South Fork The South Fork Inundation River at Floodville typically exceeds flood Inundation stage at least once each winter. River Flood stage in the Coastland area is higher than in the areas downstream because of a natural constriction in the flood plain immediately downstream of the confluence of the North and South Forks of the Inundation River. In December 1964, the Spruce Street Bridge staff gage at Coastland, indicated that the South Fork Inundation River crested at approximately 11 feet above flood stage (bankfull discharge) with an estimated discharge of 100,000 cfs. This flow has a return period greater than 500 years. Stream gage No. 19999999 on the South Fork Inundation River at Floodville recorded a peak flow of 48,900 cfs . This flow has a return period of about 500 years. Table 7 contains information about historic flood elevations in the communities within Flood County. Table 7: Historic Flooding Elevations Historic Approximate Flooding Peak (Feet Event Recurrence Source of Source Location NAVD88) Date Interval (years) Data Outlet of Inundation Inundation River at 19.8 1986 80 USGS gage River Big Ocean South Fork 700 feet upstream NRCS high Inundation 18.8 2007 50 of Fulton Road water marks River 4.3 Non-Levee Flood Protection Measures Table 8 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 Structure Type of Source Name Measure Location Description of Measure A.B. At entrance Constructed by USACE in Big Ocean Smith Jetties channel 1929 Jetty Floodville, along Several property owners in Berms and Big Ocean N/A the coast of the this city have placed berms riprap Big Ocean and riprap to protect homes Tidal Flood Weather Forecast Low-lying coastal Big Ocean N/A flooding Office issues storm tide areas warnings warnings
South Fork Inundation River The South Fork Inundation River at Floodville typically exceeds flood stage at least once each winter. Flood stage in the Coastland area is higher than in the areas downstream because of a natural constriction in the flood plain immediately downstream of the confluence of the North and South Forks of the Inundation River. In December 1964, the Spruce Street Bridge staff gage at Coastland, indicated that the South Fork Inundation River crested at approximately 11 feet above flood stage (bankfull discharge) with an estimated discharge of 100,000 cfs. This flow has a return period greater than 500 years. Stream gage No. 19999999 on the South Fork Inundation River at Floodville recorded a peak flow of 48,900 cfs . This flow has a return period of about 500 years. Table 7 contains information about historic flood elevations in the communities within Flood County. 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 Table 8 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
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