VOLUME 1 OF 2 MADISON COUNTY, ILLINOIS AND INCORPORATED AREAS COMMUNITY COMMUNITY NAME NUMBER ALHAMBRA, VILLAGE OF 170270 ALTON, CITY OF 170437 BETHALTO, VILLAGE OF 170438 COLLINSVILLE, CITY OF 170439 EAST ALTON, VILLAGE OF 170440 EDWARDSVILLE, CITY OF 170441 GLEN CARBON, VILLAGE OF 170442 GODFREY, VILLAGE OF 171031 GRANITE CITY, CITY OF 170443 GRANTFORK, VILLAGE OF 170209 HAMEL, VILLAGE OF 170160 HARTFORD, VILLAGE OF 170444 HIGHLAND, CITY OF 170445 LIVINGSTON, VILLAGE OF 170794 Madison MADISON, CITY OF 170446 County MADISON COUNTY (UNINCORPORATED AREAS) 170436 MARINE, VILLAGE OF 170199 MARYVILLE, VILLAGE OF 170299 * NEW DOUGLAS, VILLAGE OF 170316 PIERRON, VILLAGE OF 170317 PONTOON BEACH, VILLAGE OF 170447 PRELIMINARY ROXANA, VILLAGE OF 170448 SOUTH ROXANA, VILLAGE OF 170449 * ST. JACOB, VILLAGE OF 170208 TROY, CITY OF 170255 VENICE, CITY OF 170450 WILLIAMSON, VILLAGE OF 170324 WOOD RIVER, CITY OF 170451 * WORDEN, VILLAGE OF 170825 *NO SPECIAL FLOOD HAZARD AREAS IDENTIFIED Federal Emergency Management Agency FLOOD INSURANCE STUDY NUMBER 17119CV001A NOTICE TO FLOOD INSURANCE STUDY USERS Communities participating in the National Flood Insurance Program (NFIP) have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) report may not contain all data available within the Community Map Repository. It is advisable to contact the Community Map Repository for any additional data. The Federal Emergency Management Agency (FEMA) may revise and republish part or all of this FIS at any time. In addition, FEMA may revise part of this FIS report by the Letter of Map Revision (LOMR) process, which does not involve republication or redistribution of the FIS report. Therefore, users should consult with community officials and check the Community Map Repository to obtain the most current FIS report components. Selected Flood Insurance Rate Map panels for this community contain information that was previously shown separately on the corresponding Flood Boundary and Floodway Map panels (e.g., floodways, cross sections). In addition, former flood hazard zone designations have been changed as follows: Old Zones New Zone A1 through A30 AE B X C X Initial Countywide FIS Effective Date: This preliminary FIS report does not include unrevised Floodway Data tables or unrevised Flood Profiles. These Floodway Data tables and Flood Profiles will appear in the final FIS report. TABLES OF CONTENTS Table of Contents – Volume 1 Page 1.0 INTRODUCTION 1 1.1 Purpose of Study 1 1.2 Authority and Acknowledgements 1 1.3 Coordination 4 2.0 AREA STUDIED 5 2.1 Scope of Study 5 2.2 Community Description 9 2.3 Principal Flood Problems 10 2.4 Flood Protection Measures 13 3.0 ENGINEERING METHODS 16 3.1 Hydrologic Analyses 17 3.2 Hydraulic Analyses 23 3.3 Vertical Datum 26 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS 29 4.1 Floodplain Boundaries 29 4.2 Floodways 31 5.0 INSURANCE APPLICATION 75 5.1 Flood Insurance Zones 75 6.0 FLOOD INSURANCE RATE MAP 76 7.0 OTHER STUDIES 76 8.0 LOCATION OF DATA 79 9.0 BIBLIOGRAPHY AND REFERENCES 79 FIGURES FIGURE 1 – Floodway Schematic 31 i Table of Contents – Volume 1 (continued) Page TABLES TABLE 1 – Madison County CCO Meetings 5 TABLE 2 – Limits of Previously Detailed Studies 5 TABLE 3 – Limits of New Detailed Studies 7 TABLE 4 – Letters of Map Change 9 TABLE 5 – Peak Discharge Values 19 TABLE 6 – Manning’s “n” Values 24 TABLE 7 – Summary of Still Water Elevations 25 TABLE 8 – Datum Conversion Calculations by Stream 26 TABLE 9 – Mississippi River Vertical Datum Conversions 27 TABLE 10– Floodway Data Tables 34-74 TABLE 11– Community Map History 77-78 Table of Contents – Volume 2 EXHIBITS Exhibit 1 – Flood Profiles Belt Line Creek Panels 01P Cahokia Creek 02P – 09P Canteen Creek 10P – 12P Coal Branch Creek 13P – 14P East Alton Ditch 15P East Fork Silver Creek 16P – 17P East Fork Wood River 18P – 20P Honeycut Branch 21P Indian Creek 22P – 24P Joulters Creek 25P – 27P Judys Branch 28P – 32P Judys Branch Tributary 5 33P Judys Branch Tributary 5A 34P Judys Branch Tributary 5B 35P – 36P Judys Branch Tributary 9 37P Judys Branch Tributary 9A 38P Judys Branch Tributary 9B 39P Judys Branch Tributary 10 40P Judys Creek 41P – 43P Judys Creek Tributary B 44P Laurel Branch 45P – 46P Laurel Branch Tributary 1 47P Lindenthal Creek 48P – 50P Lindenthal Creek Tributary 1 51P Lindenthal Creek Tributary 2 52P Lindenthal Creek Tributary 3 53P Lindenthal Creek Tributary 4 54P Mississippi River 55P – 57P Mooney Creek 58P – 61P Mooney Creek Tributary 1 62P ii Table of Contents – Volume 2 (continued) EXHIBITS (continued) Exhibit 1 – Flood Profiles (continued) Mooney Creek Tributary 2 Panels 63P Paddock Creek 64P – 66P Sherry Creek – East Fork Sherry Creek 67P Silver Creek 68P – 69P Silver Creek Tributary No. 1 70P Silver Creek Tributary No. 2 71P – 72P Smith Lake Tributary 73P Smith Lake Tributary 2 74P Stanley Creek 75P Sugar Fork 76P Tributary E 77P Tributary F 78P Tributary G 79P Tributary X 80P Tributary Z 81P West Fork Wood River 82P – 84P Wood River 85P PUBLISHED SEPARATELY Exhibit 2 – Flood Insurance Rate Map Index Flood Insurance Rate Maps iii FLOOD INSURANCE STUDY MADISON COUNTY, ILLINOIS – AND INCORPORATED AREAS 1.0 INTRODUCTION 1.1 Purpose of Study This Flood Insurance Study (FIS) revises and supersedes the FIS reports and/or Flood Insurance Rate Maps (FIRMs) [/Flood Boundary and Floodway Maps] in the geographic area of Madison County, Illinois, including the Cities of Alton, Collinsville, Edwardsville, Granite City, Highland, Madison, Venice, and Wood River; the Villages of Bethalto, East Alton, Glen Carbon, Godfrey, Hartford, Livingston, Pontoon Beach, Roxana, South Roxana, and Worden and unincorporated areas of Madison County (hereinafter referred to collectively as Madison County), and aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. (The Village of Fairmont City appears in the St. Clair County FIS). Please note that the Villages of New Douglas, St. Jacob, and Worden have No Special Flood Hazard Areas Identified. This study has developed flood risk data for various areas of the community that will be used to establish actuarial flood insurance rates. This information will also be used by Madison County to update existing floodplain regulations as part of the Regular Phase of the National Flood Insurance Program (NFIP), and 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, the more restrictive criteria take precedence and the State (or other jurisdictional agency) will be able to explain them. The Digital Flood Insurance Rate Map (DFIRM) and FIS Report for this countywide study have been produced in digital format. Flood hazard information was converted to meet the FEMA DFIRM database specifications and Geographic Information System (GIS) format requirements. The flood hazard information was created and is provided in a digital format so that it can be incorporated into a local GIS and be accessed more easily by the community. 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. Information on the authority and acknowledgments for each of the previously printed FISs and Flood Insurance Rate Maps (FIRMs) for communities within Madison County was compiled, and is shown below. City of Alton: The hydrologic and hydraulic analyses for the City of Alton were performed by the U.S. Army Corps of Engineers (USACE), St. Louis District, for the Federal Insurance 1 Administration (FIA), under Inter-Agency Agreement No. IAA-H-7-76, Project Order No. 24. This study was completed in July 1978 (Reference 1). Village of Bethalto: The hydrologic and hydraulic analyses for this study were performed by the USACE, St. Louis District, for the FIA, under Inter-Agency Agreement IAA-H-10-77, Project Order No. 24. This study was completed in December 1978 (Reference 2). City of Collinsville: The hydrologic and hydraulic analyses for the City of Collinsville were performed by the USACE, St. Louis District, for the FIA, under Inter-Agency Agreement No. IAA-H-10-77, Project Order No. 6. This study was completed in June 1979 (Reference 3). Village of East Alton: The hydrologic and hydraulic analyses for this study were performed by the Roy F. Weston, Inc. for the FIA, under Contract No. H-3977. This study was completed in October 1977 (Reference 4). City of Edwardsville: The hydrologic and hydraulic analyses for the City of Edwardsville were obtained from the Flood Insurance Study for the County of Madison, Unincorporated Areas, Illinois. Refer to Madison County (Unincorporated Areas) below (Reference 5). City of Granite City: The hydrologic and hydraulic analyses for this study were done by the USACE, St Louis District for the FIA under Interagency Agreement IAA-H-7-76 Project Order No. 7 (Reference 6). Village of Hartford: The hydrologic and hydraulic analyses for this study were performed by the Roy F. Weston, Inc. for the FIA, under Contract No. H-3977. This study was completed in October 1977 (Reference 7). City Of Highland: The hydrologic and hydraulic analyses for this study were performed by the USACE, St. Louis District for the FIA, under Inter-Agency Agreement EMW-E-1153, Project Order No. 1. This study was completed in May 1985 (Reference 8). City of Madison: The hydrologic and hydraulic analyses for this study were performed by the USACE, St.