Table : 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 City of Coastland, Flood County Entire Coastline Entire Coastline N/A 16.3 N VE, AE, AO 1989 Culvert Creek Flood County Confluence with South Fork Inundation River 2.3 miles upstream of confluence of Ripple Creek 99999998 0.7 N AE 1997 Inundation River City of Metropolis Confluence with Big Ocean Approximately 500 feet upstream of State Highway 999 99999998 12.5 Y AE 2007 Inundation River City of Metropolis 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 City of Metropolis Pear Tree Circle Westwood Lane 99999997 1.6 N AE 2002 North Fork Inundation River City of Coastland, Flood County Confluence with Inundation River 0.7 miles upstream of Lilac Stream 99999998 4.2 Y AE 2010 South Fork Inundation River Flood County Confluence with Inundation River 3.2 miles upstream of confluence of Culvert Creek 99999998 3.8 Y AE 2010
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. lists the flood insurance zones in the unincorporated and incorporated areas of Flood County. Table : Flood Zone Designations by Community Community Flood Zone(s) Flood County, Unincorporated Areas A, AE, AO, AH, V, VE, X City of Coastland A, AE, AO, VE, X Town of Floodville A, X City of Metropolis A, AE, X 3.2 Coastal Barrier Resources System The Coastal Barrier Resources Act (CBRA) of 1982 was established by Congress to create areas along the Atlantic and Gulf coasts and the Great Lakes, where restrictions for Federal financial assistance including flood insurance are prohibited. In 1990, Congress passed the Coastal Barrier Improvement Act (CBIA), which increased the extent of areas established by the CBRA and added “Otherwise Protected Areas” (OPA) to the system. These areas are collectively referred to as the John. H Chafee Coastal Barrier Resources System (CBRS). The CBRS boundaries that have been identified in the project area are in , “Coastal Barrier Resource System Information.” Table : Coastal Barrier Resources System Information Primary Flooding Source CBRS/OPA Type Date CBRS Area Established FIRM Panel Number(s) Big Ocean CBRS 1/1/1999 12345C0235X SECTION 4.0 – AREA STUDIED 4.1 Basin Description 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 : Basin Characteristics HUC-8 Name HUC-8 Sub-Basin Number Primary Flooding Source Description of Affected Area Drainage Area (square miles)
Table : 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 Downstream side 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 At Coastland 980 73,100 86,800 101,000 116,000 119,000 136,000 Inundation River At Floodville 930 70,500 82,360 97,100 111,000 115,000 130,000 Inundation River At Metropolis 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 Above 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 Lily Pond Metropolis 8.6 * 11.6 12.6 13.3 Central Reservoir Flood County Unincorporated Areas 12.6 * 14.5 15.2 17.0 *Not calculated for this Flood Risk Project
Table : 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 With and without levee analyses were performed for the reach affected by 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 : Coastal Transect Parameters Flood Source Coastal Transect Starting Wave Conditions for the 1% Annual Chance Starting Stillwater Elevations (ft NAVD88) Range of Stillwater Elevations (ft NAVD88) Significant Wave Height Hs (ft) Peak Wave Period Tp (sec) 10% Annual Chance 4% Annual Chance 2% Annual Chance 1% Annual Chance 0.2% Annual Chance Big Ocean 1 27.2 13 5.6 5.6-5.6 * * 10.6 10.1-10.9 15.7 15.2-15.8 19.6 18.6-19.8 *Not calculated for this Flood Risk Project
Table : Summary of Alluvial Fan Analyses Flooding Source Location From (apex) Location To (toe) Drainage Area above Apex (sq mi) Model(s) Used Date Analysis was Completed Method Description Culvert Creek Fan From apex of fan Highway I-10 24.2 N/A 2005 Geomorphic Data, Post Flood Hazard Verification, and Historical Information Mountain Wash Fan Apex of fan Stan Rd 54.5 FLO-2D, version 2006.07 2006 Risk-Based Analysis Petal Creek fan From apex of fan Tangerine Road 15.8 FLO-2D version 2007.06 2009 Composite Methods Valley Creek Fan Apex of N. Fork Inundation River Fan Maple Ln 44.7 FAN Computer Program 1993 Areas identified with historical aerial photos. FAN analysis used for 1% annual chance flood in active areas. HEC-2 4.6 was used in inactive areas, where incised networks and little risk of avulsion observed. Table : Results of Alluvial Fan Analyses Location From (apex) Location To (toe) 1% Annual Chance Peak Flow at Fan Apex (cfs) Flood Zones and Depths (ft) Minimum Velocity (fps) Maximum Velocity (fps) Flooding Source Culvert Creek Fan From apex of fan Highway I-10 1,750 AO 1-2', AE 1 6 Mountain Wash Fan From apex of fan Stan Rd 2,140 AO 1-3' 2 6 Petal Creek Fan From apex of Petal Creek fan Tangerine Rd 880 AO 1-3', A 1 7
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 17,700 90 1,273 3.1 21.5 21.5 22.5 1.0 B 19,180 339 3,260 1.2 22.3 22.3 23.3 1.0 C 21,380 237 2,389 1.6 22.9 22.9 23.9 1.0 D 22,900 809 7,235 0.5 23.1 23.1 24.1 1.0 E 24,680 973 6,866 0.6 23.2 23.2 24.2 1.0 F 26,200 107 1,577 2.5 23.4 23.4 24.4 1.0 G 26,570 107 1,602 2.4 23.6 23.6 24.6 1.0 H 26,597 107 1,602 2.4 23.7 23.7 24.7 1.0 I 26,807 114 1,680 2.3 23.8 23.8 24.8 1.0 1Feet above mouth TABLE 24 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA FLOOD COUNTY, STATE FLOODING SOURCE: WINTER CREEK AND INCORPORATED AREAS
Flood County Unincorporated Areas 11/01/1974 11/01/1974 09/06/1977 08/15/1984 12/31/2011 07/23/2008 10/26/2002 02/18/1998 Floodville, Town of 11/01/1974 04/15/1975 N/A 12/15/1984 07/23/2008 01/05/2003 05/26/1998 Metropolis, City of 11/01/1974 12/21/1974 03/04/1983 10/17/1978 06/19/1986 12/31/2011 07/23/2008 09/31/2002 03/22/1999 10/04/1995 Upland, Village of1 08/15/1984 N/A N/A 09/24/1984 07/23/2008 02/18/1992 1 No Special Flood Hazard Areas Identified 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 : Summary of Contracted Studies Included in this FIS Report Flooding Source FIS Report Dated Contractor Number Work Completed Date Affected Communities Culvert Creek 12/31/2011 ABC Engineers, Inc. EMW-C-9999 April 2011 Flood County Uninc. Areas, Metropolis Inundation River 12/31/2011 ABC Engineers, Inc. EMW-C-9999 April 2011 Flood County Uninc. Areas, Metropolis North Fork Inundation River 12/31/2011 ABC Engineers, Inc. EMW-C-9999 April 2011 City of Coastland, Flood County Uninc. Areas South Fork Inundation River 12/31/2011 ABC Engineers, Inc. EMW-C-9999 April 2011 Flood County Uninc. Areas
Table : 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 Johnes 1975 A. Johnes and Associates A Report on an Engineering Study to Prepare a Master Plan of Storm Sewers for the City of Coastland, State Housing and Home Finance Agency Project No. P-ORE-3191 City of Coastland, State January 1966, reprinted November 1975 FEMA 1989 Federal Emergency Management Agency Flood Insurance Study, Flood County, State, and Unincorporated Areas Washington, D.C. 1989 FEMA Map Service Center FEMA 1996 Federal Emergency Management Agency Flood Insurance Study, City of Floodville, Flood County, State Washington, D.C. 1996 FEMA 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 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 State Geology and Mineral Industries 1975 State Department of Geology and Mineral Industries Bulletin 87: Environmental Geology of Flood County, State Tim Flow City of Coastland, State 1975 State University library State Sea Grant 1974 State University, Sea Grant College Descriptions and Information Sources for State Estuaries H. Toow City of Coastland, State May 1974 NWRBC 1968 Northwest River Basins Commission, Hydraulics and Hydrology Committee River Mile Index, Coastal Tributaries for Inundation River Basin, State City of Coastland, State June 1968 State University
City of Coastland Population Research 1981 State University, Center for Population Research and Census Population Estimates, Flood County and Incorporated Cities, July 1, 1980 City of Coastland, State March 1981 SCS 1975 U.S. Department of Agriculture, Soil Conservation Service General Soil Map, Flood County, State, Scale 1:126,700 April 1975 U.S. Census 2007 U.S. Department of Commerce, Bureau of the Census “State & County Quickfacts” Website. accessed October 12, 2010 2007 USGS 2008 U.S. Department of Interior, Geological Survey LiDAR Data, Scale 1:4,800, Contour Interval 2 Feet. Washington, D.C. 2008 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 CRREL 2004 ERDC CRREL ERDC_CRREL Technical Note 04-3: Method to Estimate River Ice Thickness Based on Meteorological Data K.D. White Hanover, NH 2004