF DETAILED STUDY

FLOOD PROFILES

BREWSTER CREEK (FRBC)

790 790

785 785

ELEVATION IN FEET (NGVD 29)

780 780

775 775 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 770 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRBC0003 CROSS SECTION LOCATION 765 27500 28000 28500 29000 29500 30000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DU PAGE RIVER 86P

3.4.2 Indian Creek (FRIC)

3.4.2.1 Tributary Description

Indian Creek is tributary to the Fox River. Within the bounds of DuPage County, the total Indian Creek watershed area is 3303 acres. The DuPage County communities that contribute watershed area to Indian Creek are Aurora and Unincorporated DuPage County. The land use on Indian Creek in DuPage County is presently under rapid development for residential subdivisions and commercial enterprises.

Indian Creek is a rather large watershed that has its headwater regions in DuPage County. Indian Creek itself begins on the upstream side of Bilter Road. Indian Creek passes under Bilter, flows to the west and exits DuPage County before crossing I-88.

The other branches to Indian Creek are found in various locations. Two branches exit to the southwest from the Fermilab property. Two other branches drain the southern section of the watershed through older residential subdivisions. A final branch follows the south side ditch of I- 88 until confluencing with the Main Stem in Kane County. None of these branches within DuPage County, outside of the Main Stem, have been analyzed or modeled.

3.4.2.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Indian Creek.

The hydrologic modeling for Indian Creek was completed using the SCS computer program for project formulation (SCS, Technical Release No. 20, May 1965), a hydrologic model that simulates flood stages and discharges. The stages and discharges are related to watershed characteristics such as drainage area, hydrologic soil group, land use and cover, time of concentration, and channel and floodplain hydraulic characteristics. Given those characteristics and the rainfall amounts, the model will develop hydrographs for local drainage areas and perform a specified series of channel and reservoir routings, as well as hydrograph additions. The result is peak discharges, hydrograph shape, and runoff volumes at specified locations throughout the watershed.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table FRIC.1.

Table FRIC.1: Indian Creek Summary of Discharges

Section printed 29 April 2004

Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Indian Creek - at mouth 16.10 1,560 2,030 2,250 2,840 - at I-88 4.90 700 925 1,040 1,380

3.4.2.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The water-surface elevations for Indian Creek were established based on the physical characteristics of the channel including channel size and shape, floodplain size and shape, bridge sizes and shapes, and estimates of Manning’s roughness coefficients. The hydraulic computations were made using the SCS WSP-2 hydraulic model (SCS, Technical Release No. 61, May 1976). This model employs the standard step method for backwater profiles, which is a procedure that estimates total energy at each stream cross section accounting for friction losses between sections. The Bureau of Public Roads method was used to account for the bridge effects on stream hydraulics. The bridge method, which is included in WSP-2, was formulated using the principle of the conservation of energy.

Roughness coefficients for Indian Creek were estimated by field inspection at the various cross section locations. Refer to Table FRIC.2 for further details.

Table FRIC.2: Indian Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Indian Creek 0.040 - 0.055 0.060 - 0.120

Section printed 29 April 2004

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.4.2.4 Flood Boundaries

To reference the flood boundaries for Indian Creek, see Map Panels: 0404, 0407, 0701 and 0704.

3.4.2.5 Floodways

No floodway information is currently available.

3.4.2.6 Flood Profiles

No flood profiles are currently available.

Section printed 29 April 2004

3.4.3 Norton Creek (FRNC)

3.4.3.1 Tributary Description

Norton Creek is tributary to the Fox River. In DuPage County, 4195 acres are contributed by the communities of Wayne, Bartlett, St. Charles, West Chicago and Unincorporated DuPage County towards Norton Creek. The land use in Norton Creek is similar to that witnessed in Brewster Creek, with the exception that a larger amount of open space is agricultural in use and is slowly becoming developed.

There are four branches of Norton Creek in DuPage County. The first branch is the most northern of the branches. Branch one begins north of Army Trail Road, east of Munger Road. The stream passes under Munger Road and continues on a westerly course through the Pratt Wayne Woods Forest Preserve. Branch one turns the southwest, crosses the Illinois Prairie Path, exits the forest preserve, enters the Village of Wayne, crosses the Chicago and Northwestern Railroad, Rochefort Lane, Army Trail Road, Honey Hill Drive and exits DuPage County. Branch one intersects with the remaining Norton Creek branches within Kane County.

The second branch begins on the south side of Army Trail Road, east of Munger and somewhat adjacent to Ridge Lane. Branch two travels to the west, passing under Munger Road, and enters the Pratt Wayne Woods Forest Preserve. While in the forest preserve, Branch two takes a long serpentine course, passing under the Illinois Prairie Path. The branch continues out of the forest preserve on a northwest bearing, entering the Village of Wayne. Branch two takes a western bearing, passes under Powis Road and the Chicago and Northwestern Railroad and joins Branch three. The joined branches continue west, passing under Honey Hill Drive and out of DuPage County.

The third branch drains the southeastern section of Norton Creek. Branch three begins in an unincorporated subdivision north of North Avenue. The branch travels to the west, exiting the subdivision and entering the Pratt Wayne Woods Forest Preserve. The branch moves to the northwest, exits the forest preserve, crosses Powis Road and intersects with branch four. Branch three travels north where it intersects branch two.

Branch four drains the southwestern part of Norton Creek. The branch begins on the north side of North Avenue, west of Powis Road, and travels north. The branch passes under Smith Road and intersects branch three on the downstream side.

3.4.3.2 Hydrologic Analysis

Section printed 29 April 2004

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Norton Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Norton Creek Tributary were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses for the streams studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented below in Table FRNC.1.

Table FRNC.1: USGS Stream Gages Used for Hydrologic Analysis of Norton Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Norton Creek at Wayne 05551050 7.35 15

There are no stream flow recording gages on Norton Creek. In order to simulate flows for Norton Creek and Norton Creek Tributary, a regional frequency analysis has been completed for the gages in the vicinity of the Norton Creek drainage basin. Thirteen USGS gages with one to 20 years of records in the DuPage River drainage basin provided data for the regional frequency analysis. To enable the regional frequency model to more accurately predict the flows for a small basin, the DuPage data have been augmented by records from gages with small drainage areas. Also included in the study are six gages from DuPage County basin having drainage areas of less than 20.0 square miles and six gages from basins within the region having drainage areas less than 2.0 square miles. The technique for a regional frequency analysis outlined in Bulletin No. 17 from the U.S. Water Resources Council (U.S. Water Resources Council, 1976) has been used to calculate the discharges for Norton Creek and Norton Creek Tributary.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table FRNC.2.

Table FRNC.2: Norton Creek Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr

Norton Creek - at Dunham Road 4.82 438 665 771 1,038 - u/s of confluence of Norton Creek Tributary 3.46 365 555 645 870

Norton Creek Tributary - at mouth 1.78 365 555 645 870

3.4.3.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Cross sections for the backwater analyses of Norton Creek and Norton Creek Tributary were determined from field surveys with some overbank cross sections being determined from topographic maps at a scale of 1:4,800, with a contour interval of four feet (U.S. Department of the Interior, 1972). Cross-section locations were at close intervals above and below bridges, dams, and culverts in order to compute the significant backwater effects of these structures.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface elevations of floods of the selected recurrence intervals on Norton Creek and Norton Creek Tributary were computed through use of the USACE HEC-2 step-backwater computer program (U.S. Army Corps of Engineers, February 1972). This program relates stream geometry, characteristics, and discharge to stream elevation.

The starting downstream water-surface elevations for Norton Creek and Norton Creek Tributary used in the HEC-2 step-backwater program were computed by the normal depth methods (USACE, February 1972).

Roughness coefficients for Norton Creek and Norton Creek Tributary were determined by field inspection and engineering judgment. Refer to Table FRNC.3 for further information.

Table FRNC.3: Norton Creek Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

Norton Creek 0.045 - 0.150 0.050 - 0.150 Norton Creek Tributary 0.030 - 0.055 0.045 - 0.055

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.4.3.4 Flood Boundaries

To reference the flood boundaries for Norton Creek, see Map Panels: 0101, 0104, 0105, 0107 and 0108.

3.4.3.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.4.3.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with Fox River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS NORTON CREEK (FRNC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Norton Creek Tributary (FRNC) FRNC0006 1,005 1 301 959 0.4 741.4 741.4 2 741.5 0.1 FRNC0007 1,936 1 87 335 1.1 743.0 743.0 743.1 0.1 FRNC0008 3,200 1 186 315 1.1 743.2 743.2 743.3 0.1 FRNC0009 4,245 1 209 510 0.7 744.3 744.3 744.4 0.1 FRNC0010 4,575 1 12 53 6.8 744.8 744.8 744.9 0.1 FRNC0011 5,922 1 95 279 1.3 746.1 746.1 746.2 0.1 FRNC0012 7,779 1 289 3 705 0.5 747.0 747.0 747.0 0.0

1 In feet above confluence with Norton Creek

2 Elevation computed without consideration of backwater effects from Norton Creek

COUNTY BOUNDARY

LIMIT OF DETAILED STUDY

750 750

FLOOD PROFILES

NORTON CREEK (FRNC)

745 745

740 740

ELEVATION IN FEET (NGVD 29)

735 735

FRNC0005 730 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRNC0001 FRNC0002 FRNC0003 FRNC0004 CROSS SECTION LOCATION 720 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 87P RAILROAD

POWIS ROAD

HONEY HILL ROAD

ARMY TRAIL ROAD

755 BILLY BURNS ROAD 755

COUNTY BOUNDARY

LIMIT OF DETAILED STUDY

750 750

FLOOD PROFILES

745 745 NORTON CREEK TRIBUTARY (FRNC)

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

FRNC0010 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRNC0006 FRNC0007 FRNC0008 FRNC0009 FRNC0011 FRNC0012 CROSS SECTION LOCATION 720 0 1000 2000 3000 4000 5000 6000 7000 8000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 88P

3.4.4 Waubansee Creek (FRWA)

3.4.4.1 Tributary Description

Waubansee Creek is tributary to the Fox River. The total watershed area for Waubansee Creek within the bounds of DuPage County is 5991 acres. The communities contributing watershed area are Aurora, Naperville and Unincorporated DuPage County. The land use characteristics of Waubansee Creek watershed, within the confines of DuPage County, are residential and commercial areas throughout.

Waubansee Creek starts on the east side of Eola Road. The creek flows to the southwest, under Eola Road and through the center of a large subdivision. Waubansee Creek then exits DuPage County.

Another branch of Waubansee Creek begins south of the Waubansee Main Stem. The area where the branch is found is within a highly dense residential area. Most of this branch, south of Montgomery Road, is in conduit and it passes into Kane County in this state.

3.4.4.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Waubansee Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Waubansee Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

For Waubansee Creek, estimates of the 10-, 50-, and 100-year floods were plotted on log-normal probability paper, and the 500-year flood discharges were estimated by straight line extrapolation. The 500-year flood discharge is less reliable than the others because the average period of record for stream gages used to prepare the regional equations is approximately 30 years. The reliability of the 100-year flood discharge is between those of the 50- and 500-year floods. The 100-year discharge value that was used in the 1978 FIS for Waubansee Creek was adopted for the May 15, 1986, restudy. The analysis did not include the 10-, 50-, or 500-year frequency flood events. To allow for zone calculations, the 10- year flood elevation was generated by approximate methods.

Section printed 29 April 2004

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table FRWA.1.

Table FRWA.1: Waubansee Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Waubansee Creek - at Kane-Kendall County boundary 16.50 770 1,220 1,447 1,950

3.4.4.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross sections for Waubansee Creek were resurveyed to reflect development within the floodplain that had occurred subsequent to the previous FIS.

The 100-year water-surface elevation for the restudy of Waubansee Creek was calculated using the USACE HEC-2 step-backwater program (U.S. Department of Agriculture, 1965).

Starting water-surface elevations for Waubansee Creek were calculated using the slope/area method.

Roughness coefficients for Waubansee Creek were determined by field inspection and engineering judgment. Refer to Table FRWA.2 for further information.

Table FRWA.2: Waubansee Creek Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

Waubansee Creek 0.035 - 0.055 0.050 - 0.070

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.4.4.4 Flood Boundaries

To reference the flood boundaries for Waubansee Creek, see Map Panels: 0702, 0704, 0705, 0707 and 0708.

3.4.4.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.4.4.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above county boundary

2 Data not available TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WAUBANSEE CREEK (FRWA) KAUTZ ROAD

COUNTY BOUNDARY

FLOOD PROFILES

WAUBANSEE CREEK (FRWA) 675 675

670 670

ELEVATION IN FEET (NGVD 29)

665 665

660 FRWA0005 FRWA0006 660 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD

FRWA0001 50-YEAR FLOOD* 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRWA0002 FRWA0003 FRWA0004 CROSS SECTION LOCATION 650 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY *DATA NOT AVAILABLE 89P EOLA ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

WAUBANSEE CREEK (FRWA) 680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

FRWA0007 FRWA0008 FRWA0009 CROSS SECTION LOCATION 655 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 90P

3.5 Salt Creek (SC)

3.5.1 Main Stem (SCSC)

3.5.1.1 Tributary Description

The Salt Creek Main Stem has a direct drainage area of 27.6 square miles. Communities that contribute watershed area to the Salt Creek Main Stem, within the bounds of DuPage County, are: Itasca, Wood Dale, Addison, Villa Park, Elmhurst, Lombard, Oakbrook Terrace, Oak Brook, Hinsdale and Unincorporated DuPage County.

Salt Creek is greatly regulated in flow by the Busse Lake, found in the Busse Woods Forest Preserve of Cook County. Upon leaving Busse Woods, Salt Creek flows to the south passing under such roads as Arlington Heights Road and Biesterfield Road in Cook County. Salt Creek crosses into DuPage County at Devon Avenue and continues south through the Salt Creek Country Club where the Main Stem confluences with the Devon Avenue Tributary. Salt Creek resumes flow to the south passing through Thorndale Avenue, the Salt Creek Marsh Forest Preserve at the southernmost tip of which where Spring Brook Creek Tributary confluences with the Main Stem. Continuing south, the Main Stem crosses through the Chicago Milwaukee St. Paul & Pacific Railroad embankment, Irving Park Road, the Salt Creek County Forest Preserve, Elizabeth Court, the Oak Meadows Golf Course, and the Eisenhower Expressway (1-290) the downstream side of which Westwood Creek joins the Salt Creek Main Stem. Still bearing south, the Main Stem passes through Addison Community Park, Lake Street, Cricket Creek Forest Preserve, Fullerton Avenue, North Avenue, the Chicago and Northwestern Railroad, St. Charles Road, Kingery Highway (I-83) and Eldridge Park, the upstream side of which is the confluence location of the Main Stem and Sugar Creek Tributary. The Main Stem crosses Butterfield Road, Roosevelt Road and joins Oakbrook Tributary at Oak Brook Mall. Persuing a more serpentine course, the Salt Creek Main Stem crosses Harger Road, the East-West Tollway (I-88), the Oak Brook Golf Club, and joins Ginger Creek at the Butler National Golf Course. The Main Stem continues south through 31st Street and joins Bronswood Tributary at the Fullersburg Forest Preserve. The Main Stem passes through York Road, and Indian Trail Road, just downstream of which Salt Creek exits DuPage County into Cook County. In Lyons, Salt Creek will confluence with the Des Plaines River.

3.5.1.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Salt Creek.

Section printed 29 April 2004

Discharges for the 10-year, 50-year, and 100-year floods for Salt Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses of the Des Plaines River studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented in Table SCSC.1 below:

Table SCSC.1: USGS Stream Gages Used for Hydrologic Analysis of Salt Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Salt Creek at Elmhurst 05531300 90.6 15

Salt Creek at Oak Brook 05531380 100.0 15

Flood frequency curves for Salt Creek were prepared for this study and are based on discharges calculated by the SCS. The SCS has completed a comprehensive flood management study of the Salt Creek watershed as part of the Chicago Metropolitan Area River Basin Plan. That study included detailed watershed modeling utilizing the SCS watershed model TR-20 (U.S. Department of Agriculture, 1974). It is an advanced hydrologic model that accurately simulates the historical flood stage- and discharge-hydrographs. The model was used for a regional analysis of the entire watershed. The model included consideration of the Busse Woods and Kingery Detention Reservoirs. Elevation-capacity and outlet rating data were included in the model and were utilized in routing the hydrographs through the watershed. Estimates of flood discharge resulting from that study are the most current, and the 100-year discharges have been approved by the State of Illinois for use in the state’s floodplain regulation program. Data are located in the Illinois State Water Survey Floodplain Repository. Harza prepared additional hydrologic analyses that provided an independent review of the suitability of the results in concurrence with FIA’s guidelines. Discharges for the 100-, 50-, and 10- year floods were computed for Salt Creek by Harza using regional flood frequency equations for Illinois (Illinois Department of Transportation, 1979). The discharges determined for Salt Creek are higher than the historic discharges because they are based on conditions projected to exist

Section printed 29 April 2004

in the year 2000. The Salt Creek discharges decrease moving downstream as a result of overbank storage. The calculated unit flood discharges were compared to those for neighboring watersheds. This review by Harza established that the flood discharges computed by the SCS using their TR- 20 program and certified by the State of Illinois are suitable for use in this FIS. The SCS discharges for the 10-, 25-, and 100-year floods for the two streams were plotted on log-normal probability paper. The 50- and 500- year flood discharges were estimated by straight-line interpolation and extrapolation, respectively.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCSC.2.

Table SCSC.2: Salt Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Salt Creek - at York Road 112 2,158 3,258 3,650 4,427 - at 31st Street 106 2,162 3,258 3,655 4,434 - at confluence with Ginger Creek 102 2,172 3,277 3,680 4,450 - at confluence with Oak Brook Tributary 99.2 2,186 3,290 3,696 4,480 - at confluence with Sugar Creek 95.0 2,187 3,301 3,698 4,495 - at St. Charles Road 90.7 1,911 2,724 3,171 4,520 - at Chicago and NW Railway 88.8 1,915 2,730 3,178 4,530 - at State Route 83 88.0 2,190 3,306 3,701 4,502 - approximately 0.67 mile d/s of I-90 85.7 2,263 3,341 3,846 5,224 - approximately 250 ft d/s of Fullerton Avenue 85.7 2,248 3,308 3,803 5,155 - at Fullerton Avenue 84.0 2,247 3,390 3,803 4,615 - approximately 4,800 ft u/s of Lake Street 82.7 2,267 3,350 3,857 5,240 - approximately 660 ft u/s of Elizabeth Drive 73.0 2,120 3,100 3,524 4,500 - approximately 527 ft d/s of Irving Park Road 71.4 2,110 3,090 3,502 4,490 - approximately 792 ft u/s of Chicago, Milwaukee, St. Paul & Pacific Railroad 70.86 2,110 3,070 3,484 4,470 - upper corporate limit

Section printed 29 April 2004

for City of Wood Dale 54.4 1,650 2,310 2,590 3,260 - at Plum Grove Road 10.18 522 792 913 1,225

3.5.1.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

The water-surface elevations for the streams studied in detail and limited detail were computed using either the SCS WSP-2 backwater computer program or the USACE HEC-2 step-backwater computer program (U.S. Department of Agriculture, 1974; USACE, HEC-2 Water-Surface Profiles, Computer Program723-X6-L202A, 1973). The USACE HEC-2 model was used for all streams studied in detail and limited detail except for Meacham Creek, Sawmill Creek, Salt Creek, Spring Brook, and Westwood Creek, which were modeled utilizing the SCS WSP-2 program (U.S. Department of Agriculture, 1974).

Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence intervals. Streams studied in detail have flood profiles drawn for the 500-year, 100-year, 50-year, and 10-year storm events, with the exception of Upper Salt Creek, Klein Creek Tributary No. 1, Klein Creek Tributary No. 2, Sawmill Creek, Sawmill Creek Tributary No. 1, Wards Creek, West Branch Tributary No. 5, West Branch Tributary No. 7, East Branch Tributary No. 1, and East Branch Tributary No. 2, which have only the 10-year and 100-year profiles.

Cross sections for the backwater analyses on Salt Creek were field surveyed by the SCS. Cross-section data for Salt Creek were obtained from Regulation of Construction Within the Floodplain of Lower Salt Creek and Tributaries (Illinois Department of Transportation, 1980). Sections were located at close intervals above and below bridges and culverts in order to compute the significant backwater effects of these structures.

Starting water-surface elevations for Salt Creek were developed by the slope/area method.

Channel roughness factors for Salt Creek were assigned on the basis of field inspection of floodplain areas and from previous studies by the SCS. Refer to Table SCSC.3 for further details.

Section printed 29 April 2004

Table SCSC.3: Salt Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Salt Creek 0.020 - 0.070 0.020 - 0.300

3.5.1.4 Flood Boundaries

To reference the flood boundaries for Salt Creek, see Map Panels: 0301, 0302, 0304, 0305, 0307, 0308, 0309, 0601, 0602, 0603, 0605, 0606, 0609 and 0903.

3.5.1.5 Floodways

Floodway widths for Salt Creek were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. For Salt Creek, because the mapped floodway extends outside the mapped 100-year floodplain, the floodway was delineated within the 100-year floodplain using engineering judgment. The floodway for Salt Creek extends beyond the corporate limits for City of Elmhurst.

Please reference attached Floodway Data Tables for further information.

3.5.1.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Salt Creek (SCSC) SCSC0001 50,268 1 158 1,155 3.2 642.5 642.5 642.6 0.1 SCSC0002 54,761 1 699 2,856 1.7 644.6 644.6 644.8 0.2 SCSC1026 55,284 1 128 2 362 9.6 645.5 645.1 645.1 0.0 SCSC1027 55,844 1 206 1,407 2.5 646.9 646.9 646.9 0.0 SCSC1028 58,044 1 243 1,564 2.2 647.3 647.3 647.3 0.0 SCSC1029 60,244 1 956 1,749 4.8 647.9 647.9 647.9 0.0 SCSC1030 62,204 1 150 977 3.5 650.3 650.3 650.4 0.1 SCSC1031 65,044 1 397 1,343 3.5 653.5 653.5 653.6 0.1 SCSC1033 65,294 1 407 1,470 3.3 653.8 653.8 653.9 0.1 SCSC1034 68,214 1 780 3,610 1.8 654.6 654.7 654.8 0.1 SCSC1035 70,454 1 1,412 4,254 2.0 655.0 655.0 655.1 0.1 SCSC1036 71,094 1 1,097 5,122 1.3 655.2 655.2 655.3 0.1 SCSC1037 71,337 1 130 1,142 2.7 655.2 655.2 655.3 0.1 SCSC1039 71,515 1 125 978 3.5 655.2 655.2 655.3 0.1 SCSC1040 71,890 1 138 865 4.1 655.4 655.4 655.5 0.1 SCSC1041 72,530 1 99 864 3.6 656.0 656.0 656.1 0.1 SCSC1042 73,090 1 129 1,025 3.1 656.3 656.3 656.5 0.1 SCSC1043 73,510 1 106 1,030 3.0 656.5 656.5 656.7 0.1

1 In feet above mouth

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain

3 Width includes floodway of Spring Brook Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SALT CREEK (SCSC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Salt Creek (SCSC) SCSC1045 73,784 1 130 1,157 2.7 656.7 656.7 656.8 0.1 SCSC1047 73,940 1 136 1,219 2.8 656.8 656.8 656.9 0.1 SCSC1049 74,098 1 532 3,066 1.9 657.0 657.0 657.1 0.1 SCSC1050 74,208 1 723 3,165 1.5 657.0 657.0 657.1 0.1 SCSC1051 74,618 1 332 1,639 2.7 657.1 657.1 657.2 0.1 SCSC1052 75,178 1 214 1,063 3.8 657.3 657.3 657.4 0.1 SCSC1053 75,489 1 232 1,167 3.7 657.5 657.5 657.6 0.1 SCSC1054 76,249 1 443 2,580 2.1 657.9 657.9 658.0 0.1 SCSC1055 76,659 1 393 1,790 2.0 658.0 658.0 658.1 0.1 SCSC1056 77,059 1 760 1,544 3.3 658.2 658.2 658.3 0.1 SCSC1057 77,469 1 673 2,224 2.5 658.5 658.5 658.6 0.1 SCSC1058 77,879 1 410 2,706 2.2 658.7 658.7 658.8 0.1 SCSC1059 78,299 1 257 1,644 2.1 658.8 658.8 658.9 0.1 SCSC1060 79,254 1 170 1,187 3.2 659.4 659.4 659.5 0.1 SCSC1061 79,844 1 136 1,123 3.2 659.9 659.9 660.0 0.1 SCSC1062 80,134 1 146 877 4.1 660.2 660.2 660.3 0.1 SCSC1063 80,649 1 395 1,553 2.8 660.8 660.8 660.9 0.1 SCSC1064 80,989 1 140 2,276 2.5 661.1 661.1 661.2 0.1

1 In feet above mouth

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain

3 Width includes floodway of Spring Brook Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SALT CREEK (SCSC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Salt Creek (SCSC) SCSC1065 81,029 1 185 1,676 1.8 661.2 661.2 661.3 0.1 SCSC0017 81,250 1 73 1,298 2.4 662.0 661.5 661.6 0.1 SCSC0018 82,935 1 130 1,438 2.2 662.5 662.5 662.5 0.0 SCSC0019 83,516 1 150 1,196 2.6 662.5 662.5 662.5 0.0 SCSC0020 84,219 1 165 1,308 2.4 662.5 662.5 662.5 0.0 SCSC0021 84,746 1 170 1,395 2.3 662.5 662.5 662.5 0.0 SCSC0022 85,504 1 250 1,479 2.6 662.7 662.7 662.7 0.0 SCSC0023 86,520 1 455 1,768 2.5 663.0 663.0 663.1 0.1 SCSC0024 86,854 1 410 1,338 3.0 663.2 663.2 663.3 0.1 SCSC0025 87,370 1 445 1,246 3.0 663.7 663.7 663.8 0.1 SCSC0026 87,988 1 500 2,629 1.8 664.1 664.1 664.2 0.1 SCSC0027 91,964 1 130 2,242 1.6 665.9 665.9 666.0 0.1 SCSC0028 92,526 1 75 1,698 2.3 666.8 666.8 666.8 0.0 SCSC0029 93,878 1 70 2,346 1.6 667.5 667.5 667.6 0.1 SCSC0030 94,550 1 120 3,387 1.0 668.0 668.0 668.1 0.1 SCSC0031 96,132 1 300 2 1,715 2.1 668.9 668.9 669.0 0.1 SCSC0032 97,866 1 210 1,935 1.8 671.5 671.5 671.6 0.1 SCSC0033 98,400 1 145 3,178 2.1 672.0 672.0 672.1 0.1

1 In feet above mouth

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain

3 Width includes floodway of Spring Brook Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SALT CREEK (SCSC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Salt Creek (SCSC) SCSC0034 99,666 1 270 3,178 2.1 672.3 672.3 672.4 0.1 SCSC0035 101,350 1 95 3,319 1.2 672.6 672.6 672.7 0.1 SCSC0036 102,501 1 387 1,537 2.3 673.1 673.1 673.2 0.1 SCSC0037 103,708 1 850 6,063 0.6 674.2 674.2 674.3 0.1 SCSC0038 106,683 1 860 3,568 1.1 674.7 674.7 674.8 0.1 SCSC0039 107,935 1 903 5,067 0.8 674.8 674.8 674.9 0.1 SCSC0040 111,935 1 397 8,431 0.4 675.1 675.1 675.2 0.1 SCSC0041 113,364 1 509 3,516 1.1 675.3 675.3 675.4 0.1 SCSC0042 114,787 1 494 3,931 1.0 675.5 675.5 675.6 0.1 SCSC0043 117,307 1 450 5,450 0.7 675.7 675.7 675.8 0.1 SCSC0044 117,986 1 490 5,738 0.6 675.8 675.8 675.8 0.0 SCSC0045 123,076 1 900 4,526 0.8 676.7 676.7 676.7 0.0 SCSC0046 125,430 1 789 4,351 0.8 677.0 677.0 677.1 0.1 SCSC0047 126,804 1 971 4,744 0.7 677.2 677.2 677.3 0.1 SCSC0048 130,335 1 429 2,685 1.3 678.2 678.2 678.3 0.1 SCSC0049 131,393 1 601 4,370 0.8 680.3 680.3 680.4 0.1 SCSC0050 132,433 1 671 4,503 0.8 680.3 680.3 680.4 0.1 SCSC0051 132,732 1 671 4,503 0.8 680.3 680.3 680.4 0.1

1 In feet above mouth

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain

1 In feet above mouth

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain

3 Width includes floodway of Spring Brook Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SALT CREEK (SCSC) COUNTY BOUNDARY COUNTY BOUNDARY COUNTY BOUNDARY

650 650

SALT CREEK (SCSC)

FLOOD PROFILES

645 645

640 640

ELEVATION IN FEET (NGVD 29)

635 635

630 630 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 625 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0001 CROSS SECTION LOCATION 620 47500 48000 48500 49000 49500 50000 50500 51000 51500 52000 52500 53000 53500 54000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 116P YORK ROAD

FULLERSBURG DAM

SALT CREEK (SCSC)

FLOOD PROFILES

650 650

645 645

ELEVATION IN FEET (NGVD 29)

640 640

SCSC1029 635 635 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 630 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0002 SCSC1026 SCSC1027 SCSC1028 CROSS SECTION LOCATION 625 54000 54500 55000 55500 56000 56500 57000 57500 58000 58500 59000 59500 60000 60500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 117P 31ST STREET

CONFLUENCE OF GINGER CREEK

660

CONFLUENCE OF BRONSWOOD CEMETARY TRIBUTARY

SALT CREEK (SCSC)

FLOOD PROFILES

655 655

650 650

ELEVATION IN FEET (NGVD 29)

645 645

640 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 635 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC1030 SCSC1031 SCSC1033 CROSS SECTION LOCATION 630 60500 61000 61500 62000 62500 63000 63500 64000 64500 65000 65500 66000 66500 67000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 118P 670 670

22ND STREET 665 665

660 660

SALT CREEK (SCSC)

FLOOD PROFILES

655 655

650 650

ELEVATION IN FEET (NGVD 29)

645 645

SCSC1041 SCSC1042 640 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 635 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC1034 SCSC1035 SCSC1036 SCSC1037 SCSC1039 SCSC1040 CROSS SECTION LOCATION 630 67000 67500 68000 68500 69000 69500 70000 70500 71000 71500 72000 72500 73000 73500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 119P 680 680

675 675

670 HARGER ROAD 670

EAST WEST TOLLWAY (I-88)

CONFLUENCE OF SPRING ROAD TRIBUTARY 665 665

SALT CREEK (SCSC)

FLOOD PROFILES

660 INTERSTATE CONNECTOR 660

655 655

ELEVATION IN FEET (NGVD 29)

650 650

SCSC1060 SCSC1061 645 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSC1050 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC1043 SCSC1045 SCSC1047 SCSC1049 SCSC1051 SCSC1052 SCSC1053 SCSC1054 SCSC1055 SCSC1056 SCSC1057 SCSC1058 SCSC1059 CROSS SECTION LOCATION 635 73500 74000 74500 75000 75500 76000 76500 77000 77500 78000 78500 79000 79500 80000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 120P FRONTAGE ROAD

ROOSEVELT ROAD

STATE ROUTE 56 (BUTTERFIELD ROAD)

665 665

SALT CREEK (SCSC)

FLOOD PROFILES

660 660

655 655

ELEVATION IN FEET (NGVD 29)

650 650

SCSC0022 645 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSC1065 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC1062 SCSC1063 SCSC1064 SCSC0017 SCSC0018 SCSC0019 SCSC0020 SCSC0021 CROSS SECTION LOCATION 635 80000 80500 81000 81500 82000 82500 83000 83500 84000 84500 85000 85500 86000 86500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 121P RAILROAD 675 675

ILLINOIS PRAIRIE PATH

CONFLUENCE OF SUGAR CREEK

670 670

SALT CREEK (SCSC)

FLOOD PROFILES

665 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655

SCSC0027 SCSC0028 650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0023 SCSC0024 SCSC0025 SCSC0026 CROSS SECTION LOCATION 640 86500 87000 87500 88000 88500 89000 89500 90000 90500 91000 91500 92000 92500 93000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 122P 685

RAILROAD RAILROAD

680 ST. CHARLES ROAD 680

675 675

SALT CREEK (SCSC)

FLOOD PROFILES

670 670

665 665

ELEVATION IN FEET (NGVD 29)

660 660

SCSC0033 655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0029 SCSC0030 SCSC0031 SCSC0032 CROSS SECTION LOCATION 645 93000 93500 94000 94500 95000 95500 96000 96500 97000 97500 98000 98500 99000 99500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 123P 680 680

STATE ROUTE 64 (NORTH AVENUE) KINGERY DIKE (SOUTH) TOP ELEVATION

675 675

SALT CREEK (SCSC)

FLOOD PROFILES

670 670

665 665

ELEVATION IN FEET (NGVD 29)

660 660

655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0034 SCSC0035 SCSC0036 SCSC0037 CROSS SECTION LOCATION 645 99500 100000 100500 101000 101500 102000 102500 103000 103500 104000 104500 105000 105500 106000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 124P LAKE STREET 680 680

FULLERTON AVENUE KINGERY DIKE (NORTH) KINGERY DIKE (SOUTH) TOP ELEVATION TOP ELEVATION 675 675

SALT CREEK (SCSC)

FLOOD PROFILES

670 670

665 665

ELEVATION IN FEET (NGVD 29)

660 660

SCSC0040 655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0038 SCSC0039 CROSS SECTION LOCATION 645 106000 106500 107000 107500 108000 108500 109000 109500 110000 110500 111000 111500 112000 112500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 125P INTERSTATE 290

COUNTRY CLUB ROAD

CONFLUENCE OF WESTWOOD CREEK

680 680

SALT CREEK (SCSC)

FLOOD PROFILES

675 675

670 670

ELEVATION IN FEET (NGVD 29)

665 665

SCSC0044 660 660 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0041 SCSC0042 SCSC0043 CROSS SECTION LOCATION 650 112500 113000 113500 114000 114500 115000 115500 116000 116500 117000 117500 118000 118500 119000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE UPSTREAM OF SCSC0043 TO STREAM DISTANCE IN FEET ABOVE MOUTH A POINT APPROXIMATELY 1,300 FEET DOWNSTREAM OF ELIZABETH ROAD 126P 685 ELIZABETH DRIVE 685

COUNTRY CLUB ROAD

680 680

SALT CREEK (SCSC)

FLOOD PROFILES

675 675

670 670

ELEVATION IN FEET (NGVD 29)

665 665

SCSC0046 660 660 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 655 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0045 CROSS SECTION LOCATION 650 119000 119500 120000 120500 121000 121500 122000 122500 123000 123500 124000 124500 125000 125500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE UPSTREAM OF SCSC0043 TO STREAM DISTANCE IN FEET ABOVE MOUTH A POINT APPROXIMATELY 1,300 FEET DOWNSTREAM OF ELIZABETH ROAD 127P RAILROAD

690 (STATE ROUTE 19) 690

IRVING PARK BOULEVARD

685 685

SALT CREEK (SCSC)

FLOOD PROFILES

680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

SCSC0049 665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0047 SCSC0048 CROSS SECTION LOCATION 655 125500 126000 126500 127000 127500 128000 128500 129000 129500 130000 130500 131000 131500 132000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 128P CONFLUENCE OF SPRING BROOK CREEK

685 685

SALT CREEK (SCSC)

FLOOD PROFILES

680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0050 SCSC0051 CROSS SECTION LOCATION 655 132000 132500 133000 133500 134000 134500 135000 135500 136000 136500 137000 137500 138000 138500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE UPSTREAM STREAM DISTANCE IN FEET ABOVE MOUTH OF 200 FEET UPSTREAM OF SCSC0054 129P COUNTY BOUNDARY

THORNDALE AVENUE

LIMIT OF DETAILED STUDY

SALT CREEK (SCSC)

FLOOD PROFILES

685 685

680 680

ELEVATION IN FEET (NGVD 29)

675 675

SCSC0057 670 670 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSC0055 SCSC0056 CROSS SECTION LOCATION 660 138500 139000 139500 140000 140500 141000 141500 142000 142500 143000 143500 144000 144500 145000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE UPSTREAM STREAM DISTANCE IN FEET ABOVE MOUTH OF 200 FEET UPSTREAM OF SCSC0054 130P

3.5.2 Bronswood Tributary (SCBW)

3.5.2.1 Tributary Description

Bronswood Tributary is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Bronswood Tributary Watershed covers approximately 3.25 square miles (2075 acres). This watershed includes parts of the Villages of Oak Brook, Hinsdale, Westmont, and Clarendon Hills, and areas in unincorporated York and Downers Grove North Townships. Bronswood Tributary flows into the main channel of Salt Creek 2,060 feet downstream of 31st Street, and 6,300 feet upstream of the Fullersburg Dam.

The South Branch of Bronswood Tributary (reach #1) begins at a detention pond located within the Illinois Department of Transportation Route 83/Ogden Avenue northwestern cloverleaf. The reach proceeds east under Route 83 into the northeastern cloverleaf, and then exits to the northeast under the northbound Route 83 on-ramp. The stream then continues to wind its way east through thick grasses passing through an old culvert and a private drive until it reaches the confluence with reach #3. The South Branch passes through two weirs and the Adams road culvert before turning to the north to open into a large wetland zone spanning 1900 lineal feet. It is at this point that the South Branch enters the Bronswood Cemetery, flowing in a northerly direction through two ponds and several weirs and bridges. Once free of the cemetery, the reach proceeds on a rapid decent towards the confluence with the North Branch (reach #2), some 3000 lineal feet in total relative distance. The stream then proceeds to the northeast for an additional 130 feet, passing under Spring Road, to join Salt Creek.

Reach #3 is a small tributary draining 0.57 sq. miles (365 acres) of the southeastern-most sections of the Bronswood watershed. The reach originates on the south side of Ogden Avenue, approximately 700 feet east of Route 83. Reach #3, 716 ft in length, flows north under Ogden Avenue, a religious center, and a parking lot before joining the South Branch (reach #1).

The North Branch of Bronswood Tributary (reach #2) begins at Lake Charles in incorporated Westmost, just west of the Pasquinelli Drive corporate areas. After flowing through a 42” and a 48” storm sewer, the stream daylights into a detention basin. The reach passes under Pasquinelli Drive into another detention basin before flowing east under Route 83. On the east side of Route 83, the North Branch expands out to form a shallow ponding area while reorienting the direction of flow to the north. Downstream of the weir forming the pond, the channel flows through some small, unnamed bridges and weirs and eventually merges

Section printed 29 April 2004

with Bronswood reach #4. After this confluence, the North Branch flows freely towards culverts at a private drive, 35th Street and Adams Street before joining the South Branch 130 ft upstream of the confluence with mainstem Salt Creek.

Reach #4 of Bronswood Tributary is 1800 ft in length, draining 0.45 sq. miles (28.8 acres) of watershed. The stream starts in the ditch line on the west side of Route 83 approximately 800 ft north of Oakmont Lane. The channel then proceeds easterly through a 24”culvert passing under Route 83. The stream continues to wind to the southeast where it converges with the North Branch.

The 0.94 sq. miles (~600 acres) directly adjacent to the Bronswood reaches are primarily found in heavily vegetated, undisturbed areas, with the exception of the very headwaters that are a combination of residential and commercial land uses. The land use for the remaining 2.31 sq. miles (~1475 acres), or 71% of the total watershed area, is residential with an interspersing of light commercial.

3.5.2.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Bronswood Creek..

Peak flows for the 10-, 50-, 100-, and 500-year floods were determined for Bronswood Tributary by the ISWS in accordance with the USGS report Technique for Estimating Magnitude and Frequency of Floods in Illinois (U.S. Department of the Interior, 1977). This report described a technique for estimating flood magnitudes at recurrence intervals ranging from 2 to 500 years, for unregulated rural streams in Illinois, having drainage areas ranging from 0.002 to 10,000 square miles. The independent variables, drainage area, slope, rainfall intensity, and an aerial factor were used to define the flood-frequency relationship. In addition, a provision included allowed for weighting the estimate to an existing gage record. The discharges used in this study were determined by the SCS and the ISWS and were approved by the DOWR.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCBW.1.

Table SCBW.1: Bronswood Tributary Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Section printed 29 April 2004

Bronswood Tributary - at confluence with Salt Creek 1.25 298 408 448 526 - east of Adams Road 0.95 255 350 384 451 - east of State Route 83 0.31 148 203 223 262

3.5.2.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for the backwater analyses of Bronswood Tributary, Ginger Creek, and Spring Road Tributary were obtained by field surveys during October 1977. At this time, the ISWS crew conducting the field work also obtained elevation data and structural geometry for the bridges on each creek.

Water-surface elevations on Bronswood Tributary, for all designated recurrence intervals, were computed through use of the USACE HEC-2 step-backwater computer program (USACE, 1976). Elevations for the approximate flooding areas were determined by field inspection. The 100- year flood elevations and resulting floodplains, floodways, and profiles were computed by the ISWS and reported in a January 1980 flood study of Salt Creek and its tributaries (Illinois Department of Transportation, 1980).

Starting water-surface elevations for Bronswood Tributary were taken from the Salt Creek profiles for the corresponding recurrence intervals.

Channel roughness factors (Manning’s “n”) used in the hydraulic computations of Bronswood Tributary were selected by engineering judgment and from field observations of the stream and floodplain areas. The factors were chosen to be consistent with commonly reported values (Dougherty, R. L, 1977; Chow, V. T., 1964; Chow, V. T., 1959). Please refer to Table SCBW.2 for more details.

Table SCBW.2: Bronswood Tributary Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Bronswood Tributary 0.015 - 0.080 0.040 - 0.200

Section printed 29 April 2004

3.5.2.4 Flood Boundaries

To reference the flood boundaries for Bronswood Tributary, see Map Panels: 0608, 0609, 0902 and 0903.

3.5.2.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.5.2.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Bronswood Cemetery Tributary (SCBW) SCBW0001 30 1 137 2 431 1.0 652.0 651.7 651.8 0.1 SCBW0002 910 1 65 87 5.2 658.5 658.5 658.5 0.0 SCBW0003 1,690 1 46 112 4.0 667.2 667.2 667.3 0.1 SCBW0004 1,970 1 80 99 4.5 669.7 669.7 669.8 0.1 SCBW0005 2,750 1 38 61 7.3 676.3 676.3 676.3 0.0 SCBW0006 2,890 1 80 230 2.0 681.9 681.9 681.9 0.0 SCBW0007 3,070 1 100 383 1.2 684.0 684.0 684.1 0.1 SCBW0008 3,570 1 128 2 176 2.6 684.4 684.4 684.5 0.1 SCBW0009 4,826 1 342 2 1,615 0.3 688.2 688.2 688.3 0.1 SCBW0010 5,856 1 155 584 0.7 688.2 688.2 688.3 0.1 SCBW0011 6,047 1 350 693 0.6 688.8 688.8 688.9 0.1 SCBW0012 6,276 1 133 2 413 0.9 688.9 688.9 689.0 0.1 SCBW0013 6,447 1 118 2 225 1.7 691.0 691.0 691.1 0.1 SCBW0014 7,080 1 29 35 6.4 691.5 691.5 691.6 0.1 SCBW0015 7,750 1 154 2 251 0.9 697.4 697.4 697.5 0.1

1 In feet above confluence with Salt Creek

2 Actual floodway width cannot be shown on the FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS BRONSWOOD TRIBUTARY CEMETERY (SCBW) 680 680

675 675

SPRING ROAD 670 670

CONFLUENCE WITH SALT CREEK THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 665 665

FLOOD PROFILES

660 660

BRONSWOOD CEMETARY TRIBUTARY (SCBW)

655 655

ELEVATION IN FEET (NGVD 29)

650 650

645 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCBW0002 SCBW0003 SCBW0004 CROSS SECTION LOCATION

SCBW0001 635 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 91P MIDDLE CEMETARY BRIDGE

NORTHERN CEMETARY BRIDGE SOUTHERN CEMETARY BRIDGE

690 690

FLOOD PROFILES

THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE 685 TO BE SHOWN SEPARATELY 685

BRONSWOOD CEMETARY TRIBUTARY (SCBW)

680 680

ELEVATION IN FEET (NGVD 29)

675 675

670 SCBW0009 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCBW0005 SCBW0006 SCBW0007 SCBW0008 CROSS SECTION LOCATION 660 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 92P 710 710

LIMIT OF DETAILED STUDY

DAM

PRIVATE DRIVE 705 ADAMS STREET 705

LIMIT OF FLOODWAY

CORPORATE LIMITS DAM

700 700

FLOOD PROFILES

695 695

BRONSWOOD CEMETARY TRIBUTARY (SCBW)

690 690

ELEVATION IN FEET (NGVD 29)

685 STATE ROUTE 83/ 685

ROBERT KINGERY HIGHWAY

CULVERT CULVERT

680 SCBW0015 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCBW0010 SCBW0011 SCBW0012 SCBW0013 SCBW0014 CROSS SECTION LOCATION 670 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 93P

3.5.3 Devon Avenue Tributary (SCDA)

3.5.3.1 Tributary Description

Devon Avenue Tributary is a 1968-acre watershed that is tributary to Salt Creek in DuPage County. The communities that contribute watershed area, within DuPage County, to Devon Avenue Tributary are Itasca and Unincorporated DuPage County. The watershed characteristics are changing as development expands in the area. Within DuPage County, the primary land use surrounding the watercourse is commercial, with residential sectors in the upper reaches of the watershed.

Devon Avenue Tributary begins in a detention area on the west side of I- 355, just north of the northwest cloverleaf at the intersection of I-355 and Thorndale Avenue. Flow proceeds to the east, under I-355 and immediately enters a corporate pond. Flow continues to the east passing under Park Boulevard, entering a series of linked corporate ponds just behind the Wyndham Resort Hotel. The stream passes through each pond’s weir structure, flows under Pierce Road and changes bearing to the northeast. On the south side of Devon Avenue, the stream runs a parallel route through ditches and corporate ponds. Devon Avenue Tributary passes underneath Arlington Heights Road and smaller crossings, always staying on the south side ditch of Devon Avenue. Devon Avenue Tributary enters the Salt Creek Country Club and confluences with Main Stem Salt Creek.

3.5.3.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Devon Avenue Tributary.

For Devon Avenue Tributary a gauging station on Salt Creek located about 20 miles downstream of Itasca was one source of data for defining discharge-frequency relationships. This gage has been operated since 1945. Values of the 10-, 50-, and 100-year peak discharges were obtained from a log-Pearson Type III distribution of annual peak flow data (U.S. Water Resources Council Hydrologic Committee, 1976). However, much channel work has been performed on Salt Creek and rapid urbanization of the watershed has occurred during the operation period of the stream gages, especially in the past 10 years. The effect of these changes has not been adequately recorded. Water from large floods has overflowed into a quarry about 10 miles upstream of the gage. Therefore, peak discharge- drainage area relationships were developed from a combination of historic flood data and unit hydrograph rainfall-runoff relationships. Flood routing was done with the “SCS-TR-20 Project Formulation Computer Program” (U.S. Department of Agriculture, 1974). Linear regression analysis was

Section printed 29 April 2004

used to determine the 10-, 50-, and 100-year peak discharges as a function of the drainage area at any given cross section. The 500-year peak discharge was determined by a log-log extrapolation of peak discharges computed for frequencies up to 100 years. The peak discharges obtained were substantiated by regional flood flow equations for northeastern Illinois.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCDA.1.

Table SCDA.1: Devon Avenue Tributary Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Devon Avenue Tributary - at lower corporate limit for the Village of Itasca 1.20 130 200 240 320 - approximately 100 feet u/s of Pierce Road 0.80 105 165 200 270

3.5.3.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for Devon Avenue Tributary were obtained from field surveys by the Illinois Division of Water Resources supplemented with field surveys by a contractor for the SCS. In some cases, these cross sections were extended using topographic maps with a 2-foot contour interval (Floodplain Topographic Maps, 1973).

Water-surface profiles for Devon Avenue Tributary, and Meacham Creek were developed using the SCS “WSP-2 Water-Surface Profile Computer Program” (U.S. Department of Agriculture, 1974). Profiles were determined for the 10-, 50-, 100-, and 500-year floods for all flooding sources.

Section printed 29 April 2004

Starting elevations for Devon Avenue Tributary, and Meacham Creek were taken from previously published data (Des Plaines River Steering Committee, 1975).

Valley and channel roughness coefficients for Devon Avenue Tributary were determined from field observations, USGS’ “Water Supply Paper 1849” (U.S. Department of the Interior, 1967), and the SCS’ “Guide for Selecting Roughness Coefficients” (U.S. Department of Agriculture, 1963). Please refer to Table SCDA.2 for further information.

Table SCDA.2: Devon Avenue Tributary Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Devon Ave Tributary 0.045 - 0.065 0.065 - 0.085

3.5.3.4 Flood Boundaries

To reference the flood boundaries for Devon Avenue Tributary, see Map Panels: 0203, 0301 and 0302.

3.5.3.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.5.3.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above Salt Creek

688 688

LIMIT OF DETAILED STUDY

687 687

FLOOD PROFILES

686 686 DEVON AVENUE TRIBUTARY (SCDA)

685 685

ELEVATION IN FEET (NGVD 29)

684 684

683 683 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 682 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCDA0001 SCDA0002 SCDA0003 CROSS SECTION LOCATION 681 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE SALT CREEK 94P

3.5.4 Ginger Creek (SCGC)

3.5.4.1 Tributary Description

Ginger Creek is a 3430-acre watershed that is tributary to Salt Creek. Communities that contribute watershed area to Ginger Creek are: Oak Brook, Oakbrook Terrace, Westmont, Lombard, Downers Grove, Clarendon Hills and Hinsdale. The overall watershed characteristics are shared between large-parceled residential and open spaces such as golf courses.

Ginger Creek begins in a long series of ponds originating north of Oakbrook Road and east of Meyers Road. Going north, the ponds proceed under Baybrook Lane, and opens up into a larger, longer pond. A restrictor at the northern end of the pond alongs Ginger Creek to pass under Baybrook Lane again. Flow proceeds to the east through a golf course, passes under Midwest Road, Regent Drive, Illinois Route 83, and Jorie Boulevard. On the east side of Jorie, Ginger Creek enters the Butler National Golf Course and confluences with Salt Creek.

3.5.4.2 Hydrologic Analysis

Section printed 29 April 2004

used in the FEQ model. The TSF contains runoff for each of the six land cover types and for each precipitation gage used to generate the runoff.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCGC.1.

Table SCGC.1: Ginger Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Ginger Creek - d/s of Jorie Boulevard * * * 1,256 * - approximately 250 ft u/s of Gabion Weir * * * 1,275 * - d/s of Route 83 * * * 1,277 * - d/s of Briarwood Lake * * * 1,271 * - u/s of confluence with Briarwood Ditch * * * 742 * - d/s of Regent Drive * * * 708 * - u/s of Regent Drive * * * 695 * - u/s of Sheet Pile Weir * * * 643 * - approximately 300 ft u/s of Sheet Pile Weir * * * 613 * - approximately 300 ft d/s of confluence with Trinity Lakes 2 Tributary * * * 566 * - d/s of Midwest Road * * * 554 * - u/s of Baybrook Lane * * * 405 * - d/s of Meyers Road * * * 341 * - u/s of Baybrook (west) * * * 175 *

Section printed 29 April 2004

Heritage Oaks Tributary - approximately 680 ft u/s of confluence with Ginger Creek * * * 160 *

Lombard Tributary - d/s of Royal Drive * * * 475 * - u/s of Royal Drive * * * 475 *

May’s Lake Tributary - u/s 31st Street * * * 170 * - approximately 250 ft u/s of 31st Street * * * 167 *

Midwest Club Tributary - approximately 450 ft u/s of confluence with Ginger Creek * * * 143 * - approximately 1,000 ft u/s of confluence with Ginger Creek * * * 124 * - approximately 1,500 ft u/s of confluence with Ginger Creek * * * 106 * - approximately 200 feet d/s of 31st Street * * * 75 *

3.5.4.3 Hydraulic Analysis

Section printed 29 April 2004

and boundary conditions. FEQ can also be applied in the simulation of a wide-range of stream configurations, such as loops, lateral-inflow conditions, and special features. The boundary conditions can be values such as the water-surface stage, discharge, or the stage-discharge relationship at a node. Wind stress may also be included in the analysis, as well as the effects of lateral inflows, when given local runoff intensity data.

FEQ model input consists of the following elements:

97. Run Control – specifies the simulation length and model execution options.

98. Branch Description – defines channel stationing, flow line elevations and cross-section locations.

99. Tributary Area – defines drainage area and land cover proportions draining to each branch and reservoir represented in the model.

100. Network Control Input – describes how the system is connected together and specifies the function tables used to represent hydraulic structures.

101. Operation of Control Structures – there are no operable structures in the Tributary No. 2 drainage network.

102. Input Files – files containing time series of external flow inputs to the system.

103. Output Files – files written by FEQ to be used as flow input to another FEQ model.

104. Special Output – text file output of flow and stage at each time step for a set of specific modeled locations.

105. Function Tables – all cross-section and hydraulic structure information is stored in tables, which must be read into the model.

106. Initial Condition – provides information FEQ needs to determine an initial network solution that can be used as a model boundary condition.

3.5.4.4 Flood Boundaries

To reference the flood boundaries for Ginger Creek, see Map Panels: 0604, 0605, 0606, 0607, 0608 and 0609.

Section printed 29 April 2004

3.5.4.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.5.4.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Ginger Creek (SCGC) SCGC5001 60 1 2 2 2 655.5 655.5 655.6 0.1 SCGC5003 200 1 2 2 2 655.5 655.5 655.6 0.1 SCGC5006 1,115 1 2 2 2 657.0 657.0 657.1 0.1 SCGC5010 2,045 1 42 212 6.4 658.3 658.3 658.4 0.1 SCGC5011 2,215 1 30 134 9.8 659.5 659.5 659.6 0.1 SCGC5012 2,550 1 80 600 2.2 662.2 662.2 662.3 0.1 SCGC5014 2,800 1 164 1,251 1.1 664.1 664.1 664.2 0.1 SCGC5015 3,040 1 335 2,581 0.6 664.1 664.1 664.2 0.1 SCGC5017 3,710 1 163 1,373 1.0 665.4 665.4 665.5 0.1 SCGC5018 3,935 1 155 1,334 1.0 655.4 655.4 655.5 0.1 SCGC5019 4,280 1 158 1,294 1.1 655.4 655.4 655.5 0.1 SCGC5020 4,565 1 120 900 1.4 655.4 655.4 655.5 0.1 SCGC5030 6,375 1 70 531 1.5 669.7 669.7 669.8 0.1 SCGC5031 6,515 1 38 237 3.3 669.7 669.7 669.8 0.1 SCGC5032 6,720 1 147 1,101 0.7 669.7 669.7 669.8 0.1 SCGC5033 6,925 1 131 842 0.9 669.7 669.7 669.8 0.1 SCGC5035 7,260 1 60 137 5.3 669.7 669.7 669.8 0.1 SCGC5036 7,450 1 55 95 7.2 673.2 673.2 673.3 0.1

1 In feet above confluence with Salt Creek

2 Data not available

3 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS GINGER CREEK (SCGC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Ginger Creek (SCGC) SCGC5037 7,615 1 163 3 923 0.7 673.9 673.9 674.0 0.1 SCGC5038 7,775 1 230 1,502 0.4 673.9 673.9 674.0 0.1 SCGC5039 8,280 1 33 139 4.3 674.2 674.2 674.3 0.1 SCGC5040 8,610 1 39 76 7.7 677.3 677.3 677.4 0.1 SCGC5041 8,740 1 189 624 0.9 678.1 678.1 678.2 0.1 SCGC5049 9,275 1 105 417 1.4 688.4 688.4 688.5 0.1 SCGC5050 9,840 1 75 250 2.3 688.4 688.4 688.5 0.1 SCGC5046 10,450 1 61 137 3.8 690.6 690.6 690.7 0.1 SCGC5067 11,500 1 80 179 2.7 695.2 695.2 695.3 0.1 SCGC5068 11,825 1 90 180 2.4 696.5 696.5 696.5 0.0 SCGC5053 12,320 1 88 385 1.1 699.3 699.3 699.4 0.1 SCGC5047 15,335 1 114 815 0.2 699.3 699.3 699.4 0.1 SCGC5051 16,290 1 155 1,268 0.2 699.3 699.3 699.4 0.1 SCGC5045 16,720 1 165 705 0.4 699.3 699.3 699.4 0.1

1 In feet above confluence with Salt Creek

2 Data not available

1 In feet above confluence with Ginger Creek

2 Elevation based on unsteady flow model TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS BRIARWOOD DITCH (SCGC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Heritage Oaks Tributary (SCGC) SCGC5044 675 1 493 5,333 0.0 699.3 2 699.3 699.4 0.1

1 In feet above confluence with Ginger Creek

2 Elevation based on unsteady flow model TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS HERITAGE OAKS TRIBUTARY (SCGC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Lombard Tributary (SCGC) SCGC5054 250 1 57 247 1.9 699.3 2 699.3 2 699.4 0.1 SCGC5056 590 1 48 139 3.4 701.0 701.0 2 701.0 0.1

1 In feet above confluence with Ginger Creek

2 Elevation based on unsteady flow model TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS LOMBARD TRIBUTARY (SCGC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Mays Lake Tributary (SCGC) SCGC5071 1,400 1 2 2 2 672.0 2 2 2 SCGC5028 1,640 1 2 2 2 679.5 2 2 2 SCGC5026 1,925 1 2 2 2 683.4 2 2 2 SCGS5057 2,635 1 2 2 2 701.2 2 2 2 SCGC5058 2,710 1 2 2 2 701.5 2 2 2

1 In feet above confluence with Ginger Creek

2 Data not available TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS MAYS LAKE TRIBUTARY (SCGC) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Midwest Club Tributary (SCGC) SCGC5066 450 1 44 122 1.1 695.5 695.5 695.6 0.1 SCGC5065 975 1 22 72 1.7 695.7 695.7 695.8 0.1 SCGC5064 1,475 1 223 505 0.2 695.8 695.8 695.9 0.1 SCGC5063 1,795 1 25 67 1.5 695.8 695.8 695.9 0.1 SCGC5062 2,310 1 38 35 2.1 697.8 697.8 697.9 0.1 SCGC5061 2,905 1 2 2 2 702.3 2 2 2

1 In feet above confluence with Ginger Creek

2 Data not available TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS MIDWEST CLUB TRIBUTARY (SCGC) 675 675

LAKE FRED

STONE WEIR

GABION WEIR GABION WEIR

RONALD LANE

MAYS LAKE TRIBUTARY

CONFLUENCE OF CONFLUENCE OF

CONCRETE WEIR BRIARWOOD DITCH

670 JORIE BOULEVARD 670

MCDONALDS SERVICE ROAD

CONFLUENCE WITH SALT CREEK

665 665

FLOOD PROFILES

GINGER CREEK (SCGC)

STONE WEIR 660 660

655 655

ELEVATION IN FEET (NGVD 29)

ROUTE 83 650 650

BRIARWOOD CENTRAL ROAD

SCGC5030 645 645 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 640 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCGC5001 SCGC5003 SCGC5006 SCGC5010 SCGC5011 SCGC5012 SCGC5014 SCGC5015 SCGC5017 SCGC5018 SCGC5019 SCGC5020 CROSS SECTION LOCATION 635 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK *DATA NOT AVAILABLE 95P 700 700

695 695

GABION WEIR

REGENT DRIVE

MIDWEST ROAD 690 SHEET PILE WEIR 690

685 685

CULVERT FLOOD PROFILES

GINGER CREEK (SCGC)

680 680

675 BAYBROOK LANE 675

ELEVATION IN FEET (NGVD 29)

CONFLUENCE OF LOMBARD TRIBUTARY

670 CONFLUENCE OF MIDWEST CLUB TRIBUTARY 670

SCGC5067 SCGC5068 SCGC5053 665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD

SCGC5041 50-YEAR FLOOD* 660 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCGC5031 SCGC5032 SCGC5033 SCGC5035 SCGC5036 SCGC5037 SCGC5038 SCGC5039 SCGC5040 SCGC5049 SCGC5050 SCGC5046 CROSS SECTION LOCATION 655 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK *DATA NOT AVAILABLE 96P DROP BOX

MYERS ROAD

BAYBROOK LANE

LIMIT OF DETAILED STUDY

CONFLUENCE OF HERITAGE OAKS TRIBUTARY

FLOOD PROFILES

GINGER CREEK (SCGC)

700 700

695 695

ELEVATION IN FEET (NGVD 29)

690 690

685 685 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 680 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCGC5047 SCGC5051 SCGC5045 CROSS SECTION LOCATION 675 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK *DATA NOT AVAILABLE 97P 690 690

685 685

680 KINGSTON DR 680

LIMIT OF DETAILED STUDY

CONFLUENCE WITH GINGER CREEK

675 675

FLOOD PROFILES

BRIARWOOD DITCH (SCGC)

670 670

665 665

ELEVATION IN FEET (NGVD 29)

660 660

655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCGC5043 SCGC5069 SCGC5073 CROSS SECTION LOCATION 645 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 98P 720

100-YEAR BACKWATER FROM GINGER CREEK 715

710

CONFLUENCE WITH GINGER CREEK 705

FLOOD PROFILES

HERITAGE OAKS TRIBUTARY 700 700

695 695

ELEVATION IN FEET (NGVD 29)

690 690

685 685 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 680 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL CROSS SECTION LOCATION

SCGC5044 675 0 200 400 600 800 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 99P ROYAL VALE DRIVE

LIMIT OF FLOODWAY

705 CONFLUENCE WITH GINGER CREEK 705

FLOOD PROFILES

LOMBARD TRIBUTARY (SCGC) 700 700

695 695

ELEVATION IN FEET (NGVD 29)

690 690

685 685 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 680 10-YEAR FLOOD* STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SCGC5054 SCGC5056 675 0 200 400 600 800 1000 1200

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 100P 100-YEAR BACKWATER FROM GINGER CREEK

685 685

680 CONCRETE WEIR CONCRETE WEIR 680

CONFLUENCE WITH GINGER CREEK 675 675

FLOOD PROFILES

MAYS LAKE TRIBUTARY (SCGC) 670 670

665 CONCRETE WEIR 665

ELEVATION IN FEET (NGVD 29)

660 660

655 655 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 650 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL CROSS SECTION LOCATION

SCGC5071 SCGC5028 SCGC5026 645 0 500 1000 1500 2000 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 101P 720 720

715 715

CONCRETE WEIR

OAK BROOK ROAD

710 MAYS LAKE II WEIR 710

LIMIT OF FLOODWAY

LIMIT OF DETAILED STUDY

705 705

FLOOD PROFILES

MAYS LAKE TRIBUTARY (SCGC) 700 700 CULVERT

695 695

ELEVATION IN FEET (NGVD 29) CULVERT

690 690

685 685 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD

SCGC5058 50-YEAR FLOOD* 680

MAYS LAKE I CULVERT 10-YEAR FLOOD*

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL CROSS SECTION LOCATION

SCGC5057 675 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 102P OAK BROOK ROAD

LIMIT OF DETAILED STUDY

CONFLUENCE WITH GINGER CREEK

710 710

FLOOD PROFILES

705 705 MIDWEST CLUB TRIBUTARY (SCGC)

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD* 685 10-YEAR FLOOD* STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SCGC5066 SCGC5065 SCGC5064 SCGC5063 SCGC5062 SCGC5061 680 0 500 1000 1500 2000 2500 3000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH GINGER CREEK 103P

3.5.5 Oak Brook Tributary (SCOB)

3.5.5.1 Tributary Description

Oak Brook Tributary (previously known as Spring Road Tributary) is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Oak Brook Tributary Watershed covers approximately 1.18 square miles (758 acres). This watershed includes parts of the Villages of Oak Brook, Oak Brook Terrace, and areas in unincorporated York Township. Oak Brook Tributary flows into the main channel of Salt Creek 2,650 feet downstream of Roosevelt Road, and 4,020 feet upstream of Harger Road.

Oak Brook Tributary finds its origins at the Luther Avenue detention basin, which drains 18.3 acres of primarily residential headwaters. The basin exits southeast through a 24” pipe connected to Lake Yelenich and a private pond. These shallow ponds are the beginning of a series of linked, west-to-east, man-made ponds that back-up to businesses on the south and to residential properties on the north. The length of the ponds from Lake Yelenich / Private Pond to the culvert at Renaissance Boulevard is approximately 1330 station feet. Once water passes through the Renaissance Boulevard culvert, it is routed through a small open area before entering a southeasterly-directed conduit to pass underneath the Staybridge Suites parking lot. Oak Brook Tributary then opens into a detention area sandwiched between Butterfield Road to the south, Terrace Boulevard to the north and east and Renaissance Boulevard to the west. Water exits this detention facility (given the name of Terrace Blvd. Pond) through an 1877 ft long 36” conduit that crosses Butterfield Road, winds around businesses and parking lots, and ends at a small detention basin west of Midwest Road and south of Butterfield Road. Oak Brook Tributary then proceeds east through a 405 ft long 48” modified conduit under Midwest Road, and daylights in a ditch for 5 ft. The stream continues through a 168 ft long 66” diameter conduit and a 195 ft long 4x7 box conduit that flows under businesses and parking lots, exiting approximately 460 ft upstream of Eisenhower Road. Oak Brook Tributary then flows in an easterly, serpentine manner through culverts at Eisenhower Road, McArthur Drive, Karban Road, and a pedestrian path before opening up to form the Oak Brook Terrace Park District Headquarters pond. At the eastern end of the pond, the channel resumes its course to the northeast passing underneath the Oak Brook Terrace Park District Entrance. Maintaining this northeast course, the Oak Brook Tributary passes through culverts at Hodges Road, Illinois State Route 83, Oak Brook Center (OBC) West Entrance, and OBC Northwest Entrance. Oak Brook Tributary flows over a weir structure and through culverts at OBC Northeast Entrance Drive and Spring Road. The confluence of Oak

Section printed 29 April 2004

Brook tributary and Salt Creek is approximately 280 ft downstream of the Spring Road culvert.

The long and thin watershed that defines Oak Brook Tributary can be best described by its land use characteristics adjacent to the stream itself. Oak Brook Tributary is heavily developed in the downstream reaches. The first 4,800 ft of stream, starting at the confluence of Oak Brook Tributary with Salt Creek, is retail, highly commercial, and has large impervious roadway surfaces. The next 4,400 ft of stream is flanked by older residential developments. The remaining ~5200 ft of stream returns to a business land use with intermittent high density residential.

3.5.5.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Oak Brook Tributary.

Peak flows for the 10-, 50-, 100-, and 500-year floods were determined for Oak Brook Tributary by the ISWS in accordance with the USGS report Technique for Estimating Magnitude and Frequency of Floods in Illinois (U.S. Department of the Interior, 1977). This report described a technique for estimating flood magnitudes at recurrence intervals ranging from 2 to 500 years, for unregulated rural streams in Illinois, having drainage areas ranging from 0.002 to 10,000 square miles. The independent variables, drainage area, slope, rainfall intensity, and an aerial factor were used to define the flood-frequency relationship. In addition, a provision included allowed for weighting the estimate to an existing gage record. The discharges used in this study were determined by the SCS and the ISWS and were approved by the DOWR.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCOB.1.

Table SCOB.1: Oak Brook Tributary Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Oak Brook Tributary - at mouth 1.25 320 440 481 565 - just u/s of Route 83 0.82 265 365 395 465

3.5.5.3 Hydraulic Analysis

Section printed 29 April 2004

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for the backwater analyses of Oak Brook Tributary were obtained by field surveys during October 1977. At this time, the ISWS crew conducting the fieldwork also obtained elevation data and structural geometry for the bridges on each creek.

Water-surface elevations on Oak Brook Tributary for all designated recurrence intervals, were computed through use of the USACE HEC-2 step-backwater computer program (USACE, 1976). Elevations for the approximate flooding areas were determined by field inspection. The 100- year flood elevations and resulting floodplains, floodways, and profiles were computed by the ISWS and reported in a January 1980 flood study of Salt Creek and its tributaries (Illinois Department of Transportation, 1980).

Starting water-surface elevations for Oak Brook Tributary were taken from the Salt Creek profiles for the corresponding recurrence intervals.

Channel roughness factors (Manning’s “n”) used in the hydraulic computations of Oak Brook Tributary were selected by engineering judgment and from field observations of the stream and floodplain areas. The factors were chosen to be consistent with commonly reported values (Dougherty, R. L, 1977; Chow, V. T., 1964; Chow, V. T., 1959). For further information refer to Table SCOB.2.

Table SCOB.2: Oak Brook Tributary Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Oak Brook Tributary 0.025 - 0.050 0.075

3.5.5.4 Flood Boundaries

To reference the flood boundaries for Oak Brook Tributary, see Map Panels: 0605 and 0606.

Section printed 29 April 2004

3.5.5.5 Floodways

The floodways for Oak Brook Tributary were taken directly from the Illinois Department of Transportation study of Salt Creek (Illinois Department of Transportation, 1980).

Please reference attached Floodway Data Tables for further information.

3.5.5.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Road Tributary (SCOB) SCOB0001 527 1 285 895 0.5 661.0 661.0 661.1 0.1 SCOB0002 1,276 1 42 210 2.3 661.1 661.1 661.2 0.1 SCOB0003 2,011 1 31 128 3.8 662.5 662.5 662.6 0.1 SCOB0004 2,188 1 28 101 4.8 663.8 663.8 663.9 0.1 SCOB0005 2,888 1 65 215 2.2 666.7 666.7 666.8 0.1 SCOB0006 3,300 1 35 132 3.7 668.2 668.2 668.3 0.1 SCOB0007 3,550 1 149 459 1.0 671.1 671.1 671.1 0.0 SCOB0008 3,852 1 226 414 1.0 671.2 671.2 671.2 0.0 SCOB0009 4,050 1 206 410 1.0 671.3 671.3 671.3 0.0 SCOB0010 4,269 1 159 280 1.4 671.7 671.7 671.7 0.0 SCOB0011 4,537 1 142 288 1.6 672.8 672.8 672.8 0.0 SCOB0012 4,830 1 200 455 0.8 672.9 672.9 672.9 0.0 SCOB0013 5,713 1 15 39 10.1 676.8 676.8 676.8 0.0 SCOB0014 6,716 1 80 341 1.2 684.6 684.6 684.7 0.1 SCOB0015 7,224 1 30 124 3.2 685.2 685.2 685.3 0.1 SCOB0016 7,800 1 190 653 0.6 685.4 685.4 685.5 0.1 SCOB0017 8,353 1 280 766 0.4 686.2 686.2 686.3 0.1

1 In feet above confluence with Salt Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SPRING ROAD TRIBUTARY (SCOB) 685 685

PARK ROAD

SPRING ROAD

ACCESS ROAD

HODGES ROAD

ACCESS ROAD 680 STATE ROUTE 83 680

CONFLUENCE WITH SALT CREEK

675 675

FLOOD PROFILES

670 670 SPRING ROAD TRIBUTARY (SCOB)

665 KARBAN ROAD 665

ELEVATION IN FEET (NGVD 29)

660 660

SCOB0013 655 655 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCOB0001 SCOB0002 SCOB0003 SCOB0004 SCOB0005 SCOB0006 SCOB0007 SCOB0008 SCOB0009 SCOB0010 SCOB0011 SCOB0012 CROSS SECTION LOCATION 645 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 104P 705 705

MIDWEST ROAD

700 EISENHOWER ROAD 700

MACARTHUR DRIVE

LIMIT OF DETAILED STUDY

695 695

CULVERT

FLOOD PROFILES

690 690 SPRING ROAD TRIBUTARY (SCOB)

685 685

ELEVATION IN FEET (NGVD 29)

680 680

675 675 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCOB0014 SCOB0015 SCOB0016 SCOB0017 CROSS SECTION LOCATION 665 6500 7000 7500 8000 8500 9000 9500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 105P

3.5.6 Spring Brook Creek (SCSB)

3.5.6.1 Tributary Description

Spring Brook is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Spring Brook watershed covers approximately 14.7 square miles (9408 acres). This watershed includes parts of the Villages of Itasca, Bloomingdale, Addison, Roselle, Elk Grove Village and Schaumburg and areas in unincorporated Addison and Bloomingdale Townships. Spring Brook discharges into Salt Creek between Thorndale Avenue and the CMSPP (Metra) Railroad.

The mainstem of Spring Brook begins in the Village of Schaumburg in an industrial park located north of the Elgin-O’Hare Expressway and west of Roselle Road. Spring Brook flows south into the Village of Roselle to the Meacham Grove Forest Preserve northeast of Bloomingdale Road and Lake Street. From there, Spring Brook flows east into Lake Kadijah. From the outlet of Lake Kadijah, Spring Brook flows generally northeast through Itasca and then the Itasca Country Club before discharging into Salt Lake Creek approximately 2000 feet north of the CMSPP railroad.

Spring Brook has two major tributaries and several minor tributaries. The major tributaries are Meacham Creek which joins Spring Brook at Lake Kadijah and Unnamed Tributary No. 1 to Spring Brook which meets Spring Brook in the Meacham Grove Forest Preserve. Meacham Creek flows from north to south parallel to Meacham/Medinah Road. It begins at a detention pond located south of Virginia Drive in Elk Grove Village. It flows south through the wetlands adjacent to the Elgin-O’Hare Expressway and then through a culvert under Medinah Road. South of Thorndale Avenue it flows into the Medinah Country Club where it eventually discharges into Lake Kadijah.

Unnamed Tributary No. 1 to Spring Brook is not very long but it has a large drainage area in the Village of Bloomingdale. It is mostly contained in storm sewers until it becomes an open channel north of Lake Street and east of Rosedale Avenue.

3.5.6.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Spring Brook Creek and Meacham Creek.

Peak flows for the 10-, 50-, 100-, and 500-year floods on Spring Brook Creek and the West Branch Tributary Spring Brook Creek were computed using the TR-20 computer program (U.S. Department of Agriculture, 1965) with data furnished by the SCS. Discharges for this study were coordinated with the ISWS and approved by the IDWR.

Section printed 29 April 2004

Discharges for the 10-year, 50-year, and 100-year floods for Meacham Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

For Meacham Creek, a gauging station on Salt Creek located about 20 miles downstream of Itasca was one source of data for defining discharge- frequency relationships. This gage has been operated since 1945. A gauging station on Meacham Creek at Medinah in the northwest part of Itasca was used in defining discharge-frequency relationships. This gage was operated from 1953-1972. Values of the 10-, 50-, and 100-year peak discharges were obtained from a log-Pearson Type III distribution of annual peak flow data (U.S. Water Resources Council Hydrologic Committee, 1976). However, much channel work has been performed on Salt Creek and rapid urbanization of the watershed has occurred during the operation period of the stream gages, especially in the past 10 years. The effect of these changes has not been adequately recorded. Water from large floods has overflowed into a quarry about 10 miles upstream of the gage. Therefore, peak discharge-drainage area relationships were developed from a combination of historic flood data and unit hydrograph rainfall-runoff relationships. Flood routing was done with the “SCS-TR- 20 Project Formulation Computer Program” (U.S. Department of Agriculture, 1974). Linear regression analysis was used to determine the 10-, 50-, and 100-year peak discharges as a function of the drainage area at any given cross section. The 500-year peak discharge was determined by a log-log extrapolation of peak discharges computed for frequencies up to 100 years. The peak discharges obtained were substantiated by regional flood flow equations for northeastern Illinois.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCSB.1.

Table SCSB.1: Spring Brook Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Spring Brook Creek - approximately 1,716 ft u/s of Route 53 12.0 642 1,040 1,264 1,800 - at mouth 14.4 493 880 1,090 1,650

- at Medinah Road 6.55 518 790 910 1,208

Section printed 29 April 2004

- at Circle Avenue 4.97 408 614 704 926 - at Foster Avenue 2.60 197 296 340 446

Meacham Creek - at Lake Kadijah 5.10 192 283 325 426 - at Thorndale Avenue 3.60 115 195 235 328

West Branch Tributary to Spring Brook Creek - at Roselle Road 1.50 124 186 211 275

3.5.6.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for the backwater analyses of Spring Brook Creek and the West Branch Tributary to Spring Brook Creek were obtained by field surveys during April-May 1979. At that time, the ISWS crew conducting the fieldwork also obtained elevation data and structural geometry for the bridges on each creek. Elevation data for portions of Spring Brook Creek were also provided by the SCS.

Cross-section and bridge data for Meacham Creek were obtained from field surveys by the Illinois Division of Water Resources supplemented with field surveys by a contractor for the SCS. In some cases, these cross sections were extended using topographic maps with a 2-foot contour interval (Floodplain Topographic Maps, 1973).

Flood profiles on Spring Brook Creek and the West Branch Tributary to Spring Brook Creek for the 10-, 50-, 100-, and 500-year floods were computed by the ISWS with the SCS WSP-2 step-backwater program (Wight Consulting Engineers, Inc., 1978); the necessary input information was supplied by SCS and the field surveys by ISWS.

Water-surface profiles for Meacham Creek were developed using the SCS “WSP-2 Water-Surface Profile Computer Program” (U.S. Department of

Section printed 29 April 2004

Agriculture, 1974). Profiles were determined for the 10-, 50-, 100-, and 500-year floods for all flooding sources.

Starting water-surface elevations on Spring Brook Creek for all designated recurrence intervals were determined from downstream profiles of Spring Brook Creek. Starting water-surface elevations for the West Branch Tributary Spring Brook Creek were taken from profiles of the mainstem Spring Brook Creek.

Starting elevations for Meacham Creek were taken from previously published data (Des Plaines River Steering Committee, 1975).

Channel roughness factors (Manning’s “n”) used in the hydraulic computations, for Spring Brook Creek and West Branch Tributary Spring Brook Creek were selected on the basis of field inspection of floodplain areas. The factors were chosen to be consistent with commonly reported values (U.S. Department of Agriculture, 1965; Chow, V. T., 1964; Chow, V. T., 1959). Refer to Table SCSB.2 for further details.

Valley and channel roughness coefficients for Meacham Creek were determined from field observations, USGS’ “Water Supply Paper 1849” (U.S. Department of the Interior, 1967), and the SCS’ “Guide for Selecting Roughness Coefficients” (U.S. Department of Agriculture, 1963). Refer to Table SCSB.2 for further details

Table SCSB.2: Spring Brook Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Spring Brook Creek 0.035 - 0.070 0.035 - 0.100 - Meacham Creek 0.045 - 0.065 0.065 - 0.085 - West Branch Tributary to Spring Brook Creek 0.040 - 0.050 0.040 - 0.120

3.5.6.4 Flood Boundaries

To reference the flood boundaries for Spring Brook Creek, see Map Panels: 0202, 0203, 0205, 0206, 0301, 0302 and 0304.

3.5.6.5 Floodways

Section printed 29 April 2004

Please reference attached Floodway Data Tables for further information.

3.5.6.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Brook Creek (SCSB) SCSB0001 528 1 1,265 8,846 0.1 680.6 680.6 680.7 0.1 SCSB0002 1,478 1 969 4,487 0.3 680.6 680.6 680.7 0.1 SCSB0003 1,795 1 1,280 4,830 0.2 680.6 680.6 680.7 0.1 SCSB0004 3,590 1 336 1,360 0.8 681.2 681.2 681.3 0.1 SCSB0005 5,772 1 123 617 1.9 683.0 683.0 683.1 0.1 SCSB0006 6,372 1 234 1,400 0.9 683.1 683.1 683.2 0.1 SCSB0007 7,047 1 155 881 1.4 686.1 686.1 686.2 0.1 SCSB0008 7,531 1 418 1,505 0.8 686.7 686.7 686.8 0.1 SCSB0009 7,951 1 327 1,847 0.7 686.8 686.8 686.9 0.1 SCSB0010 10,457 1 245 1,132 1.1 687.8 687.8 687.9 0.1 SCSB0011 12,929 1 430 1,801 0.7 688.2 688.2 688.3 0.1 SCSB0012 14,236 1 540 1,277 1.0 688.9 688.9 689.0 0.1 SCSB0013 16,116 1 130 2,310 0.6 689.6 689.6 689.7 0.1 SCSB0014 18,338 1 270 2,397 0.4 703.6 703.6 703.7 0.1 SCSB0015 20,359 1 185 1,285 0.7 704.3 704.3 704.4 0.1 SCSB0016 23,456 1 204 2 654 1.1 704.9 704.9 705.0 0.1 SCSB0017 23,719 1 230 2 707 1.0 705.5 705.5 705.6 0.1

1 In feet above confluence with Salt Creek

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SPRING BROOK CREEK (SCSB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Brook Creek (SCSB) SCSB0018 24,158 1 100 2 508 1.4 706.1 706.1 706.2 0.1 SCSB0019 24,358 1 100 2 180 4.0 706.4 706.4 706.5 0.1 SCSB0020 24,497 1 155 2 475 1.5 708.0 708.0 708.1 0.1 SCSB0021 24,660 1 46 185 3.9 708.4 708.4 708.5 0.1 SCSB0022 24,821 1 270 2 1,123 0.6 708.8 708.8 708.9 0.1 SCSB0023 26,143 1 29 151 4.7 711.5 711.5 711.6 0.1 SCSB0024 26,268 1 187 2 592 1.2 714.2 714.2 714.3 0.1 SCSB0025 26,500 1 363 2 1,092 0.6 714.3 714.3 714.4 0.1 SCSB0026 26,780 1 125 275 2.5 715.1 715.1 715.2 0.1 SCSB0027 26,968 1 163 346 2.0 715.5 715.5 715.6 0.1 SCSB0028 27,049 1 188 2 759 0.9 716.5 716.5 716.6 0.1 SCSB0029 27,376 1 140 711 1.0 716.6 716.6 716.7 0.1 SCSB0030 27,644 1 247 880 0.8 716.6 716.6 716.7 0.1 SCSB0031 28,805 1 105 282 2.4 718.0 718.0 718.1 0.1 SCSB0032 29,716 1 143 2 371 1.8 719.4 719.4 719.5 0.1 SCSB0033 30,153 1 296 2 718 0.6 719.5 719.5 719.6 0.1 SCSB0034 30,376 1 204 2 643 0.6 719.6 719.6 719.7 0.1

1 In feet above confluence with Salt Creek

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SPRING BROOK CREEK (SCSB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Brook Creek (SCSB) SCSB0035 30,801 1 70 185 2.0 720.4 720.4 720.5 0.1 SCSB0036 31,440 1 348 2 415 0.8 720.8 720.8 720.9 0.1 SCSB0037 32,372 1 97 2 140 2.4 723.9 723.9 724.0 0.1 SCSB0038 32,647 1 700 2 140 2.4 723.9 723.9 724.0 0.1 SCSB0039 32,783 1 100 2 236 1.4 724.7 724.7 724.8 0.1 SCSB0040 33,089 1 53 2 123 2.7 726.0 726.0 726.1 0.1 SCSB0041 33,322 1 33 136 2.4 729.3 729.3 729.4 0.1 SCSB0042 33,527 1 30 86 3.6 729.6 729.6 729.7 0.1 SCSB0043 34,086 1 71 2 130 1.9 730.8 730.8 730.9 0.1 SCSB0044 35,016 1 65 2 107 2.2 734.7 734.7 734.8 0.1 SCSB0045 35,455 1 22 58 4.1 738.0 738.0 738.1 0.1 SCSB0046 35,661 1 43 140 1.7 742.0 742.0 742.1 0.1 SCSB0047 36,025 1 40 136 1.8 743.4 743.4 743.5 0.1 SCSB0048 36,226 1 64 203 1.2 744.5 744.5 744.6 0.1 SCSB0049 36,605 1 27 91 2.6 745.1 745.1 745.2 0.1 SCSB0050 36,816 1 63 177 1.4 747.2 747.2 747.3 0.1 SCSB0051 37,365 1 49 89 2.4 748.4 748.4 748.5 0.1

1 In feet above confluence with Salt Creek

1 In feet above confluence with Spring Brook Creek

1 In feet above confluence with Spring Brook Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS MEACHAM CREEK (SCSB) N. PROSPECT AVENUE

CONFLUENCE WITH SALT CREEK

FLOOD PROFILES

SPRING BROOK CREEK (SCSB) 690 690

680 680

ELEVATION IN FEET (NGVD 29)

670 670

SCSB0005 SCSB0006 660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0001 SCSB0002 SCSB0003 SCSB0004 CROSS SECTION LOCATION 640 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 106P RAILROAD

MAPLE AVENUE

ROUTE 19 (IRVING PARK BLVD)

INTERSTATE 290 (NORTHBOUND)

INTERSTATE 290 (SOUTHBOUND)

FLOOD PROFILES

SPRING BROOK CREEK (SCSB)

690 690

ELEVATION IN FEET (NGVD 29)

680 680

SCSB0011 670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0007 SCSB0008 SCSB0009 SCSB0010 CROSS SECTION LOCATION 650 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 107P LAKE KADIJAH SPILLWAY

CONFLUENCE OF MEACHAM CREEK

FLOOD PROFILES

SPRING BROOK CREEK (SCSB) 710 710

700 700

ELEVATION IN FEET (NGVD 29)

690 690

SCSB0014 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0012 SCSB0013 CROSS SECTION LOCATION 660 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 108P MEDINAH ROAD

LAKEVIEW DRIVE

MEDINAH-ON-THE-LAKE ROAD

FLOOD PROFILES

SPRING BROOK CREEK (SCSB) 720 720

710 710

ELEVATION IN FEET (NGVD 29)

700 700

SCSB0021 SCSB0022 690 SCSB0020 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0015 SCSB0016 SCSB0017 SCSB0018 SCSB0019 CROSS SECTION LOCATION 670 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 109P FARM ROAD

GRAVEL ROAD

CIRCLE AVENUE

TO SPRING BROOK CREEK

CONFLUENCE OF WEST BRANCH TRIBUTARY

FLOOD PROFILES

SPRING BROOK CREEK (SCSB) 730 730

720 720

ELEVATION IN FEET (NGVD 29)

710 710

SCSB0036 SCSB0037 700 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSB0024 SCSB0028 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0023 SCSB0025 SCSB0026 SCSB0027 SCSB0029 SCSB0030 SCSB0031 SCSB0032 SCSB0033 SCSB0034 SCSB0035 CROSS SECTION LOCATION 680 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 110P PRIVATE DRIVE ROSELLE ROAD

FOSTER AVENUE

TURNER AVENUE 760 WALNUT STREET 760

BRYN MAWR AVENUE

750 750

FLOOD PROFILES

SPRING BROOK CREEK (SCSB) 740 740

730 730

ELEVATION IN FEET (NGVD 29)

720 720

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSB0039 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0038 SCSB0040 SCSB0041 SCSB0042 SCSB0043 SCSB0044 SCSB0045 SCSB0046 SCSB0047 SCSB0048 SCSB0049 SCSB0050 SCSB0051 CROSS SECTION LOCATION 690 32500 33000 33500 34000 34500 35000 35500 36000 36500 37000 37500 38000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 111P HILL STREET

ELM AVENUE

PINE AVENUE

MAPLE AVENUE

WILLOW STREET

800 CENTRAL AVENUE 800

LIMIT OF DETAILED STUDY

790 790

FLOOD PROFILES

CULVERT SPRING BROOK CREEK (SCSB) 780 780 CULVERT

770 770

ELEVATION IN FEET (NGVD 29)

760 760

CULVERT

750 750 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSB0054 50-YEAR FLOOD 740 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0052 SCSB0053 SCSB0055 SCSB0056 SCSB0057 SCSB0058 SCSB0059 CROSS SECTION LOCATION 730 38000 38500 39000 39500 40000 40500 41000 41500 42000 42500 43000 43500 44000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 112P 755 755

750 750

745 MAPLE AVENUE 745

BLOOMINGDALE ROAD

LIMIT OF DETAILED STUDY

CONFLUENCE WITH SPRING BROOK CREEK

740 740

FLOOD PROFILES

735 735

CULVERT

730 730 WEST BRANCH TRIBUTARY TO SPRING BROOK CREEK (SCSB)

ELEVATION IN FEET (NGVD 29)

725 725

720 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSB0066 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0060 SCSB0061 SCSB0062 SCSB0063 SCSB0064 SCSB0065 SCSB0067 SCSB0068 CROSS SECTION LOCATION 710 0 500 1000 1500 2000 2500 3000 3500 4000 4500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SPRING BROOK CREEK 113P 720 720

715 715

COUNTRY CLUB ROAD

LAKE KADIJAH MEDINAH MOUTH

CONFLUENCE WITH SPRING BROOK CREEK 710 710

FLOOD PROFILES

MEACHAM CREEK (SCSB)

705 705

700 700

ELEVATION IN FEET (NGVD 29)

BOULEVARD

IRVING PARK 695 695

SCSB0071 690 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 685 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0069 SCSB0070 CROSS SECTION LOCATION 680 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SPRING BROOK CREEK 114P RAILROAD

MAPLE AVENUE 725 MEDINAH ROAD 725

THORNDALE AVENUE

LIMIT OF DETAILED STUDY

720 720

FLOOD PROFILES

MEACHAM CREEK (SCSB)

715 715

710 710

ELEVATION IN FEET (NGVD 29)

705 705

700 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSB0072 SCSB0073 SCSB0074 SCSB0075 SCSB0076 CROSS SECTION LOCATION 690 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SPRING BROOK CREEK 115P

3.5.7 Sugar Creek (SCSU)

3.5.7.1 Tributary Description

Sugar Creek is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Sugar Creek Watershed covers approximately 4.06 square miles (2598 acres). This watershed includes parts of the City of Villa Park, the City of OakBrook Terrace, the Village of Lombard, and unincorporated York Township. Sugar Creek flows into the main channel of Salt Creek at approximately 3,500 feet upstream of Illinois Route 56 (Butterfield Road) and approximately 13,000 feet downstream of Illinois Route 64 (North Avenue).

Tributary Number 4 drains approximately 0.21 square miles of area in the southwestern extent of the Sugar Creek watershed. The channel in this reach consists of segments of roadside drainage ditches and backyard swales contributing to the formation of a short channel segment just upstream of the High Point Center Ponds. The mapped portion of the channel begins just north of 15th Place. The channel flows north through a culvert under an entrance into an apartment complex and continues north for approximately 1000 feet to the confluence with the mainstem channel at High Point Center Ponds. Land use in this reach is predominately residential with some light commercial uses.

Tributary Number 3 drains approximately 0.37 square miles of area in the southern portion of the Sugar Creek watershed. The reach begins at a detention pond within Montini Park located just north of 16th Street. Flowing north from the pond outlet structure, the thick grass channel continues through culverts under 14th Street and 13th Street. Flow is then restricted by a berm constructed in park property just upstream of 13th Street. Water backs up in the open park space on both sides of 13th Street. After passing through the berm culverts, flow continues through a forested reach approaching a culvert under Roosevelt Road. The reach then continues through a thick-grassed channel for approximately 1,180 feet to the confluence with the mainstem channel at Old Grove Ponds. Land use in the reach is primarily residential with inclusions of light commercial and park uses.

Tributary Number 2 drains approximately 0.26 square miles of area in the southeastern extent of the Sugar Creek Watershed. The channel in this reach consists of segments of roadside drainage ditches, storm sewers, and backyard swales contributing to the formation of a channel approximately 1,000 feet upstream of Roosevelt Road at the outfall of a storm sewer segment. The mapped portion of the channel begins approximately 500 feet south of Roosevelt Road. The channel flows north through a dense

Section printed 29 April 2004

grass ditch to the south side of Roosevelt Road. The channel then enters approximately 900 linear feet of closed conduit passing under a commercial shopping center north of Roosevelt Road. Flow leaving the conduit continues through a thick grass channel segment for approximately 600 feet to the confluence with the mainstem channel. Land use in the reach is a combination of commercial and multiple-family residential.

The mainstem channel of Sugar Creek, including contributions from its tributaries, drains a total of 4.06 square miles. A series of roadside ditches and backyard swales drain into a storm sewer segment in the southwestern extent of the watershed. The mainstem channel begins at the outfall of this storm sewer, approximately 500 feet downstream of Highland Avenue. The channel continues east to a pair of 30-inch diameter culverts under Grace Street. The area between Grace Street and Roosevelt Road consists of a pair of ponds connected by a 30-inch diameter culvert that have been modified for flood storage. Tributary No. 4 joins the mainstem channel at the southwestern edge of the western pond. Flow leaves the eastern pond through a 42-inch diameter culvert under Roosevelt Road. Flow continues north in a confined thick grass channel through a commercial area for approximately 150 feet to a 48-inch diameter culvert controlling flow into the on-line ponds upstream of Fairview Avenue. Tributary No. 3 joins the mainstem channel at the southern edge of the series of ponds. Flow continues east for approximately 3,070 linear feet through a thick grass channel that passes through four similar road crossing culverts at Fairview Avenue, Ahrens Avenue, School Street, and Westmore Avenue. Downstream of Westmore Avenue, the channel enters a meandering segment of typically short turf grass channel for approximately 2,420 linear feet through the Willowbrook High School property to Riordan Road. A series of four similar elliptical culverts are located in the channel segment at pedestrian path crossings on the High School property. Tributary No. 2 joins the mainstem channel approximately 580 feet upstream of Riordan Road. The area between Riordan Road and Ardmore Avenue consists of a short grass channel with a broad floodplain. Just upstream of Ardmore Avenue, the channel enters a short, steep segment entering the 12’ x 6’ box culvert crossing the road. The channel continues northeast for approximately 1,045 feet through a confined grass channel to a box culvert crossing at Harrison Street. Flow continues northeast through a concrete lined trapezoidal channel between Harrison Street and Summit Avenue. At Summit Avenue, flow enters a segment of closed conduit from Summit Avenue to Cross Street of approximately 1,080 feet in length. Tributary No. 1 joins the mainstem channel through a storm sewer outlet located at the downstream face of the conduit reach. Flow exits the closed conduit to the east into a short grass channel for approximately 766 feet to the triple-box culvert crossing at Villa Avenue. From Villa Avenue, flow enters the Sugar Creek Golf

Section printed 29 April 2004

Course. Flowing east for 260 feet through short grass at the edge of the property, the channel enters a segment of 1,310 linear feet of sheet pile lined channel that extends one to two feet above the normal water line. The sheet pile lining ends at a weir on the golf course property approximately 600 feet upstream of Illinois Route 83. The channel segment from the weir east to the triple-box culvert crossing Illinois Route 83 consists of a thick grass overbank. From Illinois Route 83, the thick- grassed channel continues east for approximately 310 feet to the triple-box culvert under Riverside Drive. From Riverside Drive, the channel continues east for approximately 650 feet through a steep thick grass approach to the confluence with the main channel of Salt Creek.

3.5.7.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Sugar Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Sugar Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Peak flows for the 10-, 50-, 100-, and 500-year floods on Sugar Creek were computed using the Soil Conservation Service (SCS) “Technical Release No. 20” (U.S. Department of Agriculture, 1965).

Peak flows for the 10-, 50-, 100-, and 500-year floods on Sugar Creek Tributary A were computed by the Illinois State Water Survey in accordance with the USGS report, Technique for Estimating Magnitude and Frequency of Floods in Illinois (U.S. Department of the Interior, 1977). This report describes a technique for estimating flood magnitudes at recurrence intervals ranging from 2 to 500 years, for unregulated rural streams in Illinois, having drainage areas ranging from 0.002 to 10,000 square miles. The independent variables – drainage area, slope, rainfall intensity, and an aerial factor – are used to define the flood frequency relationship. In addition, a provision included allows for weighting the estimate to an existing gage record. The discharges used in this study were coordinated with the Illinois State Water Survey and approved by the Illinois Division of Water Resources.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCSU.1.

Table SCSU.1: Sugar Creek Summary of Discharges

Section printed 29 April 2004

Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Sugar Creek - at confluence with Salt Creek 4.10 650 890 966 1,143 - at Villa Avenue 3.65 570 780 850 1,000 - at State Route 83 1.58 400 542 596 700

Sugar Creek Tributary A - at Villa Park Southern corporate limits 0.31 205 265 290 335

3.5.7.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross sections for Sugar Creek were obtained from topographic maps (USDA, SCS, 1975).

Cross-section data for the backwater analysis of Sugar Creek Tributary A were obtained by field surveys during September 1977. At this time, the Illinois State Water Survey crew conducting the fieldwork also obtained elevation data and structural geometry for all bridges on the creek.

Water-surface elevations for Sugar Creek were computed using the USACE HEC-2 step-backwater computer program (USACE, 1991). Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence intervals.

Starting water-surface elevations for Sugar Creek were taken from the Salt Creek profiles for the corresponding recurrence intervals.

Water-surface elevations on Sugar Creek Tributary A for all designated recurrence intervals were computed through use of the USACE HEC-2 step-backwater computer program (USACE, November 1976).

Roughness factors (Manning’s “n”) used in the hydraulic computations for Sugar Creek and Sugar Creek Tributary A were chosen by engineering judgment and were based on field inspections of the streams and

Section printed 29 April 2004

floodplain areas. The factors were chosen to be consistent with commonly reported values (Chow, V. T., 1964; Chow, V. T., 1959). Refer to Table SCSU.2 for further details.

Table SCSU.2: Sugar Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Sugar Creek 0.015 - 0.042 0.055 - 0.065 - Sugar Creek Tributary A 0.020 - 0.042 0.060

3.5.7.4 Flood Boundaries

To reference the flood boundaries for Sugar Creek, see Map Panels: 0602, 0604, 0605 and 0606.

3.5.7.5 Floodways

The floodway for Sugar Creek Tributary A was determined using the HUD- 15 computer program (U.S. Department of Agriculture, 1977). A portion of the floodway for Salt Creek lies outside the corporate limits of Village of Villa Park.

Please reference attached Floodway Data Tables for further information.

3.5.7.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with Salt Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SUGAR CREEK (SCSU) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Sugar Creek Tributary A (SCSU) SCSU0011 57 1 49 157 1.9 688.2 687.9 2 688.0 0.1 SCSU0012 564 1 51 162 1.8 688.4 688.4 688.5 0.1 SCSU0013 1,677 1 106 201 1.4 704.4 704.4 704.5 0.1 SCSU0014 1,911 1 40 106 2.7 704.5 704.5 704.6 0.1

1 In feet above confluence with Sugar Creek

2 Elevation computed without consideration of backwater effects from Sugar Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SUGAR CREEK TRIBUTARY A (SCSU) 685 100-YEAR BACKWATER FROM SALT CREEK

680

S. VILLA AVENUE

RIVERSIDE DRIVE

FRONTAGE ROAD SUMMIT AVENUE

STATE ROUTE 83/ 675 S. EUCLID AVENUE

ROBERT KINGERY HIGHWAY

CONFLUENCE WITH SALT CREEK

670 670

FLOOD PROFILES

SUGAR CREEK (SCSU)

665 665

CULVERT

660 660

ELEVATION IN FEET (NGVD 29)

655 655

SCSU0004 650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

STREAM BED DUPAGE COUNTY, IL AND INCORPORATED AREAS

SCSU0001 SCSU0002 SCSC0003 CROSS SECTION LOCATION 640 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 131P 695 695

690 690

ARDMORE AVENUE 685 HARRISON STREET 685

680 680

FLOOD PROFILES

SUGAR CREEK (SCSU)

675 675

RIORDON ROAD

CONFLUENCE OF

SCHOOL CROSSING SCHOOL CROSSING 670 SCHOOL CROSSING 670

SCHOOL CROSSING

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

SUGAR CREEK TRIBUTARY A

665 665

660 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 655 10-YEAR FLOOD

STREAM BED DUPAGE COUNTY, IL AND INCORPORATED AREAS

SCSU0005 SCSU0006 SCSU0007 SCSU0008 SCSU0009 SCSU0010 CROSS SECTION LOCATION 650 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 132P 100-YEAR BACKWATER FROM SUGAR CREEK

710 710

705 705

CONFLUENCE WITH SUGAR CREEK

700 700

FLOOD PROFILES

695 695

SUGAR CREEK TRIBUTARY A (SCSU)

CULVERT

690 ROOSEVELT ROAD 690

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

SCSU0011 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCSU0012 SCSU0013 SCSU0014 CROSS SECTION LOCATION 670 0 200 400 600 800 1000 1200 1400 1600 1800 2000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SUGAR CREEK 133P

3.5.8 Westwood Creek (SCWC)

3.5.8.1 Tributary Description

Westwood Creek is a 3805-acre watershed that is tributary to Salt Creek. The communities that contribute watershed area to Westwood Creek are Addison, Lombard, Villa Park and Unincorporated DuPage County. The general land use characteristics are residential throughout, with less dense area on the extreme southwest and northwest sections of the watershed.

The Westwood South Branch drains the southern portion of the watershed, with the creek origins in the Fullerton Park Forest Preserve. Flow proceeds to the north, passing under Fullerton Avenue, entering an Addison park pond. The South Branch continues to the north, passing under Army Trail Road, entering the Addison Golf Club and merging with the Westwood Creek Main Stem.

The Westwood Creek Main Stem drains the northwestern section of the watershed. The uppermost sections of the watershed are residential, with some sections in conduit, but become open channel at the Army Trail Nature center just east of Lombard Avenue and north of Army Trail Road. The Main Stem travels east, crosses Pioneer Drive, Wesley Drive and N. Country Club Drive before entering the Addison Golf Club property. The Main Stem confluences with Westwood Creek South Branch in the golf course, and changes bearing to the northeast. The Main Stem crosses Mill Road, Lake Street, Highview Avenue, Lincoln Avenue, Rozanne Drive and Addison Road before confluencing with Salt Creek

3.5.8.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Westwood Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Westwood Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Flood frequency curves for Salt Creek and Westwood Creek were prepared for this study and are based on discharges calculated by the SCS. The SCS has completed a comprehensive flood management study of the Salt Creek watershed as part of the Chicago Metropolitan Area River Basin Plan. That study included detailed watershed modeling utilizing the SCS watershed model TR-20 (U.S. Department of Agriculture, 1974). It

Section printed 29 April 2004

is an advanced hydrologic model which accurately simulates the historical flood stage- and discharge-hydrographs. The model was used for a regional analysis of the entire watershed. The model included consideration of the Busse Woods and Kingery Detention Reservoirs. Elevation-capacity and outlet rating data were included in the model and were utilized in routing the hydrographs through the watershed. Estimates of flood discharge resulting from that study are the most current, and the 100-year discharges have been approved by the State of Illinois for use in the state’s floodplain regulation program. Data are located in the Illinois State Water Survey Floodplain Repository. Harza prepared additional hydrologic analyses which provided an independent review of the suitability of the results in concurrence with FIA’s guidelines. Discharges for the 100-, 50-, and 10-year floods were computed for Salt Creek and Westwood Creek by Harza using regional flood frequency equations for Illinois (Illinois Department of Transportation, 1979). The discharges determined for Salt Creek are higher than the historic discharges because they are based on conditions projected to exist in the year 2000. The Salt Creek discharges decrease moving downstream as a result of overbank storage. The calculated unit flood discharges were compared to those for neighboring watersheds. This review by Harza established that the flood discharges computed by the SCS using their TR-20 program and certified by the State of Illinois are suitable for use in this FIS. The SCS discharges for the 10-, 25-, and 100-year floods for the two streams were plotted on log-normal probability paper. The 50- and 500-year flood discharges were estimated by straight-line interpolation and extrapolation, respectively.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SCWC.1.

Table SCWC.1: Westwood Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Westwood Creek - South Branch - just d/s of Army Trail Road 3.60 68 102 111 220 - just d/s of control structure 3.40 65 99 108 217 - just d/s of Fullerton Avenue 2.60 171 282 323 438

Westwood Creek - - at confluence with

Section printed 29 April 2004

Salt Creek 5.62 371 550 648 860 - approximately 320 ft u/s of Lincoln Street 4.25 239 345 394 570 - at Lake Street 4.22 236 343 389 520 - approximately 200 ft d/s of Country Club 0.66 49 66 74 87

3.5.8.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross sections for the backwater analyses on Westwood Creek were field surveyed by the SCS. Cross-section data for Salt Creek were obtained from Regulation of Construction Within the Floodplain of Lower Salt Creek and Tributaries (Illinois Department of Transportation, 1980). Additional cross sections on the upper portion of Westwood Creek not included in the SCS studies were surveyed by Harza. Sections were located at close intervals above and below bridges and culverts in order to compute the significant backwater effects of these structures.

Water-surface elevations of floods for selected recurrence intervals were computed using hydraulic models for Westwood Creek prepared by the SCS. The models were developed using the SCS WSP-2 backwater program (U.S. Department of the Interior, 1963). The models involve a standard step-backwater computation procedure which estimates total energy at each stream cross section and accounts for friction losses between sections using Manning’s formula. The model requires discharge, stream channel and floodplain geometry, starting water-surface elevation, and roughness data to simulate flood flow conditions.

Starting water-surface elevations for Salt Creek were developed by the slope/area method. Starting elevations for Westwood Creek were determined from the Salt Creek hydraulic model.

Channel roughness factors for Westwood Creek were assigned on the basis of field inspection of floodplain areas and from previous studies by the SCS. Further information is available in Table SCWC.2

Table SCWC.2: Westwood Creek Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

- Westwood Creek 0.045 - 0.055 0.070 - 0.075 - Westwood Creek South Branch 0.035 - 0.075 0.035 - 0.075

3.5.8.4 Flood Boundaries

To reference the flood boundaries for Westwood Creek, see Map Panels: 0206, 0209, 0304, 0305, 0307, 0308 and 0601.

3.5.8.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.5.8.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with Salt Creek

2 Data shown are computed based on upstream cross section for conditions at approach to structure

1 In feet above confluence with Westwood Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SOUTH FORK OF WESTWOOD CREEK (SCWC) 695 695

MILL ROAD

LAKE STREET

ROZANNE DRIVE

N. ADDISON ROAD 690 HIGHVIEW AVENUE 690

N. LINCOLN AVENUE

OF WESTWOOD CREEK

LIMIT OF DETAILED STUDY

CONFLUENCE OF SOUTH FORK

CONFLUENCE WITH SALT CREEK

CULVERT 685 685

FLOOD PROFILES

WESTWOOD CREEK (SCWC)

680 680

CULVERT 675 675

COUNTRY CLUB DRIVE

ELEVATION IN FEET (NGVD 29)

CULVERT 670 670 CULVERT

CULVERT

665 SCWC0009 665 CULVERT LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCWC0002 SCWC0003 SCWC0004 SCWC0005 SCWC0006 SCWC0007 SCWC0008 CROSS SECTION LOCATION

SCWC0001 655 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SALT CREEK 134P ARMY TRAIL ROAD

FULLERTON AVENUE

CONTROL STRUCTURE

LIMIT OF DETAILED STUDY

CONFLUENCE WITH WESTWOOD CREEK

FLOOD PROFILES

695 695

SOUTH FORK OF WESTWOOD CREEK (SCWC)

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 SCWC0015 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SCWC0010 SCWC0011 SCWC0012 SCWC0013 SCWC0014 CROSS SECTION LOCATION 670 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WESTWOOD CREEK 135P

3.6 Sawmill Creek (SW)

3.6.1 Sawmill Creek Main Stem (SWSW)

3.6.1.1 Tributary Description

Sawmill Creek is a 6067-acre watershed that is tributary to the Des Plaines River. The communities that contribute watershed area to Sawmill Creek are Darien, Willowbrook, Downers Grove, Burr Ridge, Westmont and Unincorporated DuPage County. The general land use characteristics of the watershed can be delineated by I-55. On the north side of I-55 development is relatively dense with residential and commercial uses. On the south side of I-55 within Sawmill Creek watershed, development is very limited because Argonne National Laboratory and the Waterfall Glen Forest Preserve dominate the landscape.

Sawmill Creek has several brachial arms. The Northeasternmost branch is called Sawmill Creek East Branch. The East Branch begins, and most greatly affects, the Darien subdivision called Marion Hills. The headwaters begin on the north side of 67th Street. Flow procedes directly south, passing under 67th Street, 68th Street, 69th Street, Roger Road, Plainfield Road, Janet Avenue, Evans Place, and Elm Street. The East Branch exits the Marion Hills area and briefly flows through residential areas of Willowbrook passing underneath 75th Street, Midway Drive, Virginia Court and 79th Street. The East Branch enters unincorporated areas and passes under 60th Place and Clarendon Hills Road. The branch continues south to pass underneath I-55. The bearing of the stream changes to the southwest where the East Branch passes underneath Webster Avenue and Leonard Drive. West of Leonard Drive, the East Branch confluences with the Sawmill Creek Main Stem.

The Sawmill Creek West Branch begins within the City of Darien on the South side of Plainfield Road, west of Bailey Road. The branch enters Lake Darien and is released to the south passing under Lakeview Drive. Several hundred feet downstream, the West Branch flows under Joliet Road and I-55. On the downstream side of I-55, the West Branch enters Waterfall Glen Forest Preserve, confluences with Wards Creek and bears to the southeast. A few hundred feet downstream, the West Branch joins Main Stem Sawmill Creek.

Two branches, Tributary 1 and Tributary 3 are found within the Argonne National Laboratory. The southernmost of these branches is known as Freund Brook. Both branches flow from west to east, confluencing with the Sawmill Creek Main Stem on the eastern edge of Argonne National Laboratory.

Section printed 29 April 2004

Main Stem Sawmill Creek finds its headwaters within the City of Darien, just north of 75th Street and southeast of Plainfield Road. The Main Stem passes south through a slightly higher density residential that that seen for the East Branch. Main Stem waters proceed underneath 75th Street, Walnut Street, 79th Street and Portsmouth Drive. Flow turns to the southwest, passing flow under Nantucket Drive and Joliet Road. Flow assumes a southeast course and passes under I-55, confluencing with the East Branch shortly thereafter. The Main Stem changes bearing to the southwest, entering the Waterfall Glen Forest Preserve, passing under Cass Avenue and confluencing with the Sawmill Creek West Branch. The Main Stem proceeds in a serpentine fashion to the south through the Argonne National Laboratory, crossing Eastwood Drive and confluencing with Sawmill Creek Tributary No.1 (Freund Brook). Continuing through Argonne, the Main Stem passes underneath Freud Road and Bluff Road. The Main Stem undergoes a rapid drop in profile and passes underneath the Santa Fe Railroad to enter the Des Plaines River.

3.6.1.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Sawmill Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Sawmill Creek, Sawmill Creek Tributary No. 1, Sawmill Creek Tributary No. 3, were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses for the streams studied in detail in the Unincorporated Areas of DuPage County, Illinois, are presented below in Table SWSW.1.

Table SWSW.1: USGS Stream Gages Used for Hydrologic Analysis of Sawmill Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Sawmill Creek near Lemont 05533400 13.00 15

The flood discharges of specified return periods were compared with those calculated by the SCS using the TR-20 program for Sawmill Creek and East Branch Sawmill Creek. The SCS discharges for Sawmill Creek were

Section printed 29 April 2004

found suitable, but the discharges for East Branch Sawmill Creek were found to be lower than the acceptable range of discharges calculated using the State Standard Method. Therefore, the discharges submitted to the SWS for East Branch Sawmill Creek are Harza values. All of the discharges for the detailed study areas were sent to the SWS for review and approval, and the 100-year discharges were certified by the DOWR for use in its floodplain regulation program. Data are located in a repository of flood-related data administered by the SWS. Discharges for the 2-, 5-, 10-, 25-, and 100-year floods were available from the SCS TR- 20 model of Sawmill Creek (U.S. Department of Agriculture, 1965). Discharges for the 10- and 100-year floods on East Branch Sawmill Creek and West Branch Sawmill Creek in the City of Darien were calculated by Harza using regional flood frequency equations (Illinois Department of Transportation, Magnitude and Frequency of Floods in Illinois, 1973). Data for the three detailed study streams were plotted separately on log- normal probability paper, and the 50- and 500-year floods were estimated by straight-line interpolation and extrapolation, respectively. The 500- year flood discharge estimates are less reliable than the others because: 1) the precipitation-frequency relationship, required for the TR-20 program, is not well defined for this rare event, and 2) the average period of record for stream gages used to derive the regional equations is about 30 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SWSW.2.

Table SWSW.2: Sawmill Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Sawmill Creek - East Branch - at 79th Street 2.10 253 410 481 690 - at 75th Street 0.99 178 290 340 480 - at Elm Street 0.55 123 200 235 332 - at Janet Road 0.32 89 140 170 239 - at Rodger Road 0.24 75 120 140 200 - at 68th Street 0.20 65 103 120 170

Sawmill Creek - - approx. 80 ft u/s of Bluff Road 13.00 1,363 * 2,588 * - at 79th Street 1.24 294 476 566 800 - at 75th Street 0.97 243 394 467 660

Sawmill Creek -

Section printed 29 April 2004

Tributary 1 - at river mile 0.23 2.33 324 * 617 *

Sawmill Creek - Tributary 3 - at mouth 1.14 241 427 559 960

Sawmill Creek - West Branch - at I-55 0.75 178 290 345 495 - near Cass School 0.58 149 245 290 420 - near Bay View 0.42 146 238 285 402

3.6.1.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Stream cross-sections and bridge sections for East Branch Sawmill Creek, Sawmill Creek, and West Branch Sawmill Creek were surveyed using land survey techniques. All of the cross sections on Sawmill Creek and the cross sections downstream from 75th Street on East Branch Sawmill Creek were surveyed by the SCS; upstream sections were surveyed by Harza. All sections on West Branch Sawmill Creek were surveyed by Harza.

Water-surface elevations for floods of the selected recurrence intervals were computed using hydraulic models for East Branch Sawmill Creek and Sawmill Creek prepared by the SCS (Des Plaines River Watershed

Section printed 29 April 2004

Steering Committee, 1976). Both models were extended by Harza to cover the entire stream within the City of Darien. The models were developed using the SCS WSP-2 step-backwater program (U.S. Department of Agriculture, 1976). Mathematical relationships used in the model include the standard step-backwater procedure which estimates total energy at each cross section and accounts for friction losses between sections using Manning’s formula. The model requires discharge, cross- section geometry, bridge geometry, starting water-surface elevation, and roughness data to simulate flood flow conditions. West Branch Sawmill Creek was modeled by Harza using the WSP-2 program.

Starting water-surface elevations for East Branch Sawmill Creek, Sawmill Creek, and West Branch Sawmill Creek were determined from previous studies by the SCS (Des Plaines River Watershed Steering Committee, 1976).

Roughness coefficients for East Branch Sawmill Creek, Sawmill Creek, and West Branch Sawmill Creek were assigned on the basis of field inspection and previous analyses by the SCS. Please refer to Table SWSW.3 for more details.

Table SWSW.3: Sawmill Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

-East Branch Sawmill Creek 0.035 - 0.075 0.040 - 0.095 -Sawmill Creek 0.055 - 0.065 0.065 - 0.090 -Sawmill Creek Tributary No. 1 0.035 - 0.080 0.070 - 0.090 -Sawmill Creek Tributary No. 3 0.040 - 0.100 0.050 - 0.120 -West Branch Sawmill Creek 0.040 - 0.060 0.035 - 0.045

All elevations are referenced from National Geodetic Vertical Datum of 1929 (NGVD); elevation reference marks used in the study are shown on the maps.

3.6.1.4 Flood Boundaries

Section printed 29 April 2004

To reference the flood boundaries for Sawmill Creek, see Map Panels: 0905, 0906, 0908, 0909, 1001, 1002 and 1005.

3.6.1.5 Floodways

The floodways for East Branch Sawmill Creek were determined from the HUD-15 computer program (U.S. Department of Agriculture, 1977). Floodways were computed without consideration of backwater from the receiving streams.

Please reference attached Floodway Data Tables for further information.

3.6.1.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with Des Plaines River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS SAWMILL CREEK (SWSW) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch Sawmill Creek (SWSW) SWSW0013 20,192 1 85 572 0.6 707.3 707.3 707.4 0.1 SWSW0014 20,362 1 60 291 1.2 707.3 707.3 707.4 0.1 SWSW0015 20,812 1 28 78 4.4 711.5 711.5 711.6 0.1 SWSW0016 21,383 1 39 70 4.2 715.1 715.1 715.2 0.1 SWSW0017 21,683 1 57 338 0.9 726.2 726.2 726.3 0.1 SWSW0018 22,630 1 61 188 1.5 728.4 728.4 728.5 0.1 SWSW0019 22,825 1 55 161 1.8 729.9 729.9 723.0 0.1 SWSW0020 23,035 1 88 226 1.3 731.8 731.8 731.9 0.1 SWSW0021 23,315 1 15 265 1.1 733.2 733.2 733.3 0.1 SWSW0022 23,693 1 66 85 3.3 734.2 734.2 734.3 0.1 SWSW0023 24,696 1 53 279 0.4 738.7 738.7 738.8 0.1 SWSW0024 25,116 1 402 2,131 0.1 738.7 738.7 738.8 0.1 SWSW0025 25,945 1 29 24 3.4 742.0 742.0 742.1 0.1 SWSW0026 26,679 1 15 16 5.1 759.0 759.0 759.1 0.1

1 In feet above confluence with Sawmill Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH SAWMILL CREEK (SWSW) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) East Branch Sawmill Creek (SWSW) SWSW0030 27,709 1 174 308 1.8 700.4 700.4 700.5 0.1 SWSW0031 29,232 1 67 181 2.7 705.2 705.2 705.3 0.1 SWSW0032 30,478 1 272 292 1.4 710.6 710.6 710.7 0.1 SWSW0033 30,718 1 147 263 1.3 714.8 714.8 714.9 0.1 SWSW0034 31,906 1 171 274 1.2 715.2 715.2 715.3 0.1 SWSW0035 32,376 1 119 2 71 3.3 717.4 717.3 717.4 0.1 SWSW0036 33,386 1 59 70 2.4 720.0 720.0 720.1 0.1 SWSW0037 34,493 1 231 515 0.3 724.1 724.1 724.2 0.1 SWSW0038 36,496 1 304 543 0.2 724.1 724.1 724.2 0.1 SWSW0039 36,746 1 386 1,173 0.1 724.1 724.1 724.2 0.1

1 In feet above confluence with Sawmill Creek

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY, IL AND INCORPORATED AREAS EAST BRANCH SAWMILL CREEK (SWSW) 630 630 100-YEAR BACKWATER FROM DES PLAINES RIVER

625 625

RAILROAD 620 620

615 615

CONFLUENCE WITH DES PLAINES RIVER

FLOOD PROFILES

SAWMILL CREEK (SWSW)

610 610

605 605

ELEVATION IN FEET (NGVD 29)

600 600

595 595 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 590 10-YEAR FLOOD

STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL

SWSW0001 CROSS SECTION LOCATION 585 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

*DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 136P 660 660

655 655

BLUFF ROAD 650 650

645 645

FLOOD PROFILES

SAWMILL CREEK (SWSW)

FRONT STREET

640 EASTWOOD DRIVE 640

635 635

ELEVATION IN FEET (NGVD 29)

630 630

625 625 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 620 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SWSW0002 615 5000 5500 6000 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER * DATA NOT AVAILABLE 137P 675 CASS AVENUE 675

CONFLUENCE OF WARDS CREEK

670 670

FLOOD PROFILES

SAWMILL CREEK (SWSW)

665 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655

650 650 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 645 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SWSW0003 SWSW0004 SWSW0005 640 11500 12000 12500 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000

FEDERAL EMERGENCY MANAGEMENT AGENCY * DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 138P JOLIET ROAD

INTERSTATE 55

CONFLUENCE OF

695 NANTUCKET DRIVE 695

SAWMILL CREEK TRIBUTARY NO. 1

690 690

FLOOD PROFILES

SAWMILL CREEK (SWSW)

685 685

680 680

ELEVATION IN FEET (NGVD 29)

675 675

670 670 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 665 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SWSW0006 SWSW0007 660 18000 18500 19000 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER * DATA NOT AVAILABLE 139P 725 725

720 720

715 715

710 710

FLOOD PROFILES

SAWMILL CREEK (SWSW)

705 75TH STREET 705

LIMIT OF DETAILED STUDY

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 685 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

SWSW0008 SWSW0009 SWSW0010 680 24500 25000 25500 26000 26500 27000 27500 28000 28500 29000 *DATA NOT AVAILABLE DOWNSTREAM OF 25,000 FEET

FEDERAL EMERGENCY MANAGEMENT AGENCY ABOVE CONFLUENCE WITH W. BRANCH DUPAGE RIVER STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DES PLAINES RIVER 140P 730 730

725 725

WEIR CULVERT

720 JOLIETE ROAD 720

LIMIT OF DETAILED STUDY

715 715

FLOOD PROFILES

710 710

WEST BRANCH SAWMILL CREEK (SWSW)

CULVERT NO. 1 705 705

COACHMAN ROAD

ELEVATION IN FEET (NGVD 29)

CULVERT 700 700

695 695 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SWSW0013 SWSW0014 SWSW0015 SWSW0016 SWSW0017 CROSS SECTION LOCATION 685 20000 20200 20400 20600 20800 21000 21200 21400 21600 21800 22000 22200 22400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 141P LAKEVIEW DRIVE

FLOOD PROFILES

740 740

THE 50-YEAR PROFILE IS TOO CLOSE WEST BRANCH SAWMILL CREEK (SWSW) TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY

735 735

ELEVATION IN FEET (NGVD 29) CULVERT

730 730 CULVERT NO. 5 CULVERT NO. 4

CULVERT NO. 3

725 SWSW0023 725 CULVERT NO. 2 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 720 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0018 SWSW0019 SWSW0020 SWSW0021 SWSW0022 715 22400 22600 22800 23000 23200 23400 23600 23800 24000 24200 24400 24600 24800 25000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 142P 760 760

755 755

FLOOD PROFILES

750 750

WEST BRANCH SAWMILL CREEK (SWSW)

745 745

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

740 740

735 735 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 730 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SWSW0024 SWSW0025 SWSW0026 CROSS SECTION LOCATION 725 25000 25200 25400 25600 25800 26000 26200 26400 26600 26800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 143P 725 725

ELM STREET

75TH STREET EVANS PLACE

MIDWAY DRIVE

VIRGINIA COURT 720 TRIBUTARY NO 1 720

CONFLUENCE WITH SAWMILL CREEK

715 715

FLOOD PROFILES

79TH STREET

JANET AVENUE

710 PLAINFIELD ROAD 710

EAST BRANCH SAWMILL CREEK (SWSW)

705 705

ELEVATION IN FEET (NGVD 29)

700 700

695 SWSW0036 695 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

SWSW0030 SWSW0031 SWSW0032 SWSW0033 SWSW0034 SWSW0035 CROSS SECTION LOCATION 685 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500 33000 33500 34000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK AT DES PLAINES RIVER 144P ROGER ROAD

69TH STREET 68TH STREET 67TH STREET

LIMIT OF DETAILED STUDY

FLOOD PROFILES

725 725

EAST BRANCH SAWMILL CREEK (SWSW)

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0037 SWSW0038 SWSW0039 700 34000 34500 35000 35500 36000 36500 37000 37500 38000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK AT DES PLAINES RIVERH 145P 690 NORTHGATE DRIVE 690

CONFLUENCE WITH SAWMILL CREEK

685 CONFLUENCE OF WEST BRANCH SAWMILL CREEK 685

FLOOD PROFILES

WARDS CREEK (SWSW)

680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0011 655 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 146P 705 S FRONTAGE ROAD 705

LIMIT OF DETAILED STUDY

700 700

FLOOD PROFILES

WARDS CREEK (SWSW)

695 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0012 670 19000 19500 20000 20500 21000

*DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 147P 700 700

81ST STREET

LEOMAR LANE

INTERSTATE 55

UNNAMED ROAD

695 WESTERN AVENUE 695

CONFLUENCE WITH SAWMILL CREEK

690 690

FLOOD PROFILES

685 685

SAWMILL CREEK TRIBUTARY NO. 1 (SWSW)

680 680

CLARENDON HILLS ROAD

ELEVATION IN FEET (NGVD 29)

675 675

670 SWSW0029 670 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 665 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DU PAGE COUNTY, IL CROSS SECTION LOCATION

SWSW0027 SWSW0028 660 18000 18500 19000 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE OF SAWMILL CREEK AT DES PLAINES RIVER *DATA NOT AVAILABLE 148P 79TH STREET

WILLIAM DRIVE

SAWMILL CREEK

CONFLUENCE OF EAST BRANCH

FLOOD PROFILES

SAWMILL CREEK TRIBUTARY NO. 1 (SWSW)

700 700

ELEVATION IN FEET (NGVD 29)

695 695

690 690 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 685 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DU PAGE COUNTY, IL CROSS SECTION LOCATION

680 24500 25000 25500 26000 26500 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE OF SAWMILL CREEK AT DES PLAINES RIVER 149P

3.6.2 Wards Creek (SWWD)

3.6.2.1 Tributary Description

Wards Creek is located in DuPage County, in northeastern Illinois, approximately 30 miles west of downtown Chicago. The Wards Creek Watershed covers 3.11 square miles (1990 acres). This watershed includes parts of the Villages of Downers Grove, Woodridge, and Darien, and areas in unincorporated Downers Grove North and South Townships. Wards Creek joins the mainstem of Sawmill Creek several hundred feet downstream of passing underneath I-55, but for the purposes of modeling, the I-55 barrier is considered Wards Creek’s downstream-most cut-off.

Wards Creek Mainstem (Reach #1) finds its headwaters west of Dunham Road. This headwater area is actually an interbasin transfer zone in which the golf course west of Dunham Road directs low flow into Prentiss Creek of the East Branch DuPage River, but under large storm events routes flow into Wards Creek. The mainstem winds its way through the Dunham wetlands and passes east underneath Lemont Road to another wetland area known as Farm Lake. Once through this area, Wards Creek enters a series of complex drop boxes and pathways known as the Farmingdale Basin region. Downstream of Farmingdale, the channel returns and turns to the south, passing under 79th Place culvert and 80th Street culvert, and opening up into Bruce Lake. A weir located on the east side of the lake directs flow into a channel that passes flow underneath Fairmount Avenue, Landsfield Avenue, Woodcreek Court and Plainfield Road. Downstream of Plainfield Road the channel opens up forming another wetland area controlled by the culverts located downstream at Kearney Road. The creek passes through approximately 510 ft of conduit and exits on the south side of Rosehill Court. Wards Creek then proceeds through the Carriage Green Golf Course, encountering two cart path bridges and a cattle-crossing culvert. The creek then exits the golf course and passes through Creekside Lane Culvert, 86th Street Culvert, the Tara Hill and Swan Lake Storage Facilies, Lake Ridge Drive Culvert, Kentwood Court Culvert and Weir, and Carlisle Court Culvert. The Mainstem reenters the Carriage Green Golf Course, passes under two cart path bridges and a berm before exiting the system at the 6’ x 6’ reinforced concrete box culvert that passes under I-55.

Reach #2 is found in the northeastern sections of the Wards Creek Watershed. Reach #2 has its headwaters with the Lake in the Woods ponds, and releases flow to the southwest. After passing under Redondo Drive, Reach#2 opens up into Woodglen Pond. The creek then flows through culverts at Woodglen Lane and Plainfield Road. The channel bottom drops steeply and joins the Mainstem (Reach #1) at the Mallard Landing pond.

Section printed 29 April 2004

Reach #3 is known only as the Lyman Avenue Basin. This area drains the north-central part of the watershed that is highly commercial and retail. The Lyman Avenue Basin is a collection point for these waters before flowing into the Farmingdale Ridge Basin.

Reach #4 drains the central part of the watershed from the highly residential Brookeridge subdividion. Lake Brookeridge and adjacent Donut Lake are the headwaters of this reach, but it is only a short distance north, flowing under Plainfield Road, when Reach #4 confluences with the Mainstem at Bruce Lake.

Reach #6 is completely on the Carriage Green Golf Course found in the southeastern portion of the watershed. Reach #6 has its headwaters at the Carriage Green Golf Course Pond. The water then flows through 125 ft of conduit before it is daylighted again, dropping steeply towards the confluence with the Mainstem.

In general, the Wards Creek Watershed is a mix of land use types. The Northern section of the watershed is highly developed for commercial and retail purposes. The far northwest, and the eastern side of the watershed are large open areas maintained as golf courses. The central and central- west sections are largely residential, but seem to be less dense in nature than typical residential areas found in DuPage County.

3.6.2.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Wards Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Wards Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table SWWD.1.

Table SWWD.1: Wards Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Wards Creek - at I-55 0.75 171 * 207 *

Section printed 29 April 2004

3.6.2.3 Hydraulic Analysis

Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence. Streams studied in detail have flood profiles drawn for the 500-year, 100-year, 50-year, and 10-year storm events, with the exception of Upper Salt Creek, Klein Creek Tributary No. 1, Klein Creek Tributary No. 2, Sawmill Creek, Sawmill Creek Tributary No. 1, Wards Creek, West Branch Tributary No. 5, West Branch Tributary No. 7, East Branch Tributary No. 1, and East Branch Tributary No. 2, which have only the 10-year and 100-year profiles.

3.6.2.4 Flood Boundaries

To reference the flood boundaries for Wards Creek, see Map Panels: 0907, 0908, 1001 and 1002.

3.6.2.5 Floodways

No floodway information is currently available for this tributary.

3.6.2.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 690 NORTHGATE DRIVE 690

CONFLUENCE WITH SAWMILL CREEK

685 CONFLUENCE OF WEST BRANCH SAWMILL CREEK 685

FLOOD PROFILES

WARDS CREEK (SWSW)

680 680

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0011 655 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 146P 705 S FRONTAGE ROAD 705

LIMIT OF DETAILED STUDY

700 700

FLOOD PROFILES

WARDS CREEK (SWSW)

695 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

SWSW0012 670 19000 19500 20000 20500 21000

*DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH SAWMILL CREEK 147P

3.7 West Branch DuPage River (WB)

3.7.1 Main Stem (WBWB)

3.7.1.1 Tributary Description

The West Branch DuPage River is a 42.2 square mile watershed (not including tributary watershed areas) found in the western third of DuPage County, Illinois. The communities that contribute watershed area to the West Branch DuPage River Main Stem are: Hanover Park, Roselle, Bartlett, Wayne, Carol Stream, West Chicago, Winfield, Warrenville, Naperville and Unincorporated DuPage County.

The West Branch DuPage River enters DuPage County within the Village of Hanover Park, on the northern edge of the county. From the northern Cook-DuPage County border, the West Branch flows directly south, passing under the Elgin-O’Hare Expressway, Lake Street and Arlington Drive before bearing west through the Mallard Lake Forest Preserve. The West Branch confluences with West Branch Tributary No. 1 in the Mallard Lake Forest Preserve and continues west to pass under County Farm Road. The Main Stem enters the Hawk Hollow Forest Preserve on the south side of Bartlett, joins West Branch Tributary No. 2 and bears immediately to the south. The West Branch passes through the Chicago Central and Pacific Railroad, Schick Road, Army Trail Road, the West Branch Forest Preserve and North Avenue, just downstream of which the Main Stem confluences simultaneously with the West Branch DuPage River Tributary No. 3 from the west and West Branch DuPage River Tributary No. 4 from the east. The Main Stem bears to the southeast, passes through the Timber Ridge Forest Preserve, and joins Klein Creek Tributary just upstream of Geneva Road. Continuing to the south, the Main Stem passes under Highlake Road and the Chicago and Northwestern Railroad, joining with West Branch Tributary No. 5 on the upstream side. The West Branch passes under Beecher, turns to the west and proceeds through the West DuPage Woods Forest Preserve, confluencing with Winfield Creek. The river bearing resumes a southerly course, passing under Roosevelt Road, and Gary’s Mill Road confluencing with Kress Creek before crossing under Mack Road. The West Branch proceeds to the southeast, passes under Williams Road and joins Springbrook No. 1 before crossing under the Illinois Prairie Path / Butterfield Road. Flow swings back to the southwest, passing under Warrenville Main Street, Warrenville Road and the East-West Tollway (I- 88), on the downstream side of which the Main Stem confluences with Ferry Creek Tributary. The Main Stem flows through the McDowell Grove Forest Preserve, changing flow to the southeast, passing through Fawell Dam, and Ogden Avenue, the downstream side of which the West Branch confluences with Cress Creek Tributary. Flow continues through

Section printed 29 April 2004

the City of Naperville passing under the Burlington Northern Railroad, Jefferson Avenue, Eagle Street, Webster Street, Main Street, and Washington Street on the downstream side of which Steeple Run Watershed joins the Main Stem. Proceeding south, flow continues through Hillside Road, Gartner Road, and Hobson Road, on either side of which West Branch Tributaries No. 6 and 7 join the Main Stem. The West Branch continues south, crossing under 75th Street and Bailey Road, confluencing with the Winding Creek Tributary on the south side of Bailey Road. The West Branch continues its course and just before exiting DuPage County for Will County, the West Branch joins the South of Foxcroft Tributary.

3.7.1.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for the West Branch DuPage River Main Stem.

Discharge-frequency data for the West Branch DuPage River were developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC- 1 rainfall-runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the HEC-1 model of the DuPage River Basin to determine the 10- year, 50-year, and 100-year peak discharges (U.S. Department of Commerce, 1963).

The USGS stream gages used for the hydrologic analyses of the West Branch DuPage River studied in detail are presented in Table WBWB.1 below:

Table WBWB.1: USGS Stream Gages Used for Hydrologic Analysis of the West Branch DuPage River USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

West Branch DuPage River at Naperville 05540130 123.0 1

West Branch DuPage River near Warrenville 05540095 90.4 10

Section printed 29 April 2004

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBWB.2.

Table WBWB.2: West Branch DuPage River Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch DuPage River - approximately 475 ft u/s of confluence with unnamed creek (south of 87th Street) 124.5 3,545 4,970 5,655 7,575 - at DuPage-Will County line 123.0 3,510 4,920 5,600 7,500 - at Hillside Road 107.3 3,075 4,000 4,400 5,250 - at Ogden Avenue 105.0 2,880 3,740 3,960 5,000 - u/s of Fawell Dam 100.0 2,900 4,100 4,600 5,850 - at confluence with Kress Creek 80.3 2,460 3,460 3,850 4,900 - above mouth, Kress Ck 62.0 1,800 2,600 2,900 3,900 - at Roosevelt Road 58.5 1,700 2,400 2,700 3,550 - at North Avenue 28.5 970 1,360 1,540 1,980 - near Jefferson Street in Hanover Park 16.4 730 1,010 1,160 1,460 - at Lake Street 10.1 600 830 930 1,170 - at Irving Park Road 4.70 335 460 505 640

3.7.1.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross sections used for the West Branch DuPage River are identical to those used in a previous Floodplain Information Report (USACE, 1975). Channel portions of these cross sections were field surveyed, while overbank portions were determined photogrammetrically.

Water-surface profiles for West Branch DuPage River were developed through use of the USACE HEC-2 step-backwater computer program

Section printed 29 April 2004

(USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6- L202A, 1973).

Starting elevations for the West Branch DuPage River were derived from the Flood Plain Information Report (USACE, 1975). Stream mileages for the West Branch DuPage River and Kress Creek were obtained from the Hydrologic Investigations Atlases (U.S. Department of the Interior, 1965). Starting water-surface elevations for the tributaries were determined from the West Branch hydraulic model (U.S. Department of Agriculture, 1973). Starting water-surface elevations for the West Branch DuPage River model in Schaumburg were obtained from downstream flood profiles prepared by the USACE for the Hanover Park FIS (U.S. Department of Housing and Urban Development, unpublished). Starting elevations were determined from the Poplar Creek hydraulic model.

Roughness coefficients (Manning’s “n”) for West Branch DuPage River were estimated by field inspection and by comparison of computed profiles with high-water marks. For further information regarding Manning’s “n” information refer to Table WBWB.3.

Table WBWB.3: West Branch DuPage River Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- West Branch DuPage River 0.035 - 0.050 0.040 - 0.100

3.7.1.4 Flood Boundaries

To reference the flood boundaries for the West Branch DuPage River, see Map Panels: 0102, 0103, 0105, 0106, 0108, 0109, 0201, 0202, 0204, 0402, 0403, 0405, 0406, 0408, 0409, 0501, 0507, 0702, 0703, 0705, 0706, 0709, 0801, 0804, 0807 and 0808.

3.7.1.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.1.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch DuPage River (WBWB) WBWB0001 12,038 1 410 2,435 2.3 647.1 647.1 647.2 0.1 WBWB0002 14,002 1 402 1,428 3.9 650.1 650.1 650.2 0.1 WBWB0003 16,777 1 217 1,543 3.6 654.1 654.1 654.2 0.1 WBWB0004 19,660 1 205 2 1,683 3.3 657.3 657.3 657.4 0.1 WBWB0005 20,580 1 154 1,200 4.7 658.5 658.5 658.6 0.1 WBWB0006 22,106 1 302 2,163 2.6 661.5 661.5 661.6 0.1 WBWB0007 24,614 1 400 1,475 3.8 663.1 663.1 663.2 0.1 WBWB0008 26,343 1 270 1,692 3.3 664.2 664.2 664.3 0.1 WBWB0009 29,106 1 450 1,059 4.2 669.6 669.6 669.6 0.0 WBWB0010 29,821 1 616 3,152 1.4 670.3 670.3 670.3 0.0 WBWB0011 30,953 1 166 1,153 3.8 670.9 670.9 671.0 0.1 WBWB0012 31,409 1 91 876 5.0 671.9 671.9 672.0 0.1 WBWB0013 32,344 1 122 1,192 3.7 673.4 673.4 673.5 0.1 WBWB0014 33,511 1 80 646 6.8 674.9 674.9 674.9 0.0 WBWB0015 34,459 1 346 2,074 2.1 676.7 676.7 676.8 0.1 WBWB0016 36,869 1 330 1,636 2.7 678.0 678.0 678.1 0.1 WBWB0017 39,519 1 550 1,585 2.8 680.1 680.1 680.2 0.1

1 In feet above confluence with DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH DUPAGE RIVER (WBWB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch DuPage River (WBWB) WBWB0018 41,159 1 400 1,221 3.2 681.5 681.5 681.6 0.1 WBWB0019 42,423 1 190 1,238 3.2 682.1 682.1 682.2 0.1 WBWB0020 46,993 1 720 7,287 0.7 691.1 691.1 691.2 0.1 WBWB0021 51,222 1 2,040 11,817 0.4 691.5 691.5 691.5 0.0 WBWB0022 52,928 1 244 1,830 2.5 691.5 691.5 691.6 0.1 WBWB0023 53,337 1 210 2 1,530 3.0 691.7 691.7 691.8 0.1 WBWB0024 55,739 1 290 1,779 2.6 692.8 692.8 692.9 0.1 WBWB0025 57,580 1 115 1,031 4.3 693.8 693.8 693.9 0.1 WBWB0026 57,804 1 189 1,229 3.6 694.6 694.6 694.7 0.1 WBWB0027 58,983 1 300 2,182 2.0 695.3 695.3 695.4 0.1 WBWB0028 59,484 1 240 1,369 3.2 695.6 695.6 695.7 0.1 WBWB0029 61,496 1 392 1,765 2.5 696.7 696.7 696.8 0.1 WBWB0030 62,029 1 433 2,213 2.0 697.5 697.5 697.6 0.1 WBWB0031 63,679 1 444 2,383 1.7 697.9 697.9 698.0 0.1 WBWB0032 63,822 1 462 2,677 1.5 698.5 698.5 698.6 0.1 WBWB0033 65,356 1 325 987 4.2 698.8 698.8 698.9 0.1 WBWB0034 65,591 1 288 990 4.1 699.1 699.1 699.2 0.1

1 In feet above confluence with DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH DUPAGE RIVER (WBWB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch DuPage River (WBWB) WBWB0035 69,409 1 294 1,600 2.6 702.2 702.2 702.3 0.1 WBWB0036 71,400 1 226 1,352 2.8 703.0 703.0 703.1 0.1 WBWB0037 74,518 1 223 1,432 2.7 705.0 705.0 705.1 0.1 WBWB0038 76,742 1 499 2,249 1.3 706.1 706.1 706.2 0.1 WBWB0039 78,384 1 192 1,269 2.3 706.5 706.5 706.6 0.1 WBWB0040 79,605 1 195 1,112 2.3 707.2 707.2 707.3 0.1 WBWB0041 79,776 1 198 1,157 2.3 707.5 707.5 707.6 0.1 WBWB0042 81,714 1 265 1,407 1.9 708.2 708.2 708.3 0.1 WBWB0043 88,642 1 339 1,438 1.9 710.9 710.9 711.0 0.1 WBWB0044 91,720 1 330 1,804 1.5 712.2 712.2 712.3 0.1 WBWB0045 93,630 1 107 698 3.4 713.1 713.1 713.2 0.1 WBWB0046 93,877 1 107 729 3.3 713.3 713.3 713.4 0.1 WBWB0047 94,400 1 107 783 3.1 713.8 713.8 713.9 0.1 WBWB0048 94,739 1 200 1,159 2.1 714.7 714.7 714.8 0.1 WBWB0049 95,051 1 540 2,225 1.1 714.9 714.9 715.0 0.1 WBWB0050 100,103 1 225 1,063 2.3 716.7 716.7 716.8 0.1 WBWB0051 101,779 1 709 3,079 0.8 720.5 720.5 720.6 0.1

1 In feet above confluence with DuPage River

2 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH DUPAGE RIVER (WBWB) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch DuPage River (WBWB) WBWB0052 102,037 1 760 3,901 0.6 721.5 721.5 721.6 0.1 WBWB0053 104,158 1 323 1,360 1.4 721.6 721.6 721.7 0.1 WBWB0054 108,649 1 647 1,792 1.1 722.5 722.5 722.6 0.1 WBWB0055 111,349 1 949 2,311 0.8 724.3 724.3 724.4 0.1 WBWB0056 112,617 1 219 1,010 1.9 726.8 726.8 726.9 0.1 WBWB0057 115,066 1 154 650 2.4 729.4 729.4 729.4 0.0 WBWB0058 116,204 1 418 1,919 0.8 730.1 730.1 730.2 0.1 WBWB0059 118,019 1 230 1,139 1.4 730.6 730.6 730.7 0.1 WBWB0060 119,018 1 206 736 2.1 731.5 731.5 731.6 0.1 WBWB0061 120,192 1 243 944 1.6 732.9 732.9 733.0 0.1 WBWB0062 122,229 1 514 1,919 0.8 733.4 733.4 733.5 0.1 WBWB0063 125,483 1 446 939 1.6 734.3 734.3 734.4 0.1 WBWB0064 128,591 1 358 775 1.8 737.8 737.8 737.9 0.1 WBWB0065 129,669 1 582 1,064 1.3 738.8 738.8 738.9 0.1 WBWB0066 131,994 1 113 376 3.8 742.0 742.0 742.1 0.1 WBWB0067 133,912 1 366 1,432 1.0 746.4 746.4 746.5 0.1 WBWB0068 136,354 1 446 1,200 1.2 747.5 747.5 747.6 0.1

1 In feet above confluence with DuPage River

BAILEY ROAD

75TH STREET

HOBSON ROAD

PRIVATE DRIVE

COUNTY BOUNDARY

670 670

CONFLUENCE OF WEST BRANCH TRIBUTARY NO. 6

FLOOD PROFILES

660 660

WEST BRANCH DUPAGE RIVER (WBWB)

650 650

ELEVATION IN FEET (NGVD 29)

640 640

630 WBWB0006 630 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 620 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0001 WBWB0002 WBWB0003 WBWB0004 WBWB0005 610 11000 12000 13000 14000 15000 16000 17000 18000 19000 20000 21000 22000 23000 24000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 185P MAIN STREET

EAGLE STREET

HILLSIDE ROAD

GARTNER ROAD

WEBSTER STREET

JEFFERSON AVENUE

WASHINGTON STREET

690 690

FLOOD PROFILES

680 680

WEST BRANCH DUPAGE RIVER (WBWB)

670 670

ELEVATION IN FEET (NGVD 29)

660 660

650 WBWB0015 WBWB0016 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0007 WBWB0008 WBWB0009 WBWB0010 WBWB0011 WBWB0012 WBWB0013 WBWB0014 630 24000 25000 26000 27000 28000 29000 30000 31000 32000 33000 34000 35000 36000 37000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 186P RAILROAD

FAWELL DAM

LOWFLOW DAM 710 OGDEN AVENUE 710

CONFLUENCE OF FERRY CREEK

CONFLUENCE OF CRESS CREEK

700 700

FLOOD PROFILES

690 690

WEST BRANCH DUPAGE RIVER (WBWB)

680 680

ELEVATION IN FEET (NGVD 29)

CULVERT 670 670 CULVERT

660 WBWB0020 660 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0017 WBWB0018 WBWB0019 640 37000 38000 39000 40000 41000 42000 43000 44000 45000 46000 47000 48000 49000 50000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 187P MACK ROAD

ACCESS ROAD

WILLIAMS ROAD

CONFLUENCE OF KRESS CREEK

FLOOD PROFILES

710 710

WEST BRANCH DUPAGE RIVER (WBWB)

700 700

ELEVATION IN FEET (NGVD 29)

690 690

680 WBWB0037 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBWB0032 WBWB0034 50-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0031 WBWB0033 WBWB0035 WBWB0036 660 63000 64000 65000 66000 67000 68000 69000 70000 71000 72000 73000 74000 75000 76000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 189P STATE ROUTE 38

GARY'S MILL ROAD

(ROOSEVELT ROAD)

CONFLUENCE OF WEST BRANCH TRIBUTARY NO. 5

FLOOD PROFILES

720 720

WEST BRANCH DUPAGE RIVER (WBWB)

710 710

ELEVATION IN FEET (NGVD 29)

700 700

690 WBWB0043 690 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBWB0041 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0038 WBWB0039 WBWB0040 WBWB0042 670 76000 77000 78000 79000 80000 81000 82000 83000 84000 85000 86000 87000 88000 89000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 190P RAILROAD

GENEVA ROAD

HIGHLAKE ROAD

UNNAMED ROAD

BEECHER AVENUE

740 740

FLOOD PROFILES

730 730

WEST BRANCH DUPAGE RIVER (WBWB)

720 720

ELEVATION IN FEET (NGVD 29)

710 710

700 WBWB0050 WBWB0051 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBWB0046 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0044 WBWB0045 WBWB0047 WBWB0048 WBWB0049 680 89000 90000 91000 92000 93000 94000 95000 96000 97000 98000 99000 100000 101000 102000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 191P RAILROAD

ABANDONED RAILROAD

CONFLUENCE OF KLEIN CREEK

740 740

CONFLUENCE OF WEST BRANCH TRIBUTARY NO. 3

CONFLUENCE OF WEST BRANCH TRIBUTARY NO. 4

FLOOD PROFILES

730 730

WEST BRANCH DUPAGE RIVER (WBWB)

720 720

ELEVATION IN FEET (NGVD 29)

710 710

700 WBWB0056 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0052 WBWB0053 WBWB0054 WBWB0055 680 102000 103000 104000 105000 106000 107000 108000 109000 110000 111000 112000 113000 114000 115000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 192P NORTH AVENUE

UNNAMED ROAD UNNAMED ROAD

ST. CHARLES ROAD

FLOOD PROFILES

740 740

WEST BRANCH DUPAGE RIVER (WBWB)

730 730

ELEVATION IN FEET (NGVD 29)

720 720

710 WBWB0063 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 700 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0057 WBWB0058 WBWB0059 WBWB0060 WBWB0061 WBWB0062 690 115000 116000 117000 118000 119000 120000 121000 122000 123000 124000 125000 126000 127000 128000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 193P RAILROAD

SCHICK ROAD

PRIVATE BRIDGE

ARMY TRAIL ROAD

WEST BRANCH TRIBUTARY NO. 2

CONFLUENCE OF COUNTRY CREEK/

FLOOD PROFILES

760 760

WEST BRANCH DUPAGE RIVER (WBWB)

750 750

ELEVATION IN FEET (NGVD 29)

740 740

730 WBWB0069 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 720 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0064 WBWB0065 WBWB0066 WBWB0067 WBWB0068 710 128000 129000 130000 131000 132000 133000 134000 135000 136000 137000 138000 139000 140000 141000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 194P COUNTY FARM ROAD

780

FLOOD PROFILES

770 770

WEST BRANCH DUPAGE RIVER (WBWB)

760 760

ELEVATION IN FEET (NGVD 29)

750 750

740 WBWB0073 740 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 730 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0070 WBWB0071 WBWB0072 720 141000 142000 143000 144000 145000 146000 147000 148000 149000 150000 151000 152000 153000 154000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 195P RAILROAD

FARM BRIDGE

U.S. ROUTE 20

ARLINGTON DRIVE

COUNTY BOUNDARY

800 800

CONFLUENCE OF WEST BRANCH TRIBUTARY NO. 1

FLOOD PROFILES

790 790

WEST BRANCH DUPAGE RIVER (WBWB)

780 780

ELEVATION IN FEET (NGVD 29)

770 770

760 760 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 750 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0074 WBWB0075 WBWB0076 WBWB0077 740 154000 155000 156000 157000 158000 159000 160000 161000 162000 163000 164000 165000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 196P 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

FOOTBRIDGE 772 772

FOREST PRESERVE ROAD

LIMIT OF DETAILED STUDY

770 770

FLOOD PROFILES

768 768

WEST BRANCH TRIBUTARY NO. 1 (WBW1)

766 766

ELEVATION IN FEET (NGVD 29)

764 764

762 762 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 760 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW10001 CROSS SECTION LOCATION 758 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 197P FOOTBRIDGE

TOLLWAY (I-88) TOLLWAY (I-88)

LOW FLOW DAM

BUTTERFIELD ROAD

STATE HIGHWAY 56

WARRENVILLE ROAD

ILLINOIS PRAIRE PATH

CONFLUENCE OF SPRING BROOK NO. 1

710 710

FLOOD PROFILES

700 700

WEST BRANCH DUPAGE RIVER (WBWB)

690 690

ELEVATION IN FEET (NGVD 29)

CULVERT

680 680

670 WBWB0029 WBWB0030 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBWB0026 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWB0021 WBWB0022 WBWB0023 WBWB0024 WBWB0025 WBWB0027 WBWB0028 650 50000 51000 52000 53000 54000 55000 56000 57000 58000 59000 60000 61000 62000 63000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH DUPAGE RIVER 188P

3.7.2 Cress Creek (WBCC)

3.7.2.1 Tributary Description

Cress Creek is a 2694-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to Cress Creek are Naperville and Unincorporated DuPage County. The bulk land use characteristic is single-family houses, but many of the undeveloped areas in the outer fringes of the watershed are quickly being transformed into single-family dwellings or commercial ventures.

Much of Cress Creek watershed is placed in conduit. Whether in conduit or not, the stream origins can be found in the corporate ponds south of I- 88 and east of Washington Street. Flow proceeds to the southwest, and continues this bearing throughout the stream length. Cress Creek passes under such roads as Diehl Road, Chippewa Drive, Breamar Avenue and Iroquis Avenue before entering the detention areas at the Jefferson School. The creek then proceeds to cross Bauer Road, Washington Street, Main Street, Webster Street, Eagle Street and Mill Street. On the west side of Mill, Cress Creek flows through a large residential subdivision crossing such roads as West Street, Burning Tree Lane, and Zaininger Avenue. Cress Creek exits the subdivison and passes under Ogden Avenue, Royal St. George Drive, and 6th Avenue before confluencing the West Branch DuPage River.

3.7.2.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Cress Creek.

For Cress Creek, synthetic frequency-discharge curves were derived using regional statistics developed in the Chicago study. These discharges assume zero skew. Discharges for the 500-year floods of all streams were determined by linear extrapolation of a log probability curve of flood discharges computed for frequencies of up to 100 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBCC.1.

Table WBCC.1: Cress Creek Summary of Discharges Summary of Discharges

Section printed 29 April 2004

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Cress Creek - at mouth 1.45 325 575 740 1,430

3.7.2.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Both overbank and channel cross sections for Cress Creek were field surveyed.

Water-surface elevations for Cress Creek were computed for the 10-, 50-, 100-, and 500-year floods using a HEC-2 computer step-backwater model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6- L202A, 1973

Starting water-surface elevations for Cress Creek were calculated using the slope/area method.

Roughness coefficients (Manning’s “n”) for Cress Creek were estimated by field inspection and by comparison of computed profiles with high- water marks. For further information, refer to Table WBCC.2

Table WBCC.2: Cress Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Cress Creek 0.030 0.800

3.7.2.4 Flood Boundaries

To reference the flood boundaries for Cress Creek, see Map Panels: 0703, 0706, 0801 and 0804.

3.7.2.5 Floodways

Section printed 29 April 2004

Floodways for streams tributary to the West Branch DuPage River were computed without consideration of backwater flooding from the West Branch. Near the mouth of a few of these streams, therefore, floodway surcharge elevations are below rather than above the 100-year elevations determined by the West Branch backwater and indicated on the flood profiles.

Please reference attached Floodway Data Tables for further information.

3.7.2.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS CRESS CREEK (WBCC) 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

700 700

5TH AVENUE

FOOTBRIDGE

WEST STREET 695 OGDEN AVENUE 695

ZAININGER AVENUE

BURNING TREE LANE

ROYAL ST. GEORGE AVENUE

690 690

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

CRESS CREEK (WBCC)

685 685

680 680

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

675 675

670 WBCC0006 WBCC0007 WBCC0008 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBCC0001 WBCC0002 WBCC0003 WBCC0004 WBCC0005 CROSS SECTION LOCATION 660 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DU PAGE RIVER 150P

3.7.3 Ferry Creek (WBFE)

3.7.3.1 Tributary Description

The Ferry Creek watershed covers approximately 12.2 square miles and includes the cities of Warrenville, Naperville, and unincorporated areas of Winfield and Naperville Townships as shown on Figure ES-1. The watershed boundary, shown in Figure ES-2, extends from Fermi National Accelerator Laboratory in the northwest, to the West Branch of the DuPage River to the east, and Country Lakes Golf Course in Naperville in the southwest. The Ferry Creek drainage system consists of approximately 3.8 miles of main stem channel with four major tributaries, listed in order from upstream to downstream: Tributary No. 1, Tributary No. 2, I-88 (East-West Tollway) Ditch Tributary (Tollway Ditch Tributary), and Tributary No. 3. The main stem of Ferry Creek begins at a series of lakes located east of Fermi Laboratory, flows generally to the southeast, and joins the West Branch of the DuPage River approximately 3,000 feet south of I-88, the East-West Tollway. The main stem of Ferry Creek is a well-defined channel at an average slope of 0.2 % with several culvert crossings. The direct drainage area to the main stem is approximately 6.2 square miles. Tributaries No. 1 and No. 2 are roadside ditches that flow east from wetland areas west of Illinois Route 59 through a series of culverts. Tributary No. 1 has a drainage area of approximately 0.3 square miles and Tributary No. 2 has a drainage area of approximately 1.1 square miles. These tributaries join the main stem of Ferry Creek just north of the Prairie Path, and approximately 2,000 feet south of Aurora Way, respectively. The Tollway Ditch, which consists of a portion of grassed channel, a portion of concrete channel, and a series of culverts and closed conduits, drains east and joins the Ferry Creek main stem immediately south of the Tollway. There are two culverts that cross under the East-West Tollway and carry flow from the area north of the Tollway to the Tollway Ditch. The Tollway Ditch has a drainage area of approximately 2.3 square miles. Tributary No. 3 flows through a series of lakes in the Country Lakes Golf Course, proceeds through a network of storm sewers, continues through two detention ponds and an open channel to join the Ferry Creek main stem just south of Diehl Road in the McDowell Grove Forest Preserve. Tributary No. 3 has a drainage area of approximately 2.3 square miles.

3.7.3.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Ferry Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Ferry Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Section printed 29 April 2004

The USGS stream gages used for the hydrologic analyses of Ferry Creek studied in detail are presented in Table WBFE.1 below:

Table WBFE.1: USGS Stream Gages Used for Hydrologic Analysis of Ferry Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Ferry Creek at Warrenville 05540110 4.27 15

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBFE.2.

Table WBFE.2: Ferry Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Ferry Creek - at East-West Tollway 8.60 380 540 615 805

Ferry Creek Tributary No. 1 - at mouth 2.39 150 265 300 390

3.7.3.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

and the SCS (State of Illinois, 1975; and Des Plaines River Watershed Steering Committee, January 1976), normal depth computations, and rating curves. Backwater effects at confluences with larger stream systems are reflected on the flood profiles.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBFE.3 for further information regarding roughness coefficients.

Table WBCC.3: Ferry Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Ferry Creek 0.015 - 0.040 0.045 - 0.080

3.7.3.4 Flood Boundaries

To reference the flood boundaries for Ferry Creek, see Map Panels: 0404, 0405, 0407, 0408, 0409, 0701, 0702, 0703, 0704 and 0705.

3.7.3.5 Floodways

Please reference attached Floodway Data Tables for further information.

Section printed 29 April 2004

3.7.3.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Ferry Creek (WBFE) WBFE0006 3,538 1 150 516 1.2 691.2 690.6 690.6 0.0 WBFE0007 3,854 1 150 423 1.0 691.2 690.6 690.6 0.0 WBFE0008 4,013 1 125 426 1.0 691.4 691.4 691.4 0.0 WBFE0009 5,227 1 227 312 1.4 692.2 692.2 692.3 0.1 WBFE0010 6,230 1 253 300 1.5 693.2 693.2 693.3 0.1 WBFE0011 7,840 1 157 263 1.7 695.1 695.1 695.2 0.1 WBFE0012 8,395 1 111 200 2.2 696.9 696.9 696.9 0.0 WBFE0013 8,712 1 62 116 3.8 697.2 697.2 697.3 0.1 WBFE0014 9,451 1 125 154 2.9 699.5 699.5 699.6 0.1 WBFE0015 10,454 1 122 177 2.5 702.0 702.0 702.1 0.1 WBFE0016 11,141 1 200 505 0.5 704.1 704.1 704.1 0.0 WBFE0017 12,672 1 90 151 1.8 704.2 704.2 704.2 0.0 WBFE0018 13,834 1 76 109 2.4 705.9 705.9 706.0 0.1 WBFE0019 14,441 1 84 134 2.0 707.1 707.1 707.2 0.1 WBFE0020 15,205 1 130 334 0.8 711.5 711.5 711.5 0.0 WBFE0021 15,630 1 49 133 2.0 711.6 711.6 711.6 0.0 WBFE0022 15,780 1 59 147 1.8 711.8 711.8 711.8 0.0 WBFE0023 16,000 1 16 46 5.8 712.7 712.7 712.7 0.0

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS FERRY CREEK (WBFE) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Ferry Creek (WBFE) WBFE0024 17,475 1 260 1,219 0.2 716.2 716.2 716.2 0.0 WBFE0025 18,955 1 246 539 0.3 716.2 716.2 716.2 0.0

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS FERRY CREEK (WBFE) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Ferry Creek Tributary No. 1 (WBFE) WBFE0001 1,135 1 116 106 2.8 691.2 687.5 2 687.5 0.0 WBFE0002 1,339 1 32 90 3.3 691.2 689.1 2 689.1 0.0 WBFE0003 3,644 1 182 293 1.0 697.4 697.4 697.5 0.1 WBFE0004 4,800 1 26 94 2.6 699.8 699.8 699.9 0.1

1 In feet above confluence with Ferry Creek

2 Elevations computed without consideration of backwater effects from Ferry Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS FERRY CREEK TRIBUTARY NO. 1 (WBFE) 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

FERRY ROAD

PRIVATE ROAD

MCDOWELL ROAD

FOREST RESERVE ROAD

EAST BOUND TOLLWAY (I-88)

WEST BOUND TOLLWAY (I-88)

700 700

CONFLUENCE OF FERRY CREEK TRIBUTARY NO. 1

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES THE 50-YEAR PROFILE IS TOO CLOSE FERRY CREEK (WBFE) TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 695 695

690 690

ELEVATION IN FEET (NGVD 29)

685 685

WBFE0009 WBFE0010 680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0006 WBFE0007 WBFE0008 CROSS SECTION LOCATION 670 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 151P RAILROAD 715 715

FARM ROAD FARM ROAD

AURORA WAY 710 PRIVATE ROAD 710

BUTTERFIELD ROAD

705 705

FLOOD PROFILES

FERRY CREEK (WBFE)

700 700

THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 695 695

ELEVATION IN FEET (NGVD 29)

690 690

WBFE0017 685 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0011 WBFE0012 WBFE0013 WBFE0014 WBFE0015 WBFE0016 CROSS SECTION LOCATION 675 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 152P AND WEIR

HOME AVENUE

PRIVATE BRIDGE

STATE ROUTE 59

720 720

FLOOD PROFILES

FERRY CREEK (WBFE)

715 715

710 710

ELEVATION IN FEET (NGVD 29)

CULVERT

705 705

700 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0018 WBFE0019 WBFE0020 WBFE0021 WBFE0022 WBFE0023 WBFE0024 CROSS SECTION LOCATION 690 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 153P LIMIT OF DETAILED STUDY

FLOOD PROFILES

FERRY CREEK (WBFE)

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0025 CROSS SECTION LOCATION 700 18000 18500 19000 19500 20000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 154P 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

RAYMOND ROAD

CONFLUENCE WITH FERRY CREEK

FLOOD PROFILES

695 695

FERRY CREEK TRIBUTARY NO. 1 (WBFE)

690 690

ELEVATION IN FEET (NGVD 29)

685 685

680 680 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 675 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0001 WBFE0002 CROSS SECTION LOCATION 670 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH FERRY CREEK 155P 705 705

FLOOD PROFILES

700 700

FERRY CREEK TRIBUTARY NO. 1 (WBFE)

695 695

ELEVATION IN FEET (NGVD 29)

690 690

685 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 675 2600 2800 3000 3200 3400 3600 3800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH FERRY CREEK 156P MC DOWELL ROAD

LIMIT OF DETAILED STUDY

705 705

FLOOD PROFILES

700 700

FERRY CREEK TRIBUTARY NO. 1 (WBFE)

695 695

ELEVATION IN FEET (NGVD 29)

690 690

WBFE0004 685 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFE0003 CROSS SECTION LOCATION 675 3600 3800 4000 4200 4400 4600 4800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH FERRY CREEK 157P

3.7.4 South of Foxcroft (WBFX)

3.7.4.1 Tributary Description

The South of Foxcroft Tributary is a 586-acre watershed tributary to the West Branch DuPage River. Communities that contribute watershed area to South of Foxcroft Tributary are Naperville and Unincorporated DuPage County. The overall land use in this small watershed located at the southern border of DuPage County, is strictly suburban residential.

The South of Foxcroft Tributary is a highly managed tributary. All aspects of the natural stream channel have been placed in conduit and routed throughout the subdivision. Open-space areas just west of Washington Street and south of 87th Street have open stream channels. The stream flows to the east, passes under Washington Street and joins the West Branch DuPage River just upstream of the DuPage-Will County line.

3.7.4.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for South of Foxcroft Tributary.

Discharge-frequency data for East Branch DuPage River, West Branch DuPage River, mouth of Lacey Creek, Klein Creek, Klein Creek Tributary No. 2 were developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC-1 rainfall-runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the HEC-1 model of the DuPage River Basin to determine the 10-year, 50-year, and 100-year peak discharges (U.S. Department of Commerce, 1963).

Discharges for South of Foxcroft and Unnamed Creek south of 87th Street in the City of Naperville, two tributaries to the West Branch DuPage River, were adjusted to reflect interbasin flow between the two streams. The Hydrologic Investigations Atlas for the Normantown quadrangle indicates that interbasin flow occurred during the October 1954 flood (U.S. Department of the Interior, 1965). Discharges for the two streams were adjusted on a trial-and-error basis until corresponding water-surface elevations in the area of interbasin flow were within 0.5 foot of each other, reflecting gently sloping sheet flow between the two streams. As a result, discharges for the unnamed creek in the area south of 87th Street were

Section printed 29 April 2004

decreased, while those for the creek in the area south of Foxcroft Road were increased.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBFX.1.

Table WBFX.1: South of Foxcroft Tributary Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

South of Foxcroft Tributary - at mouth (discharges increased due to interbasin flow ) 0.30 185 250 285 380 - approximately 1,000 ft d/s of 87th Street 0.20 85 150 185 280

3.7.4.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Both overbank and channel cross sections for South of Foxcroft Tributary were field surveyed.

Water-surface elevations for South of Foxcroft Tributary were computed for the 10-, 50-, 100-, and 500-year floods using a HEC-2 computer step- backwater model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973).

Starting water-surface elevations for South of Foxcroft Tributary were calculated using the slope/area method.

Section printed 29 April 2004

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBFX.2 for further information regarding roughness coefficients.

Table WBFX.2: South of Foxcroft Tributary Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- South of Foxcroft Tributary 0.300 0.050

3.7.4.4 Flood Boundaries

To reference the flood boundaries for South of Foxcroft, see Map Panels: 0709 and 0807.

3.7.4.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.4.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above county boundary TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS UNNAMED CREEK (SOUTH OF FOXCROFT ROAD) (WBFX) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Unnamed Creek (South of 87th Street) (WBFX) WBFX0101 6,019 1 26 256 6.1 655.1 655.1 655.1 0.0 WBFX0102 6,441 1 21 170 6.5 661.3 661.5 661.5 0.0

1 In feet above mouth TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS UNNAMED CREEK (SOUTH OF 87TH STREET) (WBFX) 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

DIKE

FOOTBRIDGE

87TH STREET

PRIVATE DRIVE

COUNTY BOUNDARY

WASHINGTON STREET

THE 50-YEAR PROFILE IS TOO CLOSE FLOOD PROFILES TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 655 655

UNNAMED CREEK (SOUTH OF FOXCROFT ROAD) (WBFX) 650 650

ELEVATION IN FEET (NGVD 29)

645 645

640 WBFX0004 640 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 635 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFX0001 WBFX0002 WBFX0003 CROSS SECTION LOCATION 630 0 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 3000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 158P LIMIT OF DETAILED STUDY

FLOOD PROFILES

UNNAMED CREEK (SOUTH OF FOXCROFT ROAD) (WBFX) 660 660

ELEVATION IN FEET (NGVD 29) THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 655 655

650 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFX0005 CROSS SECTION LOCATION 640 3000 3250 3500 3750 4000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE COUNTY BOUNDARY 159P 666 666

664 664

662 662

COUNTY BOUNDARY

660 660

FLOOD PROFILES

658 658

STORM SEWER

LIMIT OF DETAILED STUDY

UNNAMED CREEK (SOUTH OF 87TH STREET) (WBFX)

656 656

ELEVATION IN FEET (NGVD 29)

654 654

652 652 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 650 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBFX0101 WBFX0102 CROSS SECTION LOCATION 648 5000 5200 5400 5600 5800 6000 6200 6400 6600

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE MOUTH 160P

3.7.5 Klein Creek (WBKC)

3.7.5.1 Tributary Description

The Klein Creek Watershed is comprised of suburban residential communities intermixed with industrial and commercial developments and agricultural lands. The Village of Carol Stream, in Bloomingdale Township, comprises the majority of the watershed with smaller portions of Wayne, Milton and Winfield Townships also contributing. The Villages of Bloomingdale, Glendale Heights and Winfield and portions of unincorporated DuPage County are also within the watershed. Klein Creek has a total watershed area of approximately 12.7 square miles.

The headwaters of Klein Creek are comprised of residential developments located in Glendale Heights, east of Schmale Road. From Glendale Heights, Klein Creek flows in a westerly direction through a portion of unincorporated DuPage County and crosses into the Village of Carol Stream approximately 0.5 miles west of Schmale Road. Between Schmale Road and Gary Avenue, Klein Creek consists of open channel wetlands and on-line detention ponds that receive stormwater from numerous commercial developments and shopping centers located in Bloomingdale and Carol Stream.

Tributary No. 3, which has a watershed area of approximately 1.1 square miles, enters Klein Creek from the west, just south of the intersection of Gary Avenue and Army Trail Road. At this location, Klein Creek and Tributary No. 3 join on the north side of the old Home Base site retention pond. The Tributary No. 3 watershed consists of residential development (around Mallard Lake), agricultural and vacant land, and some commercial and light industrial developments.

From Gary Avenue, Klein Creek flows in a southerly direction through Lies Road and into the Mitchell Lakes area. Mitchell Lakes consists of five individual lakes connected in series and surrounded by recreational open space that is maintained by the Carol Stream Park District. Watershed areas tributary to Mitchell Lakes consist of storm sewered residential developments with single and multi-family structures. Located immediately west of the most downstream lake is Armstrong Park recreational area. This recreational facility is approximately 70 acres in size and is also operated and maintained by the Carol Stream Park District. This facility includes a stormwater retention/recreational lake (Lake George), a dry bottom detention pond and numerous athletic fields and tennis courts. Lake George and the dry bottom detention pond both serve as local stormwater management facilities and are hydraulically connected to Klein Creek, which flows in a southerly direction immediately east of

Section printed 29 April 2004

the park. Residential developments border the park on the north, west and south sides. Illini Drive parallels the southern park boundary.

Between Illini Drive and Thunderbird Trail, Klein Creek flows nearly due south and is adjoined by residential development on the east and west sides of the creek. Tributary No. 2 (Thunderbird Creek) enters Klein Creek from the east just upstream of Thunderbird Trail. Tributary No. 2 has a watershed area of approximately 1.4 square miles at the confluence with Klein Creek. The major portion of the Tributary No. 2 watershed is located east of Gary Avenue and is comprised mainly of industrial developments and vacant land. Numerous stormwater detention facilities exist within the industrial facilities in this portion of the watershed. The Tributary No. 2 Watershed west of Gary Avenue consists of single-family residential parcels.

From Thunderbird Trail, Klein Creek traverses in a westerly direction to Kuhn Road. Land use along this reach consists of municipal facilities and agricultural land south of the creek with residential and vacant/wooded land north of the creek.

Klein Creek flows in a southwest direction from Kuhn Road to its confluence with the West Branch of the DuPage River near Geneva Road. The creek is generally adjoined by agricultural land, green space and forest preserve along this reach, with numerous residential developments set back from the creek. Tributary No. 1, which enters Klein Creek approximately 0.25 miles north of Geneva Road, has a watershed area of approximately 1.2 square miles. The Tributary No. 1 watershed is comprised of mixed land use including single family residential, industrial and agricultural as major components.

3.7.5.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Klein Creek.

Discharge-frequency data for Klein Creek and Klein Creek Tributary No. 2 were developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC-1 rainfall-runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the HEC-1 model of the DuPage River Basin to determine the 10-year, 50-year, and 100-year peak discharges (U.S. Department of Commerce, 1963).

Section printed 29 April 2004

Discharges for the 10-year, 50-year, and 100-year floods for the Klein Creek, Klein Creek Tributary No. 1 and Klein Creek Tributary No. 3 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses of the West Branch DuPage River studied in detail are presented in Table WBKC.1 below:

Table WBKC.1: USGS Stream Gages Used for Hydrologic Analysis of Klein Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Klein Creek At Carol Stream 05539950 8.81 15

The hydrologic analysis of Klein Creek Tributary No. 3 was directly transferred from the DuPage County FIS (FEMA, 1982). Discharges for the 10-year and 100-year floods of Klein Creek Tributary No. 3 were computed using the log-Pearson Type III method (U.S. Water Resources Council, 1976). Discharges for the 500-year floods of all streams were determined by linear extrapolation of a log-probability graph of flood discharges computed for frequencies up to 100 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBKC.2.

Table WBKC.2: Klein Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Klein Creek - - d/s of Thunderbird Trail in the Village of Carol Stream 6.37 445 592 655 947 - approximately 1,000 ft

Section printed 29 April 2004

upstream of Dam “A” in Carol Stream 4.90 400 542 619 817

Klein Creek - Tributary No. 1 - at mouth 1.12 33 60 95 240

Klein Creek - Tributary No. 2 - at confluence with Klein Creek 1.22 220 300 355 515

Klein Creek - Tributary No. 3 - at mouth 0.78 140 * 208 *

3.7.5.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for Klein Creek, Klein Creek Tributary No. 2, and Klein Creek Tributary No. 3 were obtained by field measurement.

Water-surface elevations of floods of the selected recurrence intervals were computed using the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973) for Klein Creek, Klein Creek Tributary No. 2, and Klein Creek Tributary No. 3. Flood profiles were drawn showing

Section printed 29 April 2004

computed water-surface elevations to an accuracy of 0.5 foot for floods of the selected recurrence intervals.

Starting water-surface elevations for Klein Creek, Klein Creek Tributary No. 2, and Klein Creek Tributary No. 3 were calculated using the slope/area method.

Roughness coefficients for the hydraulic computations of Klein Creek, Klein Creek Tributary No. 2, and Klein Creek Tributary No. 3 were assigned on the basis of field inspection of floodplain areas. Refer to Table WBKC.3 for further information.

Table WBKC.3: Klein Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Klein Creek 0.030 - 0.045 0.060 - 0.080 - Klein Creek Tributary No. 2 0.035 0.065 - Klein Creek Tributary No. 2 0.055 0.070

3.7.5.4 Flood Boundaries

To reference the flood boundaries for Klein Creek, see Map Panels: 0109, 0204, 0205, 0207, 0208, 0403, 0501 and 0502.

3.7.5.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.5.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Klein Creek (WBKC) WBKC0001 1,956 1 79 218 4.2 721.5 720.7 2 720.7 0.0 WBKC0002 4,952 1 490 914 1.0 728.8 728.8 728.8 0.0 WBKC0003 6,795 1 519 1,524 0.6 735.1 735.1 735.1 0.0 WBKC0004 8,371 1 121 389 2.3 739.5 739.5 739.5 0.0 WBKC0005 8,849 1 131 303 3.0 740.3 740.3 740.3 0.0 WBKC0006 9,341 1 162 791 1.1 743.1 743.1 743.2 0.1 WBKC0007 10,952 1 40 257 3.5 743.9 743.9 744.0 0.1 WBKC0008 12,521 1 610 1,757 0.5 746.0 746.0 746.0 0.0 WBKC0009 13,880 1 250 338 2.7 746.0 746.0 746.0 0.0 WBKC0010 15,618 1 104 254 2.6 747.2 747.2 747.2 0.0 WBKC0011 17,948 1 78 262 2.4 748.4 748.4 748.4 0.0 WBKC0012 18,466 1 575 2,482 0.2 748.6 748.6 748.6 0.0 WBKC0013 20,184 1 294 5,222 0.1 751.8 751.8 751.8 0.0 WBKC0014 21,590 1 525 7,852 0.1 751.8 751.8 751.8 0.0 WBKC0015 22,804 1 294 4,174 0.1 752.9 752.9 753.0 0.1 WBKC0016 24,228 1 242 3,274 0.2 754.8 754.8 754.9 0.1 WBKC0017 25,727 1 679 1,442 0.4 755.6 755.6 755.7 0.1 WBKC0018 27,954 1 288 908 0.4 761.5 761.5 761.5 0.0

1 In feet above confluence with West Branch DuPage River

2 Elevation computed without consideration of backwater effect from West Branch DuPage River

1 In feet above confluence with West Branch DuPage River

2 Elevation computed without consideration of backwater effect from West Branch DuPage River

1 In feet above confluence with East Branch DuPage River

2 Elevations without considering backwater effect from Klein Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY

AND INCORPORATED AREAS Klein Creek Tributary NO. 2 (WBKC) 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

FARM ROAD

IL PRAIRIE PATH 735 CONFLUENCE OF 735

KLEIN CREEK TRIBUTARY NO. 1

730 730

KLEIN CREEK (WBKC)

FLOOD PROFILES

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

725 725

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 WBKC0002 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0001 CROSS SECTION LOCATION 700 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 161P RAILROAD

KUHN ROAD 755 NORTH AVENUE 755

ST. CHARLES ROAD

COUNTY FARM ROAD

750 750

KLEIN CREEK (WBKC)

FLOOD PROFILES

745 745

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 WBKC0008 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0003 WBKC0004 WBKC0005 WBKC0006 WBKC0007 CROSS SECTION LOCATION 720 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 162P DAM "A"

ILLINI DRIVE

755 SPILLWAY NO. 3 755

THUNDERBIRD TRAIL

(THUNDERBIRD TRAIL CREEK)

750 CONFLUENCE OF KLEIN CREEK TRIBUTARY NO. 2 750

KLEIN CREEK (WBKC)

FLOOD PROFILES

745 745

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 WBKC0012 730 LEGEND 500-YEAR FLOOD 500-YEAR FLOOD 500-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0009 WBKC0010 WBKC0011 CROSS SECTION LOCATION 720 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 163P 765 765

760 760

ELK TRAIL

SPILLWAY NO. 1

SPILLWAY NO. 2 755 DITCH CROSSING DITCH CROSSING 755

750 750

KLEIN CREEK (WBKC)

FLOOD PROFILES

745 745

CULVERT 740 740

ELEVATION IN FEET (NGVD 29)

CULVERT

LIES ROAD

GARY AVENUE 735 735

730 WBKC0017 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0013 WBKC0014 WBKC0015 WBKC0016 CROSS SECTION LOCATION 720 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 164P RAILROAD

CONFLUENCE OF

KLEIN CREEK TRIBUTARY NO. 3

770 770

KLEIN CREEK (WBKC)

FLOOD PROFILES

765 765

760 760

ELEVATION IN FEET (NGVD 29)

755 755

750 750 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 745 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0018 WBKC0019 CROSS SECTION LOCATION 740 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 165P SCHMALE ROAD

LIMIT OF DETAILED STUDY

KLEIN CREEK (WBKC)

FLOOD PROFILES

ELEVATION IN FEET (NGVD 29)

770 770

765 765 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 760 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0020 CROSS SECTION LOCATION 755 32500 33000 33500 34000 34500 35000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 166P 750 750

745 745

740 740

COUNTY FARM ROAD

CONFLUENCE WITH KLEIN CREEK

735 735

FLOOD PROFILES

730 CENTER AVENUE 730

KLEIN CREEK TRIBUTARY NO. 1 (WBKC)

725 725

ELEVATION IN FEET (NGVD 29)

720 720

715 715 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0021 CROSS SECTION LOCATION 705 0 500 1000 1500 2000 2500 3000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KLEIN CREEK 167P 785

WEIR WEIR

PLEASANT HILL ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

765 765

KLEIN CREEK TRIBUTARY NO. 1 (WBKC)

760 760

ELEVATION IN FEET (NGVD 29)

CULVERT CULVERT 755 755

750 750 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 745 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0022 WBKC0023 CROSS SECTION LOCATION 740 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KLEIN CREEK 168P 775 775

770 770

SEMINOLE LAKE

765 BLACKHAWK DRIVE 765

THUNDERBIRD TRAIL

LIMIT OF DETAILED STUDY

CONFLUENCE WITH KLEIN CREEK

760 760

FLOOD PROFILES

KLEIN CREEK TRIBUTARY NO. 2 755 755

750 750

ELEVATION IN FEET (NGVD 29)

745 745

740 WBKC0025 740 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBKC0024 50-YEAR FLOOD 735 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKC0026 WBKC0027 WBKC0028 WBKC0029 WBKC0030 CROSS SECTION LOCATION 730 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KLEIN CREEK 169P 84TH COURT

GARY AVENUE

OLD GARY AVENUE

LIMIT OF DETAILED STUDY

CONFLUENCE WITH KLEIN CREEK

FLOOD PROFILES

770 770

KLEIN CREEK TRIBUTARY NO. 3 (WBKC)

765 765

ELEVATION IN FEET (NGVD 29)

760 760

755 755 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 750 10-YEAR FLOOD

STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBKC0031 WBKC0032 WBKC0033 745 0 500 1000 1500 2000 2500 3000 3500 4000

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KLEIN CREEK 170P

3.7.6 Kress Creek (WBKR)

3.7.6.1 Tributary Description

Kress Creek is an 18.9-square mile watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to Kress Creek are: West Chicago, St. Charles, Batavia and Unincorporated DuPage County. Much of the upper portions of the watershed are largely open and untouched (Fermi Laboratory and the DuPage Airport), where the central and lower portions of the watershed are a mix of residential, industrial and commercial.

Kress Creek Main Stem origins lie in the West Chicago Prairie Forest Preserve, located north of the Chicago and Northwestern railroad tracks and west of the West Chicago downtown area. The Main Stem of Kress Creek flows south under the Chicago and Northwestern railroad tracks and under Washington Street. On the south side of Washington, the stream changes course to the southwest, passing by the General Mills Factory, and eventually passing under Fenton Lane. On the west side of Fenton, the stream resumes its southerly course and passes under Helena Drive and the Burlington Northern Railroad tracks. The stream again changes bearing to the southeast where it crosses under Town Road and Roosevelt Road. On the south side of Roosevelt Road, the Main Stem of Kress Creek confluences with Kress Creek Unnamed Tributary. Flow continues generally to the southeast, passing under Circle Drive, Joy Road, Joliet Road and Route 59 before confluencing with the West Branch DuPage River.

Kress Creek Unnamed Tributary origins lie in Fermi and the DuPage Airport. The respective minor tributaries join in the northern portion of Fermi and proceed to the east, passing under Fermi’s Road “A” and Town Road before confluencing with the Kress Creek Main Stem.

3.7.6.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Kress Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Kress Creek and Unnamed Tributary to Kress Creek were computed using the log- Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

Section printed 29 April 2004

The USGS stream gages used for the hydrologic analyses of the Kress Creek studied in detail are presented in Table WBKR.1 below:

Table WBKR.1: USGS Stream Gages Used for Hydrologic Analysis of Kress Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Kress Creek At West Chicago 05540050 10.01 15

Kress Creek is within sub area 6 of the Chicago Metro Study. Peak flows for this sub area, previously derived by the Chicago District, were utilized to derive peak flood flows on Kress Creek and the Unnamed Tributary to Kress Creek. A discharge-frequency relationship was developed for Kress Creek at State Highway 38, and peak flows for Kress Creek at the mouth were obtained by applying the square root of the drainage area ratio. The frequency-discharge drainage area relationships for the streams studied in detail in the community are presented in Table 1, “Summary of Discharges.” The peak discharge for a portion of the headwater area of Kress Creek studied by approximate methods was determined from a regional curve which indicated the 100-year peak discharge as a function of average streambed slope. This curve was determined by solving and plotting solutions to the multiple regression equation adopted by the State of Illinois for several streams within DuPage County (State of Illinois, 1973).

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBKR.2.

Table WBKR.2: Kress Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Kress Creek - - mouth at West Branch DuPage River 18.3 760 1,060 1,170 1,470 - at mouth 18.3 760 1,060 1,170 1,470 - at Town Road 14.8 655 915 1,000 1,270 - approximately 1.4 miles d/s of Lies Road 12.3 580 810 890 1,125 - at Roosevelt Road

Section printed 29 April 2004

(State Highway 38) 10.1 510 710 780 985 - at Indian Boundary Rd 5.40 365 510 560 705 - at Hawthorne Lane 4.20 330 460 505 635 - at river mile 7.66 1.46 40 45 52 63

Kress Creek - Unnamed Tributary - at mouth 1.00 95 135 155 195

3.7.6.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Cross-section data for part of Kress Creek and for the entire Unnamed Tributary of Kress Creek were obtained by field measurement. Cross sections for Kress Creek up to Hawthorne Lane are identical to those used for a previous USACE Flood Plain Information Report (USACE, 1975). In addition, channel modifications to Kress Creek for a distance of 600 feet upstream of the Elgin, Joliet, and Eastern Railroad, and culverts at the railroad crossing were inspected in March 1978 and incorporated into the hydraulic model.

Water-surface profiles for Kress Creek, and Unnamed Tributary to Kress Creek were developed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973). Starting water-surface elevations for Kress Creek and Unnamed Tributary to Kress Creek were calculated using the slope/area method.

Roughness coefficients for the hydraulic computations of Kress Creek and Unnamed Tributary to Kress Creek were assigned on the basis of field inspection of floodplain areas. Refer to Table WBKR.3 for further details.

Table WBKR.3: Kress Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

Section printed 29 April 2004

- Kress Creek 0.015 - 0.080 0.040 - 0.100

3.7.6.4 Flood Boundaries

To reference the flood boundaries for Kress Creek, see Map Panels: 0107, 0108, 0401, 0402, 0404 and 0405.

3.7.6.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.6.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Kress Creek (WBKR) WBKR0001 882 1 139 464 2.5 705.5 703.2 2 703.3 0.1 WBKR0002 1,122 1 150 572 2.0 705.5 704.0 2 704.1 0.1 WBKR0003 3,080 1 65 231 5.1 709.5 709.5 709.5 0.0 WBKR0004 5,613 1 95 293 4.0 715.6 715.6 715.7 0.1 WBKR0005 5,782 1 259 1,312 0.9 720.2 720.2 720.3 0.1 WBKR0006 6,805 1 250 1,289 0.9 721.3 721.3 721.4 0.1 WBKR0007 7,562 1 178 2,334 0.5 722.1 722.1 722.2 0.1 WBKR0008 8,006 1 415 3 3,128 0.4 722.1 722.1 722.2 0.1 WBKR0009 10,324 1 220 3 289 1.7 722.2 722.2 722.3 0.1 WBKR0010 11,161 1 330 3 1,508 0.7 727.2 727.2 727.2 0.0 WBKR0011 13,563 1 151 271 3.7 727.4 727.4 727.4 0.0 WBKR0012 16,205 1 290 1,076 0.9 734.3 734.3 734.3 0.0 WBKR0013 17,053 1 521 1,558 0.6 735.7 735.7 735.7 0.0 WBKR0014 18,982 1 120 557 1.6 737.9 737.9 737.9 0.0 WBKR0015 20,423 1 125 400 2.2 738.6 738.6 738.7 0.1 WBKR0016 22,175 1 33 109 2.4 738.7 738.7 738.8 0.1 WBKR0017 23,240 1 21 64 4.1 738.7 738.7 738.7 0.0 WBKR0018 23,656 1 30 89 1.6 740.1 740.1 740.1 0.0

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River

3 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS KRESS CREEK (WBKR) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Kress Creek (WBKR) WBKR0019 25,234 1 28 60 1.6 740.7 740.7 740.8 0.1 WBKR0020 25,526 1 158 3 150 2.2 744.4 744.4 744.4 0.0 WBKR0021 26,351 1 168 3 233 1.2 744.9 744.9 745.0 0.1 WBKR0022 26,579 1 166 3 235 1.0 745.2 745.2 745.3 0.1 WBKR0023 27,985 1 49 133 1.5 745.6 745.6 745.7 0.1 WBKR0024 28,158 1 81 273 0.7 746.3 746.3 746.4 0.1 WBKR0025 28,722 1 31 135 1.4 746.3 746.3 746.4 0.1 WBKR0026 28,897 1 35 212 1.0 748.4 748.4 748.5 0.1 WBKR0027 30,320 1 39 195 0.7 748.6 748.6 748.7 0.1 WBKR0028 30,482 1 40 246 0.6 749.8 749.8 749.9 0.1 WBKR0029 32,036 1 36 193 0.8 749.8 749.8 750.0 0.1 WBKR0030 32,284 1 40 164 0.9 749.8 749.8 749.8 0.0 WBKR0031 34,078 1 68 140 0.7 750.0 750.0 750.0 0.0 WBKR0032 34,185 1 38 116 1.7 750.8 750.8 750.8 0.0 WBKR0033 36,853 1 24 74 0.6 751.7 751.7 751.7 0.0 WBKR0034 37,424 1 20 52 0.9 751.7 751.7 751.7 0.0 WBKR0035 41,489 1 179 529 0.1 755.7 755.7 755.8 0.1 WBKR0036 41,620 1 222 916 0.1 755.7 755.7 755.8 0.1

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River

3 Actual floodway width cannot be shown on FIRM due to redelineation of floodplain TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS KRESS CREEK (WBKR) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Unnamed Tributary to Kress Creek (WBKR) WBKR0038 1,303 1 155 693 0.2 732.6 732.6 732.6 0.0 WBKR0039 2,106 1 28 56 2.8 732.6 732.6 732.6 0.0 WBKR0040 2,426 1 200 321 0.5 734.7 734.7 734.7 0.0 WBKR0041 2,649 1 162 334 0.5 736.7 736.7 736.7 0.0 WBKR0042 3,876 1 30 37 4.1 741.7 741.7 741.7 0.0 WBKR0043 4,105 1 77 166 0.9 744.3 744.3 744.3 0.0 WBKR0044 4,850 1 24 47 2.6 744.6 744.6 744.6 0.0 WBKR0045 5,127 1 99 221 0.8 749.0 749.0 749.0 0.0 WBKR0046 5,728 1 67 99 1.3 749.1 749.1 749.1 0.0 WBKR0047 6,118 1 31 80 1.6 749.2 749.2 749.2 0.0 WBKR0048 6,544 1 785 189 0.7 749.2 749.2 749.2 0.0 WBKR0049 7,088 1 5 15 7.9 750.1 750.1 750.1 0.0 WBKR0050 7,560 1 30 5 1.4 751.9 751.9 751.9 0.0 WBKR0051 8,001 1 125 183 0.7 752.5 752.5 752.5 0.0 WBKR0052 8,591 1 45 93 0.9 752.9 752.9 752.9 0.0 WBKR0053 9,124 1 300 985 0.1 757.0 757.0 757.0 0.0 WBKR0054 11,762 1 163 579 0.1 757.0 757.0 757.0 0.0

1 In feet above confluence with Kress Creek TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS UNNAMED TRIBUTARY TO KRESS CREEK (WBKR) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Unnamed Tributary to Kress Creek (WBKR) WBKR0055 11,950 1 35 122 0.7 758.6 758.6 758.6 0.0

725 725

FOOTBRIDGE

JOLIET STREET 720 STATE ROUTE 59 720

715 715

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

KRESS CREEK (WBKR)

710 710

705 705

ELEVATION IN FEET (NGVD 29)

JOY ROAD 700 700

695 WBKR0004 WBKR0005 695 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 690 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0001 WBKR0002 WBKR0003 CROSS SECTION LOCATION 685 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 171P RAILROAD

TOWN ROAD

FOOTBRIDGE

MAY STREET

CONFLUENCE OF

UNNAMED TRIBUTARY TO KRESS CREEK

730 730

FLOOD PROFILES

KRESS CREEK (WBKR)

725 725

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0006 WBKR0007 WBKR0008 WBKR0009 WBKR0010 CROSS SECTION LOCATION 700 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 172P ROAD A

RAILROAD 745 745

740 740

FLOOD PROFILES

KRESS CREEK (WBKR)

735 735

730 730

ELEVATION IN FEET (NGVD 29)

725 725

720 WBKR0014 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0011 WBKR0012 WBKR0013 CROSS SECTION LOCATION 710 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 173P RAILROAD

FOOTBRIDGE

ROOSEVELT ROAD

755 FABYAN PARKWAY MCCHESNEY ROAD 755

750 750

FLOOD PROFILES

KRESS CREEK (WBKR)

745 745

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 WBKR0019 WBKR0020 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD* 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0015 WBKR0016 WBKR0017 WBKR0018 CROSS SECTION LOCATION 720 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER *DATA NOT AVAILABLE UPSTREAM OF FOOTBRIDGE 174P DOWNS DRIVE

RAILROAD SPUR

WESTERN DRIVE

755 INDUSTRIAL DRIVE 755

INDIAN BOUNDARY ROAD

750 750

FLOOD PROFILES

KRESS CREEK (WBKR)

745 745

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 WBKR0029 WBKR0030 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD* 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0021 WBKR0022 WBKR0023 WBKR0024 WBKR0025 WBKR0026 WBKR0027 WBKR0028 CROSS SECTION LOCATION 720 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER *DATA NOT AVAILABLE 175P RAILROAD SPUR RAILROAD SPUR

HARVESTER ROAD

HAWTHORNE LANE

FLOOD PROFILES

KRESS CREEK (WBKR)

755 755

750 750

ELEVATION IN FEET (NGVD 29)

745 745

740 740 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBKR0032 50-YEAR FLOOD* 735 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0031 WBKR0033 WBKR0034 CROSS SECTION LOCATION 730 32500 33000 33500 34000 34500 35000 35500 36000 36500 37000 37500 38000 38500 39000

FEDERAL EMERGENCY MANAGEMENT AGENCY * DATA NOT AVAILABLE DOWNSTREAM OF APPROXIMATELY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 37,500 FT ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 176P POWIS ROAD

CROWN COURT

UNNAMED DRIVE

LIMIT OF DETAILED STUDY

760 760

FLOOD PROFILES

KRESS CREEK (WBKR)

755 755

750 750

ELEVATION IN FEET (NGVD 29)

745 745

740 740 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBKR0036 50-YEAR FLOOD 735 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0035 WBKR0037 CROSS SECTION LOCATION 730 39000 39500 40000 40500 41000 41500 42000 42500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 177P 100-YEAR BACKWATER FROM KRESS CREEK

750 750

TOWN ROAD

PRIVATE ROAD

745 ROOSEVELT ROAD 745

PARKING LOT BRIDGE

CONFLUENCE WITH KRESS CREEK

740 740 THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE TO

BE SHOWN SEPARATELY FLOOD PROFILES

RAILROAD 735 735

UNNAMED TRIBUTARY TO KRESS CREEK (WBKR)

730 730

ELEVATION IN FEET (NGVD 29)

725 725

720 WBKR0045 WBKR0046 WBKR0047 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0038 WBKR0039 WBKR0040 WBKR0041 WBKR0042 WBKR0043 WBKR0044 CROSS SECTION LOCATION 710 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KRESS CREEK 178P RAILROAD RAILROAD RAILROAD

GENEVA ROAD

INDUSTRIAL DRIVE INDUSTRIAL DRIVE

LIMIT OF DETAILED STUDY

FLOOD PROFILES

760 760

UNNAMED TRIBUTARY TO KRESS CREEK (WBKR)

755 755

ELEVATION IN FEET (NGVD 29)

750 750

CULVERT

745 WBKR0054 WBKR0055 745 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 740 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBKR0048 WBKR0049 WBKR0050 WBKR0051 WBKR0052 WBKR0053 CROSS SECTION LOCATION 735 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000

FEDERAL EMERGENCY MANAGEMENT AGENCY * DATA NOT AVAILABLE UPSTREAM OF RAILROAD CULVERT STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH KRESS CREEK 179P

3.7.7 Springbrook No. 1 (WBSP)

3.7.7.1 Tributary Description

Springbrook No. 1 is a 4921-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to Springbrook No. 1 are Wheaton, Glen Ellyn, Warrenville and Unincorporated DuPage County. Much of the land use in the upper and central portions of Springbrook No. 1 watershed is developed as single and multi-family residential, with a few pockets of commercial activity on Roosevelt Road. The lower sections of the watershed are primarily kept in open space.

Springbrook No. 1 is greatly storm-sewered in the upper reaches of the watershed. Flow consistently bears to the southwest through the downtown area of Wheaton, crossing the Chicago and Northwestern Railroad tracks and Roosevelt Road. It is on the southern side of Roosevelt Road that Springbrook No. 1 opens up to steep-sloped channels. Flow proceeds to the southwest, passing under such residential roads as Park Avenue, Elm Street, Warrenville Road, the Illinois Prairie Path, Gables Boulevard, Aurora Way, Creekside Drive, Stonebridge Terrace, Shaffner Road, Essex Road and Center Avenue. Downstream of this point, the land use for Springbrook No.1 abruptly changes from residentially developed to open agricultural land. The creek proceeds to the west, passes under Winfield Road, and enters the Blackwell Forest Preserve. Within the Forest Preserve, Springbrook No. 1 bears to the southwest and confluences with the West Branch DuPage River just north of the intersection of the Illinois Prairie Path and Batavia Road.

3.7.7.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Springbrook No.1.

Discharges for the 10-year, 50-year, and 100-year floods for Springbrook No. 1 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses of the Springbrook No. 1 studied in detail are presented in Table WBSP.1 below:

Table WBSP.1: USGS Stream Gages Used for Hydrologic Analysis of Springbrook No. 1

Section printed 29 April 2004

USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Springbrook No. 1 Near Warrenville 05540090 6.01 15

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBSP.2.

Table WBSP.2: Springbrook No. 1 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Springbrook No. 1 - - mouth at West Branch DuPage River 7.10 495 685 795 1,140 - at mile 2.917 3.30 350 480 555 800 - at Aurora Way 2.78 305 425 490 705 - at Warrenville Road 2.10 265 370 430 615

3.7.7.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBSP.3 for further information regarding roughness coefficients.

Table WBSP.3: Springbrook No. 1 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Springbrook No.1 0.035 - 0.055 0.070 - 0.100

3.7.7.4 Flood Boundaries

To reference the flood boundaries for Springbrook No.1 Tributary, see Map Panels: 0406, 0408, 0409, 0502, 0504, 0505, 0507 and 0508.

3.7.7.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.7.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Spring Brook No. 1 (WBSP) WBSP0001 454 1 190 376 2.2 697.7 693.8 2 693.9 0.1 WBSP0002 2,188 1 226 765 1.0 700.1 700.1 700.2 0.1 WBSP0003 4,685 1 184 335 2.4 707.3 707.3 707.3 0.0 WBSP0004 8,264 1 122 570 1.3 711.2 711.2 711.3 0.1 WBSP0005 11,209 1 248 482 1.5 714.1 714.1 714.2 0.1 WBSP0006 12,521 1 120 363 2.0 716.8 716.8 716.9 0.1 WBSP0007 14,528 1 194 597 1.1 720.1 720.1 720.2 0.1 WBSP0008 15,242 1 305 897 0.8 720.5 720.5 720.6 0.1 WBSP0009 15,736 1 96 496 1.1 722.4 722.4 722.5 0.1 WBSP0010 16,944 1 205 3 1,539 0.4 723.0 722.9 723.0 0.1 WBSP0011 17,974 1 292 1,466 0.4 723.5 723.5 723.6 0.1 WBSP0012 18,121 1 432 1,205 0.5 723.6 723.6 723.7 0.1 WBSP0013 18,506 1 466 1,479 0.4 723.6 723.6 723.7 0.1 WBSP0014 19,445 1 211 2,237 0.2 723.7 723.7 723.8 0.1 WBSP0015 20,118 1 118 777 0.7 723.7 723.7 723.8 0.1 WBSP0016 20,724 1 156 1,271 0.4 723.8 723.8 723.9 0.1 WBSP0017 21,606 1 64 225 2.4 723.9 723.9 724.0 0.1

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River

1 In feet above confluence with West Branch DuPage River

2 Elevations computed without consideration of backwater effects from West Branch DuPage River

715

710 PAMELA ROAD 710

MORRIS COURT ROAD

705 705

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

SPRING BROOK NO. 1 (WBSP) 700 700

695 695

ELEVATION IN FEET (NGVD 29)

690 690

685 685 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 680 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBSP0001 WBSP0002 WBSP0003 CROSS SECTION LOCATION 675 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 180P WINFIELD ROAD

UNNAMED ROAD UNNAMED ROAD

720 720

FLOOD PROFILES

SPRING BROOK NO. 1 (WBSP) 715 715

710 710

ELEVATION IN FEET (NGVD 29)

705 705

700 WBSP0006 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBSP0004 WBSP0005 CROSS SECTION LOCATION 690 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 181P ESSEX ROAD FOOTBRIDGE

W. CREEKSIDE DRIVE

SEWAGE PLANT BRIDGE SEWAGE PLANT BRIDGE SEWAGE PLANT BRIDGE

FLOOD PROFILES

SPRING BROOK NO. 1 (WBSP) 725 725

720 720

ELEVATION IN FEET (NGVD 29)

WBSP0014 715 715

WBSP0011 WBSP0013 710 WBSP0012 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBSP0007 WBSP0008 WBSP0009 WBSP0010 CROSS SECTION LOCATION 700 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 182P 740 740

FOOTBRIDGE

W. AURORA WAY 735 CREEKSIDE DRIVE 735

STONEBRIDGE TRAIL

S. GABLES BOULEVARD

730 730

FLOOD PROFILES

SPRING BROOK NO. 1 (WBSP) 725 725

720 PRAIRIE PATH 720

ELEVATION IN FEET (NGVD 29)

715 715

710 WBSP0021 WBSP0022 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBSP0015 WBSP0016 WBSP0017 WBSP0018 WBSP0019 WBSP0020 CROSS SECTION LOCATION 700 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 183P E. ELM STREET

HAWTHORNE LANE

WARRENVILLE ROAD

LIMIT OF DETAILED STUDY

735 735

LIMIT OF FLOODWAY

FLOOD PROFILES

SPRING BROOK NO. 1 (WBSP) 730 730

725 725

ELEVATION IN FEET (NGVD 29)

720 720

715 715 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBSP0023 CROSS SECTION LOCATION 705 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 184P

3.7.8 Steeple Run Tributary (WBSR)

3.7.8.1 Tributary Description

Steeple Run Tributary is a 1754-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to Steeple Run Tributary are Naperville, Lisle and Unincorporated DuPage County. The primary land use within the Steeple Run watershed is single-family residential.

Steeple Run has several feeder tributaries that branch off in all directions in the upper portions of the watershed. There is a general conglomeration of the tributaries at May Watts Park, found south of North Street, west of Charles Drive and east of Harrison Street in the City of Naperville. Flow proceeds to the south passing under Benton Avenue, Chicago Avenue and Julian Street at the intersection of Julian and Porter Streets. The tributary enters a large conduit that travels west under Porter Street. The stream enters the grounds at North Central College and joins with the West Branch DuPage River north of Hillside Avenue.

3.7.8.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Steeple Run Tributary.

Discharge-frequency data for West Branch DuPage River were developed through the use of the Chicago Metropolitan Study, DuPage River Basin performed by the USACE’s Hydrologic Engineering Center (USACE, 1974). In the Chicago study, the DuPage River Basin above Shorewood, Illinois, was divided into 20 subareas and a generalized HEC-1 rainfall- runoff computer model was calibrated for the basin (USACE, 1973). Using 24-hour rainfall data obtained from Weather Bureau Technical Paper No. 40, one-hour values, in critical order, were entered into the HEC-1 model of the DuPage River Basin to determine the 10-year, 50- year, and 100-year peak discharges (U.S. Department of Commerce, 1963).

3.7.8.3 Hydraulic Analysis

Analyses of the hydraulic characteristics of flooding from the West Branch DuPage River were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. For construction and/or floodplain

Section printed 29 April 2004

management purposes, users are encouraged to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM.

Cross-section data for West Branch DuPage River were obtained by field measurement.

The 100-year water-surface elevation on the West Branch DuPage River was computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, 1976).

Since no formal FEMA study was completed on Steeple Run Tributary, the West Branch DuPage River 100-yr elevation information, determined through the above methods, at the location of the junction between the West Branch DuPage River and Steeple Run Tributary is used for backwater effects on Steeple Run Tributary. In addition to the determined backwater zone information, the unnumbered A-zone boundary was further formed through local studies and the USGS Flood of Record Maps.

3.7.8.4 Flood Boundaries

To reference the flood boundaries for Steeple Run Tributary, see Map Panels: 0801, 0802, 0804 and 0805.

3.7.8.5 Floodways

No floodway information is available for this tributary

3.7.8.6 Flood Profiles

No flood profiles are available for this tributary.

Section printed 29 April 2004

3.7.9 West Branch Tributary No. 1 (WBW1)

3.7.9.1 Tributary Description

The West Branch Tributary No. 1 watershed covers approximately 2.7 square miles. The West Branch Tributary No.1 drainage system consists of West Branch Tributary No. 1 to the West Branch of the DuPage River (West Branch Tributary No. 1 Main Stem) with five tributaries to the West Branch Tributary No. 1 Main Stem. Most of the watershed is unincorporated, although portions are incorporated into Bloomingdale to the south, and Hanover Park and Roselle to the north. The watershed boundary in general extends from Lake Street in the north, to roughly Schick Road in the south, to the West Branch of the DuPage River to the west. The western portion of the watershed is primarily contained in the Mallard Lake Forest Preserve. The eastern portion of the watershed is mainly residential.

The West Branch Tributary No.1 Main Stem begins southeast of the intersection of Argyle and Wheaton Roads in the unincorporated area of DuPage County commonly referred to as Keeneyville. Flow proceeds to the northwest passing under such roads as Wheaton Road, Papworth Street, Argyle Avenue, Keeney Road, Virginia Road, Gary Avenue, and Cloverdale Road. On the west side of Cloverdale Road, West Branch Tributary No. 1 Main Stem enters the Mallard Lake Forest Preserve. Flow from the Main Stem bears to the southwest, eventually converging with a secondary branch in the Forest Preserve. The Tributary the proceeds to the north, encountering and joining the West Branch DuPage River in the north section of Mallard Lake Forest Preserve.

3.7.9.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 1.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 1 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW1.1.

Table WBW1.1: West Branch Tributary No. 1 Summary of Discharges

Section printed 29 April 2004

Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 1 - just upstream of Forest Preserve Road 1.41 65 140 190 305

3.7.9.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

Creek Tributary No. 1, Wards Creek, West Branch Tributary No. 5, West Branch Tributary No. 7, East Branch Tributary No. 1, and East Branch Tributary No. 2, which have only the 10-year and 100-year profiles.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBW1.2 for further information regarding roughness coefficients.

Table WBW1.2: West Branch Tributary No. 1 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 1 0.050 - 0.080 0.095

3.7.9.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 1, see Map Panels: 0103, 0106, 0201, 0202, 0204 and 0205.

3.7.9.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.9.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River

2 Elevation computed without consideration of backwater effects from West Branch DuPage River

FOOTBRIDGE 772 772

FOREST PRESERVE ROAD

LIMIT OF DETAILED STUDY

770 770

FLOOD PROFILES

768 768

WEST BRANCH TRIBUTARY NO. 1 (WBW1)

766 766

ELEVATION IN FEET (NGVD 29)

764 764

762 762 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 760 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW10001 CROSS SECTION LOCATION 758 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 197P GARY AVENUE

774 CLOVERDALE ROAD 774

LIMIT OF DETAILED STUDY

772 772

FLOOD PROFILES

770 770

WEST BRANCH TRIBUTARY NO. 1 (WBW1)

768 768

ELEVATION IN FEET (NGVD 29)

766 766

764 WBW10003 764 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 762 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW10002 CROSS SECTION LOCATION 760 8400 8600 8800 9000 9200 9400 9600 9800 10000 10200 10400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 198P

3.7.10 West Branch Tributary No. 2 (WBW2)

3.7.10.1 Tributary Description

West Branch Tributary No. 2 is a 3004-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to West Branch Tributary No. 2, within DuPage County, are Hanover Park, Bartlett and Unincorporated DuPage County. The overall land use within the upper reaches of the watershed (Cook County) is urbanized development with large stretches of commercial and residential zones. The central part of the watershed, located in DuPage County, is primarily residential. The lower sections of the watershed are Forest Preserve open prairie lands.

West Branch Tributary No. 2 begins in Cook County Illinois just north of Bartlett. Flow proceeds directly south, entering DuPage County just west of Hillandale Drive in Bartlett. Flow continues to the south passing under such roads as Amherst Drive, Wilcox Drive, Country Drive, Brookside Drive, Francine Drive, and Stearns Road. On the south side of Stearns Road, the West Branch Tributary No. 2 enters the Hawk Hollow Forest Preserve, and joins the West Branch DuPage River.

3.7.10.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 2.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 2 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW2.1.

Table WBW2.1: West Branch Tributary No. 2 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 2

Section printed 29 April 2004

- at mouth 3.70 278 390 430 569

3.7.10.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

Refer to Table WBW2.2 for further information regarding roughness coefficients.

Table WBW2.2: West Branch Tributary No. 2 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 2 0.015 - 0.035 0.035 - 0.120

3.7.10.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No.2, see Map Panels: 0102 and 0103.

3.7.10.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.10.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) West Branch Tributary No. 2 (Country Creek) (WBW2) WBW20001 2,783 1 32 63 6.8 754.4 754.4 754.5 0.1 WBW20002 6,570 1 283 331 1.2 771.3 771.3 771.4 0.1 WBW20003 7,010 1 263 1,295 0.3 771.4 771.4 771.5 0.1 WBW20004 7,775 1 104 258 1.7 773.4 773.4 773.4 0.0 WBW20005 11,120 1 84 317 0.9 781.8 781.8 781.8 0.0

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH TRIBUTARY NO. 2 (COUNTRY CREEK) (WBW2) 775 775 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

770 770

765 765

760 760

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

755 STEARNS ROAD 755

750 750 WEST BRANCH TRIBUTARY NO. 2 (COUNTRY CREEK) (WBW2)

ELEVATION IN FEET (NGVD 29)

745 745

740 740 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 735 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBW20001 730 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 199P 790 790

FOOTBRIDGE FOOTBRIDGE

FRANCINE DRIVE

785 BROOKSIDE DRIVE 785

WEST COUNTRY DRIVE

780 780

FLOOD PROFILES THE 50-YEAR PROFILE IS TOO CLOSE TO THE 100-YEAR PROFILE TO BE SHOWN SEPARATELY 775 775

DEVON AVENUE

770 770 WEST BRANCH TRIBUTARY NO. 2 (COUNTRY CREEK) (WBW2)

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

765 765

760 760 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 755 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW20002 WBW20003 WBW20004 WBW20005 CROSS SECTION LOCATION 750 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 200P

3.7.11 West Branch Tributary No. 3 (WBW3)

3.7.11.1 Tributary Description

West Branch Tributary No. 3 is a 1081-acre watershed that is tributary to the West Branch DuPage River. Communities that contribute watershed area to West Branch Tributary No. 3 are West Chicago and Unincorporated DuPage County. The overall land use for this watershed is large-parceled residential.

West Branch Tributary No. 3 begins on the west side of Waynewood Drive, just south of North Avenue and east of Route 59. Flow proceeds to the east, passing under Waynewood Drive, the Illinois Prairie Path and Prince Crossing Road. On the east side of Prince Crossing, the West Branch Tributary No. 3 enters the Timber Ridge Forest Preserve and confluences with the West Branch DuPage River.

3.7.11.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 3.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 3 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW3.1.

Table WBW3.1: West Branch Tributary No. 3 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 3 - at mouth 1.32 190 335 430 650

3.7.11.3 Hydraulic Analysis

Section printed 29 April 2004

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBW3.2 for further information regarding roughness coefficients.

Table WBW3.2: West Branch Tributary No. 3 Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 3 0.040 - 0.070 0.085

3.7.11.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No.3, see Map Panels: 0108, 0109, 0402 and 0403.

3.7.11.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.11.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River

2 Elevation computed without considering backwater effects from West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH TRIBUTARY NO. 3 (WBW3) 750 750 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

745 745

740 740

PRINCE CROSSING ROAD

735 735

FLOOD PROFILES

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

730 730

WEST BRANCH TRIBUTARY NO. 3 (WBW3)

725 725

ELEVATION IN FEET (NGVD 29)

RAILROAD 720 720

715 WBW30004 715 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW30001 WBW30002 WBW30003 CROSS SECTION LOCATION 705 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 201P 755 755

750 750

745 745

FLOOD PROFILES

740 740

WEST BRANCH TRIBUTARY NO. 3 (WBW3)

FOOTBRIDGE 735 735

WAYNEWOOD DRIVE

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NGVD 29)

730 730

725 725 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 720 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW30005 WBW30006 WBW30007 CROSS SECTION LOCATION 715 5200 5600 6000 6400 6800 7200 7600 8000 8400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 202P

3.7.12 West Branch Tributary No. 4 (WBW4)

3.7.12.1 Tributary Description

The West Branch Tributary No. 4 watershed is located in central DuPage County and drains approximately 2.86 square miles of area within the Village of Carol Stream and Unincorporated DuPage County where it meets with the West Branch of the DuPage River. At the headwaters of the watershed there is no defined channel, the watercourse generally consists of detention ponds and connecting storm sewers, and, in general, the flow is from north to south. Approximately two-thirds of the watershed is within the corporate limits of the Village of Carol Stream while the balance is in Unincorporated DuPage County.

The open-channel system of West Branch Tributary No. 4 is approximately 1.9 miles long, and has an average bed slope of 0.2 percent. It meets with the West Branch of the DuPage River in the Timber Ridge Forest Preserve. Between the confluence and North Avenue there exists Forest Preserve property, undeveloped private property, and a 32.6-acre Oak Creek Estates development of non-storm-sewered 1 acre (approximately) lots of septic fields. The only bridge or culvert in this reach is the Chicago Northwestern Railroad crossing. Between North Avenue and St. Charles Road are the Sidwell Corporation grounds, which include two small on-site water treatment ponds, which discharge into the stream. North of St. Charles Road is Benjamin School and Treetops, an approximately 37 acre residential property that includes a lake and a small non-native animal community within its confines. The north property limit of Treetops is 650 +/- feet south of Timber Lane. Between this property boundary and the corporate limits of the Village of Carol Stream is the Wayne Oaks Lake/Dam and a subdivision called Branigar’s 1st Addition to Wayne Oaks (Wayne Oaks Subdivision). Along the channel, and between the corporate limits and Evergreen Drive is Dogwood Park, a grassland area currently owned by the Village of Carol Stream. North of Evergreen Drive are the Village of Carol Stream residential homes where there is no longer a defined open channel, and West Branch Tributary No. 4 essentially consists of on-and off-line reservoir/detention facilities interconnected by storm sewers. At the headwaters of the watershed, at Army Trail Road, there is the Heritage Plaza commercial center.

3.7.12.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 4.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 4 were computed using the log-Pearson Type III method

Section printed 29 April 2004

(U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW4.1.

Table WBW4.1: West Branch Tributary No. 4 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 4 - at mouth 2.91 275 475 590 880

3.7.12.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

was used for all streams studied in detail and limited detail except for Meacham Creek, Sawmill Creek, Salt Creek, Spring Brook, and Westwood Creek, which were modeled utilizing the SCS WSP-2 program (U.S. Department of Agriculture, 1974).

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBW4.2 for further information regarding roughness coefficients.

Table WBW4.2: West Branch Tributary No. 4 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 4 0.065 0.085 - 0.100

3.7.12.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 4, see Map Panels: 0106, 0109, 0204 and 0207.

3.7.12.5 Floodways

No floodway information is currently available for this tributary.

3.7.12.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

745 745

RAILROAD 740 740

735 735

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

730 730

WEST BRANCH TRIBUTARY NO. 4 (WBW4)

725 NORTH AVENUE 725

ELEVATION IN FEET (NGVD 29)

720 720

715 WBW40004 715 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW40001 WBW40002 WBW40003 CROSS SECTION LOCATION 705 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 203P TIMBER LANE

ST. CHARLES ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

745 745

WEST BRANCH TRIBUTARY NO. 4 (WBW4)

740 740

ELEVATION IN FEET (NGVD 29)

735 735

730 730 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 725 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW40005

WBW40006 CROSS SECTION LOCATION 720 6500 7000 7500 8000 8500 9000 9500 10000 10500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 204P

3.7.13 West Branch Tributary No. 5 (WBW5)

3.7.13.1 Tributary Description

West Branch Tributary No. 5 is a 1071-acre watershed that is tributary to the West Branch DuPage River. Communities that contribute watershed area to West Branch Tributary No. 5 are West Chicago, Winfield and Unincorporated DuPage County. The primary land use in the western half of the watershed is single-family residential, where the eastern half is untouched forested areas.

West Branch Tributary No. 5 origins can be found in the Timber Ridge Forest Preserve north of Geneva Road and east of Prince Crossing Road. Flow proceeds to the southeast, through the Forest Preserve, and at the intersection of Indian Knoll and Geneva, the creek crosses Geneva Road. The stream continues a parallel course to Indian Knoll Road on the west side, crosses Indian Knoll at the intersection of Main and Indian Knoll, and enters Winfield Mounds Forest Preserve. West Branch Tributary No. 5 bears directly south through the heart of the Forest Preserve, crosses Highlake Road, turns to the southwest and joins the West Branch DuPage River near the dead-end section of Morningside Drive.

3.7.13.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 5.

Discharges for the 10-year, 50-year, and 100-year floods West Branch Tributary No. 5 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW5.1.

Table WBW5.1: West Branch Tributary No. 5 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 5

Section printed 29 April 2004

- at mouth 0.07 35 * 95 *

3.7.13.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Section printed 29 April 2004

Refer to Table WBW5.2 for further information regarding roughness coefficients.

Table WBW5.2: West Branch Tributary No. 5 Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 5 0.050 - 0.070 0.065 - 0.085

3.7.13.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 5, see Map Panels: 0402, 0403 and 0406.

3.7.13.5 Floodways

No floodway information is currently available for this tributary.

3.7.13.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

LESTER STREET

BOLLES AVENUE

DONALD AVENUE

LIMIT OF DETAILED STUDY

CHICAGO AND NORTH WESTERN RAILROAD 725 725

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

720 720

WEST BRANCH TRIBUTARY NO. 5 (WBW5)

715 715

ELEVATION IN FEET (NGVD 29)

710 710

705 705 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 700 10-YEAR FLOOD STREAM BED

AND INCORPORATED AREAS

DUPAGE COUNTY, IL CROSS SECTION LOCATION

WBW50001 WBW50002 WBW50003 695 0 250 500 750 1000 1250 1500 1750 2000 *DATA NOT AVAILABLE FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 205P

3.7.14 West Branch Tributary No. 6 (WBW6)

3.7.14.1 Tributary Description

West Branch Tributary No. 6 is a 771-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to West Branch Tributary No. 6 are Naperville, Lisle and Unincorporated DuPage County. The overall land use for this watershed is single-family residential.

West Branch Tributary No. 6 lies entirely within a large subdivision and as a result much open channel has been converted to conduit. Flow in the watershed starts in the Village of Lisle on the west side of College Road, north and proceeds to the southwest. The tributary then enter the City of Naperville still flowing in a southwesterly direction, opening up to open channel on the downstream side of Johnson Drive. The stream proceeds under Olesen Drive, Hobson Mill Drive (twice) and enters Pioneer Park Forest Preserve where it confluences with the West Branch DuPage River.

3.7.14.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 6.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 6 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW6.1.

Table WBW6.1: West Branch Tributary No. 6 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 6 - at mouth 0.18 155 240 285 675

3.7.14.3 Hydraulic Analysis

Section printed 29 April 2004

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBW6.2 for further information regarding roughness coefficients.

Table WBW6.2: West Branch Tributary No. 6 Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 6 0.070 0.100

3.7.14.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 6, see Map Panels: 0804, 0805 and 0807.

3.7.14.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.14.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River

670 670

HOBSON MILL DRIVE (WEST)

665 665

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

660 660

WEST BRANCH TRIBUTARY NO. 6 (WBW6)

655 655

ELEVATION IN FEET (NGVD 29)

650 650

645 WBW60001 645 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 635 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 206P HOBSON MILL DRIVE (EAST)

685 685

FLOOD PROFILES

680 680

WEST BRANCH TRIBUTARY NO. 6 (WBW6)

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 655 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 207P UNNAMED ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

690 690

WEST BRANCH TRIBUTARY NO. 6 (WBW6)

685 685

ELEVATION IN FEET (NGVD 29)

680 680

675 675 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 670 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW60002 CROSS SECTION LOCATION 665 2400 2500 2600 2700 2800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 208P

3.7.15 West Branch Tributary No. 7 (WBW7)

3.7.15.1 Tributary Description

West Branch Tributary No. 7 is a 375-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to West Branch Tributary No. 7 are Naperville, Lisle and Unincorporated DuPage County. The overall land use for this watershed is single-family residential.

This short tributary begins on the south side of Hobson Road. Flow proceeds to the west passing underneath Market Avenue and Hobson Oaks Drive into the Goodrich Woods Forest Preserve. Upon leaving the Forest Preserve, West Branch Tributary No.7 passes under Oxford Lane and confluences with the West Branch DuPage River at the northeast corner of Washington Street and 75th Street.

3.7.15.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for West Branch Tributary No. 7.

Discharges for the 10-year, 50-year, and 100-year floods for West Branch Tributary No. 7 were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBW7.1.

Table WBW7.1: West Branch Tributary No. 7 Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

West Branch - Tributary No. 7 - at mouth 0.16 55 110 150 210

3.7.15.3 Hydraulic Analysis

Section printed 29 April 2004

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBW7.2 for further information regarding roughness coefficients.

Table WBW7.2: West Branch Tributary No. 7 Manning’s “n” Values Manning’s “n” Values

Section printed 29 April 2004

Stream Channel "n" Overbank "n"

- West Branch Tributary No. 7 0.050 - 0.060 0.065 - 0.100

3.7.15.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 7, see Map Panels: 0804, 0805, 0807 and 0808.

3.7.15.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.15.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River

2 Cross-section is shown on FIRM; not on profile

3 Data not available TABLE 1 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WEST BRANCH TRIBUTARY NO. 7 (WBW7) 100-YEAR BACKWATER FROM WEST BRANCH DUPAGE RIVER

675 675

670 UNNAMED ROAD 670

665 665

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

FLOOD PROFILES

660 660

WEST BRANCH TRIBUTARY NO. 7 (WBW7)

655 655

ELEVATION IN FEET (NGVD 29)

650 650

645 645 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 640 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION 635 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 209P OXFORD LANE

UNNAMED ROAD

685 685

FLOOD PROFILES

680 680

WEST BRANCH TRIBUTARY NO. 7 (WBW7)

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBW70001 CROSS SECTION LOCATION 655 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 210P LIMIT OF DETAILED STUDY

685 685

FLOOD PROFILES

680 680

WEST BRANCH TRIBUTARY NO. 7 (WBW7)

675 675

ELEVATION IN FEET (NGVD 29)

670 670

665 665 LEGEND 500-YEAR FLOOD* 100-YEAR FLOOD 50-YEAR FLOOD* 660 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBW70002 655 2600 2700 2800 2900 3000 3100 3200 3300 3400 3500

FEDERAL EMERGENCY MANAGEMENT AGENCY *DATA NOT AVAILABLE STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 211P

3.7.16 West Branch Tributary No. 8 (WBW8)

3.7.16.1 Tributary Description

West Branch Tributary No. 8 is a 494-acre watershed that is tributary to the West Branch DuPage River. The communities that contribute watershed area to West Branch Tributary No. 8 are Naperville and Unincorporated DuPage County. The overall land use for this watershed is single-family residential.

This short tributary has two principal branches which join just upstream of Knoch Knolls Road in the Knoch Knolls Commons area of Naperville. The main stem then has a short run of about 800 feet before joining the West Branch DuPage River. Both of the principal branches and almost the entirety of the watershed are within Will County. The portion of the northern branch that once reached into DuPage County was pirated into the South of Foxcroft Tributary, just west of Petworth Court in Will County, when residential development took place. This change effectively cut off this watershed from DuPage County stormwater management concerns.

3.7.16.2 Hydrologic Analysis

There is no information regarding the regulatory hydrologics of West Branch Tributary No. 8 within the confines of DuPage County.

3.7.16.3 Hydraulic Analysis

There is no information regarding the regulatory hydraulics of West Branch Tributary No. 8 within the confines of DuPage County.

3.7.16.4 Flood Boundaries

To reference the flood boundaries for West Branch Tributary No. 8, see Map Panels: 0709 and 0807.

3.7.16.5 Floodways

No floodway information is currently available for this tributary.

3.7.16.6 Flood Profiles

No flood profile information is currently available for this tributary.

Section printed 26 May 2004

3.7.17 Winfield Creek (WBWF)

3.7.17.1 Tributary Description

The Winfield Creek watershed is located in central DuPage County and drains approximately 8.3 square miles of area within the Villages of Winfield, Carol Stream, Glen Ellyn, Glendale Heights, the City of Wheaton, and Unincorporated DuPage County. Winfield Creek meets with the West Branch of the DuPage River at the western corporate limits of the Village of Winfield between Beecher Avenue and Washington Avenue. The watershed consists of residential development, commercial areas, industrial parks, recreational community parks, undeveloped lots, a golf course (Cantigny Golf Club), and a Forest Preserve (Belleau Woods). The building structures within and adjacent to the floodplain are over 95% residential while the balance is business, or maintenance storage structures. There are three main parks within the floodplain of Winfield Creek which have been designated as part of the DuPage County wetland mitigation banking program – Lincoln Marsh, Northside Park, and Community Park. Lincoln Marsh is owned and maintained by the Wheaton Park District; Lincoln Marsh is jointly owned by the DuPage County Forest Preserve District and the Wheaton Park District, and maintained by the Wheaton Park District; and Community Park is owned by the Village of Carol Stream and maintained by the Wheaton Park District. A fourth major undeveloped area within the floodplain is Belleau Woods, a heavily wooded DuPage County Forest Preserve District property. Finally, there are several large lots and clusters of smaller lots that are undeveloped and are partially or completely inundated by the regulatory floodplain. Cumulatively these lots provide significant stormwater storage.

Winfield Creek is one of the larger tributary watersheds to the West Branch of the DuPage River, located to the east of the West Branch and approximately midway between where the West Branch enters and leaves DuPage County. The headwaters of the Winfield Creek watershed include areas of the Village of Glendale Heights to the north, the Village of Glen Ellyn to the south, and Unincorporated DuPage County between the two communities. There is no defined channel in any of these two communities. The watercourse consists of detention ponds and natural depressional areas connected by storm sewers. The flow is generally from north to south within the Village of Glendale Heights and from south to north within the Village of Glen Ellyn. Thereafter, Winfield Creek flows from northeast to southwest through the Village of Carol Stream and the City of Wheaton. Within the Village of Winfield, the flow is north to south up to East Street, and then from east to west until the confluence with the West Branch.

Section printed 29 April 2004

Winfield Creek is a typical Northeastern Illinois urban stream. Between the confluence with the West Branch of the DuPage River and Bloomingdale Road the open-channel (stream) system of Winfield Creek is approximately 6.7 miles long, and has an average bed slope of 0.1 percent. There are 36 hydraulic structures along Winfield Creek consisting of bridges, culverts, low flow dams, and weirs. There are several pedestrian or utility crossings at Community Park, Northside Park, Dorchester Avenue, and downstream of Summit Drive. During field reconnaissance these pedestrian crossings were assessed to by hydraulically nonobtrusive to flows. Along the main channel there are over 25 storm sewer outfalls that discharge stormwater from the tributary areas.

Between the confluence and Roosevelt Road (at Shaffner Road) is the channel reach within the Village of Winfield. The properties adjacent to the floodplain are mostly residential with a few 1-story office buildings, one industrial building and also some storage and utility structures belonging to DuPage County. There are numerous undeveloped lots adjacent to the creek and in some situations, the creek bisects the lot, many of which the regulatory floodplain completely inundates. A large number of these lots appear to be impractible to develop under the DuPage County Stormwater and Floodplain Ordinance.

The bridge or culvert crossings modeled in this reach are Summit Drive, Park Street, Winfield Road, Church Street, East Street (extention), Manchester Road, and Roosevelt Road (at Shaffner Road). The floodplain is generally flat and with some residential encroachment.

Between Roosevelt Road (at Shaffner) and Geneva Road is the channel reach within the City of Wheaton. There are three large undeveloped areas in the floodplain in this reach: Belleau Woods (DuPage County Forest Preserve District), Lincoln Marsh (Wheaton Park District and DuPage County Forest Preserve District), and Northside Park (Wheaton Park District). There is a weir structure at Northside Park that divides two level pool areas by approximately 3.5 feet during low-flow conditions. The upstream level pool is called Upper Northside Park while the downstream level pool area is called Lower Northside Park. Lincoln Marsh and Lower Northside Park provide approximately 318 acre-feet of storage up to elevation 731.0’ and Upper Northside Park provides approximately 131 acre-feet of storage up to elevation 732.0’. These two relatively large storage areas considerably attenuate the flows entering Northside Park from Main Street and surrounding tributary areas.

Belleau Woods provides approximately 87 acre-feet of storage for the August 1972 storm event between elevation 722.0’ at the downstream end (Shaffner Road) and elevation 723.7’ at the upstream property boundary.

Section printed 29 April 2004

Immediately east of Belleau Woods is St. Francis High School. Adjacent to the school are apartment buildings that have an off-line wet-bottom detention facility. Between Roosevelt Road (upstream crossing) and the Chicago and Northwestern Railroad, the floodplain area is mainly 1 composed of residential lots of approximately ¼ to /3 acre in size. There are two off-line dry-bottom floodplain storage areas with no effective outlet control between Beverly Avenue and Dorchester Lane. Just north of Childs Street is Emerson School. Upstream (north) of the Chicago and Northwestern Railroad and south of the Prairie Path, the area is part industrial, part residential, and part Lincoln Marsh. Between Lincoln Avenue and approximately 500’ west of Main Street (Wheaton) are Lincoln Marsh and Northside Park. Where Winfield Creek crosses Main Street is an area comprised mostly of commercial structures. Just east of Main Street and south of Cole Avenue is St. Mark’s Church. Between Cole Avenue and Geneva Road the creek flows through the backyards of a residential area.

North of Geneva Road is Community Park which is located in the Village of Carol Stream. Similar to Northside Park, Community Park consists of an on-line lake with surrounding parkland and provides approximately 154 acre-feet of storage up to elevation 746.0. This storage results in considerable attenuation of the upstream tributary flows, including the flow from an open-channel tributary that crosses the Great Western Railroad embankment and St. Charles Road, both crossings west of Bloomingdale Road.

The Upper Winfield Creek Basin is defined to be the headwaters of Winfield Creek near the intersection of North Avenue and Bloomingdale Road downstream to the intersection of St. Charles Road and Bloomingdale Road. The upper basin, which once was a series of wetlands and natural drainage channels, has been converted by development into a series of storage basins and storm sewer systems with overflow paths. The only “natural” wetland left in this part of the watershed is the Olive Court wetland at the northwest corner of North Avenue and Bloomingdale Road in Bloomingdale Township. This wetland has been degraded by development, sedimentation and filling. It serves as detention storage and flood control for two older subdivisions that were built before the days of stormwater detention requirements: Glen Hill in the Village of Glendale Heights and Glen Ellyn Countryside in unincorporated DuPage County. The total tributary area to the wetland is 209.5 acres. The flow then crosses under the intersection of Bloomingdale Road and North Avenue into a large detention facility for the commercial development at that corner. From this facility there is a storm sewer and overland route through an apartment complex into its detention system. The flow leaves via a storm sewer and overland route. The surface flow

Section printed 29 April 2004

crosses the Prairie Path and through a residential area before joining the Winfield Creek mainstem downstream of St. Charles Road.

A detailed description of the hydraulic structures and associated drainage features of the stream can be found under the “Drainage Network” subsection.

3.7.17.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Winfield Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Winfield Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

The USGS stream gages used for the hydrologic analyses Winfield Creek studied in detail are presented in Table WBWF.1 below:

Table WBWF.1: USGS Stream Gages Used for Hydrologic Analysis of Winfield Creek USGS Stream Gages

Flooding Source USGS Drainage Area Record and Location Gage # (sq. miles) (years)

Winfield Creek at Winfield 05540020 6.95 15

Frequency-discharge data for Winfield Creek were developed through the use of the Chicago Metropolitan Study, DuPage River Basin (USACE, 1973) performed by the USACE’s Hydrologic Engineering Center. In the Chicago Metro Study, the DuPage River basin above Shorewood, Illinois, was divided into 29 subareas and a generalized HEC-1 rainfall-runoff computer model was calibrated for the basin (USACE, 1973). One-hour increments of a 24-hour storm rainfall, obtained from the U.S. Weather Bureau Technical Paper No. 40 (U.S. Department of Commerce, 1961), were entered into the HEC-1 model of the basin to obtain the 10-, 50-, and 100-year flood peak discharges. Point rainfall-frequency curves derived from Technical Paper No. 40 were extrapolated to obtain a 500-year rainfall distribution, from which the 500-year flood peak discharges were computed. Since the discharges computed by this method applied to the total subarea tributary to the West Branch DuPage River in which each

Section printed 29 April 2004

stream was located, the corresponding subarea discharges were reduced by the square root of the drainage area ratio for each stream. Discharges for Winfield Creek below Main Street, computed by the above methods, were decreased following a reservoir routing analysis for the area between Chicago and North Western railroad bridges and Main Street. (A reservoir routing analysis was used because of the large ponding area that is very flat.)

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBWF.2.

Table WBWF.2: Winfield Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Winfield Creek - at Roosevelt and Schaffner Road 6.95 430 585 665 935 - at Beverly Avenue 6.35 340 450 510 710 - at Chicago and North- Western Railroad 5.60 225 290 320 425 - at low flow dam at mile 4.60 4.30 320 430 490 695 - at Main Street 3.69 370 510 590 855 - at d/s corporate limits for Village of Carol Stream 2.92 330 455 530 760

3.7.17.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Channel cross-section data were obtained from field surveys. All bridges and culverts were surveyed to obtain elevation data and structural geometry

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Water-surface profiles for Winfield Creek were computed through use of the USACE HEC-2 step-backwater computer program (USACE, HEC-2 Water-Surface Profiles, Computer Program 723-X6-L202A, 1973).

Section printed 29 April 2004

Profiles were determined for the 10-, 50-, 100-, and 500-year floods (Exhibit 1). For Winfield Creek between the Chicago and North Western Railroad and Main Street, two sets of profiles were computed using different sets of assumptions: (1) maximum inflow at Main Street and corresponding starting water-surface elevations at the railroad, and (2) maximum “pond” elevations behind the railroad bridge and corresponding discharges through the reach. The profiles for the second case were used since they were higher for the entire reach.

Starting water-surface elevations for Winfield Creek were calculated using the slope/area method.

Roughness coefficients (Manning’s “n”) for Winfield Creek were estimated by field inspection.

Roughness coefficients (Manning’s “n”) for the hydraulic computations were assigned on the basis of field inspection, analyses of field photographs (USACE, 1973-1979) and sound engineering judgment. Refer to Table WBWF.3 for further information regarding roughness coefficients.

Table WBWF.3: Winfield Creek Manning’s “n” Values Manning’s “n” Values

Stream Channel "n" Overbank "n"

- Winfield Creek 0.015 - 0.055 0.045 - 0.100

3.7.17.4 Flood Boundaries

To reference the flood boundaries for Winfield Creek, see Map Panels: 0207, 0208, 0403, 0406, 0501, 0502, 0504 and 0505.

3.7.17.5 Floodways

Please reference attached Floodway Data Tables for further information.

Section printed 29 April 2004

3.7.17.6 Flood Profiles

Please reference attached Flood Profile Sheets.

Section printed 29 April 2004 BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Winfield Creek (WBWF) WBWF0001 116 1 273 816 0.9 712.4 712.4 2 712.5 0.1 WBWF0002 533 1 189 480 1.6 712.4 712.4 2 712.5 0.1 WBWF0003 925 1 221 507 1.5 712.4 712.4 2 712.5 0.1 WBWF0004 1,600 1 279 493 1.5 713.6 713.6 713.7 0.1 WBWF0005 1,684 1 306 761 1.0 713.8 713.8 713.9 0.1 WBWF0006 2,006 1 307 754 1.0 715.4 715.4 715.5 0.1 WBWF0007 2,210 1 288 723 1.0 715.5 715.5 715.6 0.1 WBWF0008 2,441 1 263 675 1.1 717.2 717.2 717.3 0.1 WBWF0009 2,900 1 265 1,216 0.6 717.3 717.3 717.4 0.1 WBWF0010 3,748 1 512 2,473 0.3 717.3 717.3 717.4 0.1 WBWF0011 4,530 1 607 2,619 0.3 717.3 717.3 717.4 0.1 WBWF0012 5,400 1 183 599 1.3 717.4 717.4 717.5 0.1 WBWF0013 6,362 1 363 876 0.8 717.9 717.9 718.0 0.1 WBWF0014 7,230 1 700 1,958 0.4 718.1 718.1 718.2 0.1 WBWF0015 7,603 1 174 384 1.8 718.3 718.3 718.4 0.1 WBWF0016 8,131 1 257 623 1.1 719.5 719.5 719.6 0.1 WBWF0017 8,730 1 275 489 1.4 720.3 720.3 720.4 0.1 WBWF0018 9,000 1 685 1,932 0.3 722.2 722.2 722.3 0.1

1 In feet above West Branch DuPage River

2 Elevations include backwater effects from the West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WINFIELD CREEK (WBWF) BASE FLOOD WATER SURFACE ELEVATION FLOODING SOURCE FLOODWAY (FEET NGVD) SECTION MEAN WIDTH VELOCITY WITHOUT WITH CROSS SECTION DISTANCE AREA (FEET) (SQUARE (FEET PER REGULATORY FLOODWAY FLOODWAY INCREASE FEET) SECOND) Winfield Creek (WBWF) WBWF0019 11,119 1 401 1,017 0.7 723.5 723.5 723.6 0.1 WBWF0020 12,500 1 147 584 1.1 724.4 724.4 724.5 0.1 WBWF0021 13,440 1 103 187 3.6 724.6 724.6 724.7 0.1 WBWF0022 14,487 1 31 140 3.6 726.5 726.5 726.5 0.0 WBWF0023 15,622 1 173 497 1.0 727.5 727.5 727.6 0.1 WBWF0024 16,890 1 100 365 0.9 728.1 728.1 728.2 0.1 WBWF0025 17,296 1 34 182 1.8 728.4 728.4 728.4 0.0 WBWF0026 17,732 1 280 628 0.5 728.5 728.5 728.5 0.0 WBWF0027 18,930 1 126 234 1.4 728.9 728.9 728.9 0.0 WBWF0028 19,805 1 40 196 1.6 731.0 731.0 731.1 0.1 WBWF0029 20,100 1 43 229 1.4 731.1 731.1 731.2 0.1 WBWF0030 20,810 1 120 417 0.8 731.4 731.4 731.5 0.1 WBWF0031 21,650 1 1,710 74 4.3 732.2 732.2 732.3 0.1 WBWF0032 24,102 1 571 3,325 0.1 732.2 732.2 732.3 0.1 WBWF0033 24,389 1 494 2,365 0.1 732.2 732.2 732.3 0.1 WBWF0034 24,975 1 669 2,590 0.2 732.2 732.2 732.3 0.1 WBWF0035 25,783 1 655 2,248 0.2 732.2 732.2 732.3 0.1 WBWF0036 27,115 1 320 420 1.2 732.5 732.5 732.6 0.1

1 In feet above West Branch DuPage River

PARK STREET

FARM BRIDGE

SUMMIT DRIVE PRIVATE DRIVE

WINFIELD ROAD

CHURCH STREET

MANCHESTER ROAD

720 720

FLOOD PROFILES

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

WINFIELD CREEK (WBWF)

715 715

710 710

ELEVATION IN FEET (NGVD 29)

705 705

700 WBWF0012 WBWF0013 700 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD

WBWF0001 WBWF0005 50-YEAR FLOOD 695 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0002 WBWF0003 WBWF0004 WBWF0006 WBWF0007 WBWF0008 WBWF0009 WBWF0010 WBWF0011 CROSS SECTION LOCATION 690 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 212P ROOSEVELT ROAD

SCHAFFNER ROAD

HIGH SCHOOL ROAD

ROAD TO APARTMENTS

730 730

FLOOD PROFILES

WINFIELD CREEK (WBWF)

725 725

720 720

ELEVATION IN FEET (NGVD 29)

715 715

710 WBWF0020 710 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 705 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0014 WBWF0015 WBWF0016 WBWF0017 WBWF0018 WBWF0019 CROSS SECTION LOCATION 700 6500 7000 7500 8000 8500 9000 9500 10000 10500 11000 11500 12000 12500 13000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 213P FOOTBRIDGE FOOTBRIDGE

PRIVATE ROAD

W. CHILDS STREET

S. BEVERLY STREET

WOODLAWN STREET

W. ROOSEVELT ROAD

FLOOD PROFILES

WINFIELD CREEK (WBWF)

730 730

DORCHESTER AVENUE

725 725

ELEVATION IN FEET (NGVD 29)

720 720

715 WBWF0027 715 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 710 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0021 WBWF0022 WBWF0023 WBWF0024 WBWF0025 WBWF0026 CROSS SECTION LOCATION 705 13000 13500 14000 14500 15000 15500 16000 16500 17000 17500 18000 18500 19000 19500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 214P RAILROAD

FOOTBRIDGE

GARY AVENUE

LOW FLOW DAM LOW FLOW DAM

W. UNION AVENUE

W. LINCOLN AVENUE

ILLINOIS PRAIRIE PATH

W. MANCHESTER ROAD

ELLIS AVENUE EXTENDED

740 740

FLOOD PROFILES

WINFIELD CREEK (WBWF)

735 735

730 730

ELEVATION IN FEET (NGVD 29) CULVERT

725 725

720 WBWF0034 WBWF0035 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0028 WBWF0029 WBWF0030 WBWF0031 WBWF0032 WBWF0033 CROSS SECTION LOCATION 710 19500 20000 20500 21000 21500 22000 22500 23000 23500 24000 24500 25000 25500 26000

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 215P 750 750

MAIN STREET

E. COLE AVENUE

745 WHEATON COURT 745

DRIVE TO ST. MARKS SCHOOL

CONFLUENCE OF WINFIELD CREEK TRIBUTARY 740 740

FLOOD PROFILES

WINFIELD CREEK (WBWF)

735 735

GENEVA ROAD

730 PADDOCK COURT 730

ELEVATION IN FEET (NGVD 29)

725 725

720 WBWF0042 720 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 715 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0036 WBWF0037 WBWF0038 WBWF0039 WBWF0040 WBWF0041 CROSS SECTION LOCATION 710 26000 26500 27000 27500 28000 28500 29000 29500 30000 30500 31000 31500 32000 32500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 216P FARM ROAD

LIMIT OF DETAILED STUDY

FLOOD PROFILES

WINFIELD CREEK (WBWF)

750 750

745 745

ELEVATION IN FEET (NGVD 29)

740 740

735 735 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 730 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

WBWF0043 WBWF0044 WBWF0045 WBWF0046 CROSS SECTION LOCATION 725 32500 33000 33500 34000 34500 35000 35500

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 217P

3.7.18 Winding Creek (WBWG)

3.7.18.1 Tributary Description

Winding Creek is a 732-acre watershed that is tributary to the West Branch DuPage River. Communities that contribute watershed area to Winding Creek are Naperville and Unincorporated DuPage County. The overall land use for the watershed is single-family residential.

Winding Creek begins on the south side of 75th Street in the City of Naperville, just east of Shepherd Drive. Flow proceeds to the southeast passing between subdivision streets until crossing under Modaff Road and 79th Street. The Creek enters a conduit that runs under 79th Street all the way to the confluence with the West Branch DuPage River.

3.7.18.2 Hydrologic Analysis

Hydrologic analyses were carried out to establish the peak discharge- frequency relationship for Winding Creek.

Discharges for the 10-year, 50-year, and 100-year floods for Winding Creek were computed using the log-Pearson Type III method (U.S. Department of Commerce, 1976) for gaged streams and regional equations for ungaged streams (U.S. Department of the Interior, 1973; State of Illinois, 1973). The 500-year flood discharges for streams studied in detail were estimated by straight-line extrapolation.

For Winding Creek, synthetic frequency-discharge curves were derived using regional statistics developed in the Chicago study. These discharges assume zero skew. Discharges for the 500-year floods of all streams were determined by linear extrapolation of a log probability curve of flood discharges computed for frequencies of up to 100 years.

A summary of the drainage area-peak discharge relationships for the portions of the streams studied by detailed methods is shown in Table WBWG.1.

Table WBWG.1: Winding Creek Summary of Discharges Summary of Discharges

Flooding Source Drainage Peak Discharges (cfs) And Location Area (mi2) 10-yr 50-yr 100-yr 500-yr

Winding Creek - at mouth 1.50 195 340 420 630

Section printed 29 April 2004

3.7.18.3 Hydraulic Analysis

Analysis of the hydraulic characteristics of flooding from the sources studied was carried out to provide estimates of the elevations of floods of the selected recurrence intervals.

Locations of selected cross-sections used in the hydraulic analysis are shown on the Flood Profiles and on the Flood Insurance Rate Map.

Both overbank and channel cross sections for Winding Creek were field surveyed.

Water-surface elevations for Winding Creek were computed for the 10-, 50-, 100-, and 500-year floods using a HEC-2 computer step-backwater model (USACE, HEC-2 Water-Surface Profiles, Computer Program 723- X6-L202A, 1973). The depth of shallow flooding along Bailey Road from Winding Creek in the City of Naperville was also computed using a HEC- 2 model. The excess 100-year discharge which the underground storm sewer was incapable of handling was routed across surveyed ground- surface cross sections.

Starting water-surface elevations for Winding Creek were calculated using the slope/area method.

3.7.18.4 Flood Boundaries

To reference the flood boundaries for Winding Creek, see Map Panels: 0709 and 0807.

3.7.18.5 Floodways

Please reference attached Floodway Data Tables for further information.

3.7.18.6 Flood Profiles

Please reference attached Flood Profile Sheets.

1 In feet above confluence with West Branch DuPage River TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA DUPAGE COUNTY AND INCORPORATED AREAS WINDING CREEK (WBWG) 685 685

680 680

CHAT COURT VERDIN LANE

675 SWALLOW ROAD 675 CULVERTS

670 670

FLOOD PROFILES

WINDING CREEK (WBWG)

CONFLUENCE WITH WEST BRANCH DUPAGE RIVER

665 TERRANCE DRIVE 665

660 660

ELEVATION IN FEET (NGVD 29)

655 655 CULVERTS

650 WBWG0002 650 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 645 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWG0001 640 0 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 218P MODAFF ROAD

LIMIT OF DETAILED STUDY

690 690

FLOOD PROFILES

WINDING CREEK (WBWG)

685 685

680 680

ELEVATION IN FEET (NGVD 29)

CULVERTS

675 675

670 670 LEGEND 500-YEAR FLOOD 100-YEAR FLOOD 50-YEAR FLOOD 665 10-YEAR FLOOD

AND INCORPORATED AREAS

STREAM BED DUPAGE COUNTY, IL

CROSS SECTION LOCATION

WBWG0003 WBWG0004 660 5200 5600 6000 6400 6800

FEDERAL EMERGENCY MANAGEMENT AGENCY STREAM DISTANCE IN FEET ABOVE CONFLUENCE WITH WEST BRANCH DUPAGE RIVER 219P

4.0 INSURANCE APPLICATION

4.1 Reach Determinations

Reaches are defines as lengths of watercourses having relatively the same flood hazard, based on the average weighted difference in water-surface elevation between the 10- and 100-year floods. This difference does not have a variation greater than that indicated in the following table for more than 20 percent of the reach.

Average Difference Between 10- and 100-year Floods Variation Less than 2 feet 0.5 foot 2 to 7 feet 1.0 foot

4.2 Flood Hazard Factors

The FHF is the FIA device used to correlate flood information with the insurance rate tables. Correlations between property damage from floods and their FHF’s are used to set actuarial insurance premium rate tables based on FHFs from 005 to 200.

The FHF for a reach is the average weighted difference between the 10- and 100-year flood water-surface elevations expressed to the nearest 0.5 foot, and shown as a three- digit code. For example, if the difference between water-surface elevations of the 10- and 100-year floods is 0.7 foot, the FHF is 005, if the difference is 1.4 feet, the FHF is 015; if the difference is 5.0 feet, the FHF is 050. When the difference between to 10- and 100-year water-surface elevation is greater than 10.0 feet, accuracy for the FHF is to the nearest foot.

4.3 Flood Insurance Zones

For flood insurance rating purposes, flood insurance zone designations are assigned to a community based on the results of the engineering analyses. The zones are as follows:

Zone A

Zone A is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no base flood elevations or depths are shown within this zone.

Zone AE

Zone AE is the flood insurance rate zone that corresponds to the 100-year floodplains that are determined in the FIS by detailed methods. In most instances,

whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone.

Zone AH

Zone AH is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone.

Zone AO

Zone AO is the flood insurance rate zone that corresponds to the areas of 100-year shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average whole-depths derived from the detailed hydraulic analyses are shown within this zone.

Zone AR

Area of special flood hazard formerly protected from the 1% annual chance flood event by a flood control system that was subsequently decertified. Zone AR indicates that the former flood control system is being restored to provide protection from the 1% annual chance or greater flood event.

Zone A99

Zone A99 is the flood insurance rate zone that corresponds to areas of the 100-year floodplain that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No base flood elevations or depths are shown within this zone. Zone V

Zone V is the flood insurance rate zone that corresponds to the 100-year coastal floodplains that have additional hazards associated with storm waves. Because approximate hydraulic analyses are performed for such areas, no base flood elevations are shown within this zone.

Zone VE

Zone VE is the flood insurance rate zone that corresponds to the 100-year coastal floodplains that have additional hazards associated with storm waves. Whole-foot base flood elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone.

Zone X

Zone X is the flood insurance rate zone that corresponds to areas outside the 500-year floodplain, areas within the 500-year floodplain, and to areas of 100-year flooding where average depths are less than 1 foot, areas of 100-year flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 100-year flood by levees. No base flood elevations or depths are shown within this zone.

Zone D

Zone D is the flood insurance rate zone that corresponds to unstudied areas where flood hazards are undetermined, but possible.

4.4 Flood Insurance Rate Map Description

The FIRM is designed for flood insurance and floodplain management applications.

For flood insurance applications, the map designates flood insurance rate zones as described in Section 5.0 and, in the 100-year floodplains that were studied by detailed methods, shows selected whole-foot base flood elevations or average depths. Insurance agents use the zones and base flood elevations in conjunction with information on structures and their contents to assign premium rates for flood insurance policies.

For floodplain management applications, the map shows by tints, screens, and symbols, the 100- and 500-year floodplains. Floodways and the locations of selected cross sections used in the hydraulic analyses and floodway computations are shown where applicable.

The current FIRM presents flooding information for the entire geographic area of DuPage County. Previously, separate Flood Hazard Boundary Maps and/or FIRMs were prepared for each identified flood-prone incorporated community and the unincorporated areas of the county. This countywide FIRM also includes flood hazard information that was presented separately on Flood Boundary and Floodway Maps (FBFMs), where applicable.

5.0 OTHER STUDIES

FISs have been prepared for Kane County and incorporated areas (♦), Will County and incorporated areas (♦), and Cook County and incorporated areas (♦).

Information pertaining to revised and unrevised flood hazards for each jurisdiction within DuPage County has been compiled into this FIS. Therefore, this FIS supersedes all previously printed FIS Reports, FHBMs, FBFMs, and FIRMs for all of the incorporated and unincorporated jurisdictions within DuPage County.

Following is a list of reports and studies pertaining to the flood hazards within DuPage County:

Flood Water Management Plan of the Des Plaines River Floodplain Maps and Flood Profiles for Salt Creek and Westwood Creek A Flooding and Storm Sewer Report USGS Publication “Water Resources Data for Illinois, Part 1, Surface Water Records” Floodplain Information Report, West Branch DuPage River, Kress Creek and Klein Creek, Cook County, Illinois An SCS Study for the Des Plaines River Basin Illinois Department of Transportation, Division of Water Resources report, Strategic Planning Study for Flood Control – Bensenville Ditch, Bensenville, Illinois, DuPage County Donohue & Associates, Inc., study for Addison Creek Stormwater Management System Evaluation, DuPage and Cook Counties, Illinois Survey Report for Improvement for Spring Brook Creek Spring Brook Drainage Study West Branch Tributary to Spring Brook Creek Drainage Basin Study Engineer’s Report, Stormwater Management Plan for the Klein Creek Basin Segment of the Bloomingdale West Project Storm Water Management Plan, a part of the Klein Creek segment of the Bloomingdale West Project Surface Water Drainage Study of the Indian Lakes Subdivision and Environs Flood Plain Information Study on the Des Plaines River and its tributaries Lindley and Sons, Inc., Drainage Study on a tributary to the 63rd Street Ditch and on 79th Street Ditch for the Village of Burr Ridge Baranecki, Vigilio, and Associates, Improvement Plan for Burr Ridge Illinois Division of Water Resources, Strategic Planning Study of the Winfield Creek Basin Floodplain maps and flood profiles for Sawmill Creek and East Branch Sawmill Creek Special Flood Hazard Information Study for the East Branch DuPage River, Prentiss Creek, St. Joseph Creek, and Lacey Creek USGS Hydrologic Investigations Atlases USGS Flood-Prone Area Maps

Special Flood Hazard Information Study of the East Branch DuPage River A report by Harza Engineering, Village of Hanover Park, Illinois, West Branch DuPage River Flood Control Plan Floodwater Management Plan for the Des Plaines River Watershed Upper Salt Creek Watershed Work Plan Des Plaines River Watershed Floodwater Management Plan and Flood Plain Information, Maps and Profiles USACE, Chicago District, East Branch DuPage River Special Flood Hazard Information Report A report by the State of Illinois Department of Public Works and Buildings, Division of Waterways West Branch DuPage River Flood Plain Information Report A report analyzing flooding along Salt Creek, updated by the IDOT A Flood Hazard Information Report by Carl C. Crane, Inc., for the Chicago District USACE A Plan of Study report on the Fox River and its tributaries Southeastern Wisconsin Regional Planning Commission Report Work Plan for Watershed Protection and Flood Prevention, Upper Salt Creek Watershed Report on the Regulation of Construction Within the Flood Plain of Upper Salt Creek and Tributaries, Palatine, Schaumburg, Elk Grove Township, Cook County, Illinois Des Plaines River Flood Plain Information Maps and Profiles Regulation of Construction Within the Flood Plain of the Lower Salt Creek and Tributaries of Cook and DuPage Counties A Comprehensive Plan for the Fox River Surface Water Drainage Control Study for the Village of Westmont Des Plaines River Flood Plain Information Maps and Profiles, Cook and DuPage Counties, Illinois Stormwater Management Study, Village of Willowbrook Lindley and Sons, Inc., Several Letter Reports to the City of Darien, Illinois, on Lake Hinsdale and Sawmill Creek SCS publication, Upper Salt Creek Watershed Work Plan of the Busse Woods Reservoir City of Wood Dale Comprehensive Storm Drainage Report

6.0 LOCATION OF DATA

Information concerning the pertinent data used in the preparation of this FIS can be obtained by contacting FEMA, Federal Insurance and Mitigation Division, 536 South Clark Street, Sixth Floor, Chicago, Illinois 60605.

7.0 REFERENCES AND BIBLIOGRAPHY

American Guide Series. (1941). DuPage County: A Descriptive and Historical Guide, 1831-1939.

Baranecki, Vigilio, and Associates. (December 1977). Improvement Plans for Burr Ridge Meadows, Phase I. Burr Ridge, Illinois.

Barton-Aschman Associates, Inc. (August 1976). First Year Planning Program, Reconnaissance Study.

Baxter and Woodman, Inc. (January 1976). Winfield Creek Drainage Investigation: Engineer’s Report. Crystal Lake, Illinois.

Baxter and Woodman, Inc. (October 1975). Winfield Creek Retention Study. Crystal Lake, Illinois.

Chow, V. T. (1964). Handbook of Applied Hydrology. McGraw Hill Book Company, Inc.

Chow, V. T. (1959). Open Channel Hydraulics. McGraw Hill Book Company, Inc.

“Damage Estimate Set.” (August 29, 1972). The Daily Journal, Volume 40, No. 226, Page 1.

Des Plaines River Watershed Steering Committee, and U.S. Department of Agriculture, Soil Conservation Service. (1976). Des Plaines River Floodwater Management Plan and Environmental Assessment.

Des Plaines River Watershed Steering Committee. (December 1975). Des Plaines River Flood Plain Information Maps and Profiles, Cook and DuPage Counties, Illinois.

Dougherty, R. L., and J. B. Fanzini. (1977). Fluid Mechanics with Engineering Applications. McGraw-Hill Book Company, Inc.

Downers Grove Reporter. (October 14, 1954; July 18, 1957; and August 31, 1972). Downers Grove, Illinois.

DuPage County Zoning Ordinance. (December 10, 1935, as amended). DuPage County Board of Supervisors.

Federal Emergency Management Agency. (April 1982). Flood Insurance Study, DuPage County, Illinois (Unincorporated Areas).

Federal Emergency Management Agency, Federal Insurance Administration. (February 18, 1981). Flood Insurance Study, City of Oak Brook Terrace, DuPage County, Illinois. Washington, D.C.

Federal Emergency Management Agency, Federal Insurance Administration. (February 1981). Flood Insurance Study, Village of Villa Park, Illinois. Washington, D.C.

Federal Emergency Management Agency, Federal Insurance Administration. (April 1981). Flood Insurance Study, Village of Downers Grove, Illinois.

Federal Emergency Management Agency, Federal Insurance Administration. (May 1981). Flood Insurance Study, Village of Roselle, Illinois. Washington, D.C.

Federal Emergency Management Agency, Federal Insurance Administration. (October 1981). Flood Insurance Study, Village of Burr Ridge, Illinois. Washington, D.C.

Federal Emergency Management Agency, Federal Insurance Administration. (January 1980). Flood Insurance Study, Village of Willowbrook, Illinois. Washington, D.C.

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57 Exhibit 2 Note:

The Flood Insurance Rate Map and its Index are separate documents.

Contact the Map Repository at Dept. of Engineering County of DuPage, IL 421 N. County Farm Rd. Wheaton, IL 60187-3978 630.407.6700 voice 630.407.6701 fax