WHITFIELD COUNTY, GEORGIA AND INCORPORATED AREAS

COMMUNITY NAME Cohutta, Town of Dalton, City of Tunnel Hill, City of Varnell, City of Whitfield County (Unincorporated Areas)

COMMUNITY NUMBER 130618 130194 130489 130667 130193

Effective: September 19, 2007

FLOOD INSURANCE STUDY NUMBER 13313CV000A

Whitfield County

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. Initial Countywide FIS Effective Date: September 19, 2007

TABLE OF CONTENTS 1.0

INTRODUCTION..................................................................................................................1 1.1 Purpose of Study ..............................................................................................................1 1.2 Authority and Acknowledgments ....................................................................................1 1.3 Coordination ....................................................................................................................3

2.0

AREA STUDIED ...................................................................................................................3 2.1 Scope of Study .................................................................................................................3 2.2 Community Description...................................................................................................5 2.3 Principal Flood Problems.................................................................................................6 2.4 Flood Protection Measures ..............................................................................................6

3.0

ENGINEERING METHODS ...............................................................................................6 3.1 Hydrologic Analyses........................................................................................................7 3.2 Hydraulic Analyses........................................................................................................11 3.3 Vertical Datum...............................................................................................................13

4.0

FLOODPLAIN MANAGEMENT APPLICATIONS ......................................................14 4.1 Floodplain Boundaries ...................................................................................................15 4.2 Floodways ......................................................................................................................15

5.0

INSURANCE APPLICATIONS.........................................................................................25

6.0

FLOOD INSURANCE RATE MAP ..................................................................................25

7.0

OTHER STUDIES ...............................................................................................................26

8.0

LOCATION OF DATA.......................................................................................................26

9.0

BIBLIOGRAPHY AND REFERENCES ..........................................................................26

i

TABLE OF CONTENTS (Continued)

FIGURES Figure 1 - Floodway Schematic .........................................................................................................16

TABLES Table 1 - Redelineated Streams .......................................................................................................... 4 Table 2 - Streams Studied by Limited Detailed Methods................................................................... 4 Table 3 - Incorporated Letters of Map Revision................................................................................. 5 Table 4 - Summary of Discharges ...................................................................................................... 8 Table 5 - Summary of Stillwater Elevations..................................................................................... 11 Table 6 - Manning's "n" Values ........................................................................................................ 12 Table 7 - Vertical Datum Conversion............................................................................................... 14 Table 8 - Floodway Data................................................................................................................... 17 Table 9 - Community Map History................................................................................................... 27

EXHIBITS Exhibit 1 - Flood Profiles City Park Branch Coahulla Creek Colony Creek Crown Creek Drowning Bear Creek East Chickamauga Creek Little Creek Little Swamp Creek McLellan Creek Mill Creek Poplar Springs Creek Slaughter Pen Creek Stacy Branch Tar Creek Tar Creek Tributary

Panel Panels Panel Panel Panels Panel Panels Panels Panels Panels Panel Panels Panel Panels Panel

Exhibit 2 - Flood Insurance Rate Map Index Flood Insurance Rate Map

ii

01P 02P-03P 04P 05P 06P-07P 08P 09P-10P 11P-12P 13P-14P 15P-20P 21P 22P-23P 24P 25P-26P 27P

FLOOD INSURANCE STUDY WHITFIELD COUNTY, GEORGIA AND INCORPORATED AREAS 1.0

INTRODUCTION

1.1

Purpose of Study This Flood Insurance Study (FIS) revises and updates information on the existence and severity of flood hazards in the geographic area of Whitfield County, including the Cities of Dalton, Tunnel Hill, and Varnell; the Town of Coahulla; and the unincorporated areas of Whitfield County (referred to collectively herein as Whitfield County), and aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This study has developed flood-risk data for various areas of the community that will be used to establish actuarial flood insurance rates and to 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, 60.3. In some 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. 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 FIS are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. Information on the authority and acknowledgements for each jurisdiction included in this countywide FIS report, as compiled from their previously printed FIS reports, are shown below:

1

Dalton, City of

For the February 16, 1990, FIS report (FEMA, 1990a), the hydrologic and hydraulic analyses for City Park Branch, Colony Creek, Crown Creek, McLellan Creek, Slaughter Pen Creek, and portions of Tar Creek were performed by the U.S. Army Corps of Engineers (USACE) for the Federal Insurance Administration (FIA) (FIA, 1979). The work was completed in April 1978. The hydrologic and hydraulic analyses for the remaining streams studied in detail were obtained from the FIS for the unincorporated areas of Whitfield County (FEMA, 1990b)

Whitfield County (Unincorporated Areas)

The hydrologic and hydraulic analyses for the February 16, 1990, FIS report (FEMA 1990b) were performed by Post, Buckley, Schuh & Jernigan, Inc. (PBS&J), for FEMA, under Contract No. EMW-85-1961. The work was completed in December 1986. The hydrologic and hydraulic analyses for East Chickamauga Creek were taken from the FIS for the unincorporated areas of Catoosa County (FEMA, 1984). The hydrologic and hydraulic analyses for Slaughter Pen Creek were taken from the FIS for the City of Dalton (FIA, 1979).

No previous FIS reports were published for the Cities of Tunnel Hill, Varnell, or for the Town of Coahulla. For this countywide FIS, hydrologic and hydraulic analyses for Poplar Springs Creek, a newly studied stream, were performed by Integrated Science & Engineering for Whitfield County. The work was completed in October 2003. The hydrologic and hydraulic analyses for streams studied by limited detailed methods and redelineations for this countywide FIS were performed by PBS&J,

2

for the Georgia Department of Natural Resources (DNR), under Contract No. EMA-2003-GR-5369 with FEMA. The work was completed in June 2006. 1.3

Coordination The initial and final meeting dates for the previous FIS reports for Whitfield County and its communities are listed in the following table: Community

Dalton, City of Whitfield County (Unincorporated Areas)

FIS Date

Initial Meeting

Final Meeting

February 16, 1990 February 16, 1990

* February 28, 1985

March 30, 1989 March 30, 1989

*Data not available

For this countywide FIS, a scoping meeting was held on October 18, 2004, and attended by representatives of Whitfield County, the Georgia DNR, Georgia Environmental Protection Division, the North Georgia Regional Development Center, FEMA, and PBS&J. The purpose of the meeting was to discuss the scope of the FIS. A final meeting was held on November 2, 2006. Attending the meeting were representatives of Whitfield County, the Georgia DNR, and PBS&J. All issues raised at the meeting have been addressed.

2.0

AREA STUDIED

2.1

Scope of Study This FIS covers the geographic area of Whitfield County, Georgia, including the incorporated 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 at the time of the study. The following streams were studied by detailed methods: City Park Branch, Coahulla Creek, Colony Creek, Crown Creek, Drowning Bear Creek, East Chickamauga Creek, Little Creek, Little Swamp Creek, McLellan Creek, Mill Creek, Poplar Springs Creek, Slaughter Pen Creek, Stacy Branch, Tar Creek, and Tar Creek Tributary. The limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on the FIRM (Exhibit 2). Poplar Springs Creek was newly studied for this countywide revision. For this countywide FIS, reaches of streams that have been studied by detailed methods were selected for redelineation based on more recent topography. Whitfield County provided point elevation datasets which were used to create a

3

Digital Elevation Model (DEM) (Whitfield County, 2003). The areas that were redelineated are presented in Table 1. Table 1 - Redelineated Streams Stream

Reach Description

Coahulla Creek

From just upstream of Tibbs Bridge Road Southeast to approximately 7,800 feet upstream of U.S. Highway 76/State Highway 52/Chatsworth Highway

Drowning Bear Creek

From just upstream of Riverbend Road Southeast to approximately 5,100 feet upstream of South Hamilton Street

The areas studied by limited detailed methods were selected with priority given to all known flood hazards and areas of projected development or proposed construction. The streams studied by limited detailed methods are listed in Table 2. Table 2 - Streams Studied by Limited Detailed Methods Stream

Reach Description

Conasuaga River

From approximately 40,780 feet upstream of Tilton Bridge Road Southeast to approximately 51,520 feet upstream of Tilton Bridge Road Southeast

Mill Creek Tributary No. 1

From the confluence with Mill Creek to approximately 1,680 feet upstream of Access Road

Mill Creek Tributary No. 2

Approximately 720 feet downstream of Mill Creek Road Southwest to approximately 120 feet upstream of Mill Creek Road Southwest

Tributary to East Chickamauga Creek

From approximately 600 feet downstream of West Jimmy Drive to approximately 2,260 feet upstream of West Jimmy Drive

For this revision, 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 Universal Transverse Mercator coordinates,

4

previously referenced to the North American Datum of 1927, are now referenced to the North American Datum of 1983. Letters of Map Revision incorporated in this revised FIS are listed in Table 3. Table 3 - Incorporated Letters of Map Revision LOMR Case Number

Date Issued

Project Identifier

96-04-351P

12/06/1996

Haig Mill Dam just north of U.S. Highways 41 and 76

03-04-327P

11/21/2003

Blue Branch from a point just downstream of McGaughey Chapel Road to a point 200 feet upstream of McGaughey Chapel Road and Leisure Lake entire shoreline

Approximate analyses were used to study those areas having low development potential or minimal flood hazards. The scope and methods of study were proposed to and agreed by FEMA and Whitfield County. 2.2

Community Description Whitfield County was established in 1851 from part of Murray County. In 2005, the county had a population of 89,734 (U.S. Census Bureau, 2006). Since 1990, Whitfield County has experienced a population increase of 24%. Whitfield County, encompassing approximately 290 square miles, is situated in northwest Georgia, approximately 80 miles northwest of the City of Atlanta. It is bordered on the north by Bradley County, Tennessee; on the east by Murray County; on the south by Gordon County; and on the west by Catoosa and Walker Counties. The county seat is located in the City of Dalton. The Whitfield County is served by Interstate Highway 75, U.S. Highways 41 and 76, State Highways 2, 3, 52, 71, 201, 286, and 401, and also by the Norfolk Southern Railway and the CSX railroads. The climate of Whitfield County is classified as temperate, typical of the Southeast region of the United States. It consists of warm, humid summers, mild winters, and abundant rainfall. July temperatures average 89 degrees Fahrenheit (°F) and in January temperatures average 49°F, with an annual mean temperature of approximately 71°F (The Weather Channel, 2006).

5

The average annual precipitation in Whitfield County is 56 inches, most of which falls in the form of rain. Although unusual, snowfall is not uncommon to the region. The wettest month is March with an average of 6.34 inches of precipitation while October is the driest with an average of 3.31 inches (The Weather Channel, 2006). 2.3

Principal Flood Problems Flood problems in Whitfield County are primarily due to the overflow of Mill Creek and Coahulla Creek. In the City of Dalton, flood problems are usually due to the overflow of McLellan Creek, Crown Creek, and Mill Creek and its tributaries.

2.4

Flood Protection Measures A U.S. Soil Conservation Service (SCS) watershed work plan incorporated five flood-water retarding structures, a municipal water storage structure, and 91,624 linear feet of channel improvements along Mill Creek to provide some protection from flooding for the community (SCS, 1958). The degree of flood protection those structures provide is uncertain. Therefore, the structures were not considered to protect the county from major flood events such as the 1-percentannual-chance flood.

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-percent 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.

6

3.1

Hydrologic Analyses Hydrologic analyses were carried out to establish peak discharge-frequency relationships for each flooding source studied by detailed methods affecting the community. Precountywide Analyses Each jurisdiction within Whitfield County has a previously printed FIS report narrative. The hydrologic analyses described in those reports have been compiled and are summarized below. To define discharge-frequency data for East Chickamauga Creek, a regional relationship of peak discharge and drainage area was developed from analysis of records from gaging stations on streams in Catoosa County and on nearby streams with similar hydrologic characteristics (FEMA, 1984). Frequency curves for the stream gage locations were computed using procedures outlined in Water Resources Council (WRC) Bulletin No. 17 (WRC, 1976) with adjustments for historic information, when available. The discharge for Coahulla Creek was developed from a comparison of a regional regression analysis with a log-Pearson Type III frequency analysis (WRC, 1976). Discharges for Mill Creek, Drowning Bear Creek, Tar Creek, and Tar Creek Tributary were verified using the U.S. Geological Survey (USGS) regional frequency techniques before being incorporated into the study. Additional discharge locations, developed using the regional frequency techniques, were added to the discharges developed for Mill Creek in the 1979 FIS for the City of Dalton (FIA, 1979). The discharge-frequency relationships for City Park Branch, Colony Creek, Crown Creek, Little Creek, Little Swamp Creek, McLellan Creek, Slaughter Pen Creek, and Stacy Branch were determined using the USGS regional regression equations (USGS, 1979). The discharges were adjusted using USGS techniques (USGS, 1983) for areas where significant urbanization has occurred. A detailed discussion of the methodology used in the hydrologic analyses is presented in a hydrology study for Unincorporated Whitfield County (PBS&J, 1986). Countywide Analyses For Poplar Springs Creek, the SCS hydrology methodology (SCS, 1986) was used along with the USACE’s computer program HEC-HMS, Version 2.2.1, to compute the peak discharges for the selected flood intervals (USACE, 2002).

7

For Mill Creek Tributary No. 2, which was studied by limited detailed methods, urban regression equations were used to compute the peak discharges for the selected flood intervals. The equations were obtained from the Georgia Stormwater Management Manual, Volume 2, Section 2.1.6 (Atlanta Regional Commission, 2001). The following regression equation was used to compute the peak discharges for the selected flood intervals for the portions of Mill Creek Tributary No. 1 and Tributary to East Chickamauga Creek, which were studied by limited detailed methods: Q100 = 1,010A0.584 , where Q100 = 1-percent-annual-chance peak discharge (cubic feet per second), and A = cumulative drainage area (square miles) (USGS, 1993). ArcGIS generated watershed and sub-basin areas using a DEM based on elevation data submitted by Whitfield County (ESRI, 2005, and Whitfield County, 2003). For the limited detail study for the Consauga River, peak discharges were estimated from the weighted average of the log-Pearson Type III distribution of the maximum annual peak discharge observed at the USGS stream gage at Tilton, GA (Station Number 02387000) and the results of the regional regression equation estimates at the gage site (USGS, 1993). Peak discharge-drainage area relationships for streams studied by detailed methods are shown in Table 4. Table 4 - Summary of Discharges Peak Discharges (cubic feet per second) Flooding Source and Location City Park Branch At confluence with Mill Creek Approximately 1.0 mile upstream of confluence with Mill Creek Coahulla Creek At Keith Mill Road Southeast At U.S. Highway 76/ State Highway 52/ Chatsworth Highway At Dawnville Road

10-PercentAnnual-Chance

2-PercentAnnual-Chance

1-PercentAnnual-Chance

0.84

660

970

1,110

1,490

0.43

430

640

740

1,000

176.0

12,190

*

20,530

*

119.0

9,300

*

15,730

*

114.0

9,030

*

15,280

*

Drainage Area (square miles)

* Data not available

8

0.2-PercentAnnual-Chance

Table 4 - Summary of Discharges (Continued) Peak Discharges (cubic feet per second) Flooding Source and Location Colony Creek At confluence with Mill Creek Approximately 1,800 feet upstream of confluence with Mill Creek Crown Creek At confluence with Mill Creek Drowning Bear Creek At Riverbend Road Southeast At Antioch Road Just upstream of confluence of Tar Creek Approximately 5,150 feet upstream of South Hamilton Street East Chickamauga Creek Approximately 5,730 feet downstream of Cottonwood Mill Road Approximately 1.44 miles upstream of Cottonwood Mill Road Little Creek Approximately 12,135 feet downstream of General William A. Holland Parkway Approximately 6,325 feet downstream of General William A. Holland Parkway Just upstream of General William A. Holland Parkway Little Swamp Creek At confluence with Swamp Creek At Norfolk Southern Railway Approximately 800 feet upstream of Norfolk Southern Railway McLellan Creek At confluence with Mill Creek At North Tibbs Road

Drainage Area (square miles)

10-PercentAnnual-Chance

2-PercentAnnual-Chance

0.79

360

630

760

1,120

0.5

260

460

560

840

1.4

660

1,050

1,240

1,740

14.5

3,180

4,760

5,490

7,400

11.5 4.8

3,070 1,380

4,520 2,170

5,170 2,550

6,900 3,540

3.7

1,120

1,780

2,100

2,960

32.5

5,100

7,400

8,400

11,300

30.5

4,900

7,100

8,100

11,000

4.0

490

1,360

1,560

2,100

2.9

800

1,190

1,370

1,810

1.6

520

770

890

1,170

5.9

1,170

*

2,050

*

4.7

1,010

*

1,760

*

3.1

760

*

1,340

*

3.04

930

1,510

1,790

2,550

1.74

580

990

1,190

1,750

* Data not available

9

1-PercentAnnual-Chance

0.2-PercentAnnual-Chance

Table 4 - Summary of Discharges (Continued) Peak Discharges (cubic feet per second) Flooding Source and Location Mill Creek At confluence with Coahulla Creek At Business U.S. Highway 76/ State Highway 52/ Chatsworth Highway Just downstream of confluence of City Park Branch Just downstream of confluence of Haig Mill Creek At CSX railroad Approximately 1,120 feet downstream of Greenvalley Drive Poplar Springs Creek Approximately 670 feet downstream of Poplar Springs Road Approximately 220 feet upstream of Poplar Springs Road Just downstream of Reed Pond Road Northwest Slaughter Pen Creek At confluence with Mill Creek At Hair Street Stacy Branch At confluence with Drowning Bear Creek Approximately 1,440 feet upstream of Abutment Road Tar Creek Just downstream of confluence of Tar Creek Tributary Just upstream of confluence of Tar Creek Tributary Tar Creek Tributary At the confluence with Tar Creek

Drainage Area (square miles)

10-PercentAnnual-Chance

2-PercentAnnual-Chance

1-PercentAnnual-Chance

0.2-PercentAnnual-Chance

52.8

6,240

9,380

10,780

14,600

50.6

6,010

9,120

10,550

14,270

44.5

5,210

9,020

9,330

12,730

38.4

4,720

7,290

8,500

11,630

23.0 17.8

3,170 2,510

5,020 3,820

5,910 4,320

8,210 5,800

1.98

502

891

1,011

*

1.08

466

828

940

*

0.43

288

514

584

*

0.95

570

890

1,030

1,440

0.47

400

610

710

990

1.56

710

1,110

1,320

1,850

0.67

400

650

770

1,100

5.95

2,110

3,100

3,550

4,730

4.61

1,730

2,560

2,950

3,970

1.29

760

1,150

1,320

1,810

* Data not available

10

Stillwater elevations for Leisure Lake are shown in Table 5. Table 5 - Summary of Stillwater Elevations Water Surface Elevations (Feet /NAVD1) Flooding Source

10-PercentAnnual-Chance

Leisure Lake

*

2-PercentAnnual-Chance

1-PercentAnnual-Chance

*

757.9

0.2-PercentAnnual-Chance *

1

North American Vertical Datum of 1988 * Data not available

3.2

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 Flood Insurance Rate Map (FIRM) represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data Table 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 report in conjunction with the data shown on the FIRM. Precountywide Analyses Cross sections for East Chickamauga Creek were obtained from field surveys. Cross sections for City Park Branch, Coahulla Creek, Colony Creek, Crown Creek, Drowning Bear Creek, Little Creek, Little Swamp Creek, McLellan Creek, Mill Creek, Slaughter Pen Creek, Stacy Branch, Tar Creek, and Tar Creek Tributary were developed from aerial photography (Woolpert Consultants, 1986a). The below-water channel geometry was obtained by field measurement. All bridges, dams, and culverts were field surveyed to obtain elevation data and structural geometry. Water surface elevations (WSELs) of floods of the selected recurrence intervals were computed using the USACE’s HEC-2 step-backwater computer program (USACE, 1984). Countywide Analyses Cross sections for Poplar Springs Creek were obtained from field surveys. WSELs for floods of the selected recurrence intervals were computed using the USACE’s HEC-RAS Version 3.1.0 (USACE, 2001). Starting WSELs were determined using the slope-area method. 11

Channel roughness factors (Manning’s “n”) used in the hydraulic computations where chosen by engineering judgment and based on field observations of stream channels and overbank floodplain areas. The channel and overbank “n” values for all streams studied by detailed methods are shown Table 6. Table 6 - Manning’s “n” Values Stream City Park Branch Coahulla Creek Colony Creek Crown Creek Drowning Bear Creek East Chickamauga Creek Little Creek Little Swamp Creek McLellan Creek Mill Creek Poplar Springs Creek Slaughter Pen Creek Stacy Branch Tar Creek Tar Creek Tributary

Channel “n”

Overbank “n”

0.035-0.045 0.035-0.045 0.035-0.045 0.035-0.045 0.035-0.045 0.018-0.082 0.035-0.045 0.035-0.045 0.035-0.045 0.030-0.045 0.033-0.035 0.035-0.045 0.035-0.045 0.035-0.045 0.035-0.045

0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185 0.033-0.100 0.060-0.185 0.060-0.185 0.060-0.185 0.060-0.185

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). Detailed studied streams that were not restudied as part of this map update may include a "profile baseline" on the maps. This "profile baseline" provides a link to the flood profiles included in the FIS report. The detailed studied stream centerline may have been digitized or redelineated as part of this revision. The "profile baselines" for these streams were based on the best available data at the time of their study and are depicted as they were on the previous FIRMs. In some cases where improved topographic data was used to redelineate floodplain boundaries, the "profile baseline" may deviate significantly from the channel centerline or may be 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. Cross sections for the limited detailed flood profile hydraulic analysis developed for this countywide study for the Conasauga River, Mill Creek Tributary to East Chickamauga Creek, and Mill Creek Tributary No. 1 were obtained using digital topography and field surveys. Cross sections for Mill 12

Creek Tributary No. 2 were obtained solely from field surveys. For Conasauga River, Tributary to Hayes Branch, and Mill Creek Tributary No. 1, the 1percent-annual-chance WSELs were computed using the USACE’s HEC-RAS hydraulic model, version 3.1.3 (USACE, 2005). WSELs for Mill Creek Tributary No. 2, were computed using HEC-RAS Version 3.1.2 (USACE, 2004). HEC-GeoRAS was used to delineate the 1-percent-annual-chance floodplain (USACE, 2000). Hydraulic models were prepared using digital elevation data (USGS, 1999), without surveying bathymetric data. Where bridge or culvert data were readily available, these data were included in the hydraulic model. Where structure data were not readily available, field measurements were made to approximate the bridge geometry in the hydraulic models. Models do not include field surveys that determine the specifics of channel and floodplain geometry. A limited detailed study can be upgraded to a full detailed study at a later date by verifying stream channel and overbank geometry, bridge and culvert geometry, and by analyzing multiple recurrence intervals. Flood profiles have been developed for streams studied by limited detailed methods to be used for floodplain management and flood insurance rating purposes. The flood profiles for the streams studied by limited detailed methods were published separately from this FIS report. Please contact your local floodplain administrator for more information. 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 in use for newly created or revised FIS reports and FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD). With the finalization of the North American Vertical Datum of 1988 (NAVD), many FIS reports and FIRMs are being prepared using NAVD as the referenced vertical datum. All flood elevations shown in this FIS report and on the FIRM are referenced to NAVD. Structure and ground elevations in the community must, therefore, be referenced to NAVD. It is important to note that adjacent communities may be referenced to NGVD. This may result in differences in Base Flood Elevations (BFEs) across the corporate limits between the communities. The average conversion factor that was used to convert the data in this FIS report to NAVD was calculated using the National Geodetic Survey’s (NGS) VERTCON online utility (NGS, 2006). The data points used to determine the conversion are listed in Table 7.

13

Table 7 - Vertical Datum Conversion

Quad Name Conutta Conutta Conutta Conutta Dalton South Dalton South Dalton North Dalton North Tunnel Hill

Corner SE SW NW NE SW SE SW SE SW

Longitude 84.87 85.00 85.00 84.88 85.00 84.88 85.00 84.88 85.13

Latitude 34.88 34.88 35.00 35.00 34.62 34.62 34.75 34.75 34.75

Conversion from NGVD29 to NAVD88 0.000 0.049 0.039 -0.003 0.056 0.007 0.085 0.010 0.069

Average=

0.035

For more information on NAVD88, see the FEMA publication entitled Converting the National Flood Insurance Program to the North American Vertical Datum of 1988 (FEMA, June 1992), or contact the Vertical Network Branch, National Geodetic Survey, Coast and Geodetic Survey, National Oceanic and Atmospheric Administration, Silver Spring, Maryland 20910 (Internet address http://www.ngs.noaa.gov). 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.

4.0

FLOODPLAIN MANAGEMENT APPLICATIONS The NFIP encourages State and local governments to adopt sound floodplain management programs. Therefore, each FIS provides 1-percent-annual-chance (100year) flood elevations and delineations of the 1- and 0.2-percent-annual-chance (500year) floodplain boundaries and 1-percent-annual-chance floodway to assist communities in developing floodplain management measures. This information is presented on the FIRM and in many components of the FIS report, including Flood Profiles, Floodway Data Table, and Summary of Stillwater Elevations 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.

14

4.1

Floodplain Boundaries To provide a national standard without regional discrimination, the 1-percentannual-chance 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 that was not redelineated, the 1- and 0.2percent-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 1:4,800, with a contour interval of 4 feet (Woolpert Consultants, 1986b). For this countywide study, for redelineated streams listed in Table 2, streams studied by limited detailed methods listed in Table 3, and Poplar Springs Creek, floodplain boundaries were delineated using the DEM created by point elevation datasets submitted by Whitfield County (Whitfield County, 2003). 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 the streams studied by approximate methods, only the 1-percent-annualchance floodplain boundary is shown on the FIRM (Exhibit 2).

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. The floodways in this study are presented to local agencies as

15

minimum standards that can be adopted directly or that can be used as a basis for additional floodway studies. The floodways presented in this FIS report and on the FIRM were computed for certain stream segments on the basis of equal-conveyance reduction from each side of the floodplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. The results of the floodway computations have been tabulated for selected cross sections (Table 8). In cases where the floodway and 1-percent-annual-chance floodplain boundaries are either close together or collinear, only the floodway boundary has been shown. The area between the floodway and 1-percent-annual-chance floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the WSEL of the 1-percent-annual-chance flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 1.

Figure 1 - Floodway Schematic

16

FLOODING SOURCE

CROSS SECTION

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY

1

DISTANCE

WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

CITY PARK BRANCH A B C D

1,057 2,432 3,857 5,255

68 41 34 27

262 170 114 114

4.2 6.5 6.5 6.5

695.2 700.3 704.6 716.2

0695.12 700.3 704.6 716.2

695.8 700.6 705.3 716.2

0.7 0.3 0.7 0.0

COLONY CREEK A B

780 1,800

25 100

128 272

5.9 2.8

687.7 687.7

0681.82 0686.32

682.8 686.9

1.0 0.6

CROWN CREEK A B C D E F G H I J

116 828 1,692 1,861 1,986 2,034 2,348 2,598 2,993 3,118

130 120 116 25 48 51 139 193 120 149

616 261 260 181 280 303 232 243 1,024 857

2.0 4.7 4.8 6.8 4.4 4.1 5.3 5.1 1.2 1.4

708.6 708.6 708.9 711.9 714.7 714.9 717.2 721.4 731.7 731.7

0702.42 0704.82 708.9 711.9 714.7 714.9 717.2 721.4 731.7 731.7

703.0 705.0 709.1 712.7 715.4 715.7 717.8 721.4 731.7 731.7

0.6 0.2 0.2 0.8 0.7 0.8 0.6 0.0 0.0 0.0

1

Feet above confluence with Mill Creek Elevations computed without consideration of backwater effects from Mill Creek

2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

FLOODWAY DATA CITY PARK BRANCH – COLONY CREEK – CROWN CREEK

FLOODING SOURCE

CROSS SECTION

DISTANCE

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

DROWNING BEAR CREEK A B C D E F G H I J K

14,2551 15,2801 18,5551 20,7501 22,1251 25,3351 26,0781 26,8701 27,8301 29,7701 32,2601

560 878 483 665 739 2502 370 100 49 76 115

3,342 5,625 2,221 6,084 4,690 726 796 755 387 349 558

1.6 1.0 2.5 0.8 1.1 3.5 3.2 3.4 6.6 7.3 3.8

677.8 678.1 684.0 687.7 687.8 693.2 698.3 703.1 705.6 714.6 722.2

677.8 678.1 684.0 687.7 687.8 693.2 698.3 703.1 705.6 714.6 722.2

678.2 678.5 684.6 687.9 688.0 693.7 698.5 703.2 705.8 715.2 722.3

0.4 0.4 0.6 0.2 0.2 0.5 0.2 0.1 0.2 0.6 0.1

EAST CHICKAMAUGA CREEK A

47,3623

450/2172

3,950

2.1

808.0

808.0

808.5

0.5

1

Feet above confluence with Conasauga River Total width/width within county 3 Feet above confluence with South Chickamauga Creek 2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

DROWNING BEAR CREEK – EAST CHICKAMAUGA CREEK

FLOODING SOURCE

CROSS SECTION

DISTANCE

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

LITTLE CREEK A B C D E F G H I J

9,0801 10,6201 11,7301 12,9051 14,9151 16,9201 18,5401 19,0001 19,4401 20,1901

130 170 112 100 80 75 46 50 55 50

357 925 308 401 397 216 193 317 474 300

4.4 1.5 4.4 3.4 3.4 4.1 4.6 2.8 1.9 3.0

668.8 676.1 676.3 682.2 686.9 693.0 697.9 703.9 707.4 707.8

668.8 676.1 676.3 682.2 686.9 693.0 697.9 703.9 707.4 707.8

669.6 676.6 677.3 682.3 687.8 693.0 698.2 704.0 707.5 708.0

0.8 0.5 1.0 0.1 0.9 0.0 0.3 0.1 0.1 0.2

MCLELLAN CREEK A B C D E

5312 8862 1,7312 3,4562 4,4362

157 113 456 340 42

658 1,326 3,855 350 204

2.7 1.3 0.5 4.3 7.3

719.8 721.9 722.2 727.2 737.6

711.13 721.9 722.2 727.2 737.6

712.1 722.2 722.5 727.2 737.6

1.0 0.3 0.3 0.0 0.0

1

Feet above confluence with Conasauga River Feet above confluence with Mill Creek 3 Elevations computed without consideration of backwater effects from Mill Creek 2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

LITTLE CREEK – MCLELLAN CREEK

FLOODING SOURCE

CROSS SECTION

DISTANCE

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

MCLELLAN CREEK (CONTINUED) F G H I J K L M N

6,2861 7,7641 8,4511 8,8201 9,7091 9,8991 10,1291 10,4041 11,1291

74 47 168 78 56 58 212 65 22

302 209 532 207 133 262 1,177 166 58

3.9 5.7 2.2 5.7 6.6 3.4 0.7 3.2 9.3

744.3 756.3 759.6 761.1 766.9 769.7 774.8 775.2 783.7

744.3 756.3 759.6 761.1 766.9 769.7 774.8 775.2 783.7

745.2 756.7 760.2 761.6 766.9 770.6 775.6 776.1 783.7

0.9 0.4 0.6 0.5 0.0 0.9 0.8 0.9 0.0

MILL CREEK A B C D E F G H

2,1402 4,4102 6,8202 9,1302 9,9402 12,3452 13,3202 15,5802

658 933 353 610 746 726 450 367

4,008 3,909 3,302 4,191 5,589 6,264 3,726 2,804

2.7 2.8 3.2 2.5 1.8 1.7 2.8 3.8

682.7 682.7 682.7 683.9 687.0 687.7 688.0 689.6

0677.23 0679.83 0682.63 683.9 687.0 687.7 688.0 698.6

678.0 680.4 682.9 684.9 687.3 688.1 688.4 699.2

0.8 0.6 0.3 1.0 0.3 0.4 0.4 0.6

1

Feet above confluence with Mill Creek Feet above confluence with Coahulla Creek 3 Elevation computed without consideration of backwater effects from Coahulla Creek 2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

MCLELLAN CREEK – MILL CREEK

FLOODING SOURCE

CROSS SECTION MILL CREEK (CONTINUED) I J K L M N O P Q R S T U V W X

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY

1

DISTANCE

WIDTH (FEET)

16,940 18,825 22,780 25,280 26,630 26,950 28,610 33,130 34,430 37,260 38,400 40,550 42,250 43,450 45,600 46,685

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

568 481 762 460 160 283 327 571 361 428 221

4,198 3,812 3,845 3,840 1,484 2,773 2,019 3,870 3,012 4,335 2,004

2.5 2.8 2.4 2.4 6.3 3.4 4.6 2.4 2.8 2.0 4.2

246 711 249 100 56

1,911 6,174 2,356 1,289 879

4.4 1.4 3.6 1.4 6.7

REGULATORY (FEET NAVD)

691.3 692.2 694.6 696.6 702.1 703.5 704.3 709.1 709.9 713.9 715.3 718.5 720.1 722.7 725.4 725.7

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

691.3 692.2 694.6 696.6 702.1 703.5 704.3 709.1 709.9 713.9 715.3 718.5 720.1 722.7 725.4 725.7

692.1 693.1 695.5 697.5 702.1 703.8 704.7 709.3 710.3 714.5 716.2 718.7 720.4 722.7 725.4 726.5

1

Feet above confluence with Coahulla Creek

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

MILL CREEK

INCREASE (FEET)

0.8 0.9 0.9 0.9 0.0 0.3 0.4 0.2 0.4 0.6 0.9 0.2 0.3 0.0 0.0 0.8

FLOODING SOURCE

CROSS SECTION

DISTANCE

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

MILL CREEK (CONTINUED) Y Z AA AB AC AD AE

49,5651 50,5201 51,3801 52,1951 53,7801 56,3301 58,6901

155 149 177 123 240 345 329

2,864 1,907 2,675 1,619 2,795 3,662 2,076

2.1 3.1 2.2 3.7 2.1 1.2 2.1

738.4 738.4 739.0 739.1 739.7 740.1 740.6

738.4 738.4 739.0 739.1 739.7 740.1 740.6

738.4 738.6 739.1 739.4 740.2 740.9 741.6

0.0 0.2 0.1 0.3 0.5 0.8 1.0

SLAUGHTER PEN CREEK A B C D E F G

1942 7762 1,8002 3,2762 3,9632 4,3852 4,8002

101 24 182 38 52 34 71

512 172 678 160 277 153 318

2.0 6.0 1.5 5.3 3.1 4.6 2.2

689.4 689.4 690.6 693.9 697.7 698.5 703.4

0684.53 0688.43 690.6 693.9 697.7 698.5 703.4

685.3 688.8 691.6 694.4 698.0 698.8 703.4

0.8 0.4 1.0 0.5 0.3 0.3 0.0

1

Feet above confluence with Coahulla Creek Feet above confluence with Mill Creek 3 Elevation computed without consideration of backwater effects from Mill Creek 2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

MILL CREEK – SLAUGHTER PEN CREEK

FLOODING SOURCE

CROSS SECTION

DISTANCE

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

INCREASE (FEET)

SLAUGHTER PEN CREEK (CONTINUED) H I J K L

5,0691 5,4711 6,3391 6,7871 7,3421

133 203 156 75 36

219 1,125 216 494 129

3.2 0.6 3.3 1.4 2.5

703.8 707.6 712.2 721.3 725.3

703.8 707.6 712.2 721.3 725.3

704.0 707.9 712.3 722.1 726.3

0.2 0.3 0.1 0.8 1.0

STACY BRANCH A B C D E

3,6992 4,5412 5,9692 6,4942 7,4982

50 100 57 47 41

229 708 204 163 204

5.8 1.9 6.5 4.7 3.8

687.9 691.7 694.7 698.5 702.7

687.9 691.7 694.7 698.5 702.7

688.9 692.4 695.5 698.7 703.7

1.0 0.7 0.8 0.2 1.0

1

Feet above confluence with Mill Creek Feet above confluence with Drowning Bear Creek

2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

SLAUGHTER PEN CREEK – STACY BRANCH

FLOODING SOURCE

CROSS SECTION

DISTANCE

WIDTH (FEET)

SECTION AREA (SQUARE FEET) 2,213 3,930 1,177 853 525 1,951 319 1,255 606 204 124 186

1.6 1.2 3.0 3.5 4.0 1.1 6.5 1.7 3.4 6.7 11.0 7.3

433 403 84

1.6 1.7 5.9

TAR CREEK A B C D E F G H I J K L

3,8501 5,6701 6,6661 7,8701 10,7741 12,8861 13,6251 16,6881 17,5851 18,0021

337 421 241 192 80 324 154 228 300 50 33 37

TAR CREEK TRIBUTARY A B C

2,8503 4,3853 6,8673

135 113 15

4301 2,2701

1-PERCENT-ANNUAL-CHANCE-FLOOD WATER SURFACE ELEVATION

FLOODWAY MEAN VELOCITY (FEET PER SECOND)

WITHOUT FLOODWAY

WITH FLOODWAY

(FEET NAVD)

(FEET NAVD)

687.8 688.1 689.7 695.1 710.1 711.3 719.8 728.1 733.2 752.5 760.7 765.5

0687.02 688.1 689.7 695.1 710.1 711.3 719.8 728.1 733.2 752.5 760.7 765.5

688.0 689.1 690.6 696.1 711.1 712.3 719.8 729.1 733.5 753.4 760.7 765.5

1.0 1.0 0.9 1.0 1.0 1.0 0.0 1.0 0.3 0.9 0.0 0.0

700.7 710.0 725.2

700.7 710.0 725.2

701.7 710.7 726.2

1.0 0.7 1.0

REGULATORY (FEET NAVD)

INCREASE (FEET)

1

Feet above confluence with Drowning Bear Creek Elevation computed without consideration of backwater effects from Drowning Bear Creek 3 Feet above confluence with Tar Creek 2

TABLE 8

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

TAR CREEK – TAR CREEK TRIBUTARY

5.0

INSURANCE APPLICATIONS For flood insurance rating purposes, flood insurance zone designations are assigned to a community based on the results of the engineering analyses. These zones are as follows: Zone A Zone A is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for such areas, no BFEs or base flood depths are shown within this zone.

Zone AE Zone AE is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined in the FIS by detailed methods. In most instances, wholefoot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone X Zone X is the flood insurance risk zone that corresponds to areas outside the 0.2-percentannual-chance floodplain, areas within the 0.2-percent-annual-chance floodplain, areas of 1-percent-annual-chance flooding where average depths are less than 1 foot, areas of 1percent-annual-chance flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 1-percent-annual-chance flood by levees. 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 entire geographic area of Whitfield County. Previously, FIRMs were prepared for each incorporated community

25

and the unincorporated areas of the County identified as flood-prone. This countywide FIRM also includes flood-hazard information that was presented separately on Flood Boundary and Floodway Maps, where applicable. Historical data relating to the maps prepared for each community are presented in Table 9. 7.0

OTHER STUDIES This report either supersedes or is compatible with all previous studies on streams studied in this report and should be considered authoritative for purposes of the NFIP.

8.0

LOCATION OF DATA Information concerning the pertinent data used in the 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 30341.

9.0

BIBLIOGRAPHY AND REFERENCES Atlanta Regional Commission, Georgia Stormwater Management Manual, Volume 2, First Edition, August 2001. ESRI, ArcGIS, ArcMAP, Version 9.0, 2005. Federal Emergency Management Agency, Flood Insurance Study, Catoosa County, Georgia (Unincorporated Areas), July 5, 1984. Federal Emergency Management Agency, Flood Insurance Study, City of Dalton, Whitfield County, Georgia, February 16, 1990a. Federal Emergency Management Agency, Flood Insurance Study, Whitfield County, Georgia (Unincorporated Areas), February 16, 1990b. Federal Emergency Management Agency, Converting the National Flood Insurance Program to the North American Vertical Datum of 1988, Guidelines for Community Officials, Engineers, and Surveyors, June 1992. Federal Insurance Administration, Flood Insurance Study, City of Dalton, Whitfield County, Georgia, U.S. Department of Housing and Urban Development, December 4, 1979. Hydrologic Engineering Center, HEC-2 Water Surface Profiles, U.S. Army Corps of Engineers, Davis, California, April 1984.

26

COMMUNITY NAME

INITIAL IDENTIFICATION

FLOOD HAZARD BOUNDAY MAP REVISION DATE

FIRM EFFECTIVE DATE

Cohutta, Town of

September 19, 2007

None

September 19, 2007

Dalton, City of

August 16, 1974

August 20, 1976

December 4, 1979

February 16, 1990 September 19, 2007

Tunnel Hill, City of

October 6, 1978

None

February 1, 1991

September 19, 2007

Varnell, City of

September 19, 2007

None

September 19, 2007

Whitfield County (Unincorporated Areas)

April 14, 1978

July 16, 1987

February 16, 1990

FIRM REVISION DATE None

None September 19, 2007

TABLE 9

FEDERAL EMERGENCY MANAGEMENT AGENCY

WHITFIELD COUNTY, GA AND INCORPORATED AREAS

COMMUNITY MAP HISTORY

Hydrologic Engineering Center, HEC-GeoRAS, Version 3.0, U.S. Army Corps of Engineers, Davis, California, April 2000. Hydrologic Engineering Center, HEC-RAS River Analysis System, Version 3.1.0, U.S. Army Corps of Engineers, Davis, California, March 2001. Hydrologic Engineering Center, HEC-HMS Hydrologic Modeling System, U.S. Army Corps of Engineers, Davis, California, October 2002. Hydrologic Engineering Center, HEC-RAS River Analysis System, Version 3.1.2, U.S. Army Corps of Engineers, Davis, California, April 2004. Hydrologic Engineering Center, HEC-RAS River Analysis System, Version 3.1.3, U.S. Army Corps of Engineers, Davis, California, May 2005. National Geodetic Survey. VERTCON - North American Vertical Datum Conversion Utility. Retrieved on January 4, 2006, from http://www.ngs.noaa.gov/cgibin/VERTCON/vert_con.prl. Post, Buckley, Schuh, & Jernigan, Inc., Hydrology Study for Unincorporated Whitfield County, Atlanta, Georgia, March 1986. Soil Conservation Service, Watershed Work Plan for Mill Creek Watershed, Walker, and Whitfield Counties, Georgia. Coosa River and Soil and Water Conservation District, March 1958. Soil Conservation Service, Urban Hydrology for Small Watersheds, Technical Release 55, June 1986. The Weather Channel. Monthly Averages for Dalton, Georgia. Retrieved March 27, 2006 from http://www/weather.com. U.S. Census Bureau, American Factfinder, Whitfield County, Georgia, 2005. Retrieved on March 28, 2007, from http://www.factfinder.census.gov. U.S. Geological Survey, Floods in Georgia, Magnitude and Frequency: Techniques for Estimating the Magnitude and Frequency of Floods in Georgia with Compilation of Flood Data through 1974, Water Resources Investigations Report 78-137, McGlone Price, October 1979. U.S. Geological Survey, Flood Characteristics of Urban Watersheds in the United States, Techniques for Estimating Magnitude and Frequency of Urban Floods, Water Supply Paper 2207, V. B. Sauer, W.O. Thomas Jr., V. A. Stricker, and K. V. Wilson, 1983.

28

U.S. Geological Survey, Techniques for Estimating Magnitude and Frequency of Floods in Rural Basins of Georgia, Water Resources Investigations Report 934016, 1993. U.S. Geological Survey, National Elevation Dataset, Beaverdale, GA, Calhoun North, GA, Calhoun NE, GA, Catlett, GA, Chatsworth, GA, Cohutta, GA, Dalton North, GA, Dalton South, GA, Nickajack Gap, GA, Ringgold, GA, Sugar Valley, GA, Tunnel Hill, GA, Villanow, GA, 7.5-minute Series, Contour Interval 20 feet, USGS EROS Data Center, Sioux Falls, South Dakota, 1999. Water Resources Council, Hydrology Committee, Guidelines for Determining Flood Flow Frequency, Bulletin # 17, March 1976. Whitfield County, Georgia, Digital Elevation Model, 2003. Woolpert Consultants, Aerial Photographs, Whitfield County, Georgia, Scale 1:14,400, Mobile Alabama, 1986a. Woolpert Consultants, Topographic Maps, Whitfield County, Georgia, Scale 1:4,800, Contour Interval 4 Feet: Mobile, Alabama, 1986b.

29