VOLUME 1 OF 3 BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS

COMMUNITY COMMUNITY NAME NUMBER BLACK HAWK COUNTY, 190535 UNINCORPORATED AREAS CEDAR FALLS, CITY OF 190017 DUNKERTON, CITY OF 190018 ELK RUN HEIGHTS, CITY OF 190019 EVANSDALE, CITY OF 190020 GILBERTVILLE, CITY OF 190021 HUDSON, CITY OF 190022 LAPORTE CITY, CITY OF 190309 RAYMOND, CITY OF 190024 WATERLOO, CITY OF 190025

PRELIMINARY 1/10/2019

REVISED: TBD

FLOOD INSURANCE STUDY NUMBER 19013CV001B Version Number 2.4.3.0

TABLE OF CONTENTS Volume 1 Page

SECTION 1.0 – INTRODUCTION 1 1.1 The National Flood Insurance Program 1 1.2 Purpose of this Flood Insurance Study Report 2 1.3 Jurisdictions Included in the Flood Insurance Study Project 2 1.4 Considerations for using this Flood Insurance Study Report 6

SECTION 2.0 – FLOODPLAIN MANAGEMENT APPLICATIONS 17 2.1 Floodplain Boundaries 17 2.2 Floodways 25 2.3 Base Flood Elevations 26 2.4 Non-Encroachment Zones 26 2.5 Coastal Flood Hazard Areas 27 2.5.1 Water Elevations and the Effects of Waves 26 2.5.2 Floodplain Boundaries and BFEs for Coastal Areas 26 2.5.3 Coastal High Hazard Areas 26 2.5.4 Limit of Moderate Wave Action 26

SECTION 3.0 – INSURANCE APPLICATIONS 27 3.1 National Flood Insurance Program Insurance Zones 27 3.2 Coastal Barrier Resources System 28

SECTION 4.0 – AREA STUDIED 28 4.1 Basin Description 28 4.2 Principal Flood Problems 29 4.3 Non-Levee Flood Protection Measures 30 4.4 Levees 31

SECTION 5.0 – ENGINEERING METHODS 34 5.1 Hydrologic Analyses 34 5.2 Hydraulic Analyses 45 5.3 Coastal Analyses 64 5.3.1 Total Stillwater Elevations 64 5.3.2 Waves 64 5.3.3 Coastal Erosion 64 5.3.4 Wave Hazard Analyses 64 5.4 Alluvial Fan Analyses 65

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Figures Page

Figure 1: FIRM Index 9 Figure 2: FIRM Notes to Users 10 Figure 3: Map Legend for FIRM 13 Figure 4: Floodway Schematic 25 Figure 5: Wave Runup Transect Schematic 27 Figure 6: Coastal Transect Schematic 27 Figure 7: Frequency Discharge-Drainage Area Curves 43 Figure 8: 1% Annual Chance Total Stillwater Elevations for Coastal Areas 64 Figure 9: Transect Location Map 64

Tables Page

Table 1: Listing of NFIP Jurisdictions 2 Table 2: Flooding Sources Included in this FIS Report 19 Table 3: Flood Zone Designations by Community 28 Table 4: Coastal Barrier Resources System Information 28 Table 5: Basin Characteristics 28 Table 6: Principal Flood Problems 29 Table 7: Historic Flooding Elevations 30 Table 8: Non-Levee Flood Protection Measures 30 Table 9: Levees 32 Table 10: Summary of Discharges 35 Table 11: Summary of Non-Coastal Stillwater Elevations 43 Table 12: Stream Gage Information used to Determine Discharges 44 Table 13: Summary of Hydrologic and Hydraulic Analyses 46 Table 14: Roughness Coefficients 63 Table 15: Summary of Coastal Analyses 64 Table 16: Tide Gage Analysis Specifics 64 Table 17: Coastal Transect Parameters 64 Table 18: Summary of Alluvial Fan Analyses 65 Table 19: Results of Alluvial Fan Analyses 65

Volume 2 Page

SECTION 6.0 – MAPPING METHODS 66 6.1 Vertical and Horizontal Control 66 6.2 Base Map 66 6.3 Floodplain and Floodway Delineation 67 6.4 Coastal Flood Hazard Mapping 109 6.5 FIRM Revisions 109 6.5.1 Letters of Map Amendment 110 6.5.2 Letters of Map Revision Based on Fill 110

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6.5.3 Letters of Map Revision 111 6.5.4 Physical Map Revisions 112 6.5.5 Contracted Restudies 112 6.5.6 Community Map History 113

SECTION 7.0 – CONTRACTED STUDIES AND COMMUNITY COORDINATION 113 7.1 Contracted Studies 113 7.2 Community Meetings 118

SECTION 8.0 – ADDITIONAL INFORMATION 121

SECTION 9.0 – BIBLIOGRAPHY AND REFERENCES 122

Tables Page

Table 20: Countywide Vertical Datum Conversion 66 Table 21: Stream-Based Vertical Datum Conversion 66 Table 22: Base Map Sources 67 Table 23: Summary of Topographic Elevation Data used in Mapping 68 Table 24: Floodway Data 69 Table 25: Flood Hazard and Non-Encroachment Data for Selected Streams 109 Table 26: Summary of Coastal Transect Mapping Considerations 109 Table 27: Incorporated Letters of Map Change 111 Table 28: Community Map History 113 Table 29: Summary of Contracted Studies Included in this FIS Report 113 Table 30: Community Meetings 119 Table 31: Map Repositories 121 Table 32: Additional Information 122 Table 33: Bibliography and References 123

Exhibits

Flood Profiles Panel Big Woods Creek 01-02 P Big Woods Creek Upper Diversion 03 P Black Hawk Creek 04-09 P Blowers Creek 10-13 P Cedar River 14-21 P Cedar River Diversion 22 P City View Branch 23-25 P Crane Creek 26-31 P

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Volume 3 Exhibits

Flood Profiles Panel Crossroads Creek 32-34 P Crossroads Creek Diversion 35 P Dry Run Creek at Cedar Falls 36-40 P Dry Run Creek at Waterloo 41-45 P Dry Run Creek Diversion Channel 46 P Dry Run Creek Tributary 1 47 P Dry Run Creek Tributary 2 48 P Elk Run Creek 49-55 P Maywood Branch 56-59 P Miller Creek 60 P Northeast University Branch Tributary 61 P Northwest University Branch Tributary 62 P Poyner Creek 63-64 P Prescotts Creek 65-67 P Sink Creek 68-72 P Southwest Branch Dry Rum Creek 73-74 P Stream No. 13 75-78 P Stream No. 36 79-81 P Stream No. 37 82 P Stream No. 39 83 P Sunnyside Creek 84-86 P Sunnyside Creek Bypass 87-88 P Tributary 1 89 P University Branch Dry Run Creek 90-91 P Unnamed Stream 92 P Unnamed Tributary to Cedar River 93-95 P Unnamed Tributary to Dry Run Creek 96-97 P Virden Creek 98-100 P Virden Creek Tributary 101-102 P West Branch Dry Run Creek 103-104 P West Fork Cedar River 105-106 P Wolf Creek 107-109 P Wolf Creek Overflow 110-112 P

Published Separately

Flood Insurance Rate Map (FIRM)

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FLOOD INSURANCE STUDY REPORT BLACK HAWK COUNTY, IOWA

SECTION 1.0 – INTRODUCTION

1.1 The National Flood Insurance Program The National Flood Insurance Program (NFIP) is a voluntary Federal program that enables property owners in participating communities to purchase insurance protection against losses from flooding. This insurance is designed to provide an alternative to disaster assistance to meet the escalating costs of repairing damage to buildings and their contents caused by floods.

For decades, the national response to flood disasters was generally limited to constructing flood-control works such as dams, levees, sea-walls, and the like, and providing disaster relief to flood victims. This approach did not reduce losses nor did it discourage unwise development. In some instances, it may have actually encouraged additional development. To compound the problem, the public generally could not buy flood coverage from insurance companies, and building techniques to reduce flood damage were often overlooked.

In the face of mounting flood losses and escalating costs of disaster relief to the general taxpayers, the U.S. Congress created the NFIP. The intent was to reduce future flood damage through community floodplain management ordinances, and provide protection for property owners against potential losses through an insurance mechanism that requires a premium to be paid for the protection.

The U.S. Congress established the NFIP on August 1, 1968, with the passage of the National Flood Insurance Act of 1968. The NFIP was broadened and modified with the passage of the Flood Disaster Protection Act of 1973 and other legislative measures. It was further modified by the National Flood Insurance Reform Act of 1994 and the Flood Insurance Reform Act of 2004. The NFIP is administered by the Federal Emergency Management Agency (FEMA), which is a component of the Department of Homeland Security (DHS).

Participation in the NFIP is based on an agreement between local communities and the Federal Government. If a community adopts and enforces floodplain management regulations to reduce future flood risks to new construction and substantially improved structures in Special Flood Hazard Areas (SFHAs), the Federal Government will make flood insurance available within the community as a financial protection against flood losses. The community’s floodplain management regulations must meet or exceed criteria established in accordance with Title 44 Code of Federal Regulations (CFR) Part 60, Criteria for Land Management and Use.

SFHAs are delineated on the community’s Flood Insurance Rate Maps (FIRMs). Under the NFIP, buildings that were built before the flood hazard was identified on the community’s FIRMs are generally referred to as “Pre-FIRM” buildings. When the NFIP was created, the U.S. Congress recognized that insurance for Pre-FIRM buildings would be prohibitively expensive if the premiums were not subsidized by the Federal

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Government. Congress also recognized that most of these floodprone buildings were built by individuals who did not have sufficient knowledge of the flood hazard to make informed decisions. The NFIP requires that full actuarial rates reflecting the complete flood risk be charged on all buildings constructed or substantially improved on or after the effective date of the initial FIRM for the community or after December 31, 1974, whichever is later. These buildings are generally referred to as “Post-FIRM” buildings.

1.2 Purpose of this Flood Insurance Study Report This Flood Insurance Study (FIS) Report revises and updates information on the existence and severity of flood hazards for the study area. The studies described in this report developed flood hazard data that will be used to establish actuarial flood insurance rates and to assist communities in efforts to implement sound floodplain management.

In some states or communities, floodplain management criteria or regulations may exist that are more restrictive than the minimum Federal requirements. Contact your State NFIP Coordinator to ensure that any higher State standards are included in the community’s regulations.

1.3 Jurisdictions Included in the Flood Insurance Study Project This FIS Report covers the entire geographic area of Black Hawk County, Iowa.

The jurisdictions that are included in this project area, along with the Community Identification Number (CID) for each community and the United States Geological Survey (USGS) 8-digit Hydrologic Unit Code (HUC-8) sub-basins affecting each, are shown in Table 1. The FIRM panel numbers that affect each community are listed. If the flood hazard data for the community is not included in this FIS Report, the location of that data is identified.

Table 1: Listing of NFIP Jurisdictions HUC-8 If Not Included, Sub- Located on FIRM Location of Flood Community CID Basin(s) Panel(s) Hazard Data 19013C0020G 19013C0038G 19013C0039G 19013C0045G 19013C0065G 07080102, 19013C0070G 07080201, 19013C0090G Black Hawk County, 190535 07080202, 19013C0095G Unincorporated Areas 07080204, 19013C0115G 07080205 19013C0135G 19013C0145G 19013C0153G 19013C0154G 19013C0155G 19013C0158G

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Table 1: Listing of NFIP Jurisdictions (continued) HUC-8 If Not Included, Sub- Located on FIRM Location of Flood Community CID Basin(s) Panel(s) Hazard Data 19013C0159G 19013C0160G 19013C0161G 19013C0163G 19013C0180G 19013C0185G 19013C0187G 19013C0193G 19013C0194G 19013C0195G 19013C0205G 19013C0208G 19013C0209G 19013C0210G 19013C0215G 19013C0216G 19013C0217G 19013C0220G 19013C0230G 19013C0240G 19013C0260G 19013C0270G 07080102, 19013C0276G Black Hawk County, 07080201, 19013C0278G Unincorporated Areas 190535 07080202, 19013C0279G (continued) 07080204, 19013C0286G 07080205 19013C0287G 19013C0288G 19013C0289G 19013C0291G 19013C0292G 19013C0295G 19013C0307F 19013C0308F 19013C0309F 19013C0311G 19013C0312G 19013C0315G 19013C0316G 19013C0317G 19013C0320G 19013C0326G 19013C0327G 19013C0328F 19013C0329G 19013C0335G 19013C0337G 19013C0340G 19013C0345G

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Table 1: Listing of NFIP Jurisdictions (continued) HUC-8 If Not Included, Sub- Located on FIRM Location of Flood Community CID Basin(s) Panel(s) Hazard Data 19013C0355G 19013C0365G 19013C0385G 19013C0395G 19013C0405G 19013C0410G 19013C0415G 19013C0420G 19013C0430G 07080102, 19013C0435G Black Hawk County, 07080201, 19013C0440G Unincorporated Areas 190535 07080202, 19013C0445G (continued) 07080204, 19013C0454G 07080205 19013C0455G 19013C0458G 19013C0460G 19013C0462G 19013C0465G 19013C0466G 19013C0470G 19013C0480G 19013C0490G 19013C0145G 19013C0153G 19013C0154G 19013C0158G 19013C0161G 19013C0162G 19013C0163G 19013C0164G 19013C0166G Cedar Falls, City of 190017 07080205 19013C0168G 19013C0260G 19013C0276G 19013C0277G 19013C0278G 19013C0279G 19013C0281G 19013C0282F 19013C0283G 19013C0208G 19013C0209G Dunkerton, City of 190018 07080102 19013C0216G 19013C0217G 19013C0307F 19013C0309F Elk Run Heights, City of 190019 07080205 19013C0326G 19013C0328F

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Table 1: Listing of NFIP Jurisdictions (continued) HUC-8 If Not Included, Sub- Located on FIRM Location of Flood Community CID Basin(s) Panel(s) Hazard Data 19013C0306F 19013C0307F Evansdale, City of 190020 07080205 19013C0308F 19013C0309F 19013C0328F 19013C0337G Gilbertville, City of 190021 07080205 19013C0340G 19013C0278G 19013C0279G 19013C0283G 19013C0286G Hudson, City of 190022 07080205 19013C0287G 19013C0288G 19013C0289G 19013C0291G 07080201 19013C0038G Bremer County FIS, Janesville, City of 190023 07080205 19013C0039G 2018 19013C0454G 19013C0458G La Porte City, City of 190309 07080205 19013C0462G 19013C0466G 19013C0307F 19013C0326G Raymond, City of 190024 07080205 19013C0327G 19013C0328F 19013C0329G

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Table 1: Listing of NFIP Jurisdictions (continued) HUC-8 If Not Included, Sub- Located on FIRM Location of Flood Community CID Basin(s) Panel(s) Hazard Data 19013C0158G 19013C0159G 19013C0166G 19013C0167F 19013C0168G 19013C0169F 19013C0180G 19013C0186F 19013C0187G 19013C0188F 19013C0189F Waterloo, City of 190025 07080205 19013C0193G 19013C0194G 19013C0195G 19013C0215G 19013C0281G 19013C0282F 19013C0283G 19013C0284G 19013C0291G 19013C0292G 19013C0301F 19013C0302F 19013C0303G 19013C0304G 19013C0306F 19013C0307F Waterloo, City of 190025 07080205 19013C0308F (continued) 19013C0309F 19013C0311G 19013C0312G 19013C0316G 19013C0317G

1.4 Considerations for using this Flood Insurance Study Report The NFIP encourages State and local governments to implement sound floodplain management programs. To assist in this endeavor, each FIS Report provides floodplain data, which may include a combination of the following: 10-, 4-, 2-, 1-, and 0.2-percent annual chance flood elevations (the 1% annual chance flood elevation is also referred to as the Base Flood Elevation (BFE)); delineations of the 1% annual chance and 0.2% annual chance floodplains; and 1% annual chance floodway. This information is presented on the FIRM and/or in many components of the FIS Report, including Flood Profiles, Floodway Data tables, Summary of Non-Coastal Stillwater Elevations tables, and Coastal Transect Parameters tables (not all components may be provided for a specific FIS).

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This section presents important considerations for using the information contained in this FIS Report and the FIRM, including changes in format and content. Figures 1, 2, and 3 present information that applies to using the FIRM with the FIS Report.

 Part or all of this FIS Report may be revised and republished at any time. In addition, part of this FIS Report may be revised by a Letter of Map Revision (LOMR), which does not involve republication or redistribution of the FIS Report. Refer to Section 6.5 of this FIS Report for information about the process to revise the FIS Report and/or FIRM.

It is, therefore, the responsibility of the user to consult with community officials by contacting the community repository to obtain the most current FIS Report components. Communities participating in the NFIP have established repositories of flood hazard data for floodplain management and flood insurance purposes. Community map repository addresses are provided in Table , “Map Repositories,” within this FIS Report.

 New FIS Reports are frequently developed for multiple communities, such as entire counties. A countywide FIS Report incorporates previous FIS Reports for individual communities and the unincorporated area of the county (if not jurisdictional) into a single document and supersedes those documents for the purposes of the NFIP.

The initial Countywide FIS Report for Black Hawk County became effective on July 18, 2011. Refer to Table 28 for information about subsequent revisions to the FIRMs.

 Previous FIS Reports and FIRMs may have included levees that were accredited as reducing the risk associated with the 1% annual chance flood based on the information available and the mapping standards of the NFIP at that time. For FEMA to continue to accredit the identified levees, the levees must meet the criteria of the Code of Federal Regulations, Title 44, Section 65.10 (44 CFR 65.10), titled “Mapping of Areas Protected by Levee Systems.”

Since the status of levees is subject to change at any time, the user should contact the appropriate agency for the latest information regarding levees presented in Table 9 of this FIS Report. For levees owned or operated by the U.S. Army Corps of Engineers (USACE), information may be obtained from the USACE National Levee Database (nld.usace.army.mil). For all other levees, the user is encouraged to contact the appropriate local community.

 FEMA has developed a Guide to Flood Maps (FEMA 258) and online tutorials to assist users in accessing the information contained on the FIRM. These include how to read panels and step-by-step instructions to obtain specific information. To obtain this guide and other assistance in using the FIRM, visit the FEMA Web site at www.fema.gov/online-tutorials.

The FIRM Index in Figure 1 shows the overall FIRM panel layout within Black Hawk County, and also displays the panel number and effective date for each FIRM panel in the

7 county. Other information shown on the FIRM Index includes community boundaries, flooding sources, watershed boundaries, and USGS HUC-8 codes.

8 Figure 1: FIRM Panel Index

CITY OF JANESVILLE (AREA NOT INCLUDED) 0050F* 0075F* 0100F* 190023 HUC8 07080201 0125F* 0025F* Upper Cedar

HUC8 07080202 0040F* HUC8 07080102 Shell Rock Upper Wapsipinicon 0045G 0065G 0070G 0090G 0095G 0115G 0020G B W u k a c or p k F r 0038G 0039G s 281 C t e i «¬ es iv p re W R V19 V25 63 in e ar )"" )"" ¤£ k ed "C5"5 ic C ) o n "V4"9 "5"4 ¤£218 ) ) R HUC8 07080204 6 iv 3 e

C 0210G r 0155G 0160G o )"V4"3 West Fork Cedar e T75 N )"" d Cr a an m e r 0180G C a re 0230G CITY OF DUNKERTON R 0185G e 0135G e k i 0154G r 3 v k t 1 k 0205G 0208G 0209G e e S o e 190018 e eek r e r r N r C 0158G 0159G k er g C e Unnamed Tributary av i C

e 0153G m B e y B s a r "C6"6 r n ) To Cedar River d 27 e e r C a E o «¬ t t S d n S l o u r a n k i g e b 0250F* W C i V R 0150F* d r r e r u e i T k 0167F 0186F n V 0195G 0215G 0216G 0217G 0161G 0166G 7/18/2011 7/18/2011 0162G 0187G C 57 Blowers r «¬ Cedar River e k e e 0240G Uni e versity Creek k Branch Diversion Channel r k D "D1"6 C e 0145G ry Run C ) r D16 e reek e )"" r 0169F 0188F 0189F n C 0193G 0194G y p CITY OF 0163G 0164G 0168G 7/18/2011 7/18/2011 7/18/2011 o 0220G m P a City View Branch C RAYMOND Maywood 281 CITY OF CEDAR FALLS 0327G «¬ 190024 n CITY OF WATERLOO u Branch R 190017 0307F 0326G "D2"0 0276G y 0277G 0281G 0282F 190025 0306F ) r 7/18/2011 7/18/2011 0301F 0302F 7/18/2011 CITY OF D West Branch 58 7/18/2011 7/18/2011 0335G "D1"9 «¬ ds )"D2"2 Dry Run Creek 0260G ) rossroa ELK RUN HEIGHTS 20 k C k 0355G ¤£ k e k e Southwest Branch c e Cree e a r 0308F 0309F 0328F 0329G r 190019 l C Dry Run Creek 0278G C 0284G 0303G 0304G 7/18/2011 7/18/2011 7/18/2011 B k 20 n S £ p 0279G w ¤ ia a 0283G d r i H k In n 0375F* 0275F* e g

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r C C D25 Poyner Creek r "" k e ) n 0365G i 0312G 0316G 0317G 0337G e 0286G 0287G 0291G 0292G S k s t t 0311G )"D3"8 o k 0345G c e s CITY OF e 0270G e r r )"V6"2 C D35 0340G P )"" EVANSDALE §¨¦380 )"D3"5 0288G 0289G 0320G CITY OF HUDSON 0295G 0315G 190020 «¬21 C e 190022 BLACK HAWK COUNTY d East Branch 218 a 190535 ¤£ r )"T6"9 R Spring Creek k i e )"V2"7 v e e ¤£63 r r C 0455G 0460G CITY OF k 0430G 0435G "D4"8 0480G 0385G 0405G D46 c 0410G ) )"" o R M GILBERTVILLE iller )"V3"7 ek )"V6"5 C re 0454G 0458G «¬175 reek C k d k 190021 e u e e M e r r V52 C 0500F* 0400F* C )"" f n l e o )"V6"1 Sp iv W k ring oc G R ek Cree re k 0462G 0466G C 0395G 0415G 0420G 0440G 0445G 0490G 0465G CITY OF LA PORTE CITY 0470G 190309

HUC8 07080205 Middle Cedar

PRELIMINARY ATTENTION: The corporate limits shown on this FIRM Index are based on the best information available at the time of publication. As such, they may be more current than those shown on the panels issued before TBD. 1/10/2019

1 inch = 4 miles 1:253,542 Miles NATIONAL FLOOD INSURANCE PROGRAM 0 2 4 8 FLOOD INSURANCE RATE MAP INDEX Map Projection: Universal Transverse Mercator Zone 15N; BLACK HAWK COUNTY, IOWA and Incorporated Areas North American Datum 1983 PANELS PRINTED: THE INFORMATION DEPICTED ON THIS MAP AND SUPPORTING 0020, 0038, 0039, 0045, 0065, 0070, 0090, 0095, 0115, 0135, 0145, 0153, 0154, 0155, DOCUMENTATION ARE ALSO AVAILABLE IN DIGITAL FORMAT AT 0158, 0159, 0160, 0161, 0162, 0163, 0164, 0166, 0167, 0168, 0169, 0180, 0185, 0186 0187, 0188, 0189, 0193, 0194, 0195, 0205, 0208, 0209, 0210, 0215, 0216, 0217, 0220 HTTP://MSC.FEMA.GOV 0230, 0240, 0260, 0270, 0276, 0277, 0278, 0279, 0281, 0282, 0283, 0284, 0286, 0287 FEMA 0288, 0289, 0291, 0292, 0295, 0301, 0302, 0303, 0304, 0306, 0307, 0308, 0309, 0311 SEE FLOOD INSURANCE STUDY FOR ADDITIONAL INFORMATION 0312, 0315, 0316, 0317, 0320, 0326, 0327, 0328, 0329, 0335, 0337, 0340, 0345, 0355 MAP NUMBER 0365, 0385, 0395, 0405, 0410, 0415, 0420, 0430, 0435, 0440, 0445, 0454, 0455, 0458 19013CIND0B 0460, 0462, 0465, 0466, 0470, 0480, 0490 MAP REVISED * PANEL NOT PRINTED - OUTSIDE COUNTY BOUNDARY

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Each FIRM panel may contain specific notes to the user that provide additional information regarding the flood hazard data shown on that map. However, the FIRM panel does not contain enough space to show all the notes that may be relevant in helping to better understand the information on the panel. Figure 2 contains the full list of these notes.

Figure 2: FIRM Notes to Users NOTES TO USERS For information and questions about this map, available products associated with this FIRM including historic versions of this FIRM, how to order products, or the National Flood Insurance Program in general, please call the FEMA Map Information eXchange at 1-877- FEMA-MAP (1-877-336-2627) or visit the FEMA Flood Map Service Center website at msc.fema.gov. Available products may include previously issued Letters of Map Change, a Flood Insurance Study Report, and/or digital versions of this map. Many of these products can be ordered or obtained directly from the website. Users may determine the current map date for each FIRM panel by visiting the FEMA Flood Map Service Center website or by calling the FEMA Map Information eXchange.

Communities annexing land on adjacent FIRM panels must obtain a current copy of the adjacent panel as well as the current FIRM Index. These may be ordered directly from the Flood Map Service Center at the number listed above.

For community and countywide map dates, refer to Table 28 in this FIS Report.

To determine if flood insurance is available in the community, contact your insurance agent or call the National Flood Insurance Program at 1-800-638-6620.

PRELIMINARY FIS REPORT: FEMA maintains information about map features, such as street locations and names, in or near designated flood hazard areas. Requests to revise information in or near designated flood hazard areas may be provided to FEMA during the community review period, at the final Consultation Coordination Officer's meeting, or during the statutory 90-day appeal period. Approved requests for changes will be shown on the final printed FIRM.

The map is for use in administering the NFIP. It may not identify all areas subject to flooding, particularly from local drainage sources of small size. Consult the community map repository to find updated or additional flood hazard information.

BASE FLOOD ELEVATIONS: For more detailed information in areas where Base Flood Elevations (BFEs) and/or floodways have been determined, consult the Flood Profiles and Floodway Data and/or Summary of Non-Coastal Stillwater Elevations tables within this FIS Report. Use the flood elevation data within the FIS Report in conjunction with the FIRM for construction and/or floodplain management.

FLOODWAY INFORMATION: Boundaries of the floodways were computed at cross sections and interpolated between cross sections. The floodways were based on hydraulic considerations with regard to requirements of the National Flood Insurance Program. Floodway widths and other pertinent floodway data are provided in the FIS Report for this jurisdiction.

10 Figure 2. FIRM Notes to Users

FLOOD CONTROL STRUCTURE INFORMATION: Certain areas not in Special Flood Hazard Areas may be protected by flood control structures. Refer to Section 4.3 "Non-Levee Flood Protection Measures" of this FIS Report for information on flood control structures for this jurisdiction. PROJECTION INFORMATION: The projection used in the preparation of the map was Universal Transverse Mercator (UTM) Zone 15. The horizontal datum was the North American Datum of 1983 NAD83, GRS1980 spheroid. Differences in datum, spheroid, projection or State Plane zones used in the production of FIRMs for adjacent jurisdictions may result in slight positional differences in map features across jurisdiction boundaries. These differences do not affect the accuracy of the FIRM. ELEVATION DATUM: Flood elevations on the FIRM are referenced to the North American Vertical Datum of 1988. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. For information regarding conversion between the National Geodetic Vertical Datum of 1929 and the North American Vertical Datum of 1988, visit the National Geodetic Survey website at www.ngs.noaa.gov. Local vertical monuments may have been used to create the map. To obtain current monument information, please contact the appropriate local community listed in Table of this FIS Report. BASE MAP INFORMATION: Base map information shown on the FIRM was derived from digital orthophotography collected by the Iowa Geological and Water Survey, Department of Natural Resources. For information about base maps, refer to Section 6.2 “Base Map” in this FIS Report. The map reflects more detailed and up-to-date stream channel configurations than those shown on the previous FIRM for this jurisdiction. The floodplains and floodways that were transferred from the previous FIRM may have been adjusted to conform to these new stream channel configurations. As a result, the Flood Profiles and Floodway Data tables may reflect stream channel distances that differ from what is shown on the map. Corporate limits shown on the map are based on the best data available at the time of publication. Because changes due to annexations or de-annexations may have occurred after the map was published, map users should contact appropriate community officials to verify current corporate limit locations.

NOTES FOR FIRM INDEX REVISIONS TO INDEX: As new studies are performed and FIRM panels are updated within Black Hawk County, Iowa, corresponding revisions to the FIRM Index will be incorporated within the FIS Report to reflect the effective dates of those panels. Please refer to Table 28 of this FIS Report to determine the most recent FIRM revision date for each community. The most recent FIRM panel effective date will correspond to the most recent index date.

11 Figure 2. FIRM Notes to Users

SPECIAL NOTES FOR SPECIFIC FIRM PANELS This Notes to Users section was created specifically for Black Hawk County, Iowa, effective TBD.

ACCREDITED LEVEE: Check with your local community to obtain more information, such as the estimated level of protection provided (which may exceed the 1-percent-annual-chance level) and Emergency Action Plan, on the levee system(s) shown as providing protection for areas on this panel. To mitigate flood risk in residual risk areas, property owners and residents are encouraged to consider flood insurance and floodproofing or other protective measures. For more information on flood insurance, interested parties should visit www.fema.gov/national-flood-insurance-program.

PROVISIONALLY ACCREDITED LEVEE: Check with your local community to obtain more information, such as the estimated level of protection provided (which may exceed the 1- percent-annual-chance level) and Emergency Action Plan, on the levee system(s) shown as providing protection for areas on this panel. To maintain accreditation, the levee owner or community is required to submit the data and documentation necessary to comply with Section 65.10 of the NFIP regulations by June 10, 2010. If the community or owner does not provide the necessary data and documentation or if the data and documentation provided indicate the levee system does not comply with Section 65.10 requirements, FEMA will revise the flood hazard and risk information for this area to reflect de-accreditation of the levee system. To mitigate flood risk in residual risk areas, property owners and residents are encouraged to consider flood insurance and floodproofing or other protective measures. For more information on flood insurance, interested parties should visit www.fema.gov/national- flood-insurance-program.

PROVISIONALLY ACCREDITED LEVEE: Check with your local community to obtain more information, such as the estimated level of protection provided (which may exceed the 1- percent-annual-chance level) and Emergency Action Plan, on the levee system(s) shown as providing protection for areas on this panel. To maintain accreditation, the levee owner or community is required to submit the data and documentation necessary to comply with Section 65.10 of the NFIP regulations by November 20, 2020. If the community or owner does not provide the necessary data and documentation or if the data and documentation provided indicate the levee system does not comply with Section 65.10 requirements, FEMA will revise the flood hazard and risk information for this area to reflect de-accreditation of the levee system. To mitigate flood risk in residual risk areas, property owners and residents are encouraged to consider flood insurance and floodproofing or other protective measures. For more information on flood insurance, interested parties should visit www.fema.gov/national- flood-insurance-program.

FLOOD RISK REPORT: A Flood Risk Report (FRR) may be available for many of the flooding sources and communities referenced in this FIS Report. The FRR is provided to increase public awareness of flood risk by helping communities identify the areas within their jurisdictions that have the greatest risks. Although non-regulatory, the information provided within the FRR can assist communities in assessing and evaluating mitigation opportunities to reduce these risks. It can also be used by communities developing or updating flood risk mitigation plans. These plans allow communities to identify and evaluate opportunities to reduce potential loss of life and property. However, the FRR is not intended to be the final authoritative source of all flood risk data for a project area; rather, it should be used with other data sources to paint a comprehensive picture of flood risk.

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Each FIRM panel contains an abbreviated legend for the features shown on the maps. However, the FIRM panel does not contain enough space to show the legend for all map features. Figure 3 shows the full legend of all map features. Note that not all of these features may appear on the FIRM panels in Black Hawk County.

Figure 3: Map Legend for FIRM

SPECIAL FLOOD HAZARD AREAS: The 1% annual chance flood, also known as the base flood or 100-year flood, has a 1% chance of happening or being exceeded each year. Special Flood Hazard Areas are subject to flooding by the 1% annual chance flood. The Base Flood Elevation is the water surface elevation of the 1% annual chance flood. The floodway is the channel of a stream plus any adjacent floodplain areas that must be kept free of encroachment so that the 1% annual chance flood can be carried without substantial increases in flood heights. See note for specific types. If the floodway is too narrow to be shown, a note is shown. Special Flood Hazard Areas subject to inundation by the 1% annual chance flood (Zones A, AE, AH, AO, AR, A99, V and VE)

Zone A The flood insurance rate zone that corresponds to the 1% annual chance floodplains. No base (1% annual chance) flood elevations (BFEs) or depths are shown within this zone. Zone AE The flood insurance rate zone that corresponds to the 1% annual chance floodplains. Base flood elevations derived from the hydraulic analyses are shown within this zone. Zone AH The flood insurance rate zone that corresponds to the areas of 1% annual chance shallow flooding (usually areas of ponding) where average depths are between 1 and 3 feet. Whole-foot BFEs derived from the hydraulic analyses are shown at selected intervals within this zone. Zone AO The flood insurance rate zone that corresponds to the areas of 1% annual chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average whole-foot depths derived from the hydraulic analyses are shown within this zone. Zone AR The flood insurance rate zone that corresponds to areas that were formerly protected from the 1% annual chance flood 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. Zone A99 The flood insurance rate zone that corresponds to areas of the 1% annual chance floodplain that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No base flood elevations or flood depths are shown within this zone. Zone V The flood insurance rate zone that corresponds to the 1% annual chance coastal floodplains that have additional hazards associated with storm waves. Base flood elevations are not shown within this zone. Zone VE Zone VE is the flood insurance rate zone that corresponds to the 1% annual chance coastal floodplains that have additional hazards associated with storm waves. Base flood elevations derived from the coastal analyses are shown within this zone as static whole-foot elevations that apply throughout the zone.

13 Figure 3: Map Legend for FIRM

Regulatory Floodway determined in Zone AE.

OTHER AREAS OF FLOOD HAZARD Shaded Zone X: Areas of 0.2% annual chance flood hazards and areas of 1% annual chance flood hazards with average depths of less than 1 foot or with drainage areas less than 1 square mile. Future Conditions 1% Annual Chance Flood Hazard – Zone X: The flood insurance rate zone that corresponds to the 1% annual chance floodplains that are determined based on future-conditions hydrology. No base flood elevations or flood depths are shown within this zone. Area with Reduced Flood Risk due to Levee: Areas where an accredited levee, dike, or other flood control structure has reduced the flood risk from the 1% annual chance flood. See Notes to Users for important information. Area with Flood Risk due to Levee: Areas where a non-accredited levee, dike, or other flood control structure is shown as providing protection to less than the 1% annual chance flood. OTHER AREAS Zone D (Areas of Undetermined Flood Hazard): The flood insurance rate zone that corresponds to unstudied areas where flood hazards are undetermined, but possible.

NO SCREEN Unshaded Zone X: Areas of minimal flood hazard.

FLOOD HAZARD AND OTHER BOUNDARY LINES

Flood Zone Boundary (white line on ortho-photography-based mapping; gray line on vector-based mapping) (ortho) (vector)

Limit of Study

Jurisdiction Boundary

Limit of Moderate Wave Action (LiMWA): Indicates the inland limit of the area affected by waves greater than 1.5 feet

GENERAL STRUCTURES

Aqueduct Channel Channel, Culvert, Aqueduct, or Storm Sewer Culvert Storm Sewer

______Dam Jetty Dam, Jetty, Weir Weir

14 Figure 3: Map Legend for FIRM

Levee, Dike, or Floodwall

Bridge Bridge

COASTAL BARRIER RESOURCES SYSTEM (CBRS) AND OTHERWISE PROTECTED AREAS (OPA): CBRS areas and OPAs are normally located within or adjacent to Special Flood Hazard Areas.

Coastal Barrier Resources System Area: Labels are shown to clarify where this area shares a boundary with an incorporated area or overlaps with the floodway. CBRS AREA 09/30/2009

Otherwise Protected Area OTHERWISE PROTECTED AREA 09/30/2009

REFERENCE MARKERS

River mile Markers

CROSS SECTION & TRANSECT INFORMATION

Lettered Cross Section with Regulatory Water Surface Elevation (BFE)

Numbered Cross Section with Regulatory Water Surface Elevation (BFE)

Unlettered Cross Section with Regulatory Water Surface Elevation (BFE)

Coastal Transect

Profile Baseline: Indicates the modeled flow path of a stream and is shown on FIRM panels for all valid studies with profiles or otherwise established base flood elevation. Coastal Transect Baseline: Used in the coastal flood hazard model to represent the 0.0-foot elevation contour and the starting point for the transect and the measuring point for the coastal mapping.

Base Flood Elevation Line

ZONE AE Static Base Flood Elevation value (shown under zone label) (EL 16)

15 Figure 3: Map Legend for FIRM

ZONE AO Zone designation with Depth (DEPTH 2) ZONE AO (DEPTH 2) Zone designation with Depth and Velocity (VEL 15 FPS) BASE MAP FEATURES

Missouri Creek River, Stream or Other Hydrographic Feature

Interstate Highway

U.S. Highway

State Highway

County Highway

MAPLE LANE Street, Road, Avenue Name, or Private Drive if shown on Flood Profile

Railroad RAILROAD

Horizontal Reference Grid Line

Horizontal Reference Grid Ticks

Secondary Grid Crosshairs

Land Grant Name of Land Grant

7 Section Number

R. 43 W. T. 22 N. Range, Township Number

42 000m 76 E Horizontal Reference Grid Coordinates (UTM)

365000 FT Horizontal Reference Grid Coordinates (State Plane)

80 16’ 52.5” Corner Coordinates (Latitude, Longitude)

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SECTION 2.0 – FLOODPLAIN MANAGEMENT APPLICATIONS

2.1 Floodplain Boundaries To provide a national standard without regional discrimination, the 1% annual chance (100-year) flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2% annual chance (500-year) flood is employed to indicate additional areas of flood hazard in the community.

Each flooding source included in the project scope has been studied and mapped using professional engineering and mapping methodologies that were agreed upon by FEMA and Black Hawk County as appropriate to the risk level. Flood risk is evaluated based on factors such as known flood hazards and projected impact on the built environment. Engineering analyses were performed for each studied flooding source to calculate its 1% annual chance flood elevations; elevations corresponding to other floods (e.g. 10-, 4-, 2-, 0.2-percent annual chance, etc.) may have also been computed for certain flooding sources. Engineering models and methods are described in detail in Section 5.0 of this FIS Report. The modeled elevations at cross sections were used to delineate the floodplain boundaries on the FIRM; between cross sections, the boundaries were interpolated using elevation data from various sources. More information on specific mapping methods is provided in Section 6.0 of this FIS Report.

Depending on the accuracy of available topographic data (Table 23), study methodologies employed (Section 5.0), and flood risk, certain flooding sources may be mapped to show both the 1% and 0.2% annual chance floodplain boundaries, regulatory water surface elevations (BFEs), and/or a regulatory floodway. Similarly, other flooding sources may be mapped to show only the 1% annual chance floodplain boundary on the FIRM, without published water surface elevations. In cases where the 1% and 0.2% annual chance floodplain boundaries are close together, only the 1% annual chance floodplain boundary is shown on the FIRM. Figure 3, “Map Legend for FIRM”, describes the flood zones that are used on the FIRMs to account for the varying levels of flood risk that exist along flooding sources within the project area. Table 2 and Table 3 indicate the flood zone designations for each flooding source and each community within Black Hawk County, respectively.

Table 2, “Flooding Sources Included in this FIS Report,” lists each flooding source, including its study limits, affected communities, mapped zone on the FIRM, and the completion date of its engineering analysis from which the flood elevations on the FIRM and in the FIS Report were derived. Descriptions and dates for the latest hydrologic and hydraulic analyses of the flooding sources are shown in Table 13. Floodplain boundaries for these flooding sources are shown on the FIRM (published separately) using the symbology described in Figure 3. On the map, the 1% annual chance floodplain corresponds to the SFHAs. The 0.2% annual chance floodplain shows areas that, although out of the regulatory floodplain, are still subject to flood hazards.

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

17 data. The procedures to remove these areas from the SFHA are described in Section 6.5 of this FIS Report.

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Table 2: Flooding Sources Included in this FIS Report

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis Black Hawk County, Confluence with Beaver Creek Unincorporated Areas; County boundary 07080205 5.7 -- N A 2016 Cedar River Cedar Falls, City of Black Hawk County, Approximately 200 Confluence with Big Woods Creek Unincorporated Areas; feet downstream of 07080205 1.6 -- Y AE 2007 Cedar River Cedar Falls, City of Road Iowa - 27 Black Hawk County, Approximately 200 Approximately 3520 Big Woods Creek Unincorporated Areas; feet downstream of feet upstream of 07080205 3.0 -- N AE 2007 Cedar Falls, City of Road Iowa - 27 Road Iowa - 27 Black Hawk County, Approximately 3520 Approximately 90 Big Woods Creek Unincorporated Areas; feet upstream of Road feet upstream of 07080205 1.2 -- Y AE 2007 Cedar Falls, City of Iowa - 27 Cedar Wapsi Road Big Woods Creek Black Hawk County, Confluence with Big Divergence from Big 07080205 0.6 -- Y AE 2007 Upper Diversion Unincorporated Areas Woods Creek Woods Creek Black Hawk County, Unincorporated Areas; 1 Confluence with Black Hawk Creek Cedar Falls, City of; County boundary 07080205 20.8 -- Y AE 2007 Cedar River Hudson, City of; Waterloo, City of Approximately 0.4 1 Confluence with mile upstream of Blowers Creek Waterloo, City of 07080205 3.2 -- Y AE 1980 Cedar River Martin Luther King Drive Black Hawk County, Unincorporated Areas; City of Janesville 07080201 Cedar River Cedar Falls, City of; County boundary 45.2 -- Y AE 2007 corporate limits 07080205 Evansdale, City of; Waterloo, City of Cedar River Cedar Falls, City of; Confluence with Divergence from 1 07080205 2.1 -- Y AE 2007 Diversion Channel Waterloo, City of Cedar River Cedar River

19 Table 2: Flooding Sources Included in this FIS Report (continued)

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis

1 Confluence with City View Branch Waterloo, City of Railroad 07080205 0.8 -- Y AE 1980 Blowers Creek Black Hawk County, Approximately 110 1 Confluence with Crane Creek Unincorporated Areas; feet downstream of N 07080102 5.5 -- Y AE 2007 Wapsipinicon River Dunkerton, City of Pilot Grove Rd Approximately 1.5 Black Hawk County, Approximately 110 1 miles upstream of Crane Creek Unincorporated Areas; feet downstream of N 07080102 7.5 -- N AE 2007 East Bennington Dunkerton, City of Pilot Grove Rd Road Approximately 125 1 Confluence with Crossroads Creek Waterloo, City of feet upstream of 07080205 1.6 -- Y AE 2007 Cedar River Hammond Avenue Approximately 0.4 Dry Run Creek at Confluence with 1 Cedar Falls, City of miles upstream of 07080205 6.1 -- Y AE 2007 Cedar Falls Cedar River Ridgeway Avenue Approximately 0.5 Dry Run Creek at Confluence with 1 Waterloo, City of mile upstream of 07080205 4.5 -- Y AE 2007 Waterloo Cedar River Kimball Avenue Confluence with Dry Divergence from Dry Dry Run Creek 1 Cedar Falls, City of Run Creek at Cedar Run Creek at Cedar 07080205 0.4 -- Y AE 2007 Diversion Channel Falls Falls Confluence with Dry Dry Run Creek Downstream side of Cedar Falls, City of Run Creek Diversion 07080205 0.9 -- N AE 2012 Tributary 1 Waterloo Road Channel Confluence with Dry Approximately 1,300 Dry Run Creek Cedar Falls, City of Run Creek Diversion feet upstream of 07080205 0.4 -- N AE 2012 Tributary 2 Channel Seerly Boulevard Black Hawk County, Approximately 100 1 Unincorporated Areas; Confluence with Elk Run Creek feet upstream of East 07080205 7.2 -- Y AE 1980 Elk Run Heights, City Cedar River Donald Street of; Evansdale, City of

20 Table 2: Flooding Sources Included in this FIS Report (continued)

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis Approximately 50 1 Confluence with Maywood Branch Waterloo, City of feet upstream of 07080205 2.3 -- Y AE 1980 Blowers Creek Newell Street

1 Black Hawk County, Confluence with Miller Creek At railroad 07080205 2.4 -- Y AE 1980 Unincorporated Areas Cedar River Confluence with Approximately 50 Northeast University Cedar Falls, City of University Branch Dry feet upstream of W 07080205 0.6 -- N AE 2012 Branch Tributary th Run Creek 12 street Northwest Confluence with Approximately 50 University Branch Cedar Falls, City of University Branch Dry feet downstream of 07080205 0.6 -- N AE 2012 Tributary Run Creek W 12th street Black Hawk County, 1 Confluence with Poyner Creek Unincorporated Areas; At Young Road 07080205 2.6 -- Y AE 1980 Cedar River Raymond, City of Black Hawk County, Approximately 535 1 Confluence with Black Prescotts Creek Unincorporated Areas; feet upstream of Hoff 07080205 3.5 -- Y AE 1980 Hawk Creek Waterloo, City of Road Black Hawk County, Approximately 0.5 1 Confluence with Sink Creek Unincorporated Areas; mile upstream of 07080205 6.1 -- Y AE 1980 Cedar River Waterloo, City of Hammond Avenue Confluence with Dry Approximately 1.8 Southwest Branch 1 Cedar Falls, City of Run Creek at Cedar miles upstream of 07080205 4.0 -- Y AE 2007 Dry Run Creek Falls Greenhill Road Black Hawk County, Confluence with Spring Creek County boundary 07080205 18.8 -- N A 2007 Unincorporated Areas Cedar River Approximately 1,390 Black Hawk County, 1 Confluence with feet upstream of Stream No. 13 Unincorporated Areas; 07080205 3.5 -- Y AE 2007 Cedar River confluence of Stream Waterloo, City of No. 39 Black Hawk County, Approximately 0.9 1 Confluence with Stream No. 36 Unincorporated Areas; mile upstream of 07080205 2.1 -- Y AE 2007 Stream No. 13 Waterloo, City of Wagner Road

21 Table 2: Flooding Sources Included in this FIS Report (continued)

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis Approximately 100 Confluence with Stream No. 37 Waterloo, City of feet upstream of 07080205 0.7 -- Y AE 1980 Stream No. 13 Burton Avenue Approximately 100 1 Confluence with Stream No. 39 Waterloo, City of feet upstream of 07080205 0.4 -- Y AE 1980 Stream No. 13 Burton Avenue Approximately 115 1 Confluence with Black th Sunnyside Creek Waterloo, City of feet upstream of 4 07080205 1.7 -- Y AE 2007 Hawk Creek Street Sunnyside Creek Confluence with Black Divergence from 1 Waterloo, City of 07080205 1.0 -- N AE 2007 Bypass Hawk Creek Sunnyside Creek Approximately 1,250 Confluence with feet upstream of Tributary 1 Cedar Falls, City of 07080205 0.1 -- N AE 2012 Unnamed Stream confluence with Unnamed Stream Confluence with Dry Approximately 0.6 University Branch 1 Cedar Falls, City of Run Creek at Cedar mile upstream of 07080205 3.2 -- Y AE 1981 Dry Run Creek Falls Waterbury Drive Approximately 600 Confluence with feet upstream of Unnamed Stream Cedar Falls, City of 07080205 0.1 -- N A 2012 Stream No. 6 confluence with Stream No. 6 Approximately 600 Approximately 2,600 feet upstream of feet upstream of Unnamed Stream Cedar Falls, City of 07080205 0.4 -- N AE 2012 confluence with confluence with Stream No. 6 Stream No. 6 Approximately 765 Unnamed Tributary 1 Cedar Falls, City of Clayton Ulrich Dam feet upstream of 07080205 1.2 -- Y AE 1981 to Cedar River Union Road Confluence with Dry Approximately 50 Unnamed Tributary 1 Cedar Falls, City of Run Creek at Cedar feet upstream of 07080205 1.0 -- Y AE 2012 to Dry Run Creek Falls Greenhill Road

22 Table 2: Flooding Sources Included in this FIS Report (continued)

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis Black Hawk County, Confluence with 1 Confluence with Virden Creek Unincorporated Area; Virden Creek 07080205 2.1 -- Y AE 1980 Cedar River Waterloo, City of Tributary Black Hawk County, Approximately 130 Virden Creek Confluence with 1 Unincorporated Area; feet upstream of Big 07080205 1.6 -- Y AE 1980 Tributary Virden Creek Waterloo, City of Rock Road Black Hawk County, Confluence with Approximately 0.4 West Branch Dry 1 Unincorporated Areas; Southwest Branch Dry mile upstream of 07080205 2.6 -- Y AE 1981 Run Creek th Cedar Falls, City of Run Creek West 27 Street 07080201 West Fork Cedar Black Hawk County, Confluence with 1 County boundary 07080204 6.4 -- Y AE 1980 River Unincorporated Areas Cedar River 07080205 Black Hawk County, Approximately 1.3 1 Confluence with Wolf Creek Unincorporated Areas; miles upstream of 07080205 6.1 -- Y AE 2002 Cedar River La Porte City, City of Main Street Black Hawk County, Approximately 0.8 Wolf Creek Confluence with Wolf 1 Unincorporated Areas; mile upstream of 07080205 2.7 -- N AE 2002 Overflow Creek La Porte City, City of Poplar Street Black Hawk County, Unincorporated Areas; Cedar Falls, City of; 07080102 Dunkerton, City of; 07080201 Zone A Flooding Elk Run Heights, City Within Black Hawk Within Black Hawk 07080202 337.4 -- N A 2016 Sources of; Gilbertville, City of County County 07080204 Hudson, City of; La 07080205 Porte, City of; Raymond, City of; Waterloo, City of

23 Table 2: Flooding Sources Included in this FIS Report (continued)

Length (mi) Area (mi2) Zone HUC-8 Sub- (streams or (estuaries Floodway shown on Date of Flooding Source Community Downstream Limit Upstream Limit Basin(s) coastlines) or ponding) (Y/N) FIRM Analysis Black Hawk County, Unincorporated Areas; Zone A Flooding Elk Run Heights, City Various locations Various locations 07080205 6.3 -- N A 2007 Sources of; Evansdale, City of; Raymond, City of; Waterloo, City of 1Source was redelineated using the effective modeling information

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2.2 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 balancing floodplain development against increasing flood hazard. With this approach, the area of the 1% annual chance floodplain on a river is divided into a floodway and a floodway fringe based on hydraulic modeling. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment in order to carry the 1% annual chance flood. The floodway fringe is the area between the floodway and the 1% annual chance floodplain boundaries where encroachment is permitted. The floodway must be wide enough so that the floodway fringe could be completely obstructed without increasing the water surface elevation of the 1% annual chance flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 4.

To participate in the NFIP, Federal regulations require communities to limit increases caused by encroachment to 1.0 foot, provided that hazardous velocities are not produced. The floodways in this project are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway projects.

Figure 4: Floodway Schematic

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Floodway widths presented in this FIS Report and on the FIRM were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. For certain stream segments, floodways were adjusted so that the amount of floodwaters conveyed on each side of the floodplain would be reduced equally. The results of the floodway computations have been tabulated for selected cross sections and are shown in Table 24, “Floodway Data.”

All floodways that were developed for this Flood Risk Project are shown on the FIRM using the symbology described in Figure 3. In cases where the floodway and 1% annual chance floodplain boundaries are either close together or collinear, only the floodway boundary has been shown on the FIRM. For information about the delineation of floodways on the FIRM, refer to Section 6.3.

2.3 Base Flood Elevations The hydraulic characteristics of flooding sources were analyzed to provide estimates of the elevations of floods of the selected recurrence intervals. The Base Flood Elevation (BFE) is the elevation of the 1% annual chance flood. These BFEs are most commonly rounded to the whole foot, as shown on the FIRM, but in certain circumstances or locations they may be rounded to 0.1 foot. Cross section lines shown on the FIRM may also be labeled with the BFE rounded to 0.1 foot. Whole-foot BFEs derived from engineering analyses that apply to coastal areas, areas of ponding, or other static areas with little elevation change may also be shown at selected intervals on the FIRM.

Cross sections with BFEs shown on the FIRM correspond to the cross sections shown in the Floodway Data table and Flood Profiles in this FIS Report. BFEs are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS Report in conjunction with the data shown on the FIRM.

2.4 Non-Encroachment Zones Some States and communities use non-encroachment zones to manage floodplain development. For flooding sources with medium flood risk, field surveys are often not collected and surveyed bridge and culvert geometry is not developed. Standard hydrologic and hydraulic analyses are still performed to determine BFEs in these areas. However, floodways are not typically determined, since specific channel profiles are not developed. To assist communities with managing floodplain development in these areas, a “non-encroachment zone” may be provided. While not a FEMA designated floodway, the non-encroachment zone represents that area around the stream that should be reserved to convey the 1% annual chance flood event. As with a floodway, all surcharges must fall within the acceptable range in the non-encroachment zone.

General setbacks can be used in areas of lower risk (e.g. unnumbered Zone A), but these are not considered sufficient where unnumbered Zone A is replaced by Zone AE. The NFIP requires communities to ensure that any development in a non-encroachment area causes no increase in BFEs. Communities must generally prohibit development within the area defined by the non-encroachment width to meet the NFIP requirement.

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Non-encroachment determinations may be delineated where it is not possible to delineate floodways because specific channel profiles with bridge and culvert geometry were not developed. Any non-encroachment determinations for this Flood Risk Project have been tabulated for selected cross sections and are shown in Table 25, “Flood Hazard and Non-Encroachment Data for Selected Streams.” Areas for which non- encroachment zones are provided show BFEs and the 1% annual chance floodplain boundaries mapped as zone AE on the FIRM but no floodways.

2.5 Coastal Flood Hazard Areas This section is not applicable to this Flood Risk Project.

2.5.1 Water Elevations and the Effects of Waves This section is not applicable to this Flood Risk Project.

Figure 5: Wave Runup Transect Schematic [Not Applicable to this Flood Risk Project]

2.5.2 Floodplain Boundaries and BFEs for Coastal Areas This section is not applicable to this Flood Risk Project.

2.5.3 Coastal High Hazard Areas This section is not applicable to this Flood Risk Project.

Figure 6: Coastal Transect Schematic [Not Applicable to this Flood Risk Project]

2.5.4 Limit of Moderate Wave Action This section is not applicable to this Flood Risk Project.

SECTION 3.0 – INSURANCE APPLICATIONS

3.1 National Flood Insurance Program Insurance Zones For flood insurance applications, the FIRM designates flood insurance rate zones as described in Figure 3, “Map Legend for FIRM.” Flood insurance zone designations are assigned to flooding sources based on the results of the hydraulic or coastal analyses. Insurance agents use the zones shown on the FIRM and depths and base flood elevations in this FIS Report in conjunction with information on structures and their contents to assign premium rates for flood insurance policies.

The 1% annual chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (e.g. Zones A, AE, V, VE, etc.), and the 0.2% annual chance floodplain boundary corresponds to the boundary of areas of additional flood hazards.

Table 3 lists the flood insurance zones in Black Hawk County.

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Table 3: Flood Zone Designations by Community

Community Flood Zone(s) Black Hawk County, Unincorporated Areas A, AE, X Cedar Falls, City of A, AE, X Dunkerton, City of A, AE, X Elk Run Heights, City of A, AE, X Evansdale, City of A, AE, AH, X Gilbertville, City of A, AE, X Hudson, City of A, AE, X La Porte, City of A, AE, X Raymond, City of A, AE, X Waterloo, City of A, AE, AO, X

3.2 Coastal Barrier Resources System This section is not applicable to this Flood Risk Project.

Table 4: Coastal Barrier Resources System Information [Not Applicable to this Flood Risk Project]

SECTION 4.0 – AREA STUDIED

4.1 Basin Description Table 5 contains a description of the characteristics of the HUC-8 sub-basins within which each community falls. The table includes the main flooding sources within each basin, a brief description of the basin, and its drainage area.

Table 5: Basin Characteristics

Drainage HUC-8 Primary Area HUC-8 Sub- Sub-Basin Flooding (square Basin Name Number Source Description of Affected Area miles) The land drained by the Cedar River is flat to gently rolling farmland. Vegetal cover is typically Middle Cedar 07080205 Cedar River 2,417 pastureland grass or row crops, with some timber, especially near streams. Shell Rock Basin is located in southern Shell Rock 07080202 1,080 River Minnesota and northern Iowa.

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Table 5: Basin Characteristics (continued)

Drainage HUC-8 Primary Area HUC-8 Sub- Sub-Basin Flooding (square Basin Name Number Source Description of Affected Area miles) Watershed is located in Northeast Iowa. It covers Worth, Mitchell, Upper Cedar 07080201 Cedar River 1,683 Floyd, Chickasaw, Butler, Bremer, and Black Hawk Counties. Watershed is located in northeast Iowa. It spans across Mitchell, Upper Wapsipinicon Howard, Floyd, Chickasaw, Bremer, 07080102 1,568 Wapsipinicon River Fayette, Black Hawk, Buchanan, Delaware, Linn, and Jones Counties. Watershed stretches across Franklin, Butler, Cerro Gordo, Black West Fork West Fork 07080204 Hawk, Bremer and Hancock 861 Cedar Cedar River counties with a majority of landuse in agriculture.

4.2 Principal Flood Problems Table 6 contains a description of the principal flood problems that have been noted for Black Hawk County by flooding source.

Table 6: Principal Flood Problems

Flooding Source Description of Flood Problems All Flooding The history of flooding in Black Hawk County indicates that flooding may occur Sources during any non-winter month. The majority of floods have occurred during the spring or early summer as a result of heavy rainfall and/or snowmelt. However, locally heavy thunderstorms in late summer or autumn have also caused flooding problems. Cedar River The low-lying areas of Cedar Falls and Evansdale are subject to periodic flooding caused by overflow of the Cedar River. The severe occurs generally during the early spring as a result of rapid snow melt in conjunction with warm, heavy rains, with flooding further aggravated by ice jams. Damage to the unincorporated areas of Black Hawk County from Cedar River floods includes crop losses, fences, livestock and farmsteads. Flooding along the Cedar River and its tributaries is significantly affected by such factors as hydraulic constrictions caused by bridges, culverts, debris, and ice jams. Dry Run There have been significant flooding problems, especially on University Creek Branch, primarily caused by heavy rains.

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Table 7 contains information about historic flood elevations in the communities within Black Hawk County.

Table 7: Historic Flooding Elevations

Historic Approximate Flooding Peak (Feet Event Recurrence Source of Source Location NAVD88) Date Interval (years) Data Cedar River at Cedar River 16.8 1961 50 USGS gage Cedar Falls, Iowa INRC high Crane Creek Within Dunkerton * 1968 300 water marks Black Hawk Black Hawk Creek * 1969 85 USGS gage Creek at Hudson *Data not available

4.3 Non-Levee Flood Protection Measures Table 8 contains information about non-levee flood protection measures within Black Hawk County such as dams, jetties, and or dikes. Levees are addressed in Section 4.4 of this FIS Report.

Table 8: Non-Levee Flood Protection Measures

Flooding Structure Type of Source Name Measure Location Description of Measure Blowers Closure Structure prevents backwater N/A Downstream end Creek Structure from the Cedar River. Dry Run Underground culverts that run N/A Culverts At Waterloo Creek in lower reaches. Three detention basins have Dry Run Detention N/A At Waterloo been built along the upper Creek Basins reaches. University Detention N/A Hudson Road Constructed in 1982. Branch Pond Underground culverts that run Virden Creek N/A Culverts At Waterloo in lower reaches. Large detention basin Detention Northeastern Virden Creek N/A construction outside of Basin corporate limits northeastern corporate limits. System of dikes that offer 1- Virden Creek N/A Dikes Various locations percent-annual-chance flood protection. Downstream urban Floodgates control the Virden Creek N/A Floodgates areas flooding in urban areas.

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4.4 Levees For purposes of the NFIP, FEMA only recognizes levee systems that meet, and continue to meet, minimum design, operation, and maintenance standards that are consistent with comprehensive floodplain management criteria. The Code of Federal Regulations, Title 44, Section 65.10 (44 CFR 65.10) describes the information needed for FEMA to determine if a levee system reduces the risk from the 1% annual chance flood. This information must be supplied to FEMA by the community or other party when a flood risk study or restudy is conducted, when FIRMs are revised, or upon FEMA request. FEMA reviews the information for the purpose of establishing the appropriate FIRM flood zone.

Levee systems that are determined to reduce the risk from the 1% annual chance flood are accredited by FEMA. FEMA can also grant provisional accreditation to a levee system that was previously accredited on an effective FIRM and for which FEMA is awaiting data and/or documentation to demonstrate compliance with Section 65.10. These levee systems are referred to as Provisionally Accredited Levees, or PALs. Provisional accreditation provides communities and levee owners with a specified timeframe to obtain the necessary data to confirm the levee’s certification status. Accredited levee systems and PALs are shown on the FIRM using the symbology shown in Figure 3 and in Table 9. If the required information for a PAL is not submitted within the required timeframe, or if information indicates that a levee system not longer meets Section 65.10, FEMA will de-accredit the levee system and issue an effective FIRM showing the levee-impacted area as a SFHA.

FEMA coordinates its programs with USACE, who may inspect, maintain, and repair levee systems. The USACE has authority under Public Law 84-99 to supplement local efforts to repair flood control projects that are damaged by floods. Like FEMA, the USACE provides a program to allow public sponsors or operators to address levee system maintenance deficiencies. Failure to do so within the required timeframe results in the levee system being placed in an inactive status in the USACE Rehabilitation and Inspection Program. Levee systems in an inactive status are ineligible for rehabilitation assistance under Public Law 84-99.

FEMA coordinated with the USACE, the local communities, and other organizations to compile a list of levees that exist within Black Hawk County. Table 9, “Levees,” lists all accredited levees, PALs, and de-accredited levees shown on the FIRM for this FIS Report. Other categories of levees may also be included in the table. The Levee ID shown in this table may not match numbers based on other identification systems that were listed in previous FIS Reports. Levees identified as PALs in the table are labeled on the FIRM to indicate their provisional status.

Please note that the information presented in Table 9 is subject to change at any time. For that reason, the latest information regarding any USACE structure presented in the table should be obtained by contacting USACE and accessing the USACE National Levee Database. For levees owned and/or operated by someone other than the USACE, contact the local community shown in Table .

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Table 9: Levees

Covered Levee USACE Under PL84- Community Flooding Source Location Levee Owner Levee Levee ID 99 Program? FIRM Panel(s) Black Hawk County, 19013C0187F Unincorporated Areas; Virden Creek * * Yes 5105920005 No 19013C0195F Waterloo, City of Right 19013C0162F Cedar Falls, City of Cedar River * Yes 5105520001 Yes Bank 19013C0164F

Cedar River/ Dry 19013C0164F Cedar Falls, City of Run Creek at Left Bank * No 1705990649 * Cedar Falls 19013C0168F Evansdale, City of Cedar River Left Bank * * 1705000219 * 19013C0309F Evansdale, City of; Cedar River Left Bank * Yes 5105920004 No 19013C0306F Waterloo, City of 19013C0167F 19013C0169F 19013C0186F 19013C0188F Left and Evansdale, City of; Cedar River/ Elk 19013C0189F Right * Yes 5105920003 No Waterloo, City of Run 19013C0302F Banks 19013C0306F 19013C0307F 19013C0308F 19013C0309F 19013C0169F Left and 19013C0188F Waterloo, City of Black Hawk Creek Right * * 5105920001 * 19013C0282F Banks 19013C0301F

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Table 9: Levees (continued)

Covered Levee USACE Under PL84- Community Flooding Source Location Levee Owner Levee Levee ID 99 Program? FIRM Panel(s) 19013C0188F Left and Black Hawk Creek/ 19013C0282F Waterloo, City of Right * Yes 5105920002 No Cedar River 19013C0301F Banks 19013C0302F Left and Waterloo, City of Cedar River Right * Yes 1705990657 * 19013C0169F Banks Waterloo, City of Virden Creek Left Bank * * 1705000168 * 19013C0189F Right Waterloo, City of Virden Creek * * 1705000172 * 19013C0189F Bank *Data not available

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SECTION 5.0 – ENGINEERING METHODS

For the flooding sources in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude that are expected to be equaled or exceeded at least once on the average during any 10-, 25-, 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-, 25-, 50-, 100-, and 500-year floods, have a 10-, 4-, 2-, 1-, and 0.2% annual 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 exceedance) during the term of a 30-year mortgage is approximately 26 percent (about 3 in 10); 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 community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes.

5.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak elevation-frequency relationships for floods of the selected recurrence intervals for each flooding source studied. Hydrologic analyses are typically performed at the watershed level. Depending on factors such as watershed size and shape, land use and urbanization, and natural or man-made storage, various models or methodologies may be applied. A summary of the hydrologic methods applied to develop the discharges used in the hydraulic analyses for each stream is provided in Table 13. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation.

A summary of the discharges is provided in Table 10. Stream gage information is provided in Table 12.

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Table 10: Summary of Discharges

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Above Big Woods Road Big Woods Creek 0.99 680 * 1,280 1,460 2,015 (North Crossing) Above Cedar-Wapsie Big Woods Creek 0.33 380 * 700 830 1,145 Road Across and South of Big Woods Creek Bennington Road along * 135 * 445 570 735 Upper Diversion Highway 218 Black Hawk At mouth 344 10,900 * 17,900 21,100 29,400 Creek At western corporate Black Hawk limits of Waterloo and 332 10,700 * 17,600 20,700 29,000 Creek Cedar Falls in Section 32 Black Hawk At West Shaulis Road 313 10,500 * 17,100 20,200 28,200 Creek Upstream of confluence Black Hawk with tributary at center 305 10,390 * 16,930 20,010 27,900 Creek of Section 23 (Station 56.5) Black Hawk At gaging station in 303 10,360 * 16,880 19,950 27,830 Creek Hudson (Station 65.2 About 1.0 mile Black Hawk upstream of Zoneta 283 10,020 * 16,390 19,390 27,090 Creek Road

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Black Hawk At Grundy Road 278 9,940 * 16,260 19,240 26,910 Creek Blowers Creek At mouth 7.0 2,490 * 3,900 4,720 5,960 Above City View Blowers Creek 5.5 1,990 * 3,140 3,810 4,820 Branch Above Maywood Blowers Creek 2.36 780 * 1,230 1,500 1,900 Branch Above Tributary about Blowers Creek 1.0 mile north of Newell 1.53 710 * 1,130 1,370 1,730 Street At Waterloo gaging Cedar River 5,146 55,000 * 83,000 94,000 123,000 station Above confluence of Cedar River 1,676 25,900 * 40,700 46,900 61,100 West Fork Cedar River At Janesville gaging Cedar River 1,661 25,800 * 40,500 46,700 60,900 station Cedar River At confluence with * 1,500 * 17,000 20,000 33,000 Diversion Cedar River Cedar River Diversion At US 218 * 5,000 * 12,700 16,700 25,900 Channel City View Branch At mouth 0.91 520 * 790 950 1,190 At Chicago & North City View Branch 0.69 440 * 670 800 1,010 Western Railroad

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Crane Creek At mouth 109 6,140 * 9,990 11,700 16,000 Crane Creek At Canfield Road 103 5,950 * 9,700 11,350 15,600 Crane Creek At Ordway Road 83 5,230 * 8,590 10,100 13,900 Crossroads At mouth 1.4 1,000 * 1,740 2,120 2,880 Creek Crossroads Upstream of Sarah 0.8 770 * 1,360 1,650 2,270 Creek Drive Dry Run Creek At mouth 23.5 7,510 * 10,590 12,460 17,000 Dry Run Creek At Waterloo Road 23.4 7,430 * 10,540 12,390 16,990 Dry Run Creek At 18th Street 20.6 6,340 * 8,920 10,600 14,500 South of Seerley Dry Run Creek 9.4 2,950 * 4,280 5,010 6,850 Boulevard Dry Run Creek At South Main Street 9.2 2,440 * 3,540 4,140 5,700 Dry Run Creek North of Viking Road 7.6 2,230 * 3,210 3,800 5,250 Dry Run Creek At Viking Road 6.0 2,080 * 2,930 3,429 4,750 Total Inflow to Liberty Dry Run Creek 3.46 1,215 * 1,860 2,180 3,300 Park Inflow to Bontrager Dry Run Creek 2.62 950 * 1,720 2,155 3,405 Park Outflow from Bontrager Dry Run Creek 2.62 565 * 650 950 2,260 Park Dry Run Creek At State Highway 412 1.81 600 * 930 1,110 1,630

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Inflow to U.S. 520 Dry Run Creek 1.4 660 * 1,315 1,685 2,830 Detention Basin Outflow from U.S. 520 Dry Run Creek 1.35 410 * 535 580 685 Detention Basin At Dry Run Creek Dry Run Creek Diversion Channel 0.86 * * * 1,170 * Tributary 1 confluence At Dry Run Creek Dry Run Creek Diversion Channel 0.34 * * * 550 * Tributary 2 confluence Elk Run Creek At mouth 34.6 3,130 * 5,750 7,090 10,300 Elk Run Creek At Elk Run Road 32.0 3,130 * 5,750 7,090 10,300 Elk Run Creek At Osage Road 25.7 2,840 * 5,260 6,500 9,700 Elk Run Creek At Newell Street 23.0 2,700 * 5,030 6,220 9,320 About 300 feet upstream of Chicago Elk Run Creek 15.2 2,200 * 4,170 5,200 7,910 and North Western Railroad Elk Run Creek At Donald Street 11.1 1,920 * 3,680 4,600 7,080 Elk Run Creek At mouth 7.6 1,890 * 3,410 4,140 6,080 Tributary Elk Run Creek Above Tributary ¼ East 6.5 1,790 * 3,250 3,950 5,830 Tributary of Dewar

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Elk Run Creek Just South of Donald 4.9 1,570 * 2,870 3,500 5,200 Tributary Street Maywood Branch At mouth 2.96 1,140 * 1,800 2,180 2,750 Maywood Branch Above Stream 17 2.20 980 * 1,550 1,870 2,370 Above Ranch Aero Maywood Branch 1.44 740 * 1,170 1,420 1,790 Drainage Maywood Branch Above Stream 19 1.03 530 * 830 1,010 1,270 Miller Creek At mouth 67.2 5,030 * 8,740 10,580 15,440 At Illinois Central Gulf Miller Creek 57.2 4,660 * 8,170 9,910 14,530 Railroad Northwest At University Branch University Branch Dry Run Creek 0.60 * * * 580 * Tributary confluence Poyner Creek At mouth 17.3 2,620 * 4,830 5,980 9,080 Poyner Creek At Gilbertville Road 16.2 2,540 * 4,690 5,810 8,850 Poyner Creek At Young Road 14.2 2,380 * 4,430 5,500 8,410 Prescotts Creek At Sargeant Road 11.5 2,880 * 4,320 6,570 8,890 Prescotts Creek At West Shaulis Road 10.4 2,860 * 4,270 6,460 8,720 Scott Avenue Local Drainage At Huntington Road 0.3 * * * 425 517 Area Sink Creek At East Shaulis Road 7.2 2,110 * 3,180 4,620 6,170

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Sink Creek At Cedar Terrace Drive 6.8 2,020 * 3,050 4,430 5,970 Sink Creek At U.S. Highway 218 5.9 1,960 * 2,960 4,310 5,750 Sink Creek At Hess Road 4.2 1,650 * 2,450 3,540 4,620 Sink Creek At Orange Road 1.8 1,170 * 1,730 2,520 3,210 Above Tributary, SE ¼ Sink Creek 1.15 940 * 1,380 2,020 2,570 NE ¼ Section 22 Sink Creek At Hawkeye Road 0.73 750 * 1,110 1,610 2,050 Southwest Branch Dry Run At Main Street 9.6 3,380 * 4,860 5,700 7,700 Creek Southwest Branch Dry Run At Hudson Creek 8.7 2,710 * 3,820 4,530 6,200 Creek Southwest Above confluence with Branch Dry Run 5.4 1,750 * 2,460 2,880 3,900 West Branch Creek Stream No. 13 At mouth 21.9 2,800 * 4,850 5,800 8,270 Stream No. 36 At mouth 9.3 1,650 * 2,950 3,560 5,170 Stream No. 37 At mouth 0.81 450 * 685 815 1,105 Stream No. 39 At mouth 1.73 885 * 1,330 1,580 2,140 Sunnyside Creek At mouth 2.4 1,020 * 1,920 2,360 3,560 At confluence with Tributary 1 0.12 N/A * 103 118 N/A Unnamed Stream

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance University Branch Above confluence with 2.7 1,050 * 1,480 1,630 2,020 Dry Run Creek Dry Run Creek University Branch At Clay Street 2.4 870 * 1,200 1,375 1,650 Dry Run Creek University Branch At College Street 2.2 750 * 1,120 1,360 1,630 Dry Run Creek Just upstream of University Branch Hudson Road 1.9 1,025 * 1,525 1,770 2,275 Dry Run Creek Detention Area Just downstream of University Branch Hudson Road 1.9 660 * 1,055 1,290 1,540 Dry Run Creek Detention Area Approximately 1,800 Unnamed Stream feet upstream of Cedar 0.29 N/A * 324 381 N/A Heights Drive Unnamed Tributary to At Clayton Ulrich Dam 1.20 1,100 * 1,510 1,760 * Cedar River Unnamed About 2,500 feet Tributary to downstream of Union 0.73 630 * 900 1,040 * Cedar River Road Unnamed Tributary to At Union Road 0.28 330 * 460 545 * Cedar River

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Unnamed Tributary to Dry At South Main Street 0.94 660 * 920 1,070 * Run Creek Unnamed At Approximately 700 Tributary to Dry feet upstream of South 0.72 270 * 360 415 * Run Creek Lawn Road Unnamed Tributary to Dry At Greenhill Road 0.31 81 * 91 97 * Run Creek Inflow to Gates Park Virden Creek 12.85 1,632 * 2,840 3,370 4,690 Detention Area Outflow from Gates Virden Creek 12.85 1,550 * 2,365 2,640 3,425 Park Detention Area Virden Creek At mouth 1.47 650 * 965 1,150 1,565 Tributary West Branch Dry Above confluence with 3.3 1,140 * 1,630 1,900 2,600 Run Creek Southwest Branch West Branch Dry At Union Road 2.1 1,000 * 1,420 1,680 2,300 Run Creek West Fork Cedar At mouth 2,639 39,000 * 60,000 69,000 90,000 River West Fork Cedar Upstream of confluence 855 19,100 * 30,650 35,650 47,000 River with Shell Rock River West Fork Cedar At the Finchford gaging 846 19,000 * 30,500 35,500 46,800 River station

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Table 10: Summary of Discharges (continued)

Peak Discharge (cfs) Drainage Area (Square 10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Miles) Chance Chance Chance Chance Chance Wolf Creek At mouth 328 10,760 * 17,480 20,630 28,700 *Not calculated for this Flood Risk Project

Figure 7: Frequency Discharge-Drainage Area Curves [Not Applicable to this Flood Risk Project]

Table 11: Summary of Non-Coastal Stillwater Elevations

Elevations (feet NAVD88)

10% Annual 4% Annual 2% Annual 1% Annual 0.2% Annual Flooding Source Location Chance Chance Chance Chance Chance Pointe West * Cedar Falls, City of * * * 936.9 Detention Basin 12th Street * * * * Cedar Falls, City of 909.2 Detention Basin *Data not available

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Table 12: Stream Gage Information used to Determine Discharges

Agency Drainage Period of Record that Area Flooding Gage Maintains (Square Source Identifier Gage Site Name Miles) From To Beaver Creek Beaver Creek 05463000 USGS at New 347 03/07/1946 06/25/2013 Hartford, IA Black Hawk Black Hawk 05463500 USGS Creek at 299 04/01/1952 05/30/2013 Creek Hudson, IA Buck Creek Buck Creek 5420875 USGS 37.9 07/14/1905 07/14/1966 near Oran, IA Cedar River Cedar River 5457000 USGS near Austin, 399 11/14/1909 02/29/2012 MN Cedar River at Cedar River 5457700 USGS 1,054 09/07/1946 05/06/2012 Charles City, IA Cedar River at Cedar River 05464500 USGS Cedar Rapids, 6,502 05/31/1851 06/02/2013 IA Cedar River Cedar River 05465000 USGS near 7,787 02/28/1929 06/03/2013 Conesville, IA Cedar River at Cedar River 5458500 USGS 1,661 05/17/1905 05/08/2012 Janesville, IA Cedar River at Cedar River 05464000 USGS 5,142 03/16/1929 05/31/2013 Waterloo, IA Cedar River at Cedar River 5458300 USGS 1,547 04/14/2001 05/08/2012 Waverly, IA Miller Creek Miller Creek 05464025 USGS near Eagle 3.4 07/20/1990 03/10/2013 Center, IA Shell Rock Shell Rock 05462000 USGS River at Shell 1,039 01/29/1905 06/14/2013 River Rock, IA Wapsipinicon Wapsipinicon River at 5421000 USGS 1,048 04/11/1934 05/09/2012 River Independence, IA Wapsipinicon Wapsipinicon 5420680 USGS River near 346 07/01/1969 05/07/2012 River Tripoli, IA

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Table 12: Stream Gage Information used to Determine Discharges (continued)

Agency Drainage Period of Record that Area Flooding Gage Maintains (Square Source Identifier Gage Site Name Miles) From To Wapsipinicon Wapsipinicon 5420680 USGS Tributary at 0.7 07/26/1953 05/26/2012 River Winthrop, IA West Fork West Fork 5458900 USGS Cedar River at 846 03/01/1929 05/05/2012 Cedar River Finchford, IA Wolf Creek Wolf Creek 05464220 USGS 298 06/18/1996 05/27/2013 near Dysart, IA

5.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Base flood elevations on the FIRM represent the elevations shown on the Flood Profiles and in the Floodway Data tables in the FIS Report. Rounded whole-foot elevations may be shown on the FIRM in coastal areas, areas of ponding, and other areas with static base flood elevations. These whole-foot elevations may not exactly reflect the elevations derived from the hydraulic analyses. Flood elevations shown on the FIRM are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS Report in conjunction with the data shown on the FIRM. The hydraulic analyses for this FIS were based on unobstructed flow. The flood elevations shown on the profiles are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail.

For streams for which hydraulic analyses were based on cross sections, locations of selected cross sections are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 6.3), selected cross sections are also listed in Table 24, “Floodway Data.”

A summary of the methods used in hydraulic analyses performed for this project is provided in Table 13. Roughness coefficients are provided in Table 14. Roughness coefficients are values representing the frictional resistance water experiences when passing overland or through a channel. They are used in the calculations to determine water surface elevations. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation.

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Table 13: Summary of Hydrologic and Hydraulic Analyses

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations Confluence with Beaver Creek County boundary * HEC-RAS 2016 A * Cedar River Starting water-surface elevations were calculated using the slope-area method in Approximately 200 Slope-Area HEC-RAS (USACE 2005). Confluence with AE w/ Big Woods Creek feet downstream of HEC-HMS Method, HEC- 2007 Cedar River Floodway The flood hazard area was redelineated based Road Iowa - 27 RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Starting water-surface elevations were calculated using the slope-area method in Approximately 200 Approximately Slope-Area HEC-RAS (USACE 2005). Big Woods Creek feet downstream of 3520 feet upstream HEC-HMS Method, HEC- 2007 AE The flood hazard area was redelineated based Road Iowa - 27 of Road Iowa - 27 RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Starting water-surface elevations were calculated using the slope-area method in Approximately Approximately 90 Slope-Area HEC-RAS (USACE 2005). AE w/ Big Woods Creek 3520 feet upstream feet upstream of HEC-HMS Method, HEC- 2007 Floodway The flood hazard area was redelineated based of Road Iowa - 27 Cedar Wapsi Road RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Starting water-surface elevations were calculated using the slope-area method in Slope-Area HEC-RAS (USACE 2005). Big Woods Creek Confluence with Divergence from AE w/ HEC-HMS Method, HEC- 2007 Upper Diversion Big Woods Creek Big Woods Creek Floodway The flood hazard area was redelineated based RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations A statistical analysis using the methodology prescribed in the U.S. Water Resources Council Bulletin No. 17 was performed (USWRC 1977). Flow-frequency data were modified from the values determined for an earlier flood plain report (USACE December 1968). Values for the Black Hawk County Flood Insurance Study (FEMA 1982) utilizing the longer gage period Slope-Area Black Hawk Confluence with WRC Bulletin AE w/ were accepted for the 2011 revision. County boundary Method, HEC- 2007 Creek Cedar River No. 17 Floodway 2, HEC-RAS Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and the USACE HEC-2 step-backwater computer program and HEC-RAS (USACE 1968 and USACE 2005). A portion of the flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Discharge estimates were computed using the U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), hydrograph development method (USDA Approximately 0.4 1972). NRCS Confluence with mile upstream of Slope-Area AE w/ The hydraulic analysis downstream of the Blowers Creek Hydrograph 1980 Cedar River Martin Luther King Method Floodway Illinois Central Gulf Railroad required an Development Drive analysis of the ponding effect of the closed structure. The flood hazard area was redelineated on newly developed topographic data in the 2011 revision and TBD revisions. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The discharge values were taken from the Cedar River study (Brice, Petrides & Associates, Inc. undated), which revised the former discharge values in the 1970 flood plain study (USACE 1970). Starting water-surface conditions and water- surface profiles were developed using a slope- Slope-Area City of Janesville AE w/ area method to model free flow conditions and Cedar River County boundary * Method, HEC- 2007 corporate limits Floodway the USACE HEC-2 step-backwater computer 2, HEC-RAS program and HEC-RAS (USACE 1968 and USACE 2005). A portion (From Cross Section A to L and AM to BG) of the flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. The discharges used for the model were developed on a balance of the energy between the Cedar River and Cedar River Diversion. Cedar River Diversion discharges have been coordinated with the Iowa Department of Natural Resources. Starting water-surface conditions and water- Cedar River Slope-Area Confluence with Divergence with AE w/ surface profiles were developed using a slope- Diversion * Method, HEC- 2007 Cedar River Cedar River Floodway area method to model free flow conditions and Channel 2, HEC-RAS the USACE HEC-2 step-backwater computer program and HEC-RAS (USACE 1968 and USACE 2005). The flood hazard area was redelineated on newly developed topographic data in the 2011 revision and TBD revisions. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa Confluence with SCS AE w/ 1974). City View Branch Railroad HEC-2 1980 Blowers Creek Hydrograph Floodway A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and State of Iowa the USACE HEC-2 step-backwater computer Approximately 110 Slope-Area Confluence with 2000 AE w/ program and HEC-RAS (USACE 1968 and Crane Creek feet downstream of Method, HEC- 2007 Wapsipinicon River Regression Floodway USACE 2005). N Pilot Grove Rd 2, HEC-RAS Equations The flood hazard area was redelineated on newly developed topographic data in the 2011 revision and TBD revisions. No new flood hazard analysis was performed. Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and Approximately 1.5 State of Iowa the USACE HEC-2 step-backwater computer Approximately 110 Slope-Area miles upstream of 2000 program and HEC-RAS (USACE 1968 and Crane Creek feet downstream of Method, HEC- 2007 AE East Bennington Regression USACE 2005). N Pilot Grove Rd 2, HEC-RAS Road Equations The flood hazard area was redelineated on newly developed topographic data in the 2011 revision and TBD revisions. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The discharges were modified by a nationwide urbanization adjustment technique (USGS State of Iowa Approximately 125 Slope-Area 1993). Crossroads Confluence with 2000 AE w/ feet upstream of Method, HEC- 2007 Creek Cedar River Regression Floodway A portion of the flood hazard information was Hammond Avenue 2, HEC-RAS Equations redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. For the Dry Run Creek drainage basin, the hydrology in the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980) was adopted. Starting water-surface conditions and water- surface profiles were developed using a slope- Approximately 0.4 Slope-Area Dry Run Creek at Confluence with AE w/ area method to model free flow conditions and mile upstream of HEC-1 Method, HEC- 2007 Cedar Falls Cedar River Floodway the USACE HEC-2 step-backwater computer Ridgeway Avenue 2, HEC-RAS program and HEC-RAS (USACE 1968 and USACE 2005). The flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. For the Dry Run Creek drainage basin, the hydrology in the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980) was adopted. Starting water-surface conditions and water- surface profiles were developed using a slope- Approximately 0.5 Slope-Area AE w/ Dry Run Creek at Confluence with area method to model free flow conditions and mile upstream of HEC-HMS Method, HEC- 2007 Floodway, Waterloo Cedar River the USACE HEC-2 step-backwater computer Kimball Avenue 2, HEC-RAS AO program and HEC-RAS (USACE 1968 and USACE 2005). A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations For the Dry Run Creek drainage basin, the hydrology in the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980) was adopted. Starting water-surface conditions and water- surface profiles were developed using a slope- Dry Run Creek Confluence with Divergence from Slope-Area AE w/ area method to model free flow conditions and Diversion Dry Run Creek at Dry Run Creek at HEC-1 Method, HEC- 2007 Floodway the USACE HEC-2 step-backwater computer Channel Cedar Falls Cedar Falls 2, HEC-RAS program and HEC-RAS (USACE 1968 and USACE 2005). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Confluence with Dry Run Creek Downstream side Dry Run Creek HEC-1 HEC-RAS 2012 AE * Tributary 1 of Waterloo Road Diversion Channel Approximately Confluence with Dry Run Creek 1,300 feet Dry Run Creek HEC-1 HEC-RAS 2012 AE * Tributary 2 upstream of Seerly Diversion Channel Boulevard Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and the USACE HEC-2 step-backwater computer Approximately 100 Bulletin No. 11 Slope-Area Confluence with AE w/ program and HEC-RAS (USACE 1968 and Elk Run Creek feet upstream of Regional Method, HEC- 1980 Cedar River Floodway USACE 2005). East Donald Street Equations 2, HEC-RAS A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

51

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The discharge estimates were determined using the NRCS hydrograph development method (USDA 1972) with Huff rainfall distribution (Huff, F.A. 1970). Rainfall data for this method were obtained from U.S. Weather Bureau Technical Paper No. 40 (USDOC Approximately 50 NRCS 1961). Confluence with AE w/ Maywood Branch feet upstream of Hydrograph HEC-2 1980 Cross sections for the backwater analysis Blowers Creek Floodway Newell Street Development were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974). A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Bulletin No. 11 The flood hazard area was redelineated based Confluence with Regional AE w/ on newly developed topographic data in the Miller Creek At railroad HEC-2 1980 Cedar River Regression Floodway TBD revision. No new flood hazard analysis Equations was performed. Northeast Confluence with Approximately 50 University University Branch feet upstream of W HEC 1 HEC-2 2012 AE * Branch Tributary Dry Run Creek 12th street Northwest Confluence with Approximately 50 University University Branch feet downstream of HEC 1 HEC-RAS 2012 AE * Branch Tributary Dry Run Creek W 12th street Bulletin No. 11 A portion of the flood hazard information was Confluence with Regional AE w/ redelineated based on newly developed Poyner Creek At Young Road HEC-2 1980 Cedar River Regression Floodway topographic data in the TBD revision. No new Equations flood hazard analysis was performed.

52

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The analyses of two previous similar studies (City of Waterloo, Iowa 1977 and City of Waterloo, Iowa 1974) were reviewed and discharges compared to the values computed using the Iowa Regional Equations (USGS 1973). In general, the hydrograph parameters used to determine the discharges in the Comprehensive Drainage Study (City of Waterloo, 1974) were utilized in the 2011 revision. Rainfall amounts were extracted either from the Flood Plain and Flood Control Study (City of Waterloo, Iowa 1977) or from Approximately 535 Confluence with Hydrograph AE w/ the Prescotts Creek portion of the Prescotts Creek feet upstream of * 1980 Black Hawk Creek Models Floodway Comprehensive Drainage Study (City of Hoff Road Waterloo, Iowa 1974). Unit hydrographs were then developed and peak discharge values were computed at the selected frequency intervals. Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

53

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The analyses of two previous similar studies (City of Waterloo, Iowa 1977 and City of Waterloo, Iowa 1974) were reviewed and discharges compared to the values computed using the Iowa Regional Equations (USGS 1973). In general, the hydrograph parameters used to determine the discharges in the Comprehensive Drainage Study (City of Waterloo, 1974) were utilized in the 2011 revision. Rainfall amounts were extracted either from the Flood Plain and Flood Control Study (City of Waterloo, Iowa 1977) or from Approximately 0.5 Confluence with Hydrograph AE w/ the Prescotts Creek portion of the Sink Creek mile upstream of * 1980 Cedar River Models Floodway Comprehensive Drainage Study (City of Hammond Avenue Waterloo, Iowa 1974). Unit hydrographs were then developed and peak discharge values were computed at the selected frequency intervals. Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974). A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. The flood hazard area was redelineated based Southwest Confluence with Approximately 1.8 Slope-Area AE w/ on newly developed topographic data in the Branch Dry Run Dry Run Creek at miles upstream of * 2007 Method Floodway TBD revision. No new flood hazard analysis Creek Cedar Falls Greenhill Road was performed. Confluence with Spring Creek County boundary * HEC-RAS 2007 A * Cedar River

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations Approximately State of Iowa A portion of the flood hazard information was 1,390 feet Confluence with 2000 Slope-Area AE w/ redelineated based on newly developed Stream No. 13 upstream of 2007 Cedar River Regression Method Floodway topographic data in the TBD revision. No new confluence of Equations flood hazard analysis was performed. Stream No. 39 State of Iowa A portion of the flood hazard information was Approximately 0.9 Confluence with 2000 Slope-Area AE w/ redelineated based on newly developed Stream No. 36 mile upstream of 2007 Stream No. 13 Regression Method Floodway topographic data in the TBD revision. No new Wagner Road Equations flood hazard analysis was performed. The discharge estimates were determined using the NRCS hydrograph development method (USDA 1972) with Huff rainfall distribution (Huff, F.A. 1970). Rainfall data for this method were obtained from U.S. Weather Bureau Technical Paper No. 40 (USDOC Approximately 100 NRCS Confluence with AE w/ 1961). The 0.2-percent-annual-chance Stream No. 37 feet upstream of Hydrograph HEC-2 1980 Stream No. 13 Floodway discharge value was determined by Burton Avenue Development extrapolation of the 10-, 2-, and 1-percent- annual-chance events on log probability paper. Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974).

55

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The discharge estimates were determined using the NRCS hydrograph development method (USDA 1972) with Huff rainfall distribution (Huff, F.A. 1970). Rainfall data for this method were obtained from U.S. Weather Bureau Technical Paper No. 40 (USDOC Approximately 100 NRCS Confluence with AE w/ 1961). The 0.2-percent-annual-chance Stream No. 39 feet upstream of Hydrograph HEC-2 1980 Stream No. 13 Floodway discharge value was determined by Burton Avenue Development extrapolation of the 10-, 2-, and 1-percent- annual-chance events on log probability paper. Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974). A portion of the flood hazard information was Approximately 100 NRCS Stream No. 39 Confluence with AE w/ redelineated based on newly developed feet upstream of Hydrograph HEC-2 1980 (continued) Stream No. 13 Floodway topographic data in the TBD revision. No new Burton Avenue Development flood hazard analysis was performed. State of Iowa A portion of the flood hazard information was Approximately 115 Confluence with 2000 Slope-Area AE w/ redelineated based on newly developed Sunnyside Creek feet upstream of 2007 Black Hawk Creek Regression Method Floodway topographic data in the TBD revision. No new 4th Street Equations flood hazard analysis was performed. State of Iowa A portion of the flood hazard information was Sunnyside Creek Confluence with Divergence from 2000 Slope-Area redelineated based on newly developed 2007 AE Bypass Black Hawk Creek Sunnyside Creek Regression Method topographic data in the TBD revision. No new Equations flood hazard analysis was performed. Approximately 1,250 feet Confluence with Tributary 1 upstream of * * 2012 AE * Unnamed Stream confluence with Unnamed Stream

56

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations They hydrology in the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980) was adopted for use in the 2011 revision. Since no gages are located in the drainage basin, they hydrologic evaluation was based on a computer runoff model that yielded discharges for the 10-, 50-, and 100-year events. The 500-year discharges were subsequently determined by a log-Pearson University Confluence with Approximately 0.6 Runoff model, Slope-Area Type III curve extrapolation of the 10-, 50-, AE w/ Branch Dry Run Dry Run Creek at mile upstream of Log-Pearson Method, HEC- 1981 and 100-year events. Floodway Creek Cedar Falls Waterbury Drive Type III 2, HEC-RAS Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and the USACE HEC-2 step-backwater computer program and HEC-RAS (USACE 1968 and USACE 2005). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. Approximately State of Iowa 2,600 feet Unnamed Confluence with 2000 upstream of HEC-2* 2012 A, AE * Stream Stream No. 6 Regression confluence with Equations * Stream No. 6

57

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The hydrology was adopted from the Lakeview Watershed Flood Plain and Floodway Study for use in the 2011 revision (Brice, Petrides & Associates, Inc. November 1980). The profiles were based on discharges associated with projected land uses. Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and the USACE HEC-2 step-backwater computer program and HEC-RAS (USACE 1968 and Unnamed Approximately 765 Slope-Area USACE 2005). AE w/ Tributary to Clayton Ulrich Dam feet upstream of * Method, HEC- 1981 The flood hazard area was redelineated based Floodway Cedar River Union Road 2, HEC-RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

On Unnamed Tributary to Cedar River (panel 0161), it appears that a pond/dam was added on the stream since the effective study and the dam was redelineated to the top of dam elevations, which was higher than the two lettered crosssections, resulting in them being removed from the map along with the floodway.

58

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The hydrology was adopted from the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980). Since no gages are located in the drainage basin, the hydrologic evaluation was based on a computer runoff model that yielded discharges for the 10-, 2-, and 1-percent-annual-chance events. The 0.2- percent-annual-chance discharge was subsequently determined by a log-Pearson Unnamed Confluence with Approximately 50 Slope-Area Type III curve extrapolation of the 10-, 2-, and Log-Pearson AE w/ Tributary to Dry Dry Run Creek at feet upstream of Method, HEC- 2012 1-percent-annual-chance data. Type III, HEC 1 Floodway Run Creek Cedar Falls Greenhill Road 2, HEC-RAS Starting water-surface conditions and water- surface profiles were developed using a slope- area method to model free flow conditions and the USACE HEC-2 step-backwater computer program and HEC-RAS (USACE 1968 and USACE 2005). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

59

Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations Virden Creek is an ungaged stream and contains complex flow-altering structures which cause decreasing discharge downstream. Subarea discharge estimates were based on the NRCS hydrograph development method (USDA 1972). The rainfall data was obtained from Technical Confluence with NRCS Paper No. 40. Subarea hydrographs were Confluence with AE w/ Virden Creek Virden Creek Hydrograph HEC-2 1980 combined and routed downstream where Cedar River Floodway Tributary Development necessary. Cross sections for the backwater analysis were obtained from previous floodplain and drainage area studies (ref 28). A portion of the flood hazard information was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. The discharge estimates were determined using the NRCS hydrograph development method (USDA 1972) with Huff rainfall distribution (Huff, F.A. 1970). Rainfall data for this method were obtained from U.S. Weather Bureau Technical Paper No. 40 (USDOC Approximately 130 1961). Virden Creek Confluence with NRCS AE w/ feet upstream of HEC-2 1980 Cross sections for the backwater analysis Tributary Virden Creek Hydrograph Floodway Big Rock Road were obtained from previous floodplain and drainage area studies (City of Waterloo, Iowa 1974). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations The hydrology was adopted from the Dry Run Creek Flood Control Study (Brice, Petrides & Associates, Inc. 1980). Since no gages are located in the drainage basin, the hydrologic evaluation was based on a computer runoff model that yielded discharges for the 10-, 2-, Confluence with Approximately 0.4 and 1-percent-annual-chance events. The 0.2- West Branch Dry Log-Pearson AE w/ Southwest Branch mile upstream of HEC-2 1981 percent-annual-chance discharge was Run Creek Type III Floodway Dry Run Creek West 27th Street subsequently determined by a log-Pearson Type III curve extrapolation of the 10-, 2-, and 1-percent-annual-chance data. The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. The discharge values were taken from the Cedar River study (Brice, Petrides & Associates, Inc. undated), which revised the former discharge values in the 1970 flood plain study (USACE 1970). Starting water-surface elevations correspond to the water-surface elevations on the Cedar River at their confluence for the same West Fork Cedar Confluence with AE w/ frequency flood. County boundary * HEC-2 1980 River Cedar River Floodway Water-surface elevations of floods of the selected recurrence intervals were computed through the use of the USACE's HEC-2 step- backwater computer program (Aerial Services, Inc. 1999, 2000, 2002, and 2003). The flood hazard area was redelineated based on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed.

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Table 13: Summary of Hydrologic and Hydraulic Analyses (continued)

Hydrologic Hydraulic Date Flood Study Limits Study Limits Model or Model or Analyses Zone on Flooding Source Downstream Limit Upstream Limit Method Used Method Used Completed FIRM Special Considerations Starting water-surface elevations were calculated using the slope-area method at a Approximately 1.3 Bulletin No. 11 Slope-Area point downstream from the start of the study. Confluence with AE w/ Wolf Creek miles upstream of Regional Method, HEC- 2002 Cedar River Floodway The flood hazard area was redelineated based Main Street Equations RAS on newly developed topographic data in the TBD revision. No new flood hazard analysis was performed. The flood hazard area was redelineated based Approximately 0.8 Bulletin No. 11 Wolf Creek Confluence with on newly developed topographic data in the mile upstream of Regional HEC-RAS 2002 AE Overflow Wolf Creek TBD revision. No new flood hazard analysis Poplar Street Equations was performed. Peak flood discharges were calculated using USGS developed regionally-based regression Zone A Flooding Regression Various locations Various locations HEC-RAS 4.0 2016 A equations in 1987 (Lara, O.G. 1987) and 2001 Sources Equations (Eash, D.A. 2001) to calculate annual exceedance discharges in Iowa streams. Hydraulic analyses were performed using the Zone A Flooding Various locations Various locations * N-FECT 2007 A Nebraska Department of Natural Resources Sources (NDNR) N-FECT tool (NDNR 2006). *Data not available

62

Table 14: Roughness Coefficients

Flooding Source Channel “n” Overbank “n” Beaver Creek 0.035 0.020-0.120 Black Hawk Creek 0.035 0.030-0.100 Blowers Creek 0.045 0.030-0.070 Buck Creek 0.035 0.030-0.120 Camp Creek 0.045 0.030-0.120 Cedar River 0.035 0.020-0.120 Cedar River Diversion Channel 0.050-0.100 0.050-0.120 City View Branch 0.045 0.030-0.150 Crane Creek 0.035 0.030-0.120 Dry Run Creek 0.030-0.045 0.030-0.200 Dry Run Creek Tributary 1 0.025 0.035 Dry Run Creek Tributary 2 0.040 0.060 East Branch Spring Creek 0.035 0.030-0.120 Elk Run Creek 0.035 0.030-0.070 Given Creek 0.035 0.030-0.120 Indian Creek 0.035 0.020-0.120 Maywood Branch 0.045 0.030-0.070 Miller Creek 0.035 0.030-0.035 Mud Creek 0.035 0.030-0.120 Northwest University Branch 0.040 0.060 Poyner Creek 0.035 0.030-0.070 Prescotts Creek 0.045 0.070 Rock Creek 0.035 0.035-0.100 Shell Rock River 0.035 0.020-0.100 Sink Creek 0.045 0.035-0.070 Southwest Branch Dry Run 0.045 0.035-0.070 Creek Spring Creek 0.035 0.035-0.120 Stream No. 13 0.045 0.070 Stream No. 36 0.045 0.030-0.070 Sunnyside Creek 0.045 0.030-0.050 Unnamed Tributary to Cedar 0.045 0.100-0.120 River

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Table 14: Roughness Coefficients (continued)

Flooding Source Channel “n” Overbank “n” Unnamed Tributary to Dry Run 0.013-0.030 0.030-0.050 Creek Virden Creek 0.045 0.070 Virden Creek Tributary 0.045 0.050-0.070 Wapsipinicon River 0.035 0.020-0.120 West Fork Cedar River 0.035 0.020-0.100 Wolf Creek 0.035 0.070-0.100

5.3 Coastal Analyses This section is not applicable to this Flood Risk Project.

Table 15: Summary of Coastal Analyses [Not Applicable to this Flood Risk Project]

5.3.1 Total Stillwater Elevations This section is not applicable to this Flood Risk Project.

Figure 8: 1% Annual Chance Total Stillwater Elevations for Coastal Areas [Not Applicable to this Flood Risk Project]

Table 16: Tide Gage Analysis Specifics [Not Applicable to this Flood Risk Project]

5.3.2 Waves This section is not applicable to this Flood Risk Project.

5.3.3 Coastal Erosion This section is not applicable to this Flood Risk Project.

5.3.4 Wave Hazard Analyses This section is not applicable to this Flood Risk Project.

Table 17: Coastal Transect Parameters [Not Applicable to this Flood Risk Project]

Figure 9: Transect Location Map [Not Applicable to this Flood Risk Project]

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5.4 Alluvial Fan Analyses This section is not applicable to this Flood Risk Project.

Table 18: Summary of Alluvial Fan Analyses [Not Applicable to this Flood Risk Project]

Table 19: Results of Alluvial Fan Analyses [Not Applicable to this Flood Risk Project]

65