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
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 Flood County. , “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 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 9: Levees Community Flooding Source Levee Location Levee Owner USACE Levee Levee ID Covered Under PL84-99 Program? FIRM Panel(s) Levee Status Flood County, Unincorporated Areas Inundation River Right Bank Flood County Water Supply Yes 1354212346 Yes 123450C234X Accredited Flood County, Unincorporated Areas Inundation River Left Bank Flood County Water Supply Yes 1234545362 Yes 12345C0234X Provisionally Accredited Town of Floodville Inundation River Left Bank Floodville Waterworks No 1901990990 No 12345C0245X
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 : Roughness Coefficients Flooding Source Channel “n” Overbank “n” Culvert Creek 0.040-0.060 0.040-0.080 Inundation River 0.040-0.060 0.040-0.080 North Fork Inundation River 0.080-0.100 0.040-0.080 South Fork Inundation River 0.030 0.030-0.035 5.3 Coastal Analyses For the areas of Flood County that are impacted by coastal flooding processes, coastal flood hazard analyses were performed to provide estimates of coastal BFEs. Coastal BFEs reflect the increase in water levels during a flood event due to extreme tides and storm surge as well as overland wave effects. The following subsections provide summaries of how each coastal process was considered for this FIS Report. Greater detail (including assumptions, analysis, and results) is available in the archived project documentation. summarizes the methods and/or models used for the coastal analyses. Refer to Section 2.5.1 for descriptions of the terms used in this section. Table : Summary of Coastal Analyses Flooding Source Study Limits From Study Limits To Hazard Evaluated Model or Method Used Date Analysis was Completed Big Ocean Entire coastline of Flood County Entire coastline of Flood County Storm Surge ADCIRC 99/99/9999 Big Ocean Entire coastline of Flood County Entire coastline of Flood County Wave setup Direct Integration Method (DIM) 99/99/9999 Big Ocean Entire coastline of Flood County Entire coastline of Flood County Statistical Analyses JPM 99/99/9999 Big Ocean Entire coastline of Flood County Entire coastline of Flood County Wave Runup TAW 99/99/9999 Big Ocean Entire coastline of Flood County Entire coastline of Flood County Wave Generation ACES 99/99/9999
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
Table : 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
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