ZONE AO (DEPTH 2) (VEL 15 FPS) Zone designation with Depth and Velocity 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 4276000mE Horizontal Reference Grid Coordinates (UTM) 365000 FT Horizontal Reference Grid Coordinates (State Plane) 80 16’ 52.5” Corner Coordinates (Latitude, Longitude) 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 Flood 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
Table 2: Flooding Sources Included in this FIS Report Flooding Source Community Downstream Limit Upstream Limit HUC-8 Length (mi) (streams or coastlines) Area (mi2) (estuaries or ponding) Floodway (Y/N) Zone shown on FIRM Date of Analysis Big Ocean Coastland, City of; Flood County, Unincorporated Areas Entire Coastline Entire Coastline N/A 16.3 N VE, AE, AO 1989 Culvert Creek Flood County, Unincorporated Areas Confluence with South Fork Inundation River 2.3 miles upstream of confluence of Ripple Creek 99999998 0.7 N AE 1997 Inundation River Flood County, Unincorporated Areas; Metropolis, City of Confluence with Big Ocean Approximately 500 feet upstream of State Highway 999 99999998 12.5 Y AE 2007 Inundation River Flood County, Unincorporated Areas; Metropolis, City of Approximately 500 feet upstream of State Highway 999 Confluence of North Fork Inundation River and South Fork Inundation River 99999998 3.8 N A 1997 Lily Pond Metropolis, City of Pear Tree Circle Westwood Lane 99999997 1.6 N AE 2002 North Fork Inundation River Coastland, City of; Flood County, Unincorporated Areas Confluence with Inundation River 0.7 miles upstream of Lilac Stream 99999998 4.2 Y AE 2010 South Fork Inundation River Flood County, Unincorporated Areas Confluence with Inundation River 3.2 miles upstream of confluence of Culvert Creek 99999998 3.8 Y AE 2010 West River and Zone A Tributaries Flood County, Unincorporated Areas Confluence of West River with Inundation River 1 square mile drainage area of all Zone A streams 99999998 206.8 N A 2010
Table 7: Historic Flooding Elevations Flooding Source Location Historic Peak (Feet NAVD88) Event Date Approximate Recurrence Interval (years) Source of Data Inundation River Outlet of Inundation River at Big Ocean 19.8 1986 80 USGS gage South Fork Inundation River 700 feet upstream of Fulton Road 18.8 2007 50 NRCS high water marks 4.3 Non-Levee Flood Protection Measures contains information about non-levee flood protection measures within Flood 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 Source Structure Name Type of Measure Location Description of Measure Big Ocean A.B. Smith Jetty Jetties At entrance channel Constructed by USACE in 1929 Big Ocean N/A Berms and riprap Floodville, along the coast of the Big Ocean Several property owners in this city have placed berms and riprap to protect homes Big Ocean N/A Tidal flooding warnings Low-lying coastal areas Flood Weather Forecast Office issues storm tide warnings Inundation River N/A Dam 1.5 miles upstream of Rockhampton Circle Maintained by Floodville Waterworks Inundation River N/A Dike Various locations Not high enough to completely prevent flooding 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.
Table 9: Levees Community Flooding Source Levee Location Levee Owner USACE Levee Levee ID Covered Under Program? FIRM Panel(s) Flood County, Unincorporated Areas Inundation River Left Bank Flood County Water Supply Yes 1234545362 Yes 12345C0234X Flood County, Unincorporated Areas Inundation River Right Bank Flood County Water Supply Yes 1354212346 Yes 123450C234X Floodville, Town of Inundation River Left Bank Floodville Waterworks No 1901990990 No 12345C0245X
A summary of the discharges is provided in . Frequency Discharge-Drainage Area Curves used to develop the hydrologic models may also be shown in for selected flooding sources. A summary of stillwater elevations developed for non-coastal flooding sources is provided in . (Coastal stillwater elevations are discussed in Section 5.3 and shown in .) Stream gage information is provided in .
Table 10: Summary of Discharges Peak Discharge (cfs) Flooding Source Location Drainage Area (Square Miles) 10% Annual Chance 4% Annual Chance 2% Annual Chance 1% Annual Chance Existing 1% Annual Chance Future 0.2% Annual Chance Culvert Creek Just downstream of Smith Lane 1.0 130 * 170 190 * 240 Inundation River Confluence with Big Ocean 1,058 77,200 * 107,000 122,000 132,000 143,000 Inundation River 1.2 miles downstream of US Highway 27 980 73,100 86,800 101,000 116,000 119,000 136,000 Inundation River 2,000 feet downstream of 3rd Avenue 930 70,500 82,360 97,100 111,000 115,000 130,000 Inundation River 500 feet upstream of Main Street 902 69,000 81,100 95,000 109,000 113,000 128,000 Inundation River Confluence with North Fork Inundation River and South Fork Inundation River 879 67,700 * 93,200 107,000 114,00 125,000 North Fork Inundation River Just upstream of State Highway 42 137 18,100 * 24,000 27,000 * 31,600 South Fork Inundation River Confluence with North Fork 598 51,100 * 69,700 79,600 * 93,300 *Not calculated for this Flood Risk Project
Table 11: Summary of Non-Coastal Stillwater Elevations Elevations (feet NAVD88) Flooding Source Location 10% Annual Chance 4% Annual Chance 2% Annual Chance 1% Annual Chance 0.2% Annual Chance Central Reservoir Flood County Unincorporated Areas 12.6 * 14.5 15.2 17.0 Lily Pond Metropolis 8.6 * 11.6 12.6 13.3 *Not calculated for this Flood Risk Project
Table 13: Summary of Hydrologic and Hydraulic Analyses Flooding Source Study Limits Downstream Limit Study Limits Upstream Limit Hydrologic Model or Method Used Hydraulic Model or Method Used Date Analyses Completed Flood Zone on FIRM Special Considerations Culvert Creek Confluence with South Fork Inundation River 2.3 miles upstream of confluence of Ripple Creek 1994 State Regression Equations – Region 3 HEC-2 4.6 03/22/1997 AE Ice jam analysis evaluated by Modified Indirect Method (CRREL 2004). Flood Profile reflects results of ice jam analysis. Inundation River Confluence with Big Ocean Approximately 500 feet upstream of State Highway 999 2004 State Regression Equations – Region 3 HEC-RAS 3.1 06/30/2007 AE w/ Floodway Levee analysis and mapping procedures were applied to Levee IDs 1354212346 and 1234545362. Inundation River Approximately 500 feet upstream of State Highway 999 Confluence of N. Fork Inundation River and S. Fork Inundation River 2004 State Regression Equations – Region 3 HEC-RAS 3.1 06/30/2007 A Effects of hydraulic structures were not considered in the model. Lily Pond Pear Tree Circle Westwood Lane ICPR 2.20 ICPR 2.20 05/28/2002 AE Elevations determined using ICPR. Survey data utilized in model was based on county information collected in 2008. North Fork Inundation River Confluence with Inundation River 0.7 miles upstream of confluence of Lilac Stream Log Pearson Type III Frequency Analysis HEC-RAS 4.0 12/12/2010 AE Gage No. 19999998 was used in hydrologic analysis. Hydraulic models incorporated field measured bridge and culvert data. South Fork Inundation River Confluence with Inundation River 3.2 miles upstream of confluence of Culvert Creek HEC-HMS 3.4 Unsteady HEC-RAS 4.0 12/12/2010 AE w/ Floodway Hydraulic model was calibrated to high water marks collected for flood of 2007, which was estimated to be the 2% annual chance flood.
Table 24: Floodway Data LOCATION FLOODWAY 1% ANNUAL CHANCE FLOOD WATER SURFACE ELEVATION ( FEET NAVD88) CROSS SECTION DISTANCE1 WIDTH (FEET) SECTION AREA (SQ. FEET) MEAN VELOCITY (FEET/ SEC) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE A 60 46 262 5.8 20.1 20.1 20.2 0.1 B 160 51 353 4.3 21.5 21.5 22.5 1.0 C 680 170 1,253 1.2 22.0 22.0 22.9 0.9 1Feet above mouth TABLE 24 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA FLOOD COUNTY, STATE FLOODING SOURCE: CULVERT CREEK AND INCORPORATED AREAS
Floodville, Town of 04/15/1974 04/15/1975 N/A 12/15/1984 07/23/2008 01/05/2003 05/26/1998 Metropolis, City of1 11/01/1974 11/01/1974 09/06/1977 08/15/1984 12/31/2011 07/23/2008 10/26/2002 02/18/1998 Upland, Village of2, 3 07/23/2008 N/A N/A 07/23/2008 12/31/2011 Water, City of3 07/23/2008 N/A N/A 07/23/2008 N/A 1 Dates for this community were taken from Flood County, Unincorporated Areas 2 No Special Flood Hazard Areas Identified 3 This community did not have a FIRM prior to the first countywide FIRM for Flood County SECTION 7.0 – CONTRACTED STUDIES AND COMMUNITY COORDINATION 7.1 Contracted Studies provides a summary of the contracted studies, by flooding source, that are included in this FIS Report. Table 29: Summary of Contracted Studies Included in this FIS Report Flooding Source FIS Report Dated Contractor Number Work Completed Date Affected Communities Big Ocean 02/18/1998 ABC Engineers, Inc. EMW-B-8888 September 1989 Coastland, City of; Flood County, Unincorporated Areas Culvert Creek 02/18/1998 ABC Engineers, Inc. EMW-C-9999 April 1997 Flood County, Unincorporated Areas Inundation River (Zone AE) 07/23/2008 State DNR MAS-B-1234 March 2007 Flood County, Unincorporated Areas; Metropolis, City of Inundation River (Zone A) 02/18/1998 ABC Engineers, Inc. EMW-C-9999 March 1997 Flood County, Unincorporated Areas; Metropolis, City of Lily Pond 10/26/2002 State DNR HSF-J-7654 January 2002 Metropolis, City of
Table 33: Bibliography and References Citation in this FIS Publisher/ Issuer Publication Title, “Article,” Volume, Number, etc. Author/Editor Place of Publication Publication Date/ Date of Issuance Link ABC Eng, 1978 ABC Engineers, Inc. Flower Creek Water Supply, Coastland Water Board, City of Coastland, State, C10933.00 City of Coastland, State April 1978 City of Coastland Water Board Coastland 1977 City of Coastland Inventory of Coastal Resources for the 1990 Comprehensive Plan December 1977 City of Coastland library Coastland 1978 City of Coastland 1990 Comprehensive Plan September 1978 City of Coastland library FEMA 1989 Federal Emergency Management Agency Flood Insurance Study, Flood County, State, and Unincorporated Areas Washington, D.C. 1989 FEMA Flood Map Service Center FEMA 1996 Federal Emergency Management Agency Flood Insurance Study, City of Floodville, Flood County, State Washington, D.C. 1996 FEMA Flood Map Service Center FIA 1977 U.S. Department of Housing and Urban Development, Federal Insurance Administration Flood Hazard Boundary Map, Flood County, USA, Community-Panel Numbers 410042 0001 through 0021 Sidney McFlood Washington, D.C. September 1977 FEMA Flood Map Service Center State CES 1967 State University, Resource Development Section, Cooperative Extension Service Resources Analysis, Flood County, State Dave Waters and Gary Mapper City of Coastland, State December 1967
USGS 1988 U.S. Department of Interior, Geological Survey 7.5-Minute Series Topographic Maps, Scale 1:24,000, Contour Interval 10 Feet. Coastland, ST (1984, revised 1988) Washington, D.C. Various USGS 2008 U.S. Department of Interior, Geological Survey LiDAR Data, Scale 1:4,800, Contour Interval 2 Feet. Washington, D.C. 2008