BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS

Transcription

1 VOLUME 2 OF 3 BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS COMMUNITY NAME BLACK HAWK COUNTY, UNINCORPORATED AREAS COMMUNITY NUMBER CEDAR FALLS, CITY OF DUNKERTON, CITY OF ELK RUN HEIGHTS, CITY OF EVANSDALE, CITY OF GILBERTVILLE, CITY OF HUDSON, CITY OF LAPORTE CITY, CITY OF RAYMOND, CITY OF WATERLOO, CITY OF PRELIMINARY 1/10/2019 REVISED: TBD FLOOD INSURANCE STUDY NUMBER 19013CV002B Version Number

2 TABLE OF CONTENTS Volume 1 Page 1.0 INTRODUCTION The National Flood Insurance Program Purpose of this Flood Insurance Study Report Jurisdictions Included in the Flood Insurance Study Project Considerations for using this Flood Insurance Study Report FLOODPLAIN MANAGEMENT APPLICATIONS Floodplain Boundaries Floodways Base Flood Elevations Non-Encroachment Zones Coastal Flood Hazard Areas Water Elevations and the Effects of Waves Floodplain Boundaries and BFEs for Coastal Areas Coastal High Hazard Areas Limit of Moderate Wave Action INSURANCE APPLICATIONS National Flood Insurance Program Insurance Zones Coastal Barrier Resources System AREA STUDIED Basin Description Principal Flood Problems Non-Levee Flood Protection Measures Levees ENGINEERING METHODS Hydrologic Analyses Hydraulic Analyses Coastal Analyses Total Stillwater Elevations Waves Coastal Erosion Wave Hazard Analyses Alluvial Fan Analyses 65 i

3 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 6.0 MAPPING METHODS Vertical and Horizontal Control Base Map Floodplain and Floodway Delineation Coastal Flood Hazard Mapping FIRM Revisions Letters of Map Amendment Letters of Map Revision Based on Fill 110 ii

4 6.5.3 Letters of Map Revision Physical Map Revisions Contracted Restudies Community Map History CONTRACTED STUDIES AND COMMUNITY COORDINATION Contracted Studies Community Meetings ADDITIONAL INFORMATION 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 Big Woods Creek Big Woods Creek Upper Diversion Black Hawk Creek Blowers Creek Cedar River Cedar River Diversion City View Branch Crane Creek Panel P 03 P P P P 22 P P P iii

5 Volume 3 Exhibits Flood Profiles Crossroads Creek Crossroads Creek Diversion Dry Run Creek at Cedar Falls Dry Run Creek at Waterloo Dry Run Creek Diversion Channel Dry Run Creek Tributary 1 Dry Run Creek Tributary 2 Elk Run Creek Maywood Branch Miller Creek Northeast University Branch Tributary Northwest University Branch Tributary Poyner Creek Prescotts Creek Sink Creek Southwest Branch Dry Rum Creek Stream No. 13 Stream No. 36 Stream No. 37 Stream No. 39 Sunnyside Creek Sunnyside Creek Bypass Tributary 1 University Branch Dry Run Creek Unnamed Stream Unnamed Tributary to Cedar River Unnamed Tributary to Dry Run Creek Virden Creek Virden Creek Tributary West Branch Dry Run Creek West Fork Cedar River Wolf Creek Wolf Creek Overflow Panel P 35 P P P 46 P 47 P 48 P P P 60 P 61 P 62 P P P P P P P 82 P 83 P P P 89 P P 92 P P P P P P P P P Published Separately Flood Insurance Rate Map (FIRM) iv

6 6.0 MAPPING METHODS 6.1 Vertical and Horizontal Control All FIS Reports and FIRMs are referenced to a specific vertical datum. The vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared. Until recently, the standard vertical datum used for newly created or revised FIS Reports and FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD29). With the completion of the North American Vertical Datum of 1988 (NAVD88), many FIS Reports and FIRMs are now prepared using NAVD88 as the referenced vertical datum. Flood elevations shown in this FIS Report and on the FIRMs are referenced to NAVD88. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. For information regarding conversion between NGVD29 and NAVD88 or other datum conversion, visit the National Geodetic Survey website at Temporary vertical monuments are often established during the preparation of a flood hazard analysis for the purpose of establishing local vertical control. Although these monuments are not shown on the FIRM, they may be found in the archived project documentation associated with the FIS Report and the FIRMs for this community. Interested individuals may contact FEMA to access these data. To obtain current elevation, description, and/or location information for benchmarks in the area, please visit the NGS website at Base Map Table 20: Countywide Vertical Datum Conversion [Not Applicable to this Flood Risk Project] Table 21: Stream-Based Vertical Datum Conversion [Not Applicable to this Flood Risk Project] The FIRMs and FIS Report for this project have been produced in a digital format. The flood hazard information was converted to a Geographic Information System (GIS) format that meets FEMA s FIRM Database specifications and geographic information standards. This information is provided in a digital format so that it can be incorporated into a local GIS and be accessed more easily by the community. The FIRM Database includes most of the tabular information contained in the FIS Report in such a way that the data can be associated with pertinent spatial features. For example, the information contained in the Floodway Data table and Flood Profiles can be linked to the cross sections that are shown on the FIRMs. Additional information about the FIRM Database and its contents can be found in FEMA s Guidelines and Standards for Flood Risk Analysis and Mapping, 66

7 Base map information shown on the FIRM was derived from the sources described in Table 22. Table 22: Base Map Sources Data Type Digital Orthophoto Political boundaries Public Land Survey System (PLSS) Transportation Features Transportation Features Data Provider Iowa Geological and Water Survey, Department of Natural Resources U.S. Department of Commerce, U.S. Census Bureau, Geography Division Iowa Department of Natural Resources Iowa Department of Transportation U.S. Department of Commerce, U.S. Census Bureau, Geography Division Data Date Data Scale Data Description 2010 * Digital orthoimagery 2010 * Municipal and county boundaries :24,000 PLSS data of Iowa :5,000 Road centerlines :24,000 TIGER Line railroad data 6.3 Floodplain and Floodway Delineation The FIRM shows tints, screens, and symbols to indicate floodplains and floodways as well as the locations of selected cross sections used in the hydraulic analyses and floodway computations. For riverine flooding sources, the mapped floodplain boundaries shown on the FIRM have been delineated using the flood elevations determined at each cross section; between cross sections, the boundaries were interpolated using the topographic elevation data described in Table 23. In cases where the 1% and 0.2% annual chance floodplain boundaries are close together, only the 1% annual chance floodplain boundary has been shown. Small areas within the floodplain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. The floodway widths presented in this FIS Report and on the FIRM were computed for certain stream segments on the basis of equal conveyance reduction from each side of the floodplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. Table 2 indicates the flooding sources for which floodways have been determined. The results of the floodway computations for those flooding sources have been tabulated for selected cross sections and are shown in Table 24, Floodway Data. 67

8 Table 23: Summary of Topographic Elevation Data used in Mapping Community Flooding Source Description Black Hawk County; Cedar Falls; Dunkerton, City of; Gilbertville, City of; Hudson, City of; La Porte, City of; Waterloo, City of Big Woods Creek, Big Woods Creek Upper Diversion, Black Hawk Creek, Blowers Creek, Cedar River, Cedar River Diversion Channel, City View Branch, Crane Creek, Crossroads Creek, Dry Run Creek at Cedar Falls, Dry Run Creek at Waterloo, Dry Run Creek Diversion Channel, Elk Run Creek, Maywood Branch, Miller Creek, Poyner Creek, Prescotts Creek, Sink Creek, Southwest Branch Dry Run Creek, Stream No. 13, Stream No. 36, Stream No. 39, Sunnyside Creek, Sunnyside Creek Bypass, University Branch Dry Run Creek, Unnamed Tributary to Cedar River, Unnamed Tributary to Dry Run Creek, Virden Creek, Virden Creek Tributary, West Branch Dry Run Creek, West Fork Cedar River, Wolf Creek, Wolf Creek Overflow, Zone A Flooding Sources Source for Topographic Elevation Data Light Detection and Ranging data (LiDAR) Vertical Accuracy 18.0 cm RMSEz Horizontal Accuracy 1 meter at 95% confidence level Citation IDNR 2010 BFEs shown at cross sections on the FIRM represent the 1% annual chance water surface 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. 68

9 TABLE 24 Table 24: Floodway Data CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/ SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B 3, C 3, D 4, , E 8, F 24, G 25, H 30, Feet from mouth 2 Elevations computed without consideration of backwater effects from storage areas or Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BIG WOODS CREEK 69

10 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B C D E 1, F 1, G 1, H 1, I 2, J 2, K 2, L 2, M 3, N 3, O 3, P 3, Feet above storage area from Big Woods Creek 2 Elevations computed without consideration of backwater effects from Big Woods Creek FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BIG WOODS CREEK UPPER DIVERSION 70

11 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A N/A N/A B 1, N/A N/A C 1, N/A N/A D 2, N/A N/A E 2, N/A N/A F 2, N/A N/A G 2, N/A N/A H 2, N/A N/A I 3, N/A N/A J 3, N/A N/A K 4, N/A N/A L 4,499 1,630 N/A N/A M 6,694 1,870 N/A N/A N 6,849 1,765 N/A N/A O 7,939 1,565 N/A N/A P 9,949 1,570 N/A N/A Q 10,154 1,595 N/A N/A R 12,584 1,470 N/A N/A S 14,599 2,600 N/A N/A T 16,009 1,590 N/A N/A U 18,349 1,013 6, V 21,359 2,185 11, Feet above confluence with Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheet 08P(a) 2 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BLACK HAWK CREEK 71

12 TABLE 24 CROSS LOCATION DISTANCE 3 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE W 25,722 1,731 4, X 27,793 1,800 10, Y 28,002 1,700 11, Z 30,882 3,061 12, AA 35,129 2,770 13, AB 36, , AC 41,636 1,339 10, AD 45,107 1,870 10, AE 45,220 1,880 10, AF 46,283 2,110 11, AG 47,918 2,140 9, AH 50,276 2,337 9, AI 51,857 2,650 8, AJ 52,722 2,697 11, AK 53,263 2,509 11, AL 54,830 2,841 11, AM 56,680 2,862 15, AN 59,213 2,340 10, AO 60,034 1,860 8, AP 61,492 2,040 10, AQ 62,488 2,160 11, AR 64,184 1,970 11, AS 65,984 1,830 11, AT 67,387 1,540 11, This portion of Black Hawk Creek redelineated, and distance references feet above confluence with Cedar River. FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BLACK HAWK CREEK 72

13 TABLE 24 CROSS LOCATION DISTANCE 3 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE AU 68,402 1,660 10, AV 70,099 1,360 6, AW 70, , AX 70,953 1,330 7, AY 71,870 1,592 10, AZ 73,180 2,289 17, BA 74,386 2,330 14, BB 75,720 2,240 12, BC 77,452 1,880 10, BD 78,677 2,276 8, BE 80,468 2,550 11, BF 82,022 2,636 11, BG 83,663 2,237 10, BH 86,856 1,200 5, BI 93,700 2,524 15, BJ 97,693 2,500 13, BK 102,590 2,500 12, BL 105,631 2,499 12, BM 109,888 2,337 16, This portion of Black Hawk Creek redelineated, and distance references feet above confluence with Cedar River. FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BLACK HAWK CREEK 73

14 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 1, B 1, , C 2, , D 2, , E 2, F 3, , G 3, , H 3, I 4, J 5, K 5, L 6, M 7, N 8, O 8, P 9, Q 10, R 10, S 10, T 11, U 11, V 12, W 12, X 12, Feet above mouth with Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Blowers Creek redelineated, and distance references feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BLOWERS CREEK 74

15 TABLE 24 CROSS LOCATION DISTANCE 2 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE Y 12, Z 12, , AA 13, AB 13, AC 15, AD 16, AE 16, This portion of Blowers Creek redelineated, and distance references feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: BLOWERS CREEK 75

16 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A ,625 24, B ,000 61, C ,900 29, D ,610 29, E ,940 33, F ,175 86, G ,600 88, H ,900 58, I ,825 35, J ,700 55, K ,600 56, L ,000 43, M ,300 27, N ,200 30, O ,200 24, P ,245 19, Q ,800 23, R ,975 24, S ,220 26, T , U , V , W , X , This portion of Cedar River redelineated, and distance references miles above confluence with Iowa River 2 Miles above mouth. See 2011 Black Hawk County stream profile, reprinted on profile sheets FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CEDAR RIVER 76

17 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE Y , Z , AA , AB , AC , AD , AE , AF , AG ,400 19, AH ,245 21, AI ,415 19, AJ ,580 56, AK ,999 41, AL ,999 34, AM ,199 48, AN ,267 43, AO ,730 18, AP ,830 29, AQ , AR , AS , AT , AU ,130 59, This portion of Cedar River redelineated, and distance references miles above confluence with Iowa River 2 Miles above mouth. See 2011 Black Hawk County stream profile, reprinted on profile sheets FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CEDAR RIVER 77

18 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE AV ,863 37, AW ,445 39, AX ,594 35, AY ,571 49, AZ ,150 51, BA ,400 66, BB ,000 49, BC ,500 32, BD ,500 31, BE ,000 22, BF ,100 21, BG ,586 15, This portion of Cedar River redelineated, and distance references miles above confluence with Iowa River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CEDAR RIVER 78

19 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 9, , B 10, , C 10,964 1,550 17, D 11,522 2,030 8, E 12,402 2,980 26, F 16,516 5,100 68, G 18,481 3,150 30, Feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CEDAR RIVER DIVERSION 79

20 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B C D E 1, F 1, G 1, H 1, I 1, J 1, K 2, L 2, M 2, N 3, O 3, P 4, Feet above mouth at Blowers Creek. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of City View Branch redelineated, and distance references feet above confluence with Blowers Creek 3 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CITY VIEW BRANCH 80

21 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 3, , B 3, , C 4, , D 5,057 1,032 8, E 5,702 1,004 6, F 6, , G 8, , H 9, , I 10, , J 11, , K 12, , L 12, , M 12, , N 13,706 1,463 6, O 15,584 1,667 11, P 16,146 1,950 12, Q 17,398 1,570 9, R 19,135 1,080 7, S 19, , T 20, , U 20, , V 21, , W 22,570 1,143 8, Feet above confluence with Wapsipinicon River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CRANE CREEK 81

22 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE X 22,969 1,343 8, Y 24,174 2,160 12, Z 25,014 1,490 9, AA 25,557 1,320 7, AB 26,591 1,200 7, AC 28,349 1,240 7, AD 29,039 1,190 7, AE 29,171 1,190 7, Feet above confluence with Wapsipinicon River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CRANE CREEK 82

23 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B C 1, D 1, E 1, F 1, G 2, H 2, I 3, J 3, K 4, L 4, M 5, N 5, O 5, P 5, Q 5, R 6, S 6, T 6, U 6, V 7, W 7, Feet above mouth at Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Crossroads Creek redelineated, and distance references feet above confluence with Cedar River 3 Elevation computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: CROSSROADS CREEK 83

24 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A , B , C , D 1, , E 2, F 2, , G 3, , H 3, I 3, , J 4, , K 4, , L 5, M 6, N 6, O 6, P 7, Q 7, R 8, S 8, T 9, U 9, V 10, W 10, X 11, Feet above confluence with Cedar River 2 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: DRY RUN CREEK AT CEDAR FALLS 84

25 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE Y 11, Z 13, AA 14, AB 15, AC 18, , AD 19, AE 20, AF 20, AG 21, AH 23, AI 23, AJ 23, AK 23, , AL 27, AM 27, , AN 29, , AO 30, , AP 31, , AQ 32, , Feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: DRY RUN CREEK AT CEDAR FALLS 85

26 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 6, B 7, C 7, D 7, E 7, F 8, G 8, H 8, I 8, J 8, K 9, L 10, M 10, N 10, O 12, P 12, Q 12, R 13, S 13, T 13, U 14, , V 14, W 14, X 14, Y 15, Z 15, Feet above mouth. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Dry Run Creek at Waterloo redelineated, and distance references feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: DRY RUN CREEK AT WATERLOO 86

27 TABLE 24 CROSS LOCATION DISTANCE 2 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE AA 15, AB 16, AC 16, AD 17, AE 17, AF 17, AG 17, AH 17, AI 18, AJ 18, AK 18, AL 19, AM 19, AN 20, AO 21, AP 21, AQ 21, AR 22, AS 22, , AT 22, AU 23, AV 23, AW 24, AX 24, AY 24, This portion of Dry Run Creek at Waterloo redelineated, and distance references feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: DRY RUN CREEK AT WATERLOO 87

28 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A , B , C 1, , Feet above confluence with Dry Run Creek at Cedar Falls FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: DRY RUN CREEK DIVERSION CHANNEL 88

29 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A , B 1, , C 3, , D 6, , E 9, , F 10, , G 10, , H 11, , I 11, , J 12, , K 14, , L 16, , M 20, , N 29, , O 33, , P 34, , Q 39, , R 41, , Feet above confluence with Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Elk Run Creek redelineated, and distance references feet above confluence with Cedar River 3 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: ELK RUN CREEK 89

30 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 1, B 1, , C 2, D 3, E 4, , F 4, , G 5, , H 6, I 7, J 8, K 10, L 10, , M 10, , N 11, O 11, P 12, Q 12, Feet above above mouth at Blowers Creek. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Maywood Branch redelineated, and distance references feet above confluence with Blowers Creek FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: MAYWOOD BRANCH 90

31 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 8, , B 10, , C 12, , Feet above confluence with Cedar River 2 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: MILLER CREEK 91

32 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 3, ,200 11, B 5, , C 12, , This portion of Poyner Creek redelineated, and distance references feet above confluence with Cedar River 2 Feet above mouth at Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 3 Elevations computed without consideration of backwater effects from Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: POYNER CREEK 92

33 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 4, B 4, , C 4, , D 5, , E 6, , F 7, , G 7, , H 8, , I 8, , J 9, , K 9, , L 9, , M 9, , N 10, , O 10, , P 12, , Q 15, , R 17, , S 17, , T 17, , Feet above confluence with Black Hawk Creek 2 Elevations computed without consideration of backwater effects from Black Hawk Creek FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: PRESCOTTS CREEK 93

34 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 6, B 6, , C 7, , D 10, , E 11, , F 14, , G 14, , H 17, , I 18, J 21, , K 21, , L 24, M 25, N 25, O 26, P 26, , Q 27, , R 29, , S 29, , T 30, , U 30, , V 31, W 32, X 32, Y 33, Feet above in feet above mouth. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Sink Creek redelineated, and distance references feet above confluence with Cedar River 3 Elevations computed without consideration of backwater effects from Cedar River Overflow FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: SINK CREEK 94

35 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B C 1, D 2, E 2, F 4, G 5, , H 7, I 8, J 9, K 10, L 11, , M 14, N 16, , O 17, P 21, , Feet above confluence with Dry Run Creek at Cedar Falls 2 Elevations computed without consideration of backwater effects from Dry Run Creek at Cedar Falls FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: SOUTHWEST BRANCH DRY RUN CREEK 95

36 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 2, , B 4, , C 4, D 5, , E 5, , F 5, G 6, , H 6, , I 6, , J 7, , K 7, , L 8, , M 9, , N 11, O 13, , P 14, Q 14, , R 15, , S 15, , T 16, , U 20, , Feet above mouth at Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Stream No. 13 redelineated, and distance references feet above confluence with Cedar River FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: STREAM NO

37 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A 10, , B 10, , C 11, D 12, E 13, F 14, , G 14, , H 15, , I 16, , J 8, , K 9, L 10, Feet above Stream No. 13 mouth at Cedar River. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Stream No. 36 redelineated, and distance references feet above confluence with Stream No. 13 FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: STREAM NO

38 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B 1, C 1, D 3, E 3, Feet above mouth at Stream No. 13 FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: STREAM NO

39 TABLE 24 CROSS LOCATION DISTANCE 1 WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B 1, C 2, D 2, Feet above mouth at Stream No Elevations computed without consideration of backwater effects from Stream No. 13 FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: STREAM NO

40 TABLE 24 CROSS LOCATION DISTANCE WIDTH (FEET) AREA (SQ. FEET) MEAN VELOCITY (FEET/SEC) 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION (FEET NAVD88) REGULATORY WITHOUT WITH INCREASE A B 1, C 2, D 3, E 3, F 4, , G 4, H 4, I 5, J 5, K 6, L 6, M 6, N 6, O 6, P 7, Q 8, R 8, S 8, T 8, U 8, Feet above mouth at Black Hawk Creek. See 2011 Black Hawk County stream profile, reprinted on profile sheets 2 This portion of Sunnyside Creek redelineated, and distance references feet above confluence with Black Hawk Creek FEDERAL EMERGENCY MANAGEMENT AGENCY BLACK HAWK COUNTY, IOWA AND INCORPORATED AREAS DATA FLOODING SOURCE: SUNNYSIDE CREEK 100