LUMPKIN COUNTY, GEORGIA

Transcription

1 LUMPKIN COUNTY, GEORGIA AND INCORPORATED AREAS Lumpkin County COMMUNITY NAME COMMUNITY NUMBER DAHLONEGA, CITY OF LUMPKIN COUNTY (UNINCORPORATED AREAS) SEPTEMBER 26, 2008 FLOOD INSURANCE STUDY NUMBER 13187CV000A 42125CV1A

2 NOTICE TO FLOOD INSURANCE STUDY USERS Communities participating in the National Flood Insurance Program have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) report may not contain all data available within the Community Map Repository. Please contact the Community Map Repository for any additional data. The Federal Emergency Management Agency (FEMA) may revise and republish part or all of this FIS report at any time. In addition, FEMA may revise part of this FIS report by the Letter of Map Revision process, which does not involve republication or redistribution of the FIS report. Therefore, users should consult with community officials and check the Community Map Repository to obtain the most current FIS report components. Selected Flood Insurance Rate Map (FIRM) panels for this community contain information that was previously shown separately on the corresponding Flood Boundary and Floodway Map (FBFM) panels (e.g., floodways, cross sections). In addition, former flood hazard zone designations have been changed as follows: Old Zone(s) Al through A30 B C New Zone AE X X Initial Countywide FIS Effective Date: September 26, 2008

3 TABLE OF CONTENTS 1.0 INTRODUCTION Purpose of Study Authority and Acknowledgments Coordination AREA STUDIED Scope of Study Community Description Principal Flood Problems Flood Protection Measures ENGINEERING METHODS Hydrologic Analyses Hydraulic Analyses Vertical Datum FLOODPLAIN MANAGEMENT APPLICATIONS Floodplain Boundaries Floodways INSURANCE APPLICATIONS FLOOD INSURANCE RATE MAP OTHER STUDIES LOCATION OF DATA BIBLIOGRAPHY AND REFERENCES i

4 TABLE OF CONTENTS (Continued) TABLES Table 1 Initial and Final CCO Meetings... 2 Table 2 Streams Restudied by Approximate Method... 3 Table 3 Summary of Discharges... 6 Table 4 Vertical Datum Conversion... 9 Table 5 Community Map History EXHIBITS Exhibit 1 Flood Profiles Cane Creek Panels 01P-02P Cane Creek/Little Cane Creek Panel 03P Clay Creek Panels 04P-06P Dowdy Branch Panel 07P Happy Hollow Creek Panels 08P-09P Left Fork Cavender Creek Panels 10P-11P Tanyard Branch Panels 12P-14P Tributary B Panels 15P-17P Tributary C Panels 18P-19P Tributary D Panels 20P-21P Tributary E Panel 22P Ward Creek Panels 23P-25P Yahoola Creek Panels 26P-33P Exhibit 2 Flood Insurance Rate Map Index Flood Insurance Rate Map ii

5 FLOOD INSURANCE STUDY LUMPKIN COUNTY, GEORGIA AND INCORPORATED AREAS 1.0 INTRODUCTION 1.1 Purpose of Study This Flood Insurance Study (FIS) revises and updates the information on the existence and severity of flood hazards in the geographic area of Lumpkin County, including the City of Dahlonega; and the unincorporated areas of Lumpkin County (referred to collectively herein as Lumpkin County), and aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of This study has developed flood risk data for various areas of the community that will be used to establish actuarial flood insurance rates and assist the community in its efforts to promote sound floodplain management. Minimum floodplain management requirements for participation in the National Flood Insurance Program (NFIP) are set forth in the Code of Federal Regulations at 44 CFR, In same states or communities, floodplain management criteria or regulations may exist that are more restrictive or comprehensive than the minimum Federal requirements. In such cases, the more restrictive criteria take precedence and the State (or other jurisdictional agency) will be able to explain them. This FIS was prepared by compiling existing hydrologic and hydraulic technical and scientific data prepared originally for purposes other than the NFIP. The data were identified as applicable at the time of compilation of this FIS and should depict the general conditions of the flooding sources with relative accuracy. The FEMA performed a cursory review and accepted the data as valid for purposes of this FIS and the NFIP. The Digital Flood Insurance Rate Map (DFIRM) and FIS report for this countywide study have been produced in digital format. Flood hazard information was converted to meet the Federal Emergency Management Agency (FEMA) DFIRM database specifications and Geographic Information System (GIS) format requirements. The flood hazard information was created and is provided in a digital format so that it can be incorporated into a local GIS and be accessed more easily by the community. 1.2 Authority and Acknowledgments The sources of authority for this Flood Insurance Study are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of The hydrologic and hydraulic analyses for this study were obtained from "Flood Plain Management Study of Dahlonega and Lumpkin County, Georgia" prepared by the Soil Conservation Service (Reference 1) This Countywide FIS Report For this countywide FIS revision, streams restudied by approximate methods were performed by PBS&J, for the Georgia Department of Natural Resources (DNR), under 1

6 Contract No. EMA-2006-CA-5615, with FEMA. All other streams previously studied by approximate methods were redelineated to better match existing topography. The work was completed in September Detailed study information for Cane Creek, Clay Creek, Dowdy Creek, Happy Hollow Creek, Left Fork Cavender Creek, Tanyard Branch, Tributary B, Tributary C, Tributary D, Tributary E, and Ward Creek Yahoola Creek was taken from the FIS for City of Dahlonega, Georgia (Reference 2) and Lumpkin County, Georgia and Incorporated Areas (Reference 3). Base map information shown on the Flood Insurance Rate Map (FIRM) was derived from Sanborn Aerial Survey and Digital Mapping, black and white photography dated 2006 or later. The projection used in the preparation of this map is North American Datum of 1983 StatePlane Georgia West, and the horizontal datum used is North American Datum of Coordination An initial meeting is held with representatives from FEMA, the community, and the study contractor to explain the nature and purpose of a FIS, and to identify the streams to be studied or restudied. A final meeting is held with representatives from FEMA, the community, and the study contractor to review the results of the study. The initial and final meeting dates for previous FIS reports for Lumpkin County and its communities are listed in the following table: Table 1 Initial and Final CCO Meetings 2.0 AREA STUDIED Community FIS Date Initial Meeting Final Meeting Dahlonega, City of September 18, 1991 December 29, 1989 September 5, 1990 Lumpkin County (Unincorporated Areas) April 2, 1991 December 29, 1989 September 5, 1990 For this countywide FIS, a scoping meeting was held on January 18, 2006, and attended by representatives of Lumpkin County, the Georgia Department of Natural Resources, FEMA, Georgia Environmental Protection Division, and PBS&J. The purpose of the meeting was to discuss the scope of the FIS. 2.1 Scope of Study This FIS covers the geographic area of Lumpkin County, Georgia, including incorporate communities listed in Section 1.1. The areas studied by detailed methods were selected with priority given to all known flood hazards and areas of projected development or proposed construction. 2

7 The following streams are studied by detailed methods in this FIS report: Cane Creek Cane Creek/Little Can Creek Clay Creek Dowdy Branch Happy Hollow Creek Tanyard Branch Tributary B Tributary C Tributary D Tributary E Ward Creek Yahoola Creek The limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on the FIRM (Exhibit 2). The areas restudied by approximate methods were selected with priority given to all known flood hazards and areas of projected development or proposed construction through September The streams restudied by approximate methods are presented in Table 2, Streams Restudied by Approximate Method. Table 2 - Streams Restudied by Approximate Method Stream Reach Description Cane Creek From the confluence of Chestatee River to approximately 700 feet west of J W MX Road Chestatee River From the confluence of Long Branch to the confluence of Yahoola Creek Clay Creek From approximately 950 feet East of Dawsonville Hwy to approximately 900 feet Southeast of the intersection of Clay Creek Falls Road and Gordon Seabolt Road Long Branch Tanyard Branch From the confluence of Chestatee River to approximately 2600 feet South of the intersection of Long Branch Road and State Route 52. From the Confluence of Yahoola (DS) to approximately 2100 feet along Mechanicsville Road toward the east. Ward Creek From approximately 1900 feet North of Cavender Creek Road approximately 400 feet South of Wards Creek Drive Ward Creek Tributary 2 From the confluence of Ward Creek to approximately 200 feet Southeast of Shepherds Way Yahoola Creek (DS) From the confluence of Chestatee River to State Route 52 3

8 Table 2 - Streams Restudied by Approximate Method Stream Reach Description Yahoola Creek (US) From Wimpy Mill Road to approximately 900 feet North of Woody BND All other streams studied by approximate methods were redelineated to better match existing topography. For this countywide FIS, the FIS report and FIRM were converted to countywide format, and the flooding information for the entire county, including both incorporated and unincorporated areas, is shown. Also, the vertical datum was converted from the National Geodetic Vertical Datum of 1929 (NGVD) to the North American Vertical Datum of 1988 (NAVD). In addition, the Transverse Mercator, State Plane coordinates, previously referenced to the North American Datum of 1927, are now referenced to the North American Datum of Approximate analyses were used to study those areas having a low development potential or minimal flooding hazards. The scope and methods of study were proposed to, and agreed upon, by FEMA and the communities. 2.2 Community Description Lumpkin County is in northern Georgia, approximately 40 miles north of the City of Atlanta, Georgia. It is bordered on the north by Union County, Georgia; on the east by White County, Georgia; on the south by Hall and Dawson Counties, Georgia; and on the west by Fannin County, Georgia. It is served by U.S. Route 19 and State Routes 9, 52, 60, and 115. The 2000 population was reported to be 21,016 (Reference 5). The mean annual temperature is 59 degrees Fahrenheit ( F), varying from a mean of 41 F in January to 76 F in July. The average freeze-free period is about 200 days, extending from mid-april to late October. Precipitation averages 62 inches annually and varies from 3.4 inches in October to 7.2 inches in March (Reference 6). The development in the floodplain is mostly agricultural, except in the region surrounding the City of Dahlonega, which is mostly residential and commercial. 2.3 Principal Flood Problems A damaging flood, estimated to be a 4-percent-annual chance, occurred in April Damages from this flood were estimated to be $250,000, with about 40-percent of this amount being agricultural damages. Nonagricultural damages were largely to road crossing structures. An estimated 900 acres were inundated by this flood; 500 acres were farmland. The largest flood on record that of August 1967, was nearly a 1-percent annual chance frequency event. Detailed data regarding damages are not available for this flood. 2.4 Flood Protection Measures A dam on Yahoola Creek, within the corporate limits, may provide some protection from flooding. However, the dam does not protect from the 1-percent-annual chance. 4

9 Lumpkin County has adopted structural measures conforming to the Georgia Erosion and Sedimentation Act of These measures require adequate erosion control plans prior to issuance of permits for any major land-disturbing activity. Congress authorized the Lake Lanier-Buford Dam project in the Rivers and Harbors Act approved July 24, This legislation targeted developing the nation s rivers systems for national defense, flood control, power production, navigation and water supply. The scope of developing the nation s waterways was a massive and unprecedented undertaking. The Lake Lanier-Buford Dam construction began in 1950 and was completed in 1955 at a cost of approximately 46 million dollars. Initially the project was authorized to provide hydropower, flood control and downstream navigation. Later, additional purposes were added to the project for water supply, water quality, recreation and fish and wildlife management. The Lake Lanier-Buford Dam project encompasses approximately 39,000 acres of water and 18,000 acres of land. It is among top three mostvisited corps recreation sites (Reference 7). 3.0 ENGINEERING METHODS For the flooding sources studied by detailed methods in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude that are expected to be equaled or exceeded once on the average during any 10-, 50-, 100-, or 500-year period (recurrence interval) have been selected as having special significance for floodplain management and for flood insurance rates. These events, commonly termed the 10-, 50-, 100-, and 500-year floods, have a 10-, 2-, 1-, and 0.2-percentannual-chance, respectively, of being equaled or exceeded during any year. Although the recurrence interval represents the long-term, average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood that equals or exceeds the 1-percent-annual-chance (100-year) flood in any 50-year period is approximately 40 percent (4 in 10); for any 90-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes. 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak discharge-frequency relationships for the flooding source studied by detailed methods affecting the community. Precountywide Analysis The discharges are based on statistical analysis of discharge records covering a 46-year period of the United States Geological Survey (USGS) gaging station for the Chestatee River located approximately 2.5 miles east of the City of Dahlonega on State Route 52. It has a drainage area of 153 square miles and is judged to be hydrologically and geologically similar to the study area. This analysis followed the standard log-pearson Type III method (Reference 8). 5

10 This Countywide FIS Report Peak flood discharges for Cane Creek, Clay Creek, Dowdy Creek, Happy Hollow Creek, Left Fork Cavender Creek, Tanyard Branch, Tributary B, Tributary C, Tributary D, Tributary E, and Ward Creek Yahoola Creek were estimated using the 1976 regional regression equations for Georgia (Reference 9). The single drainage area regression parameter was measured using topographic maps and compared to the USGS drainage area data (Reference 10). The USGS data was adopted where the data corresponded to the flow change locations in the hydraulic models. For the approximate study streams listed in Table 1, peak flows were determined using the rural regression equations for Georgia (Reference 11). Peak discharge-drainage area relationships for detailed studied streams in Chattooga County are shown in Table 3, Summary of Discharges. DRAINAGE AREA (SQ.MILES) Table 3 Summary of Discharges 10%- ANNUAL- CHANCE 2%- ANNUAL- CHANCE 1%- ANNUAL- CHANCE 0.2%- ANNUAL- CHANCE FLOODING SOURCE AND LOCATION CANE CREEK At State Route ,800 7,440 8,640 12,000 At Oak Grove Road ,000 4,650 5,400 7,500 At Wash Ridler Road ,010 1,170 1,630 CLAY CREEK At Clay Creek Falls Road 8.0 2,380 3,690 4,280 5,950 At Horton Road 4.0 1,350 2,090 2,430 3,380 DOWDY BRANCH At Oak Grove Road HAPPY HOLLOW CREEK At Happy Hollow Road LEFT FORK CAVENDERS CREEK At Rock Mouse Road ,030 1,250 1,680 TANYARD BRANCH At Pine Tree Road TRIBUTARY B At Elbert Gaddis Road TRIBUTARY C Approximately 1,000 feet upstream of confluence TRIBUTARY D At Ranger Camp Road

11 Table 3 Summary of Discharges FLOODING SOURCE AND LOCATION DRAINAGE AREA (SQ.MILES) 10%- ANNUAL- CHANCE 2%- ANNUAL- CHANCE 1%- ANNUAL- CHANCE 0.2%- ANNUAL- CHANCE TRIBUTARY E At Siloam Church Road WARD CREEK At Cavender Creek Road 4.0 1,340 2,080 2,410 3,350 YAHOOLA CREEK At State Route ,900 9,150 10,600 14,800 At Wimpy Mill Road ,850 7,520 8,730 12,100 At U.S. Route ,640 7,190 8,350 11,600 Approximately 7,850 feet upstream of Duffle Grizzle Road ,980 6,170 7,160 9,950 At Remer Gooch Road ,930 4,540 5,270 7,320 At Black Mountain Road 2.8 1,010 1,560 1,820 2, Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data tables in the FIS report. Flood elevations shown on the FIRM are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS in conjunction with the data shown on the FIRM. Precountywide Analysis Channel and overbank roughness coefficients (Manning s n ) used in the hydraulic computations were estimated by engineering judgment and based on field observation at each cross-section and adjusted with known high-water marks and stream gage rating curves where possible. Cross sections were used using topographic maps (Reference 12). Locations of selected cross sections used in the hydraulic analyses are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2), selected cross-section locations are also shown on the FIRM (Exhibit 2). Elevation-discharge relationships were established using the WSP-2 water-surface profile computer program (Reference 13). Flood Profiles were drawn showing the computed water-surface elevations for floods of the selected recurrence intervals. In cases where the 50- and 100-year flood elevations are close together, due to limitations of the profile scale, only the 100-year profile has been shown. 7

12 The hydraulic analyses for this study were based on the effects of unobstructed flow. The flood elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail. This Countywide FIS Report For Cane Creek, Clay Creek, Dowdy Creek, Happy Hollow Creek, Left Fork Cavender Creek, Tanyard Branch, Tributary B, Tributary C, Tributary D, Tributary E, and Ward Creek Yahoola Creek cross sections were obtained from field surveys. All bridges, dams, and culverts were field surveyed to obtain elevation data and structural geometry. The USACE HEC-2 computer program (Reference 14) was used to calculate the WSELs for Armuchee Creek, and Little Armuchee Creek. Starting WSELs for Armuchee Creek, and Little Armuchee Creek were determined by the slope/area method. For the approximate study streams listed in Table 2, cross section data was obtained from the USGS 7.5 Minute Series topographic quadrangles (Reference 15 and 16). Low flow channels were added to the cross section data, based on the estimated depth of the 50-percent-annual-chance flow. Roads appearing on the topographic maps were modeled as weirs; top of the road elevations were estimated from the topography. The studied streams listed in Table 2 were modeled using HEC-RAS Version (Reference 17). Locations of selected cross sections used in the hydraulic analyses are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2), selected cross section locations are also shown on the FIRM (Exhibit 2). The profile baselines depicted on the FIRM represent the hydraulic modeling baselines that match the flood profiles on this FIS report. As a result of improved topographic data, the profile baseline, in some cases, may deviate significantly from the channel centerline or appear outside the Special Flood Hazard Area. The hydraulic analyses for this study were based on unobstructed flow. The flood elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail. 3.3 Vertical Datum 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 (NGVD). With the completion of the North American Vertical Datum of 1988 (NAVD), many FIS reports and FIRMs are now prepared using NAVD as the referenced vertical datum. 8

13 All flood elevations shown in this FIS report and on the FIRM are referenced to NAVD. Structure and ground elevations in the community must, and therefore be referenced to NAVD88 the same vertical datum. It is important to note that adjacent communities may be referenced to NGVD29. This may result in differences in Base Flood Elevations (BFEs) across the corporate limits between the communities. In this revision were taken from the prior effective FIS reports and FIRMs and adjusted to NAVD. The datum conversion factor from NGVD to NAVD in Lumpkin County is The data points used to determine the conversion are listed in Table 4, Vertical Datum Conversion. Table 4 Vertical Datum Conversion Conversion from NGVD to NAVD Quad Name Corner Longitude Latitude Noontootla SE Nimblewill SE Suches SE Campbell Mountain SE Coosa Bald SE Neels Gap SE Dahlonega SE AVERAGE feet For additional information regarding conversion between NGVD and NAVD, visit the National Geodetic Survey website at or contact the National Geodetic Survey at the following address: NGS Information Services NOAA, N/NGS12 National Geodetic Survey, SSMC-3, # East-West Highway Silver Spring, Maryland (301) 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 Technical Support Data Notebook associated with the FIS report and FIRM for this community. Interested individuals may contact FEMA to access these data. To obtain current elevation, description, and/or location information for benchmarks shown on this map, please contact the Information Services Branch of the NGS at (301) , or visit their website at FLOODPLAIN MANAGEMENT APPLICATIONS The NFIP encourages State and local governments to adopt sound floodplain management programs. Therefore, each FIS provides 1-percent-annual-chance (100-year) flood elevations and delineations of the 1- and 0.2-percent-annual-chance (500-year) floodplain boundaries and 1- percent-annual-chance floodway to assist communities in developing floodplain management 9

14 measures. This information is presented on the FIRM and in many components of the FIS report, including Flood Profiles and Floodway Data Table. Users should reference the data presented in the FIS report as well as additional information that may be available at the local map repository before making flood elevation and/or floodplain boundary determinations. 4.1 Floodplain Boundaries To provide a national standard without regional discrimination, the 1-percent-annualchance flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2-percent-annual-chance flood is employed to indicate additional areas of flood risk in the community. For each stream studied by detailed methods, the 1- and 0.2-percent-annual-chance floodplain boundaries have been delineated using the flood elevations determined at each cross section. Between cross sections, the boundaries were interpolated using topographic maps at a scale of 1:12,000 with a contour interval of 2- foot lidar contours (Reference 12). The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the FIRM (Exhibit 2). On this map, the 1-percent-annual-chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (Zones A and AE), and the 0.2- percent-annual-chance floodplain boundary corresponds to the boundary of areas of moderate flood hazards. In cases where the 1- and 0.2-percent-annual-chance floodplain boundaries are close together, only the 1-percent-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. For streams studied by approximate methods, only the 1-percent-annual-chance floodplain boundary is shown on the FIRM. 4.2 Floodways Encroachment on floodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to assist local communities in this aspect of floodplain management. Under this concept, the area of the 1-percent-annual-chance floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that the 1-percent-annual-chance flood can be carried without substantial increases in flood heights. Minimum Federal standards limit such increases to 1 foot, provided that hazardous velocities are not produced. No floodways have been mapped for Lumpkin County. 10

15 5.0 INSURANCE APPLICATIONS Zone A Zone A is the flood insurance rate zone that corresponds to the 1-percent-annual-chance floodplains that are determined in the FIS report by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no base (1-percent-annual-chance) flood elevations (BFEs) or depths are shown within this zone. Zone AE Zone AE is the flood insurance rate zone that corresponds to the 1-percent-annual-chance floodplains that are determined in the FIS report by detailed methods. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone X Zone X (Future Base Flood) Zone X (Future Base Flood) is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined based on future-conditions hydrology. No BFEs or base flood depths are shown within this zone. 6.0 FLOOD INSURANCE RATE MAP The FIRM is designed for flood insurance and floodplain management applications. For flood insurance applications, the map designates flood insurance risk zones as described in Section 5.0 and, in the 1-percent-annual-chance floodplains that were studied by detailed methods, shows selected whole-foot BFEs or average depths. Insurance agents use the zones and BFEs in conjunction with information on structures and their contents to assign premium rates for flood insurance policies. For floodplain management applications, the map shows by tints, screens, and symbols, the 1- and 0.2-percent-annual-chance floodplains, floodways, and the locations of selected cross sections used in the hydraulic analyses and floodway computations. The countywide FIRM presents flooding information for the geographic area of Lumpkin County. Previously, FIRMs were prepared for each incorporated and unincorporated area of the county identified as flood-prone. This countywide FIRM also includes flood hazard information that was presented separately on FBFMs, where applicable. Historical data relating to the maps prepared for each community are presented in Table 6, Community Map History. 7.0 OTHER STUDIES This FIS report either supersedes or is compatible with all previous studies published on streams studied in this report and should be considered authoritative for the purposes of the NFIP. 11

16 8.0 LOCATION OF DATA Information concerning the pertinent data used in preparation of this study can be obtained by contacting FEMA, Federal Insurance and Mitigation Division, Koger Center Rutgers Building, 3003 Chamblee Tucker Road, Atlanta, Georgia

17 TABLE 5 Table 5 Community Map History COMMUNITY NAME INITIAL IDENTIFICATION FLOOD HAZARD BOUNDARY MAP REVISIONS DATE FIRM EFFECTIVE DATE FIRM REVISIONS DATE Dahlonega, City of June 28, 1974 January 23, 1976 September 18, 1991 September 26, 2008 Lumpkin County (Unincorporated Areas) April 2, 1976 * April 2, 1991 September 26, 2008 * Data Not Available FEDERAL EMERGENCY MANAGEMENT AGENCY LUMPKIN COUNTY, PA AND INCORPORPATED AREAS COMMUNITY MAP HISTORY 13

18 9.0 BIBLIOGRAPHY AND REFERENCES 1. U.S. Department of Agriculture, Soil Conservation Service, Flood Plain Management Study of Dahlonega and Lumpkin County, Georgia, August Federal Emergency Management Agency, Flood Insurance Study, City of Dahlonega, Georgia, Washington, D.C. September 18, Federal Emergency Management Agency, Flood Insurance Study, Lumpkin County, Georgia and Unincorporated Areas, Georgia, Washington, D.C. April 2, Federal Emergency Management Agency, Flood Insurance Study, Hall County, Georgia and Unincorporated Areas, Georgia, Washington, D.C. March 21, U.S. Census Bureau, 2000 Census: Lumpkin County, Georgia. Retrieved on May 9, 2007 from 6. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Environmental Data Services, Climatological Data for Georgia, Asheville, North Carolina, U.S. Army Corps of Engineers, Mobile District, Buford Dam. Retrieved September 20, 2007 from 8. Georgia Department of Natural Resources, Flood Frequency Analysis for Small Streams in Georgia, U.S. Department of the Interior, Geological Survey, Interagency Advisory Committee on Water Data, Office of Water Data Coordination, Hydrology Subcommittee, Guidelines for Determining Flood Flow Frequency, Bulletin No. 17B, September 1981, revised March U.S. Geological Survey, 7.5-Minute Series Topographic Maps, Scale 1:24,000, Contour Interval 20 feet: Armuchee, Georgia, U.S. Department of the Interior, Stamey, T.C., and C.W. Hess, Techniques for Estimating Magnitude and Frequency of Floods in Rural Basins of Georgia, Water Resources Investigations Report , U.S. Geological Survey, Lumpkin County Planning Department, Lidar, Scale 1:12,000, Contour Interval 2 feet, Lumpkin County Georgia, U.S. Department of Agriculture, Soil Conservation Service, Technical Release No. 61, WSP- 2 Computer Program, Washington, D.C., May 1976, revised September Hydrologic Engineering Center, HEC-2 Water Surface Profiles, U.S. Army Corps of Engineers, Davis, California, September 1984b. 14

19 15. U.S. Geological Survey, 7.5 Minute Series Topographic Map, Scale 1:24,000, Contour Interval 20 Feet: Campbell Mountain, Georgia, 1950; Cleveland, Georgia, 1951; Dawsonville, Georgia, 1964; Murrayville, Georgia, 1964; Nimblewill, Georgia, U.S. Geological Survey, 7.5 Minute Series Topographic Map, Scale 1:24,000, Contour Interval 20 feet: Dahlonega, Georgia. 17. Hydrologic Engineering Center, HEC-RAS River Analysis System, Version 3.1.3, U.S. Army Corps of Engineers, Davis, California, April

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