Federal Emergency Management Agency

ORANGE COUNTY, TEXAS AND INCORPORATED AREAS COMMUNITY NAME BRIDGE CITY, CITY OF ORANGE, CITY OF ORANGE COUNTY UNINCORPORATED AREAS PINE FOREST, CITY OF PINEHURST, CITY OF ROSE CITY, CITY OF VIDOR, CITY OF WEST ORANGE, CITY OF COMMUNITY NUMBER 480511 480512 480510 480697 480513 481061 480514 480515 Effective, Federal Emergency Management Agency Flood Insurance Study Number 48361CV000A i

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 may not contain all data available within the repository. It is advisable to contact the community repository for any additional data. Selected Flood Insurance Rate Map panels for the community contain information that was previously shown separately on the corresponding Flood Boundary and Floodway Map panels (e.g., floodways, cross-sections). In addition, former flood hazard zone designations have been changed as follows: Old Zone A1 through A30 V1 through V30 B C New Zone AE VE X X This preliminary revised Flood Insurance Study contains profiles presented at a reduced scale to minimize reproduction costs. All profiles will be included and printed at full scale in the final published report. Part or all of this Flood Insurance Study (FIS) may be revised and republished at any time. In addition, part of this Flood Insurance Study may be revised by the Letter of Map Revision process, which does not involve republication or redistribution of the Flood Insurance Study. It is, therefore, the responsibility of the user to consult with community officials and to check the community repository to obtain the most current Flood Insurance Study components. Initial countywide FIS effective date: ii

TABLE OF CONTENTS 1.0 INTRODUCTION... 1 Page 1.1 Purpose of Study... 1 1.2 Authority and Acknowledgments... 1 1.3 Coordination... 2 2.0 AREA STUDIED... 2 2.1 Scope of Study... 2 2.2 Community Description... 4 2.3 Principal Flood Problems... 9 2.4 Flood Protection Measures... 14 3.0 ENGINEERING METHODS... 15 3.1 Hydrologic Analyses... 15 3.2 Hydraulic Analyses... 17 3.3 Coastal Analyses... 18 3.3.1 Storm Surge Analysis and Modeling... 19 3.3.2 Statistical Analysis... 20 3.3.3 Stillwater Elevations... 21 3.3.4 Wave Height Analysis... 21 3.4 Vertical Datum... 29 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS... 29 4.1 Floodplain Boundaries... 30 4.2 Floodways... 30 4.3 Base Flood Elevations... 44 4.4 Velocity Zones... 44 5.0 INSURANCE APPLICATIONS... 44 6.0 FLOOD INSURANCE RATE MAP... 45 7.0 OTHER STUDIES... 47 8.0 LOCATION OF DATA... 48 9.0 BIBLIOGRAPHY AND REFERENCES... 49 iii

TABLE OF CONTENTS (Cont d) FIGURES Figure 1 Transect Schematic... 22 Figure 2 Transect Location Map... 23 Figure 3 Floodway Schematic... 31 TABLES Table 1 Scope of Previous Studies... 3 Table 2 Stream Name Changes... 4 Table 3 Summary of Discharges... 16 Table 4 Coastal Data Table... 24 Table 5 Floodway Data... 32 Table 6 Community Map History... 46 Page Exhibit 1 Flood Profiles EXHIBITS Adams Bayou Panels 01P-03P Anderson Gully Panels 04P-05P Caney Creek Panel 06P Coon Bayou Panel 07P Coopers Gully Panel 08P Cow Bayou Panels 09P-10P Cow Bayou Lateral No. 14 Panel 11P Gum Gully Panel 12P Hudson Gully Panel 13P Little Cypress Bayou Panel 14P Little Cypress Bayou Tributary Panel 15P Meyers Bayou Panel 16P Neches River Panels 17P-18P Sabine River Panels 19P-20P Sandy Creek Panel 21P Ten Mile Creek Panel 22P Ten Mile Creek West Fork Panel 23P Tiger Creek Panel 24P Walnut Run Creek Panel 25P Exhibit 2 Flood Insurance Rate Map Index Flood Insurance Rate Maps Exhibit 3 0.2 Percent Annual Chance Wave Envelope - Transect Profiles iv

1.0 INTRODUCTION FLOOD INSURANCE STUDY ORANGE COUNTY, TEXAS [AND INCORPORATED AREAS] 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 Orange County, Texas, including the Cities of Bridge City, Orange, Pine Forest, Pinehurst, Rose City, Vidor, and West Orange; and the unincorporated areas of Orange County (referred to collectively herein as Orange 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. 1.2 Authority and Acknowledgments The sources of authority for this FIS report are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. The initial hydrologic and hydraulic analyses for the original studies in Orange County were performed by Tetra Tech, Inc. for the Federal Emergency Management Agency (FEMA), under Contract No. H-4788. This study was completed in June 1980. Updated hydrologic and hydraulic analyses for Cow Bayou were performed by Dodson and Associates, Inc., for the Orange County Drainage District. This study was completed in December 2002. The Comprehensive Flood Risk Resources & Response Joint Venture (CF3R) completed the base mapping activities and floodplain mapping (redelineating using effective flood profiles and updated topographic data) in accordance with Task Order 29, Task 40 for Orange County, Texas under Contract No. EMT-2002-CO-0049. The topographic data consist of countywide LiDAR data collected and processed by Sanborn from Colorado Springs, Colorado from June 2006 to April 2007. Michael Baker Jr., Inc. (Baker), a member of CF3R Joint Venture, managed the LiDAR data acquisition and processing effort. The Texas Coastal LiDAR Campaign Final Report for Orange County was completed in April 2007. Several sources were used for the base map data in this study. USGS Quadrangle information, obtained from the US Geological Survey was used primarily in the development of the FIRM Panel index layout. This data was obtained in November of 2007 with an unknown publication date. The original geographic coordinate system, North American Datum NAD 83, was converted to state plane Texas Central Zone 4203. Permanent 1

benchmark data was obtained from NOAA, National Geodetic Survey in October of 2007 with a publication date of 2004. North American Datum NAD 83 was the original geographic coordinate system converted to state plane Texas Central Zone 4203, using NGVD 88 vertical datum. All other base map data was provided by the Orange County Drainage District to be used in the study. The data was delivered in ArcGIS shapefile format in July 2008 and included transportation, surface water features (rivers, bayous, lakes, ponds), structures and political boundary areas projected in state plane Texas Central Zone 4203. All base map data was at a scale of 1:257,687, and all data was converted, if not already in, to state plane Texas Central Zone 4203 with NGVD 88 vertical datum. The storm surge analyses for this study were performed by the U.S. Army Corps of Engineers (USACE), for FEMA. This study was completed in November 2011. 1.3 Coordination 2.0 AREA STUDIED The following organizations were contacted for coordination in the development of the original Orange County studies: City of Bridge City, City of Orange, City of Pine Forest, City of Pinehurst, City of Vidor, City of West Orange, Orange County, National Oceanic and Atmospheric Administration, Orange Chamber of Commerce, C.P. Smith Associates, Inc., Southeast Texas Regional Planning Commission, Texas Highway Department, Texas State Department of Community Affairs, Texas State Department of Highways and Public Transportation, Texas Department of Water Resources, U.S. Army Corps of Engineers, Galveston District, U.S. Geological Survey, and the U.S. Natural Resource Conservation Service. The State Coordinator was involved with this study through the Denton Regional office of FEMA. The results of the initial study were reviewed at a final coordination meeting in Orange, Texas on February 11, 1982. For this initial countywide FIS, the initial Consultation Coordination Officer (CCO) meeting was held on March 16, 2006, and attended by representatives of FEMA, CF3R Joint Venture, and community representatives. The results of this study were reviewed at the final CCO meeting held on, and attended by representatives of. All problems raised at that meeting have been addressed in this study. 2.1 Scope of Study This FIS report covers the geographic area of Orange County, Texas, including the incorporated communities listed in Section 1.1. The areas studied by detailed methods in the previously developed FISs were selected with priority given to all known flood hazards and areas of projected development or proposed construction. No new areas, except the coastal area, were studied by detailed methods during the preparation of this countywide FIS. Redelineation of effective floodplain boundaries (Zone AE) were performed by using the updated topographic data developed as part of Terrain Data Development for the Digital Flood Insurance Rate Map (DFIRM) Update Project for Orange County, Texas. 2

Table 1, Scope of Previous Studies, documents the limits of study for those streams studied by detailed methods in previous FISs. TABLE 1 SCOPE OF PREVIOUS STUDIES Stream Limits of Detailed Study Adams Bayou 8.6 miles from a point approximately 8,280 feet upstream of F.M. 3247 to Dupont Drive Anderson Gully From Interstate Highway 10 to Southern Pacific Railroad Caney Creek From a point approximately 2,717 feet upstream of North Tram Road to its confluence with Tiger Creek Coon Bayou From a point approximately 2,680 feet upstream of East Hoo Hoo Road to its confluence with Cow Bayou Coopers Gully From 10 th Street to the Pier Road Pump Station in the City of Orange Cow Bayou From a point approximately 1,175 feet upstream of the confluence of Cow Bayou Lateral No. 14 to a point approximately 200 feet downstream of East Round Bunch Road Cow Bayou Lateral No. 14 From a point approximately 150 feet downstream of Interstate Highway 10 to its confluence with Cow Bayou Gum Gully From a point approximately 5,300 feet upstream of Alley Payne Road to F.M. 3247 Hudson Gully From a point approximately 900 feet upstream of 37 th Street in the City of Orange to its confluence with Adams Bayou Little Cypress Bayou From a point approximately 12,500 feet upstream of the confluence of Little Cypress Bayou Tributary to its confluence with the Sabine River Little Cypress Bayou Tributary Approximately 1.7 miles downstream to its confluence with Little Cypress Bayou Meyers Bayou From F.M. 105 to Old Spanish Trail Neches River From the Orange-Jasper County boundary downstream to the Kansas City Southern Railroad Sabine River From the Orange-Newton County boundary downstream to the southern corporate boundary of the City of Orange Sandy Creek From a point approximately 80 feet upstream of Burton Drive to its confluence with Cow Bayou Ten Mile Creek From a point approximately 8,000 feet upstream of F.M. 1131 to a point approximately 5,400 fee downstream of Lake View Road Ten Mile Creek West Fork From a point approximately 2,000 feet upstream of F.M. 1131 to its confluence with Ten Mile Creek Tiger Creek From a point approximately 8,300 feet upstream of F.M. 105 to a point approximately 3,200 feet downstream of the Caney Creek confluence Walnut Run Creek From a point approximately 2,200 feet upstream of Isaac Street to F.M. 1131 3

All or portions of the remaining significant creeks and tributaries in the county were studied by approximate methods. Approximate analyses were used to study those areas having a low development potential or minimal flood hazards. The scope and methods of study were proposed to, and agreed upon, by FEMA, the communities and CF3R. Table 2, Stream Name Changes lists those streams whose name has changed or differs from that published in the previous FIS report for Orange County or any of the communities within. TABLE 2 STREAM NAME CHANGES Community Old Name New Name Unincorporated Area Cow Bayou Tributary Cow Bayou Lateral No. 14 Unincorporated Area Walnut Run Walnut Run Creek The study analysis includes coastline flooding due to hurricane induced storm surge. Both the open coast surge and its inland propagation were studied; in addition, the added effects of wave heights were also considered. 2.2 Community Description Orange County occupies an area of approximately 380 square miles in southeastern Texas. The study area is bounded on the north by Newton and Jasper Counties, on the east by the Sabine River and the State of Louisiana, on the south by Sabine Lake, and on the west by Hardin and Jefferson Counties. The City of Orange, the county seat, is located approximately 110 miles east of Houston and approximately 20 miles northeast of Port Arthur. The U.S. Bureau of the Census recorded the 2010 population of Orange County at 81,837, which represented approximately a 3.7 percent decrease from the 2000 census estimate of 84,966 (Reference 1). The majority of developed land in the county is primarily forest and agricultural land. Major urban, residential, and recreational areas are generally located in the extreme eastern and western portions of the county. Most commercial development extends along U.S. Interstate Highway 10 that runs east to west through the county. Major industrial development is located along the Sabine River. Leading industries in the area produce oil, timber, iron, steel and petrochemicals. A naval base and shipyard in the City of Orange contribute to the economy. Orange County is located in a humid subtropical climatic zone, which is characterized by moderate winters and warm summers. Rainfall is abundant and, on the average, is evenly distributed throughout the year. The hurricane season extends from June through October. The annual precipitation average is 56 inches, and the average humidity is 89 percent at 6:00 A.M. and 69 percent at 6:00 P.M. The annual average temperature is 68 F, with average temperatures ranging in January from a low of 42 F to a high of 61 F and in July from 74 F to 91 F. Soils in Orange County are clayey and loamy, have low to moderate infiltration rates, and produce a moderate to high runoff potential. The soils are classified into Soil Conservation Service Groups A, B, C, and D for hydrologic purposes. 4

Orange County is heavily wooded, with extensive wetlands along the Neches and Sabine River basins. Large stands of natural cypress in swamps exist north of the City of Orange along the lower Sabine River. Physiographically, Orange County lies within the Gulf Coastal Plain province, which is characterized by relatively flat terrain with level or nearly level areas in the floodplains, and higher areas in the northern portions of the county. The elevations in the county range from sea level to about 30 feet above sea level using the North American Vertical Datum (NAVD) of 1988. Some areas in Orange County have undergone minor subsidence due to continued groundwater withdrawal and the inelastic behavior of the underlying clay in those areas. The magnitude of the subsidence has been less than one foot (Reference 2). The major streams within Orange County are the Neches and Sabine Rivers; Adams, Cow, and Little Cypress Bayous; Caney, Ten Mile and Tiger Creeks; and Anderson Gully. The Sabine River, which forms the county's eastern border, rises in northwestern Hunt County and discharges into Sabine Lake at Orange County's southern border. It is about 579 miles long and drains about 9,756 square miles in eastern Texas and western Louisiana (7,426 square miles in Texas). It has an average annual flow of 8,700 cubic feet per second (cfs). The Neches River, which forms the county's southern border, rises southeast of Dallas and flows generally southeastward for 416 miles to Sabine Lake south of Vidor. It drains about 10,011 square miles and has an average annual runoff of about 7,200 cfs. Cow Bayou flows southward from Jasper County and empties into Sabine River near Bridge City. It drains about 174 square miles of mostly forested and undeveloped land. Sandy Creek and Cow Bayou Lateral No. 14 are the major tributaries of Cow Bayou. Adams Bayou drains approximately 85 square miles in southern Newton and eastern Orange Counties. Gum Gully, a tributary of Adams Bayou drains about 5 square miles. Little Cypress Bayou flows through the north end of the Orange study limits. The watershed comprises about 25 square miles of southeast Texas. Little Cypress Bayou Tributary is the major tributary of Little Cypress Bayou. Tiger, Caney, and Ten Mile Creeks drain watershed areas of 30, 12, and 48 square miles respectively. Anderson and Terry Gullies, small coastal streams with poorly defined channels, drain a total area of 24 square miles. The City of Orange, county seat of Orange County, is located in the southeastern region of Orange County. It occupies an area of approximately 21 square miles on the Texas-Louisiana border between the west bank of Sabine River and the east bank of Adams Bayou. Portions of the city extend west of the Cities of Pinehurst and West Orange, which lie on the west bank of Adams Bayou. The city also is bounded on the north and south by unincorporated areas of Orange County. The city is located approximately 20 miles northeast of Port Arthur. Orange was incorporated as a city in 1881. The U.S. Bureau of the Census recorded the 2010 population of Orange at 18,595, which represented a slight decrease from the 2000 census of 18,643. Physiographically, the City of Orange lies in the transition zone between the Gulf Coastal Plain and the East Texas Pineywoods. It has relatively flat terrain with level or nearly level areas in the floodplains, and higher areas in the northwestern portion of the city. The average elevation in the city is approximately 7 feet NAVD. There was a flood protection levee and floodwall system along the Sabine River; however the levee was damaged in Hurricane Rita in September 2005. The northern end of the 5

system ties into the embankment of Simmons Drive which, in turn, ties into the Interstate Highway 10 embankment. The southern end of the system ends downstream of the city, and is not tied to high ground. The major streams within the City of Orange are Adams Bayou, Little Cypress Bayou, and the Sabine River. The rate of runoff in the area is generally slow because of the small conveyance capacities of the natural channel conditions along the lower Sabine River and Adams Bayou. These small capacities cause floods to frequently exceed the bankfull stage for long periods of time. Three separate interior drainage areas exist behind the damaged levee and floodwall system. The Brownwood and Naval Station watersheds drain about 0.4 and 0.1 square miles of the City of Orange, respectively. Runoff from these basins is discharged to the Sabine by gravity drainage structures located along and in the damaged levee. Coopers Gully watershed drains about 1.6 square miles of the city. Coopers Gully flows southeasterly through the central portion of the city. Runoff from this basin is pumped to the Sabine River via a pump station located at the mouth of Coopers Gully. The City of Bridge City, incorporated in 1970, is located in the southern portion of Orange County. It occupies an area of approximately 5.4 square miles just north of Sabine Lake and is surrounded by unincorporated areas of Orange County. The city is located approximately 20 miles east of Beaumont and 5 miles southwest of Orange. The U.S. Census Bureau recorded the 2010 population of Bridge City at 7,840, which represented a 9.4 percent decrease from the 2000 census of 8,651 (Reference 1). Bridge City s major commercial developments are generally located along U.S. Highway 87. Leading industries in the area produce steel, rubber, petrochemical products, ships and concrete. Agricultural products such as timber, rice, and soybeans also contribute to the economy of the area. Physiographically, Bridge City lies in the transition zone between the Gulf Coastal Plain and the East Texas Pineywoods, on the watershed divide separating the Neches and Sabine Rivers. The terrain is relatively flat; its elevations are relatively low and range from about 5 to about 10 feet above NAVD 88. Substantial areas are less than 10 feet NAVD. The major stream within Bridge City is Cow Bayou. The Sabine River is to the east and the Neches River is to the southwest of the city. Since the city is located on the watershed divide between these two rivers, it is subject to only minimal flooding from them. Cow Bayou flows southward from Jasper County through the northeastern corner of Bridge City, and empties into the Sabine River at the swamp east of Bridge City. It drains about 174 square miles of mostly forested and undeveloped land. The rate of runoff in the Bridge City area is generally slow because of the small conveyance capacities of the natural channel along Cow Bayou. These small capacities cause floods to frequently exceed bankfull stages for long periods of time. The City of Pine Forest is located in the northwest portion of Orange County. It occupies an area of approximately 2.8 square miles. It is bounded by unincorporated areas of Orange County. The city is located approximately 70 miles northeast of Galveston, approximately 70 miles east of Houston, about 1 mile north of the City of Vidor, approximately 3 miles northeast of Beaumont, and 18 miles northwest of Port Arthur. The city's 2010 population was recorded at 487 people, which represents a 23 percent decrease from the 2000 census of 632 (Reference 1). The city is primarily a residential area which lies in the Gulf Coastal 6

Plain, in a forest wetland. It has flat terrain with relatively higher areas in the north central portion of the city. The elevations in the city range from 5 to about 25 feet NAVD. The major streams within the City of Pine Forest are Ten Mile Creek and Tiger Creek. Caney Creek lies to the south of the city. The Neches River flows approximately 4 miles west of the city. Ten Mile Creek flows south from Jasper County and empties into the Neches River 3 miles south of Pine Forest. It drains approximately 48 square miles. The western portion of the study area lies within this watershed. Tiger Creek, which flows southwest through the city drains approximately 30 square miles and empties into the Neches River 3 miles south of Pine Forest. The rate of runoff in the area is generally slow because of the small conveyance capacities of the natural channel conditions. These small capacities cause floods to frequently exceed bankfull stages for long periods of time. The City of Pinehurst is located in the southeastern portion of Orange County. It occupies an area of approximately 1.8 square miles near the Texas-Louisiana border, on the west bank of Adams Bayou, about 4 miles west of the Sabine River. It is bounded on the north and east by the City of Orange, on the south by the City of West Orange, and on the west by the unincorporated areas of Orange County. The U.S. Bureau of the Census recorded the 2010 population of Pinehurst at 2,097, which represented a 7.8 percent decrease from the 2000 census of 2,274 (Reference 1). The city is primarily a residential area whose economy is based on the commercial and industrial (petrochemical) activity of the City of Orange. Physiographically, the City of Pinehurst lies in the transition zone between the Gulf Coastal Plain and the East Texas Pineywoods. The zone has relatively flat terrain with level or nearly level areas in the floodplains. The elevations of the city are relatively low and range from sea level to about 10 feet NAVD. The major stream within the City of Pinehurst is Adams Bayou, which forms the city's eastern boundary. Adams Bayou flows southeasterly through the city and drains approximately 86 square miles in southern Newton and eastern Orange Counties. Hudson Gully, a small tributary of Adams Bayou, flows into Adams Bayou at the southern portion of the city. The drainage area of the gully is less than 2 square miles. The City of Rose City is located in the western region of Orange County. It occupies an area of approximately 1.7 square miles just east of the Neches River. The city is approximately 15 miles west of Orange, 80 miles east of Houston, 2 miles east of Beaumont, and about 13 miles north of Port Arthur. It is bounded on the north, south, west, and partially on the east by unincorporated marshland areas of Orange County. On the western border is Baird's Bayou. To the northeast, the city is bounded by the City of Vidor. The U.S. Census Bureau recorded the 2010 population of Rose City at 502. The population has been relatively stable since 2000 when the population was 519 (Reference 1). This population is expected to remain quite stable since there is little possibility of expanding the city limits because the area is mostly surrounded by swamp. Most of the work force of Rose City commutes out of town to plants or businesses, generally in Beaumont. However, Rose City does have steel and sheet metal fabricating plants, as well as a few small businesses. 7

The major stream within the Rose City is Tiger Creek. Tiger Creek, whose headwaters are in Jasper County, runs through the eastern part of the city and enters the marshes southeast of Rose City. Tiger Creek's watershed area of about 30 square miles drains the most westerly portion of Orange County. The small, narrow, poorly defined channel has a restricted conveyance capacity, causing extensive overbank flooding which generally lasts for periods of several days. Within Rose City corporate limits Tiger Creek is controlled by flooding from Neches River. The Neches River is about 1 to 1.5 miles west of the city. The Neches River originates from Van Zandt County, flows generally southeastward for 416 miles, and then empties into Sabine Lake at Port Arthur. There are also several small lakes and bayous within the city limits. The elevation of the land in Rose City ranges from about 5 feet to 13 feet NAVD. Because of this low elevation, and because the surrounding area is lowland swamp, high winds during storms restrict water from draining until the storms subside. When the waters are allowed to drain, they run south into the swamp, and subsequently into the Neches River. Most of the flooding in Rose City is caused by backwater from the Neches River, as well as from heavy rainfall ponding. When flooding occurs in Baird's Bayou on the western border of the city, the feeder road to Interstate Highway 10 also floods. This road is eight feet below the highway. Interstate Highway 10 also has some low bridges which become inundated during intense rains. Another road in the southern part of town frequently floods during heavy rainfall. This is due to the fact that it is located in a depression between the elevated railroad and another area of higher elevation. The City of Vidor is located in the western region of Orange County. It occupies an area of approximately 10.6 square miles, approximately 13 miles west of the City of Orange approximately 80 miles east of Houston, approximately 8 miles east of Beaumont, and about 20 miles north of Port Arthur. It is bounded on the north and east, and partially on the south and west, by unincorporated areas of Orange County. To the southwest it is bounded by the City of Rose City. The U.S. Census Bureau recorded the 2010 population of the City of Vidor at 10,579, which represented a 7.5 percent decrease from the 2000 census of 11,440 (Reference 1). The City of Vidor was incorporated in 1960. It was a residential community until 1974, when a steel mill was built to the southwest of the city and other industries followed. The city's major residential developments surround the business area. Relatively large residential areas and some important commercial establishments exist within the floodplains. Major business and commercial development extend along State Highway 105 between the Kansas City Southern Railroad and Interstate Highway 10. Leading industries in the area are steel and paper mills. Some ranching and farming of the fertile delta soil in the Vidor area also contribute to the city's economy. The city's rapid commercial and residential development is expected to continue. Physiographically, the city lies in the Gulf Coastal Plain. The zone has flat terrain with relatively higher elevations in the areas adjacent to the Neches River Delta marshland, and is surrounded by forest. The elevation of the city ranges from sea level near the marshlands to about 23 feet NAVD. 8

The major streams within the City of Vidor are Tiger Creek, Meyers Bayou, and Anderson and Terry Gullies. Tiger Creek, whose headwaters are in Jasper County, runs through the western part of the city and enters the marshes southwest of Vidor. Its watershed area of about 30 square miles drains the most westerly portion of Orange County. Meyers Bayou, with a watershed area of 3.3 square miles, enters the marshlands south of Vidor. Anderson Gully, with a watershed area of 10.4 square miles, flows through the center of the city and drains about 2 square miles of the city. Terry Gully, another small coastal stream, has a watershed area of 10.3 square miles. These streams encompass a total drainage area of about 52 square miles. Their small, narrow, poorly defined channels have restricted conveyance capacities, causing extensive overbank flooding generally for periods of several days. The Neches River flows about 2 miles west of the city. The City of West Orange is located in the southeastern region of Orange County. It occupies an area of approximately 3.2 square miles near the Texas-Louisiana border, on the west bank of Adams Bayou, about 1 mile west of the Sabine River. It is bounded on the north by the City of Pinehurst and on the east, south and west by the City of Orange. The city is located approximately 100 miles northeast of Galveston, approximately 110 miles east of Houston, and approximately 25 miles east of Beaumont. West Orange was incorporated as a city in 1955. The U.S. Census Bureau recorded the 2010 population of West Orange at 3,443, which represented a 16 percent decrease from the 2000 census of 4,111 (Reference 1). The city is primarily urban. Its major residential and commercial developments are generally located in the flat terrain that extends along Adams Bayou. Some homes have been built in the low floodplains of Adams Bayou. The city's economy is based on petrochemicals, the leading industry in the Orange area. Physiographically, the city lies in the transition zone between the Gulf Coastal Plain and the East Texas Pineywoods. It has relatively flat terrain with level or nearly level areas in the floodplains. The elevation of the city is relatively low and ranges from sea level to about elevation 10 feet NAVD. The major stream within the City of West Orange is Adams Bayou, which flows southward through the city and forms the city's eastern boundary. It drains approximately 86 square miles in southern Newton and eastern Orange Counties. Three small tributaries flow eastward throughout the city, and empty into Adams Bayou. These tributaries divided the City of West Orange into three sub-basins with areas less than one square mile. The FIRMs identify the tributaries as Adams Bayou Lateral No. 1, Adams Bayou Lateral No. 10 and Forman Road Ditch. The rate of runoff in the area is generally slow because of the small conveyance capacities of the natural channel along Adams Bayou, causing floods to frequently exceed bankfull stages for long periods of time. 2.3 Principal Flood Problems Flooding in Orange County results primarily from stream overflow (caused by rainfall runoff, ponding, and sheet flow), and from tidal surges and associated wave action (caused by hurricanes and tropical storms) transmitted through the streams. High tide levels can intensify the stream overflow caused by rainfall runoff. Because of the flatness of the terrain, many inland areas are characterized by shallow flooding during heavy rainfall. Not all storms which pass close to the study area produce extremely high tides. Similarly, storms which produce extreme conditions in one area may not necessarily produce critical conditions in 9

other parts of the study area. The Sabine River and nearby streams are estuarine, and under certain conditions tides generated at their mouths can intrude far upstream. Rainfall which accompanies hurricanes aggravates the tidal flood situation. Storms passing Texas in the vicinity of Orange County have produced severe floods as well as structural damage. Brief descriptions of several significant storms provide historic information to which flood hazards and flood depths can be compared (References 3, 4, 5, 6, 7, 8 and 9). April 25, 1913 The Sabine River crested at elevation 6.6 feet NAVD at the staff gage at the Gulf State Utilities Pier in the City of Orange. April to June 1953 Heavy rainfall, produced by two storms occurring in the same general area, followed a period of above normal rainfall that had greatly built up the moisture content of the soil. Rainfall from April 28 to May 5 was more than 11 inches in the Lower Sabine and Neches River basins. From May 11 to 19, this storm brought heavy rainfall to the Sabine River basin. From May 13 to 19, 11.91 inches of rainfall was recorded in Orange. The storm caused extensive flooding in the lower areas. This storm caused homes to be flooded, buildings damaged, and roads inundated. There was minor flooding in downtown Orange on Water Street. The estimated velocities in the Sabine channel in the vicinity of Orange ranged up to 5 feet per second (fps); overbank velocities were lower (0.5 fps). The Sabine River was 6.2 feet NGVD. The staff gage at Gulf State Utilities Pier in the City of Orange reached 6.0 feet NAVD on May 24. Flood damage to the area was estimated at $460,000. June 27 to 28, 1957 (Hurricane Audrey) This first hurricane of the season hit the Louisiana coast near Cameron and passed inland with its center about 25 miles east of Sabine Pass. It was accompanied by 4 to 8 inch rains. Tide records at Sabine Lake near Port Arthur indicated a maximum water level of 4.8 feet above MSL, and a peak of 4.5 feet was recorded on the Neches River near Rose City. September 21 to 23, 1958 This storm produced 10.05 inches of rain in 24 hours, and 18.5 inches in 2 days. (Unofficial records show 14 inches in 9 hours in the City of Orange). A privately maintained gage at Bridge City recorded 14.75 inches on September 21 and a 2-day total of 18.5 inches of rainfall. There was serious flooding in areas along the unimproved section of Adams Bayou. Estimated damages in the cities of Orange, West Orange and Pinehurst were $630,000. Of this, about $320,000 in damage was to homes and buildings and about $240,000 to county roadways and structures. September 9 to 12, 1961 (Hurricane Carla) This hurricane, which made landfall near Port O Connor, flooded more than 1.5 million acres of land in Texas. Tide levels reached 9.4 feet NGVD along the northern shore of Sabine Pass. Tides caused the Sabine River to rise to 7.4 feet at the City of Orange, and near Cow Bayou, Bridge City was under approximately 7 feet of water. A storm surge level of 7.1 feet above MSL was reported at Port Arthur. Floodwater moved inland from the Gulf beaches for 15 to 20 miles and along the Neches River Valley to the vicinity of Rose City. 10

Flood levels reached 8.5 feet above the mouth of the Neches River, 7.9 feet near Port Neches, and 7.7 feet at Beaumont. Rainfall of 1.96 inches on the 11th and 12th in the City of Orange added to the flood conditions. Carla flooded 64 square miles of land in Orange County (18 percent of the total land area). Low-lying areas adjacent to the Sabine River were completely inundated by hurricane-driven waters. Unprotected areas at elevations of 7 feet or less were flooded, especially in the south side of the city and along Adams Bayou. Total damages were estimated at $1,707,000, of which $767,000 were attributed to tidal overflow. September 17 to 28, 1963 (Hurricane Cindy) This hurricane, which made landfall at High Island, brought 15.8 inches of rain in 24 hours in the Adams Bayou watershed. Adams Bayou reached a crest height of 8.22 feet NAVD about midway between the underclearance and floor level of the Southern Pacific Railroad Bridge. The Sabine River crested at 4.4 feet NAVD and Adams Bayou reached 8.2 feet NAVD on September 18th. The peak discharge (maximum runoff) produced on Cow Bayou near Mauriceville was 4,600 cfs. The torrential rainfall caused flooding and millions of dollars of damage to the Sabine-Neches area. Damages were estimated at $249,000 in Bridge City. June 25, 1968 Nine days of rainfall dropped more than 13 inches of water onto an already damp earth. Homes in the east and northeast areas of Vidor suffered flood damage. October 27 to 28, 1970 Estimated rainfall of 12 to 15 inches in a 24-hour period washed out bridges and flooded homes and underpasses. Caney Creek Road was reported to have been covered with about 5 feet of water during one period of the storm. The Cow Bayou gage near Mauriceville indicated a peak discharge of 4,420 cfs. April 19 to 24, 1979 Rainfall during this storm was recorded at more than 7 inches in Orange County, and caused flooding in many areas along the Neches and Sabine Rivers and Adams, Cow and Little Cypress Bayous. Most severely affected was the Lakeview area in the northwestern section of the county, where approximately 200 dwellings were damaged. The City of Vidor was the hardest hit area in Orange County, with $168,000.00 worth of damage to the city's roads and bridges, and flood damage to homes and automobiles. High water was also reported in the south Bridge City area. The Neches River crested at 11 feet NAVD near Rose City and Vidor (7 feet above flood stage), and the Sabine River crested at 1.3 feet above flood stage. July 25, 1979 (Tropical Storm Claudette) Tropical Storm Claudette, an upper air low pressure cell, originated in the Atlantic near Puerto Rico and moved westward into the Gulf of Mexico. It brought gale force winds and heavy rainfall to many parts of southeastern Texas, causing severe flooding along streams and coastal areas. Rainfall in Bridge City was estimated at 16 inches in 48 hours. In Orange County, power lines were down in some rural areas and home, road and agricultural damages were high. Major damage to 29 homes occurred in Orange County. High water in Adams Bayou caused some residential flooding in the Hillbrook Estates area in north Orange and also in the south Orange area. In the downtown area, water was reported 2 feet deep, and in the Riverside area up to 4 feet of water was reported. Cow Bayou and Adams Bayou overflowed their banks and flooded nearby low-lying areas. In Bridge City, the area around Ferry Drive and West Round Bunch Road was flooded when Cow Bayou overflowed its 11

banks. The southeast addition to the southeast of Bridge City was also flooded. Texas Highway 87 between Bridge City and Rainbow Bridge was under water. In Pinehurst, Adams Bayou overflowed its banks and some homes in the Camelot and Concord additions were flooded. There were nearly 33 inches of water on Camelot Drive. Mountain Drive, just east of Camelot Drive, was closed. There was also heavy flooding on many streets in Pinehurst. The streets in Vidor were flooded, but were generally passable. The Interstate 10 underpass was also flooded. In West Orange, Western and Austin Avenues were reported under water. Some of the city's low-lying areas were evacuated. July 13, 1994 Heavy rainfall produced widespread flooding. The roof of the Hillcrest Memorial Gardens building was damaged by the weight of water from the heavy rainfall. Total estimated damage was $55,000. September 27, 1996 Nearly nine inches of rain fell in less than six hours, resulting in significant flooding across Orange County. The hardest hit area was Vidor, where a housing complex on Highway 105 had several feet of water in it. Other areas with flooding included all the exit ramps and underpasses along Interstate 10. Estimated damage was $20,000. September 9 to 11, 1998 (Tropical Storm Frances) Tropical Storm Frances was the third tropical system to impact southeast Texas in 3 weeks, and caused the worst damage. Wind gusts in excess of 50 mph occurred along the coast on September 11 th, but most of the damage occurred from the high tides. At Sabine Pass, the tide reading reached 5.3 ft MSL, which was one of the highest tides in the previous 30 years. On top of the high tides, heavy rain lasting several days dropped 8 to 10 inches of rain across the region. At Sea Rim State Park, water got to the top of the dunes, which is 8 to 9 feet higher than normal. Offshore oil workers evacuated before 70 to 80 mph wind gusts impacted the rigs offshore. Many of these evacuees landed in Sabine Pass, and were caught in town due to the high tides. Sabine Pass was totally isolated from road traffic for three days due to high water. Nearly every home and business in Sabine Pass had salt water enter into them (over 70 structures). Highway 87 between Sabine Pass and Port Arthur received major damage, as did Highway 87 between Port Arthur and Bridge City, around the Rainbow Bridge. Pleasure Island received significant damage to the levee from the high tides and heavy wave action. The worst hit areas in Orange County included Bridge City and Vidor. Several roads were closed from September 11 th through the 13 th. Over 4,000 sandbags were passed out so homeowners could protect their homes from the high water. Estimated damage from Tropical Storm Frances was $7.0 million. March 4 to -12, 2001 The Sabine River had a major flood in early March, cresting five to six feet above flood stage between the 9 th and 11 th. Significant erosion occurred on the river bank, and many homes and camps immediately on the river were flooded. Many roads leading to the river were damaged from the rapidly moving water. Estimated damages were $300,000. June 5 to 6, 2001 (Tropical Storm Allison) Tropical Storm Allison caused minor problems along coastal sections of southeast Texas, but eventually resulted in catastrophic flood losses further inland. Wind gusts of 30 to 40 mph resulted in minor roof damage to less than ten homes along the coast in Orange County between the evening of June 5 th and the early morning hours of June 6 th. A two foot storm 12

surge resulted in minor beach erosion and portions of Highway 82 between Sabine Pass and Port Arthur to be under water during high tide during the nighttime high tide of June 5 th to 6 th. The specific flood events that occurred between June 7 th and 9 th were a result of the remnants of Tropical Storm Allison, as it meandered across southeast and east Texas. October 29, 2002 Over 600 homes across Orange County were flooded after 6 to 8 inches of rain fell in less than 6 hours. Of the 600 homes, around 300 were located in Orange, and 150 in Vidor. Total estimated damages were $3.0 million. September 23 to 24, 2005 (Hurricane Rita) Although Hurricane Rita made landfall just east of the Texas-Louisiana border, it moved northwest and moved across southeast Texas in the morning hours of September 24 th as a dangerous category 3 hurricane with sustained winds of 120 mph. Along the coast of Orange County, storm surges near 10 feet occurred near Sabine Pass, where over 90 percent of the homes were severely damaged or destroyed. The storm surge backed up the Sabine River, and flooded a small section of downtown Orange with around 4 to 5 feet of storm surge. Winds blew over 100 mph across the entire region, snapping and uprooting trees, and damaged over 125,000 homes and businesses. Total estimated property damage was $2.1 billion. October 16 to 21, 2006 Two day rain totals of 12 to 16 inches resulted in long duration flooding across portions of Orange County. The hardest hit areas were near Mauriceville, and along the Neches River near Lakeview. At least 40 homes were destroyed and another 60 were damaged. An abundance of moisture and high wind shear resulted in several tornadoes and flash floods across southeast Texas. Total estimated damage was $4.0 million. September 13, 2007 (Hurricane Humberto) Hurricane Humberto moved into Orange County around 3:15 A.M. between Vidor and Bridge City. Damage was primarily trees blown down, roof damage, and power lines downed. One fatality occurred in Bridge City. Power outages occurred to over 20,000 customers. Some flash flooding occurred in the urban areas between Beaumont and Orange. Highest estimated winds were around 80 knots or 90 mph, but hurricane-force wind only extended 15 miles. The lowest pressure reading was estimated to be 985 mb at landfall. Coastal storm tides were 3 to 5 feet, with the highest occurring at Texas Point. Total estimated damage was $10.0 million. August 5, 2008 (Tropical Storm Edouard) Tropical Storm Edouard produced minor wind damage and some coastal flooding along the southeast Texas coast before it made landfall around 7 A.M. CDT near McFaddin Wildlife Refuge in Jefferson County, Texas. The lowest pressure reading in southeast Texas occurred at Sea Rim State Park, where the barometer dropped to 996.6 mb. The strongest wind gusts were mainly 50 to 70 mph across Jefferson and Orange counties, including 56 mph at Southeast Texas Regional Airport ASOS and 71 mph at the Texas Point gage. Rainfall totals were between 1 and 3 inches. The highest storm tides were between 2 and 5 ft MLLW, including 3.75 ft at Sabine Pass North and 4.66 ft at Texas Point. In Orange County, a few trees and power lines were blown down. Up to 700 customers lost power. Minor roof damage occurred to some homes and businesses. Total estimated damage was $250,000. 13

September 12 to 13, 2008 (Hurricane Ike) Hurricane Ike made landfall near Galveston, Texas early in the morning on September 13 th as a strong category 2 hurricane. Sustained hurricane force winds were measured in western Orange County. Hurricane Ike caused wind damage and significant storm surge flooding across southeast Texas. The highest recorded winds were at Southeast Texas Regional Airport with sustained winds of 70 mph and gusts of 96 mph. The lowest pressure reading also occurred at Southeast Texas Regional Airport, with a low of 982.4 mb. Storm surge was significant. Sabine Pass had its highest water level recorded during Ike, with a maximum of 14.24 ft MLLW. This storm surge almost topped the seawall around Port Arthur. Large waves did crash over the seawall, causing some flooding of homes within 3 blocks of the seawall. In Orange County, Bridge City had nearly all of their homes flooded (over 3,000), and this extended north to Rose City, and northeast to the city of Orange, where water topped the levee on the east side of town. Over 3,000 homes were also flooded in Orange. Maximum storm total rainfall was between 5 and 8 inches across Orange and surrounding counties. One fatality occurred during Ike due to a vehicle being swept off Highway 73 near Rainbow Bridge by the large storm surge and waves. Total damages were estimated to be at least $1.3 billion across southeast Texas. 2.4 Flood Protection Measures Several structural flood protection measures were constructed in Orange County. Reservoirs (such as Toledo Bend, Murvaul, and Tawakoni), in the Sabine Watershed, and flood retarding structures in the upper basin of the Sabine River, provide flood storage volume and assist in prevention of floods. In the Bridge City area, the Cow Bayou channel was enlarged in 1952 to a 13-foot depth and 100-foot width from its mouth to stream mile 6.7. The channel enlargement eased Cow Bayou from rainfall flooding but did not prevent surge intrusion. Additionally, channel improvements were completed by USACE on Adams Bayou. A diversion ditch north of Pinehurst traverses the Adams and Little Cypress Bayou watersheds and partially diverts runoff from the upper 32 square miles of Adams Bayou and 10 square miles of Little Cypress Bayou watersheds into the Sabine River. The City of Orange is partially protected from Sabine River floods by the locally-owned levee along Little Cypress Bayou and by an adjoining levee and floodwall along the Sabine River. The levee reduces the threat of flooding directly from Sabine River, but introduces some interior drainage problems. Also, the levee system does not prevent surge intrusion into Adams Bayou and resulting flooding of the surrounding low-lying areas. The levees in the vicinity of the City of Orange were damaged in storms and hurricanes during recent years, and are currently not certifiable and are not shown on the FIRMs. Nonstructural flood protection measures in the county consist of flood damage prevention ordinances, which were originally adopted by communities during the late 1970s and early 1980s. The ordinances place controls on the types of development and activities which are permissible in the floodplain. The National Weather Service provides forecasting and community flash flood warning services. 14

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 is 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 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 peak discharge-frequency relationships for each flooding source studied by detailed methods affecting the community. Flood magnitude and frequency for areas subject to runoff flooding from the streams studied in detail were estimated using the Corps of Engineers HEC-1 Flood Hydrograph Package (Reference 10). Regionalized unit hydrograph and rainfall loss rate parameters were developed by hydrograph reconstitution studies using thirty storms in six gaged basins. The transposition of the HEC-1 model parameters from gaged to ungaged basins was based on hydrologic similarity, as assessed from soil maps (References 11 and 12), USGS topographic maps (Reference 13), aerial photos (Reference 14) and field reconnaissance. Urbanized watersheds were studied further using methodology developed by Beard (References 15 and 16). Rainfall data used to estimate flood discharges for the various frequency events were developed from hourly rainfall records from the National Climatic Data Center (Reference 17) and from TP-40 (Reference 18). The resulting "computational" storms used to generate peak discharges of selected frequency have depth-area-duration characteristics consistent with the Texas Gulf Coast area. The effects of flow restrictions due to culverts and excessive backwater have been included in the hydrology. Flood discharge-frequency estimates for the Sabine and Neches Rivers were taken from the previously published Bridge City Flood Insurance Study (Reference 19) prepared by the USACE. The profiles for the 0.2-percent-annual-chance flood on both Ten Mile Creek and Tiger Creek were controlled by the 0.2-percent-annual-chance flood of the Neches River, overtopping the drainage divide. Peak discharge-drainage area relationships for each stream studied in detail are shown in Table 3, Summary of Discharges. 15

TABLE 3. SUMMARY OF DISCHARGES DRAINAGE AREA (sq. miles) 10% Annual Chance PEAK DISCHARGES (cfs) 2% 1% Annual Annual Chance Chance 0.2% Annual Chance FLOODING SOURCE AND LOCATION Adams Bayou At Water Supply Canal Upstream of Orange 69.0 (36.5) 1 3,440 4,800 5,400 6,780 At F.M. 1006/Dupont Road 82.50 4,180 5,870 6,630 8,330 Anderson Gully At North Feeder Interstate 10 1.80 1,200 1,500 1,650 2,000 At South Feeder Interstate 10 1.80 200 230 260 320 At Southern Corporate Boundary Limit 2.10 310 370 420 505 At Kansas City Southern Railroad Bridge 3.9 (2.4) 1 1,350 1,650 1,850 2,200 Caney Creek At confluence with Tiger Creek 11.90 2,460 3,370 3,750 4,520 Coon Bayou At confluence with Cow Bayou 6.30 1,900 2,470 2,680 3,200 Coopers Gully At Pumphouse 1.60 1,250 1,470 1,640 1,780 Cow Bayou At Farm Road 105 151.00 7,290 10,300 11,900 14,900 At Roundbunch Road 165.00 7,700 10,800 12,500 15,700 Cow Bayou Lateral No. 14 2 Gum Gully At confluence with Adams Bayou 4.90 1,790 2,290 2,470 2,910 Hudson Gully At confluence with Adams Bayou 1.80 1,120 1,360 1,470 1,640 Little Cypress Bayou At confluence with Little Cypress Bayou Tributary 12.3 (4.3) 1 1,700 2,080 2,330 2,800 At Little Cypress Creek 20.7 (10.3) 1 2,220 2,960 3,270 3,970 At Jacks Landing 25.1 (15.7) 1 2,470 3,370 3,750 4,620 Little Cypress Bayou Tributary At Little Cypress Creek 7.8 (6.4) 1 1,940 2,430 2,720 3,280 Meyers Bayou At Southern Corporate Boundary 3.50 1,560 1,920 2,150 2,580 Neches River At Beaumont 10,000 60,000 107,000 136,000 240,000 Notes: 1 Effective drainage area contributing to the peak flow 2 Data not available / Not determined / Not computed 16

TABLE 3. SUMMARY OF DISCHARGES (continued) PEAK DISCHARGES (cfs) DRAINAGE 10% 2% 1% 0.2% AREA Annual Annual Annual Annual (sq. miles) FLOODING SOURCE AND LOCATION Chance Chance Chance Chance Sabine River At IH-10 bridge 9,490 66,070 98,660 113,840 150,000 At mouth 10,000 60,000 107,000 136,000 240,000 Sandy Creek At confluence with Cow Bayou 7.00 1,970 2,580 2,810 3,370 Ten Mile Creek At F.M. 1131 Bridge 45.00 3,870 5,450 6,400 7,700 Ten Mile Creek West Fork At Junction with Ten Mile Creek 2.3 (1.3) 1 1,200 1,500 1,600 1,800 Tiger Creek At confluence of Caney Creek 12.80 2,347 3,220 3,607 4,365 At mouth 30.40 3,151 4,417 5,036 6,000 Walnut Run Creek At F.M. 1131 3.30 1,600 2,050 2,200 2,600 Notes: 1 Effective drainage area contributing to the peak flow 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 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. For areas subject to stream overflow, water-surface elevations of floods of the selected recurrence intervals were developed using the USACE HEC-2 water-surface profile computer model (References 20 and 21). Starting water-surface elevations for Caney Creek, Little Cypress Bayou Tributary, Gum Gully, Coon Bayou, Hudson Gully, Little Cypress Bayou, Ten Mile Creek West Fork, and Sandy Creek were set equal to the water-surface elevations at their confluence with the main stream. The starting water-surface elevation for Anderson Gully was determined by the method of convergent profiles. Starting water-surface elevations for the Neches and Sabine Rivers and Adams Bayou were set equal to mean high tide. All other starting water-surface elevations were calculated at normal depth. 17

Cross-sectional data for the backwater analyses for the Neches and Sabine Rivers, and Adams and Cow Bayous were obtained from the USACE, Galveston District. Crosssectional data for the other streams studied in detail were obtained from field surveys and USGS 7.5-minute topographic maps (Reference 13). All bridges, dams, and culverts were field checked to obtain elevation data and structural geometry necessary for backwater analyses. Channel roughness factors (Manning's "n") used in the hydraulic computation were based on field observations, aerial photos of the streams and floodplain areas, and on USGS Water Supply Paper 1849 (Reference 22). Roughness values used for the main channels ranged from 0.025 to 0.08 and the values for their tributaries range from 0.014 to 0.05, with floodplain roughness values ranging from 0.05 to 0.25 for all floods. Flood levels along the rivers and streams resulting from coastal flooding (surge and waves) and rainfall were determined independently of each other and combined statistically (Reference 23). In Orange County, the results of the analysis show that surge flooding predominates rainfall flooding. Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence intervals. The floodways for riverine areas were computed on the basis of equal conveyance reduction from each side of the floodplain. Floodway analyses were based on increasing the computed 1-percent-annual-chance rainfall. The results of these computations are tabulated at selected cross-sections for each stream studied in detail (Table 1). 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 FIRMs. 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. As shown on the FIRMs (Exhibit 2), the floodway boundaries were determined at crosssections. Between cross-sections, the boundaries were interpolated. 3.3. Coastal Analysis The hydraulic characteristics of coastal flood sources were analyzed to provide estimates of flood elevations for 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 in the coastal data tables and flood profiles provided in the FIS Report. 18

3.3.1. Storm Surge Analysis and Modeling For areas subject to coastal flood effects, the 10-, 2-, 1-, and 0.2-percent-annualchance stillwater elevations were taken directly from a detailed storm surge study documented in Flood Insurance Study: Coastal Counties, Texas Intermediate Submission 2 Scoping and Data Review prepared by the U.S. Army Corps of Engineers (Reference 24). This storm surge study was completed in November 2011. The Advanced Circulation (ADCIRC) model for coastal ocean hydrodynamics developed by the USACE was applied to calculate stillwater elevations for coastal Texas. The ADCIRC model uses an unstructured grid and is a finite element long wave model. It has the capability to simulate tidal circulation and storm surge propagation over large areas and is able to provide highly detailed resolution in areas of interest along shorelines, open coasts and inland bays. It solves three dimensional equations of motion, including tidal potential, Coriolis, and non-linear terms of the governing equations. The model is formulated from the depth-averaged shallow water equations for conservation of mass and momentum which result in the generalized wave continuity equation. In performing the coastal analyses, nearshore waves were required as inputs to wave runup and overland wave propagation calculations, and wave momentum (radiation stress) was considered as contribution to elevated water levels (wave setup). The Steady State Spectral Wave (STWAVE) model was used to generate and transform waves to the shore for the Texas Joint Storm Surge (JSS) Study. STWAVE is a finite difference model that calculates wave spectra on a rectangular grid. The model outputs zero-moment wave height, peak wave period (T p ), and mean wave direction at all grid points and two-dimensional spectra at selected grid points. STWAVE includes an option to input spatially variable wind and storm surge field. Storm surge significantly alters wave transformation and generation for the hurricane simulations in shallow-flooded areas. STWAVE was applied on five grids for the Texas JSS: NE, CE, SW, NEn, and CEn. Three large grids (NE, CE, SW) with offshore boundaries at depths near 100 feet (30 meters) encompassed the entire coast of Texas and applied the efficient half-plane version of STWAVE (which must approximately align with the shoreline). Two nested grids (NEn and CEn) covered Galveston Bay and Corpus Christi Bay and applied the fullplane version of STWAVE to allow generation of wind waves in all directions. Notably, memory requirements for the full-plane model precluded its use for the large grids with offshore boundaries. The input for each grid includes the bathymetry (interpolated from the ADCIRC domain), surge fields (interpolated from ADCIRC surge fields), and wind fields (interpolated from the ADCIRC wind fields, which apply land effects to the base wind fields). The wind and surge applied in STWAVE are spatially and temporally variable for all domains. STWAVE was run at 30-minute intervals for 93 quasi-time steps (46.5 hours). The ADCIRC model computational domain and the geometric/topographic representation developed for the Joint Coastal Surge effort was designated as the TX2008 mesh. This provided a common domain and mesh from the Texas-Mexico border to western Louisiana, extends inland across the floodplains of Coastal Texas 19

(to the 30- to 75-foot contour NAVD88), and extends over the entire Gulf of Mexico to the deep Atlantic Ocean. The TX2008 domain boundaries were selected to ensure the correct development, propagation, and attenuation of storm surge without necessitating nesting solutions or specifying ad hoc boundary conditions for tides or storm surge. The TX2008 computational mesh contains more than 2.8 million nodes and nodal spacing varies significantly throughout the mesh. Grid resolution varies from approximately 12 to15 miles in the deep Atlantic Ocean to about 100 ft. in Texas. Further details about the terrain data as well as the ADCIRC mesh creation and grid development process can be found in Flood Insurance Study: Coastal Counties, Texas Intermediate Submission 2 Scoping and Data Review (Reference 24). 3.3.2. Statistical Analysis The Joint Probability Method (JPM) is a simulation methodology that relies on the development of statistical distributions of key hurricane input variables such as central pressure, radius to maximum wind speed, maximum wind speed, translation speed, track heading, etc., and sampling from these distributions to develop model hurricanes. The resulting simulation results in a family of modeled storms that preserve the relationships between the various input model components, but provides a means to model the effects and probabilities of storms that historically have not occurred. Due to the excessive number of simulations required for the traditional JPM method, the JPM-Optimum Sampling (JPM-OS) was utilized to determine the stillwater elevations associated with tropical events. JPM-OS is a modification of the JPM method and is intended to minimize the number of synthetic storms that are needed as input to the ADCIRC model. The methodology entails sampling from a distribution of model storm parameters (e.g., central pressure, radius to maximum wind speed, maximum wind speed, translation speed, and track heading) whose statistical properties are consistent with historical storms impacting the region, but whose detailed tracks differ. The methodology inherently assumes that the hurricane climatology over the past 60 to 65 years (back to 1940) is representative of the past and future hurricanes likely to occur along the Texas coast. A set of 446 storms (two sets of 152 low frequency storms plus two sets of 71 higher frequency storms) was developed by combining the probable combinations of central pressure, radius to maximum winds, forward speed, angle of track relative to coastline, and track. Tracks were defined by five primary tracks and four secondary tracks. Storm parameters for synthetic storms are provided in Table 11 of Flood Insurance Study: Coastal Counties, Texas Intermediate Submission 2 Scoping and Data Review (Reference 24). The estimated range of storm frequencies using the selected parameters was between the 10-percent and 0.2-percent-annual-chance storm events. The ADCIRC-STWAVE modeling system was validated using five historic storms: Hurricanes Carla (1961), Allen (1980), Bret (1999), Rita (2005), and Ike (2008). 20

3.3.3 Stillwater Elevations The results of the ADCIRC model and JPM-OS provided 10-, 2-, 1-, and 0.2- percent-annual-chance stillwater elevations which include wave setup effects. Stillwater elevations are assigned at individual ADCIRC mesh nodes throughout the Texas coast. Triangular Irregular Networks (TINs) and raster datasets were built from these nodes for use in wave analysis and floodplain mapping. An Independent Technical Review (ITR) was performed on the overall storm surge study process. This review process was performed in accordance with USACE regulations. The ITR team was composed of experts in the fields of coastal engineering and science, and was engaged throughout the study. Appendix K of Flood Insurance Study: Coastal Counties, Texas Intermediate Submission 2 Scoping and Data Review includes all comments received from the ITR panel, as well as responses to those comments (Reference 24). 3.3.4. Wave Height Analysis Using storm surge study results, wave height analysis was performed to identify areas of the coastline subject to overland wave propagation or wave runup hazards. Figure 1 shows a cross-section for a typical coastal analysis transect, illustrating the effects of energy dissipation and regeneration of wave action over inland areas. This figure shows the wave crest elevations being decreased by obstructions, such as buildings, vegetation, and rising ground elevations, and being increased by open, unobstructed wind fetches. Figure 1 also illustrates the relationship between the local stillwater elevations, the ground profile, and the location of the VE/AE Zone boundary at the limit of 3-foot breaking waves. This inland limit of the coastal high hazard area is delineated to ensure that adequate insurance rates apply and appropriate construction standards are imposed, should local agencies permit building in this coastal high hazard area. It has been shown in laboratory tests and observed in field investigations that wave heights as little as 1.5 feet can cause damage to and failure of typical Zone AE construction. Therefore, for advisory purposes only, a Limit of Moderate Wave Action (LiMWA) boundary has been added in coastal areas subject to wave action. The LiMWA represents the approximate landward limit of the 1.5-foot breaking wave. The effects of wave hazards in the Zone AE between the Zone VE (or shoreline in areas where VE Zones are not identified) and the limit of the LiMWA boundary are similar to, but less severe than, those in Zone VE where 3-foot breaking waves are projected during a 1-percent-annual-chance flooding event. 21

In areas where wave runup elevations dominate over wave heights, such as areas with steeply sloped beaches, bluffs, and/or shore-parallel flood protection structures, there is no evidence to date of significant damage to residential structures by runup depths less than 3 feet. However, to simplify representation, the LiMWA was continued immediately landward of the VE/AE boundary in areas where wave runup elevations dominate. Similarly, in areas where the Zone VE designation is based on the presence of a primary frontal dune or wave overtopping, the LiMWA was also delineated immediately landward of the Zone VE/AE boundary. Figure 1: Transect Schematic The locations of transects used in this study are shown in Figure 2. Information regarding each transect is included in Table 4. The transect profiles for the 0.2 percent annual chance wave envelopes are shown on Exhibit 3. 22

Figure 2: Transect Location Map 23

Table 4: Coastal Data Table FIS Transect No. Description Latitude & Longitude at Start of Transect (Lat, Long) Starting Stillwater Elevation & Range of Stillwater Elevations (ft. NAVD88) NOTE: range of stillwater elevations provided for 1%- & 0.2%-annual-chance events only 10%-annualchance 2%-annualchance 1%-annualchance 0.2%-annualchance Zone Designation & BFE Range (ft. NAVD88) 1 Originates in the Neches River and extends north to inland limit of surge. 30.0766, - 94.0598 5.5 7.4 8.6 8.0 9.1 11.9 10.9 12.8 VE (11) AE (8 11) 2 Originates in the Neches River and extends north to inland limit of surge. 30.0671, - 94.0352 5.6 7.3 8.8 8.8 9.0 11.6 11.6 12.0 VE (11) AE (9 11) 3 Originates in the Neches River and extends north to inland limit of surge. 30.0309, - 94.0213 5.5 7.3 8.8 8.2 9.1 11.6 10.7 12.9 VE (11 12) AE (8 11) 4 Originates in the Neches River and extends north to inland limit of surge. 30.0311, - 94.0078 5.5 7.4 8.8 8.7 9.2 12.0 11.8 12.9 VE (9 11) AE (11 12) 5 Originates in the Neches River and extends north to inland limit of surge. 30.0226, - 93.9860 5.5 7.4 8.9 8.9 9.2 12.3 12.3 13.4 AE (10 11) 6 Originates in the Neches River and extends north to inland limit of surge. 30.0127, - 93.9727 5.4 7.4 9.0 8.3 9.3 12.4 12.0 13.5 VE (11 12) AE (9 11) 7 Originates in the Neches River and extends north to inland limit of surge. 29.9960, - 93.9403 5.4 7.4 9.0 8.9 9.3 13.0 12.2 13.3 VE (11 13) AE (9 11) 24

Table 4: Coastal Data Table FIS Transect No. Description Latitude & Longitude at Start of Transect (Lat, Long) Starting Stillwater Elevation & Range of Stillwater Elevations (ft. NAVD88) NOTE: range of stillwater elevations provided for 1%- & 0.2%-annual-chance events only 10%-annualchance 2%-annualchance 1%-annualchance 0.2%-annualchance Zone Designation & BFE Range (ft. NAVD88) 8 Originates in the Neches River and extends north to inland limit of surge. 29.9975, - 93.9160 5.4 7.4 9.1 9.0 9.3 13.1 12.5 13.5 VE (11 13) AE (9 11) 9 Originates in the Neches River and extends north to inland limit of surge. 29.9865, - 93.8979 5.3 7.4 9.1 8.5 9.3 13.4 12.6 13.8 VE (11 12) AE (9 11) 10 Originates in the Neches River and extends north to inland limit of surge. 29.9829, - 93.8767 5.3 7.5 9.2 8.9 9.3 13.7 12.8 14.0 VE (11 13) AE (9 11) 11 Originates in the Neches River and extends north to inland limit of surge. 29.9786, - 93.8593 5.4 7.6 9.3 8.7 9.6 14.0 12.6 14.3 VE (11 14) AE (9 12) 12 Originates in Sabine Lake and extends north to inland limit of surge. 29.9682, - 93.8502 5.4 7.5 9.4 8.9 9.5 14.2 12.2 14.3 VE (11 14) AE (9 12) 13 Originates in Sabine Lake and extends north to inland limit of surge. 29.9846, - 93.8417 5.5 7.6 9.5 8.6 9.6 14.3 12.5 14.3 VE (12 15) AE (9 12) 14 Originates in Sabine Lake and extends north to inland limit of surge. 29.9752, - 93.8307 5.4 7.6 9.4 8.4 9.5 14.3 11.7 14.4 VE (11 14) AE (8 12) 25

Table 4: Coastal Data Table FIS Transect No. Description Latitude & Longitude at Start of Transect (Lat, Long) Starting Stillwater Elevation & Range of Stillwater Elevations (ft. NAVD88) NOTE: range of stillwater elevations provided for 1%- & 0.2%-annual-chance events only 10%-annualchance 2%-annualchance 1%-annualchance 0.2%-annualchance Zone Designation & BFE Range (ft. NAVD88) 15 Originates in Sabine Lake and extends north to inland limit of surge. 29.9864, - 93.8151 5.3 7.8 9.5 8.3 9.7 14.5 11.2 14.6 VE (12 15) AE (8 12) 16 Originates in Sabine Lake and extends north to inland limit of surge. 29.9933, - 93.8008 5.3 7.9 9.8 8.4 9.8 14.8 11.5 14.8 VE (11 15) AE (8 12) 17 Originates in Sabine Lake and extends north to inland limit of surge. 29.9881, - 93.7910 5.2 7.9 9.8 8.4 9.8 14.9 11.5 14.9 VE (12 15) AE (8 12) 18 Originates in the Sabine River and extends north to inland limit of surge. 29.9944, - 93.7839 5.0 7.9 9.7 8.6 9.7 14.7 12.7 14.7 VE (12 13) AE (9 12) 19 Originates in the Sabine River and extends north to inland limit of surge. 29.9968, - 93.7765 5.0 7.7 9.5 8.6 9.5 14.6 12.8 14.6 VE (12) AE (9 11) 20 Originates in the Sabine River and extends north to inland limit of surge. 30.0035, - 93.7695 4.9 7.5 9.6 8.7 9.6 14.4 12.8 14.4 VE (11 14) AE (9 11) 21 Originates in the Sabine River and extends north to inland limit of surge. 30.0115, - 93.7628 4.7 7.4 9.2 8.8 9.2 14.2 11.8 14.5 VE (11 12) AE (9 11) 26

Table 4: Coastal Data Table FIS Transect No. Description Latitude & Longitude at Start of Transect (Lat, Long) Starting Stillwater Elevation & Range of Stillwater Elevations (ft. NAVD88) NOTE: range of stillwater elevations provided for 1%- & 0.2%-annual-chance events only 10%-annualchance 2%-annualchance 1%-annualchance 0.2%-annualchance Zone Designation & BFE Range (ft. NAVD88) 22 Originates in the Sabine River and extends north to inland limit of surge. 30.0187, - 93.7555 4.6 7.3 9.0 8.8 9.1 14.0 11.8 14.8 VE (11 12) AE (9 11) 23 Originates in the Sabine River and extends north to inland limit of surge. 30.0205, - 93.7477 4.5 7.2 9.0 8.1 9.1 14.1 11.8 14.8 VE (11) AE (8 11) 24 Originates in the Sabine River and extends north to inland limit of surge. 30.0260, - 93.7414 4.4 7.2 9.1 8.2 9.1 13.8 12.0 13.8 VE (11 12) AE (8 11) 25 Originates in the Sabine River and extends north to inland limit of surge. 30.0426, - 93.7357 4.4 7.2 9.1 8.3 9.1 13.8 12.1 13.8 VE (11 12) AE (8 11) 26 Originates in the Sabine River and extends north to inland limit of surge. 30.0492, - 93.7281 4.3 7.0 8.9 8.1 8.9 13.2 11.7 13.2 VE (11) AE (8 11) 27 Originates in the Sabine River and extends north to inland limit of surge. 30.0534, - 93.7228 4.2 7.0 8.9 8.1 8.9 13.2 11.6 13.2 VE (11) AE (8 10) 28 Originates in the Sabine River and extends north to inland limit of surge. 30.0670, - 93.7186 4.3 6.6 8.6 7.5 8.6 12.7 11.7 12.7 VE (11) AE (8 11) 27

Table 4: Coastal Data Table FIS Transect No. Description Latitude & Longitude at Start of Transect (Lat, Long) Starting Stillwater Elevation & Range of Stillwater Elevations (ft. NAVD88) NOTE: range of stillwater elevations provided for 1%- & 0.2%-annual-chance events only 10%-annualchance 2%-annualchance 1%-annualchance 0.2%-annualchance Zone Designation & BFE Range (ft. NAVD88) 29 Originates in the Sabine River and extends north to inland limit of surge. 30.0559, - 93.7067 4.2 6.4 8.3 7.5 8.5 12.5 11.5 13.1 VE (10 11) AE (8 11) 30 Originates in the Sabine River and extends north to inland limit of surge. 30.0598, - 93.7006 4.2 6.2 8.2 7.0 8.7 12.4 10.5 13.2 VE (10 11) AE (7 10) 31 Originates in the Sabine River and extends north to inland limit of surge. 29.9745, - 93.8474 5.4 7.6 9.4 7.6 9.4 14.1 11.6 14.2 VE (11 14) AE (8 11) 32 Originates in the Sabine River and extends north to inland limit of surge. 29.9903, - 93.8577 5.6 7.6 9.5 8.4 9.5 14.2 12.5 14.2 VE (11 15) AE (8 12) 28

3.4 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. Flood elevations shown in this FIS report and on the FIRM are referenced to the NAVD88. These flood elevations must be compared to structure and ground elevations referenced to the same vertical datum. Some of the data used in this revision were taken from the prior effective FIS reports and FIRMs and adjusted to NAVD88. The datum conversion factor from NGVD29 to NAVD88 in Orange County is +0.02 feet. For additional information regarding conversion between the NGVD and NAVD, visit the National Geodetic Survey website at www.ngs.noaa.gov, or contact the National Geodetic Survey at the following address: Vertical Network Branch, N/CG13 National Geodetic Survey, NOAA Silver Spring Metro Center 3 1315 East-West Highway Silver Spring, Maryland 20910 (301) 713-3191 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) 713-3242, or visit their website at www.ngs.noaa.gov. 4.0 FLOODPLAIN MANAGEMENT APPLICATIONS The NFIP encourages State and local governments to adopt sound floodplain management programs. To assist in this endeavor, each FIS report provides 1-percent-annual-chance floodplain data, which may include a combination of the following: 10-, 2-, 1-, and 0.2-percent-annual-chance flood elevations; delineations of the 1- and 0.2-percent-annual-chance floodplains; and a 1-percent-annual-chance floodway. This information is presented on the FIRM and in many components of the FIS report, including Flood Profiles, Floodway Data tables, and Summary of Stillwater Elevation tables. Users should reference the data presented in the FIS report as well as additional information that may be available at the local community map repository before making flood elevation and/or floodplain boundary determinations. 29

4.1 Floodplain Boundaries To provide a national standard without regional discrimination, the 1-percent-annual-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. The boundaries of the 1-percent-annual-chance flood that were delineated in previous FIS reports published for communities in Orange County used the computed flood elevations, and topographic maps at a scale of 1:24,000 with a contour interval of 5 feet (Reference 13). Additionally, aerial photographs were used to assist in the floodplain delineation (Reference 14). For each stream studied by detailed methods, the 1- and 0.2-percent-annual-chance floodplain boundaries have been redelineated for this countywide study using the flood elevations determined at each cross-section. Between cross-sections, the boundaries were interpolated using LIDAR data with a contour interval of 2 feet. Redelineation of effective floodplain boundaries (Zone AE) were performed by using the updated topographic data developed as part of Terrain Data Development for the DFIRM Update Project for Orange County, Texas (Reference 24). The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the FIRM. On this map, the 1-percent-annual-chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (Zones A, AE, and VE), 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-annual-chance floodplain boundary is shown on the FIRM. Approximate flood elevations for Terry Gully were taken from the previously published flood plain information report (Reference 25). Flood boundaries were determined using topographic maps (Reference 13). 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 base 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 minimum standards 30

that can be adopted directly or that can be used as a basis for additional floodway studies. Floodways were not computed along reaches of streams dominated by coastal flooding. The floodways for riverine areas were computed on the basis of equal conveyance reduction from each side of the floodplain. Floodway analyses were based on increasing the computed 1-percent-annual-chance rainfall. The results of these computations are tabulated in Table 5 at selected cross-section locations for each stream studied in detail. Floodway widths were computed at cross-sections. Between cross-sections, the floodway boundaries were interpolated. The results of the floodway computations are tabulated for selected crosssections (see Table 5, Floodway Data). In cases where the floodway and 1-percent-annual-chance floodplain boundaries are either close together or collinear, only the floodway boundary is shown. The area between the floodway and the boundary of the 1-percent-annual-chance flood is termed the floodway fringe. The floodway fringe thus encompasses the portion of the floodplain that could be completely obstructed without increasing the water-surface elevation of the 1-percent-annual-chance flood more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 3. The surcharge identified in Figure 3 and tabulated in the last column of Table 5 represents the maximum 1-percent-annual-chance water level increase that is permitted with encroachment. The tabulated values are the maximum increase in water level for the reaches studied such that the maximum water increase in areas considered anywhere upstream does not exceed one foot. Figure 3. Floodway Schematic 31

FLOODING SOURCE CROSS SECTION DISTANCE 1 WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Adams Bayou A 18,700 320 2,990 2.2 7.8 5.0 2 5.9 0.9 B 20,540 340 3,160 2.1 7.8 5.4 2 6.3 0.9 C 21,690 432 3,590 1.6 7.8 5.7 2 6.7 1.0 D 22,560 500 2,670 2.2 7.8 5.9 6.8 0.9 E 24,480 380 2,612 2.3 7.8 6.5 7.5 1.0 F 26,420 550 3,570 1.7 7.9 7.0 8.0 1.0 G 28,520 640 4,360 1.4 8.0 7.4 8.4 1.0 H 30,600 500 3,740 1.6 8.2 7.7 8.7 1.0 I 32,160 340 3,920 1.5 8.4 7.8 8.8 1.0 J 33,760 540 4,452 1.3 8.4 8.0 9.0 1.0 K 36,860 355 3,690 1.6 8.7 8.3 9.3 1.0 L 37,262 355 3,670 1.6 8.8 8.5 9.5 1.0 M 39,690 720 5,340 1.0 9.1 8.8 9.7 0.9 N 41,370 450 3,350 1.6 9.2 9.0 10.0 1.0 O 43,390 850 6,030 0.9 9.4 9.2 10.2 1.0 P 45,790 150 1,730 3.1 9.6 9.5 10.4 0.9 Q 47,340 453 3,070 1.8 10.2 10.2 11.1 0.9 R 49,840 865 5,440 1.0 10.9 10.9 11.8 0.9 S 54,040 516 3,552 1.5 14.5 14.5 14.5 0.0 1 Feet above confluence with the Sabine River 2 Elevations computed without consideration of coastal effects from Sabine Lake TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA ADAMS BAYOU 32

FLOODING SOURCE CROSS SECTION DISTANCE 1 WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Anderson Gully A 0 45 347 5.3 17.3 17.3 18.1 0.8 B 922 518 1,968 0.9 18.3 18.3 19.0 0.7 C 5,700 905 5,026 0.4 19.4 19.4 20.2 0.8 D 8,840 1,424 6,648 0.3 19.4 19.4 20.2 0.8 E 11,140 116 571 3.2 20.4 20.4 21.3 0.9 F 12,790 237 918 1.4 21.2 21.2 22.2 1.0 G 14,370 511 1,489 0.8 21.6 21.6 22.6 1.0 H 16,240 449 2,310 0.5 21.8 21.8 22.8 1.0 I 19,020 433 1,911 0.4 21.9 21.9 22.9 1.0 J 21,560 248 1,247 0.3 22.0 22.0 23.0 1.0 K 22,475 395 2,014 0.2 22.0 22.0 23.0 1.0 L 23,075 520 2,517 0.1 22.0 22.0 23.0 1.0 M 24,630 282 1,032 0.3 22.0 22.0 23.0 1.0 N 25,620 290 750 0.3 22.1 22.1 23.1 1.0 O 26,770 443 1,336 0.2 22.1 22.1 23.1 1.0 P 27,855 320 914 0.3 22.2 22.2 23.2 1.0 1 Feet above Southern Pacific Railroad TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA ANDERSON GULLY 33

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Caney Creek A 1,470 1 609 4,024 0.9 12.5 12.3 2 13.3 1.0 B 4,170 1 558 3,765 1.0 14.5 14.5 15.5 1.0 C 5,520 1 207 1,394 2.4 16.2 16.2 17.2 1.0 D 6,650 1 270 1,751 1.9 19.3 19.3 20.2 0.9 E 7,890 1 354 2,080 1.6 21.7 21.7 22.6 0.9 F 8,810 1 986 6,666 0.5 22.3 22.3 23.2 0.9 G 9,910 1 559 2,624 1.3 23.2 23.2 24.0 0.8 H 11,210 1 829 4,479 0.7 24.8 24.8 25.6 0.8 I 13,940 1 835 4,672 0.7 27.2 27.2 28.0 0.8 Coon Bayou A 400 3 768 2,997 0.9 7.6 4.5 4 5.5 4 1.0 B 4,800 3 328 2,056 1.3 7.6 5.2 4 6.2 4 1.0 C 10,170 3 451 1,590 1.7 8.2 8.2 9.1 0.9 D 14,312 3 771 3,306 0.8 9.3 9.3 10.3 1.0 E 16,970 3 748 3,111 0.9 9.8 9.8 10.7 0.9 1 Feet above confluence with Tiger Creek 2 Elevations computed without consideration of backwater effects 3 Feet above confluence with Cow Bayou 4 Elevations computed without consideration of coastal flooding effects from Sabine Lake/Sabine River BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA CANEY CREEK - COON BAYOU 34

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Coopers Gully A 0 1 100 855 1.9 7.8 2.0 2 3.0 1.0 B 1,250 1 29 208 7.3 7.8 2.0 2 3.0 1.0 C 1,984 1 78 567 2.6 7.8 3.8 2 4.8 1.0 D 3,110 1 80 344 3.9 7.8 7.1 2 7.1 0.0 E 4,500 1 100 434 2.8 7.8 7.3 2 7.5 0.2 F 6,169 1 238 1,076 1.0 7.8 7.6 2 8.1 0.5 G 7,807 1 89 276 3.5 7.9 7.9 8.5 0.6 Cow Bayou A 15,592 3 323 3,374 3.7 7.6 3.5 4 4.5 4 1.0 B 18,902 3 605 4,906 2.6 7.6 4.2 4 5.1 4 0.9 C 21,987 3 582 4,259 2.9 7.6 4.8 4 5.7 4 0.9 D 24,652 3 752 5,311 2.4 7.6 5.4 4 6.2 4 0.8 E 26,352 3 800 6,676 1.9 7.6 5.6 4 6.5 4 0.9 F 27,732 3 1,870 9,775 1.3 7.6 5.6 4 6.5 4 0.9 G 28,832 3 1,950 9,243 0.7 7.6 5.8 4 6.7 4 0.9 H 30,032 3 2,557 11,257 1.1 7.6 6.1 4 7.0 4 0.9 I 32,082 3 2,200 13,068 1.0 7.6 6.2 4 7.1 4 0.9 J 35,332 3 1,910 13,270 0.9 7.6 6.3 4 7.3 4 1.0 1 Feet above Pier Road Pump Station 2 Elevations computed without consideration of backwater effects 3 Feet above confluence with the Sabine River 4 Elevations computed without consideration of coastal flooding effects from Sabine Lake BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA COOPERS GULLY - COW BAYOU 35

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Cow Bayou (continued) K 38,717 1 840 3,968 3.0 7.6 7.2 2 8.2 2 1.0 L 45,499 1 1,316 9,057 1.3 9.2 9.2 10.2 1.0 M 55,049 1 751 7,839 1.5 10.9 10.9 11.8 0.9 N 61,299 1 2,009 16,521 0.7 11.7 11.7 12.7 1.0 O 66,507 1 600 6,837 1.7 12.3 12.3 13.2 0.9 P 69,857 1 1,962 19,113 0.6 12.6 12.6 13.4 0.8 Q 76,857 1 1,073 11,465 1.0 13.4 13.4 14.2 0.8 R 79,257 1 982 13064 0.9 13.7 13.7 14.5 0.8 Cow Bayou Lateral No. 14 A 3,320 3 692 4,473 2.7 17.6 17.6 18.4 0.8 Gum Gully A 1,040 4 1,262 5,529 0.4 9.5 7.4 5 8.3 0.9 B 3,792 4 958 2,119 1.2 10.5 10.1 5 10.5 0.4 C 9,106 4 104 576 4.3 18.5 18.5 19.5 1.0 1 Feet above confluence with the Sabine River 2 Elevations computed without consideration of coastal flooding effects from Lake Sabine 3 Feet above confluence with Cow Bayou 4 Feet above confluence with Adams Bayou 5 Elevations computed without consideration of backwater effects TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA COW BAYOU - COW BAYOU LATERAL NO. 14 GUM GULLY 36

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Hudson Gully A 1,750 1 79 266 5.5 8.0 7.4 2 7.9 0.5 B 2,150 1 19 195 7.5 9.2 9.2 10.1 0.9 C 2,250 1 19 208 7.1 9.8 9.8 10.8 1.0 D 3,920 1 37 281 4.7 10.9 10.9 11.6 0.7 E 5,400 1 30 237 5.0 11.1 11.1 11.9 0.8 F 6,280 1 30 229 4.8 11.5 11.5 12.3 0.8 Little Cypress Bayou A 11,000 3 502 4 2,744 1.4 9.8 5.0 2 6.0 1.0 B 16,200 3 346 4 2,056 1.8 9.8 6.3 2 7.3 1.0 C 17,364 3 134 966 3.9 9.8 7.5 2 8.5 1.0 D 18,289 3 120 1,029 3.6 9.8 8.2 2 9.1 0.9 E 20,853 3 125 1,100 3.4 9.8 9.2 2 10.2 1.0 F 22,103 3 461 2,504 1.5 9.8 9.7 2 10.7 1.0 G 24,933 3 100 1,085 3.5 10.6 10.6 11.6 1.0 H 26,658 3 90 678 4.8 12.6 12.6 13.3 0.7 I 28,758 3 297 1,554 2.1 13.9 13.9 14.7 0.8 J 29,908 3 783 3,701 0.9 14.3 14.3 15.2 0.9 K 32,574 3 1,044 1,612 1.4 16.1 16.1 16.4 0.3 1 Feet above confluence with Adams Bayou 2 Elevations computed without consideration of backwater effects 3 Feet above confluence with the Sabine River 4 Cross section not shown on maps; floodway lies outside county limits TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA HUDSON GULLY - LITTLE CYPRESS BAYOU 37

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Little Cypress Bayou (continued) L 35,274 1 1,486 3,849 0.6 16.8 16.8 17.2 0.4 M 37,074 1 941 2,539 0.9 17.4 17.4 17.8 0.4 N 43,399 1 856 2,054 1.1 21.6 21.6 22.2 0.6 Little Cypress Bayou Tributary A 2,950 2 549 2,120 1.3 16.6 16.6 17.6 1.0 B 9,075 2 288 1,095 2.5 20.6 20.6 21.6 1.0 Meyers Bayou A 0 3 129 447 4.8 7.2 7.2 7.8 0.6 B 2,110 3 499 2,586 0.8 8.7 8.7 9.7 1.0 C 3,990 3 319 1,805 1.2 10.1 10.1 11.1 1.0 D 5,800 3 380 1,215 1.6 15.4 15.4 15.9 0.5 E 7,465 3 600 2,365 0.7 15.9 15.9 16.7 0.8 F 9,170 3 300 732 2.1 17.1 17.1 17.7 0.6 G 10,285 3 22 218 7.1 18.7 18.7 19.2 0.5 1 Feet above confluence with the Sabine River 2 Feet above confluence with Little Cypress Bayou 3 Feet above Old Spanish Trail TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA LITTLE CYPRESS BAYOU - LITTLE CYPRESS BAYOU TRIBUTARY - MEYERS BAYOU 38

FLOODING SOURCE CROSS SECTION DISTANCE 1 WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Neches River A 108,600 7,000 67,481 2.0 10.8 10.8 11.2 0.4 B 116,100 9,064 112,933 1.2 11.9 11.9 12.5 0.6 C 120,600 13,926 156,204 0.9 12.4 12.4 13.0 0.6 D 128,500 9,045 104,945 1.3 13.2 13.2 14.0 0.8 E 139,000 14,711 194,385 0.7 14.0 14.0 14.9 0.9 F 146,200 7,898 92,964 1.5 14.7 14.7 15.6 0.9 G 157,500 11,610 142,328 1.0 16.2 16.2 17.1 0.9 H 159,900 9,604 122,709 1.1 16.7 16.7 17.7 1.0 I 172,100 14,637 203,033 0.7 17.6 17.6 18.6 1.0 J 179,600 28,750 261,164 0.5 18.0 18.0 18.9 0.9 K 185,900 18,800 205,543 0.7 18.7 18.7 19.6 0.9 L 191,900 18,600 202,646 0.7 19.7 19.7 20.6 0.9 M 192,800 22,070 217,020 0.6 19.8 19.8 20.7 0.9 N 197,800 18,851 216,881 0.6 20.5 20.5 21.3 0.8 1 Feet above mouth TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA NECHES RIVER 39

FLOODING SOURCE CROSS SECTION DISTANCE 1 WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Sabine River A 48,000 11,200 57,226 2.0 7.8 5.1 2 6.0 2 0.9 B 49,000 11,200 59,035 1.9 7.8 5.2 2 6.1 2 0.9 C 53,200 9,500 63,874 1.8 7.8 5.7 2 6.6 2 0.9 D 55,700 8,400 67,931 1.7 7.8 5.9 2 6.8 2 0.9 E 57,400 11,470 72,543 1.6 7.9 6.0 2 6.9 2 0.9 F 64,200 15,500 90,566 1.3 8.1 7.0 2 7.8 2 0.8 G 69,400 18,300 131,352 0.9 8.3 8.3 9.0 0.7 H 80,750 21,000 150,742 0.8 9.1 9.1 9.8 0.9 I 91,450 12,300 48,644 2.3 9.8 9.8 10.5 0.7 J 91,500 12,300 46,557 2.4 9.8 9.8 10.5 0.7 K 96,620 22,100 190,919 0.6 11.1 11.1 11.8 0.7 L 108,120 16,400 142,009 0.8 12.1 12.1 12.9 0.8 M 115,120 12,800 122,581 0.9 13.0 13.0 13.9 0.9 N 126,320 15,200 154,278 0.7 14.0 14.0 15.0 1.0 O 132,820 17,400 171,972 0.7 14.5 14.5 15.5 1.0 P 138,920 18,200 157,277 0.7 15.0 15.0 15.9 0.9 Q 150,820 17,300 132,075 0.9 15.9 15.9 16.9 1.0 1 Feet above mouth 2 Elevations computed without consideration of coastal flooding effects from Lake Sabine BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA SABINE RIVER 40

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Sandy Creek A 0 1 1,254 7,904 0.4 8.9 8.9 9.9 1.0 B 814 1 890 7,252 0.4 8.9 8.9 9.9 1.0 C 5,533 1 420 2,888 1.0 9.2 9.2 10.2 1.0 D 9,899 1 514 2,651 1.1 10.1 10.1 11.1 1.0 E 11,324 1 131 909 3.1 11.0 11.0 12.0 1.0 Ten Mile Creek A -4,734 2 773 6,191 1.0 12.9 12.9 13.8 0.9 B -1,821 2 918 8,445 0.8 14.2 14.2 15.2 1.0 C -213 2 1,076 7,950 0.8 14.6 14.6 15.5 0.9 D 200 2 1,401 10,693 0.6 14.9 14.9 15.9 1.0 E 3,000 2 863 7,048 0.9 16.0 16.0 16.9 0.9 F 4,821 2 1,120 8,958 0.7 16.6 16.6 17.5 0.9 G 6,024 2 626 5,495 1.2 16.9 16.9 17.8 0.9 H 6,820 2 1,196 10,597 0.6 17.4 17.4 18.2 0.8 I 9,120 2 704 5,020 1.3 18.4 18.4 19.2 0.8 J 11,520 2 1,029 6,959 0.9 20.0 20.0 20.8 0.8 K 14,320 2 603 5,032 1.3 21.7 21.7 22.5 0.8 1 Feet above confluence with Cow Bayou 2 Feet above Lake View Road FLOODWAY BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA SANDY CREEK - TEN MILE CREEK 41

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Ten Mile Creek West Fork A 500 1 323 1,734 0.9 15.7 10.0 2 11.0 1.0 B 1,900 1 512 2,794 0.6 15.7 11.0 2 12.0 1.0 C 3,900 1 211 582 2.7 15.7 13.4 2 13.9 0.5 D 4,715 1 347 1,143 1.4 15.7 14.8 2 15.2 0.4 E 5,250 1 330 1,459 1.1 15.7 15.7 2 16.6 0.9 F 6,790 1 312 1,595 1.0 17.5 17.5 18.5 1.0 G 8,590 1 885 3,934 0.4 18.5 18.5 19.4 0.9 Tiger Creek A 0 3 600 3,601 1.4 12.5 10.2 2 11.2 1.0 B 3,600 3 777 5,294 1.0 12.5 11.6 2 12.6 1.0 C 7,600 3 1200 7,878 0.5 12.8 12.8 13.8 1.0 D 10,030 3 796 4,691 0.8 14.2 14.2 15.1 0.9 E 11,744 3 354 1,559 2.3 15.3 15.3 16.2 0.9 F 12,264 3 458 2,005 1.8 15.6 15.6 16.5 0.9 G 15,264 3 120 984 3.2 18.2 18.2 18.9 0.7 1 Feet above confluence with Ten Mile Creek 2 Elevations computed without consideration of backwater effects 3 Feet above Cross Section A TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA TEN MILE CREEK WEST FORK - TIGER CREEK 42

FLOODING SOURCE CROSS SECTION DISTANCE WIDTH (FEET) FLOODWAY SECTION AREA (SQUARE FEET) MEAN VELOCITY (FEET PER SECOND) BASE FLOOD WATER SURFACE ELEVATION (FEET NAVD) REGULATORY WITHOUT FLOODWAY WITH FLOODWAY INCREASE Tiger Creek (continued) H 16,353 1 120 1,042 3.0 18.7 18.7 19.3 0.6 I 19,253 1 415 2,199 1.4 21.9 21.9 22.6 0.7 J 21,453 1 455 2,902 1.1 23.7 23.7 24.6 0.9 K 23,153 1 673 3,509 0.9 25.0 25.0 26.0 1.0 L 24,576 1 511 3,483 0.9 26.0 26.0 27.0 1.0 Walnut Run Creek A 100 2 387 2,344 0.9 16.2 15.6 3 16.5 0.9 B 1,300 2 263 1,790 1.2 16.6 16.6 17.4 0.8 C 2,300 2 379 2,935 0.7 17.4 17.4 18.2 0.8 D 3,100 2 376 2,207 1.0 18.0 18.0 18.8 0.8 E 4,426 2 558 3,232 0.7 19.3 19.3 20.3 1.0 F 6,426 2 578 3,231 0.7 20.6 20.6 21.6 1.0 1 Feet above Cross Section A 2 Feet above FM 1131 3 Elevations computed without consideration of backwater effects TABLE 5 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS FLOODWAY DATA TIGER CREEK - WALNUT RUN CREEK 43

4.3 Base Flood Elevations Areas within the county studied by detailed engineering methods have base flood elevations established in AE and VE Zones. These are the elevations of the base (1-percent-annualchance) flood relative to NAVD88. In coastal areas affected by wave action, base flood elevations are generally maximum at the normal open shoreline. These elevations generally decrease in a landward direction at a rate dependent on the presence of obstructions capable of dissipating the wave energy. Where possible, changes in base flood elevations have been shown in 1-foot increments on the FIRMs. However, where the scale did not permit, 2-or 3- foot increments were sometimes used. Base flood elevations shown in the wave action areas present the average elevation within the zone. These elevations vary from 7 to 12 feet above NAVD in Orange County and are shown on the FIRMs. Current program regulations generally require that all new construction be elevated such that the first floor, including basement, is above the base flood elevation in AE and VE Zones. 4.4 Velocity Zones The USACE (Reference 24) has established the 3foot wave as the criterion for identifying coastal high hazard zones. This was based on a study of wave action effects on structures. This criterion has been adopted by FEMA for the determination of VE Zones. Because of the additional hazards associated with high-energy waves, the NFIP regulations require much more stringent floodplain management measures in these areas, such as elevating structures on piles or piers. In addition, insurance rates in VE Zones are higher than those in AE Zones with similar numerical designations. The location of the VE Zone is determined by the 3-foot wave as discussed previously. The detailed analysis of wave heights performed in this study allowed a much more accurate location of the VE Zone to be established. The VE Zone generally extends inland to the point where the 1-percent-annual-chance flood depth is insufficient to support a 3-foot wave. 5.0 INSURANCE APPLICATION 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 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. 44

Zone VE Zone VE is the flood insurance rate zone that corresponds to the 1-percent-annual-chance coastal floodplains that have additional hazards associated with storm waves. Whole-foot BFEs derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Zone X Zone X is the flood insurance rate zone that corresponds to areas outside the 0.2-percent-annual-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 1-percent-annual-chance flooding where the contributing drainage area is less than 1 square mile (sq. mi.), and areas protected from the base flood by levees. No BFEs or 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 rate 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 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 Orange County. Previously, FIRMs were prepared for each incorporated community 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 (FBFMs), where applicable. Historical data relating to the maps prepared for each community are presented in Table 6, Community Map History. 45

COMMUNITY NAME INITIAL IDENTIFICATION FLOOD HAZARD BOUNDARY MAP REVISIONS DATE FIRM EFFECTIVE DATE Bridge City, City of May 24, 1974 None September 2, 1982 FIRM REVISIONS DATES Orange, City of June 14, 1975 May 24, 1977 January 6, 1983 June 5, 1997 Orange County, Unincorporated Areas March 11, 1977 None January 6, 1983 June 5, 1997 Pine Forest, City of December 13, 1974 None February 16, 1983 Pinehurst, City of May 24, 1974 None January 6, 1983 Rose City, City of July 12, 1977 None January 6, 1983 Vidor, City of March 22, 1974 November 21, 1975 January 6, 1983 West Orange, City of May 31, 1974 None January 6, 1983 TABLE 6 FEDERAL EMERGENCY MANAGEMENT AGENCY ORANGE COUNTY, TEXAS AND INCORPORATED AREAS COMMUNITY MAP HISTORY 46

7.0 OTHER STUDIES A Type 15 Flood Insurance Study for Orange County was prepared by the Corps of Engineers, Galveston District, in 1970, and revised in 1973 (Reference 26). Other flood related studies that concentrate on portions of the study area include the preliminary Flood Insurance Studies for the area from Sabine Lake to Matagorda Bay (Reference 27), for the cities of Orange and West Orange (Reference 3), Orange (Reference 28), Vidor (Reference 29), Bridge City (Reference 19), and Pinehurst (Reference 30), Flood Plain and Flood Hazard Information Reports on Sabine River and Adams Bayou (Reference 5), and on Tiger and Caney Creeks, Meyers Bayou, and Anderson and Terry Gullies (Reference 25), a comprehensive basin study on the Sabine River (Reference 31), the National Shoreline Study (Reference 32) and the Texas Coast Hurricane Study (Reference 6), the Flood Insurance Studies for neighboring Jefferson County and City of Beaumont, Texas, Cameron and Calcasieu Parishes, Louisiana (References 33, 34, 35, 36 and 37), and the Hurricane Surge Frequency Study by the USACE, Coastal Engineering Research Center (Reference 38). A number of other information sources were also used for background purposes (References 39, 40, 41, and 42). The 1-percent-annual-chance hurricane surge elevations for the open Gulf Coast at Sabine were originally published by the USACE, Coastal Engineering Research Center in 1969 (Reference 38) and by the Galveston District in 1979 (Reference 6). The USACE 1977 study (Reference 3) predicted a 1-percent-annual-chance flood level of 13 feet NGVD. The original FISs published for the City of Orange and Orange County in 1983 were updated and revised in 1997 to incorporate data from a detailed restudy along the Sabine River, from approximately 34,500 feet above its mouth to approximately 46,500 feet above its mouth (City of Orange corporate limit) and from profile station 70,000 to profile station 150,820 (boundary of Newton County), prepared for Calcasieu Parish, Louisiana (Reference 37). The discharges through the reaches are based on the log-pearson Type III analysis of USGS Gage No. 08030500 at Ruliff, Texas. The Manning's "n" value is 0.035 for the channel and ranges from 0.10 to 0.12 for the overbanks. The elevations of a flood having a 1-percent-annual-chance of being equaled or exceeded in any given year (base flood) decreased through the revised reach. The maximum base flood elevation (BFE) decrease, 4.2 feet, occurred approximately 96,620 feet above its mouth. The BFEs along Little Cypress Bayou decreased because of the lower backwater conditions induced by the Sabine River. The maximum BFE decrease, 3.5 feet, occurred at its confluence with the Sabine River. The width of the Special Flood Hazard Area (SFHA), the area inundated by the base flood, has also decreased along the Sabine River and Little Cypress Bayou. Along the Sabine River, the maximum decrease in SFHA width, approximately 2,000 feet, occurred approximately 122,000 feet above its mouth. Along Little Cypress Bayou, the maximum decrease in SFHA width, approximately 400 feet, occurred approximately 15,200 feet upstream of its confluence with the Sabine River. The floodway widths along the Sabine River, from approximately 70,000 feet to approximately 108,000 feet above its mouth and from approximately 132,000 feet to approximately 140,000 feet above its mouth. The floodway width along the Sabine River from approximately 108,000 feet to approximately 132,000 feet above its mouth increased to produce a HEC-2 hydraulic model with surcharges less than or equal to 1.00 foot. The floodway width along the Sabine River from approximately 140,000 feet to approximately 150,820 feet above its mouth also increased to match the floodway boundary of Newton County. The maximum increase in floodway width, approximately 1,200 feet, occurred approximately 126,320 feet above the mouth of the Sabine River. 47

The City of Orange and Orange County FISs were also revised in 1997 to incorporate data from a detailed restudy of the Sabine River, from 46,500 feet to 70,000 feet above the mouth, prepared for Calcasieu Parish, Louisiana (Reference 37). The discharges through the reach are based on the log- Pearson Type III analysis of U.S. Geological Survey Gage No. 08030500 at Ruliff, Texas. The Manning's "n" values range from 0.020 to 0.035 for the channel and from 0.040 to 0.100 for the overbanks. The base flood elevations (BFEs) along the Sabine River decreased throughout the revised reach. The maximum BFE decrease, 2.7 feet, occurred approximately 69,400 feet above its mouth. The BFEs along Little Cypress Bayou decreased because of the lower backwater conditions induced by the Sabine River. The maximum BFE decrease, 3.5 feet, occurred along the entire reach of Little Cypress Bayou that lies within the corporate limits of the City of Orange. The width of the Special Flood Hazard Area (SFHA), the area inundated by the base flood, has also been revised along the Sabine River and Little Cypress Bayou. Along the Sabine River, the SFHA width decreased a maximum of approximately 600 feet approximately 80,500 feet above its mouth. Along Little Cypress Bayou, the maximum decrease in SFHA width, approximately 500 feet, occurred approximately 17,750 feet upstream of its confluence with the Sabine River, and the maximum increase in SFHA width, approximately 250 feet, occurred approximately 16,600 feet upstream of its confluence with the Sabine River. Countywide FIS reports have been published for the incorporated and unincorporated areas of Jasper and Hardin Counties, Texas and Calcasieu and Cameron Parishes, Louisianan. A countywide preliminary study for Jefferson County, Texas is being published simultaneously with this study. This Orange County study is in agreement with those studies. This countywide FIS incorporates the original and revised community FIS reports as referenced in Table 6. 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. 8.0 LOCATION OF DATA Information concerning the pertinent data used in the preparation of this study can be obtained by contacting Federal Insurance and Mitigation Division, FEMA Region VI, Federal Regional Center, Room 206, 800 North Loop 288, Denton, Texas 76201-3698. 48

9.0 BIBLIOGRAPHY AND REFERENCES 1. U.S. Department of Commerce, Bureau of the Census, Profile of General Population and Housing Characteristics: 2010 Demographic Profile Data, http://factfinder2.census.gov/. 2. U.S. Department of the Interior, Geological Survey, Land-Surface Subsidence in the Texas Coastal Region, Texas Water Development Board, Report 272, November 1982. 3. U.S. Army Corps of Engineers, Galveston District, for Federal Insurance Administration, Flood Insurance Study, Cities of Orange and West Orange, Orange County, Texas, 1977. 4. U.S. Department of the lnterior, Geological Survey, Floods of April-June 1953, Sabine River Basin, Texas and Louisiana, and Neches River Basin, Texas, OFR No.50, prepared by Texas District Surface Water Branch, 1954. 5. U.S. Army Corps of Engineers, Galveston District, Flood Plain Information, Sabine River and Adams Bayou, Orange, Texas Area, July 1968. 6. U.S. Army Corps of Engineers, Galveston District, Texas Coast Hurricane Study, March 1979. 7. Orange Leader, Galveston Daily News, Houston Chronicle, Houston Post, News clippings compiled for storms of 1953, 1958, 1961, 1963, and 1979. 8. U.S. Army Corps of Engineers, Galveston District, Report on Hurricane Carla 9-12, September 1961, January 1962. 9. National Climatic Data Center. Extreme Weather Events. 2011. http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwevent~showevent~343896. 10. U.S. Department of the Army, Corps of Engineers, Hydrologic Engineering Center, Computer Program 723-X6-L20 10, HEC-1 Flood Hydrograph Package, Users Manual, Davis, California, January 1973. 11. U.S. Department of Agriculture, Soil Conservation Service, Generalized Soils Map for Orange County, October 1963 (Revised November 1970). 12. U.S. Department of Agriculture, Soil Conservation Service, Generalized Soils Map for Jasper County, March 1976. 13. U.S. Department of the Interior. Geological Survey, 7.5-Minute Series Topographic Maps, Scale 1:24,000, contour interval 5 feet: Beaumont East 1943 (photorevised 1970), Echo 1960 (photorevised 1975), Mauriceville 1943 (photorevised 1970), Orange 1955 (photorevised 1975), Orangefield 1943 (photorevised 1970), Pine Forest 1943 (photorevised 1970), Port Arthur North 1943 (photorevised 1970), Port Arthur South 1943 (photorevised 1970), Terry 1943 (photorevised 1970), Texas Point 1943 (photorevised 1970), Texla 1943 (photorevised 1970), West of Greens Bayou 1943 (photorevised 1970), and West of Johnsons Bayou 1943 (photorevised 1970). 14. Tetra Tech, Inc., Aerial Maps, Scale 1:9600, December 1978. 49

15. Beard, L.R. and S. Chang, An Urban Runoff Model for Tulsa, Oklahoma, Technical Report CRWR 160, Department of Civil Engineering, University of Texas, Austin, Texas, August 1978. 16. Beard, L.R. and S. Chang, Urbanization Impact on Streamflow, Journal of the Hydraulics Division, ASCE, HY6, June 1979. 17. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Climatic Center, Deck 488, Hourly Precipitation, 1948-1975. 18. Hershfield, D.M., Rainfall Frequency Atlas of the United States, Technical Paper No. 40, U.S. Weather Bureau, 1961. 19. U.S. Army Corps of Engineers, Galveston District, Flood Insurance Study, City of Bridge City, Orange County, Texas, for Federal Insurance Administration, January 1977. 20. U.S. Department of the Army, Corps of Engineers, Hydrologic Engineering Center, Applications of the HEC-2 Bridge Routines, June 1974. 21. U.S. Army Corps of Engineers, HEC-2 Water-Surface Profiles, Users Manual, August 1979. 22. Barnes, H.H., Roughness Characteristics of Natural Channels, U.S. Geological Survey, Water Supply Paper 1849, 1967. 23. Tetra Tech, Inc., Coastal Flooding Handbook, Parts 1 and 2, for Federal Emergency Management Agency, August 1979. 24. Sanborn, Texas Coastal LiDAR Campaign Final Report for Orange County, April 2007. 25. U.S. Army Corps of Engineers, Galveston District, Flood Plain Information. Tiger and Caney Creeks, Meyers Bayou, Anderson and Terry Gullies, Vidor, Texas, December 1971. 26. U.S. Army Corps of Engineers, Galveston District, Preliminary Flood Insurance Study, Orange County, Texas, for Federal Insurance Administration, 1970 (Revised 1973). 27. U.S. Army Corps of Engineers, Galveston District, Flood Insurance Study, Texas Gulf Coast, Sabine Lake to Matagorda Bay, Texas, Volume 1, for Federal Insurance Administration, May 1970. 28. Shaw, Bob, Consulting Engineers, Flood Insurance Study for the City of Orange, Texas, Prepared for the City of Orange, March 1977. 29. U.S. Army Corps of Engineers, Galveston District, Flood Insurance Study, City of Vidor, Orange County, Texas, for Federal Emergency Management Agency, July 1982. 30. U.S. Army Corps of Engineers, Galveston District, Flood Insurance Study, City of Pinehurst, Texas, for Federal Insurance Administration, July 1982. 50

31. U.S. Army Corps of Engineers, Fort Worth and Galveston Districts, Comprehensive Basin Study, Sabine River and Tributaries, Texas and Louisiana, December 1967. 32. U.S. Army Corps of Engineers, Galveston District, National Shoreline Study, Texas Coast Shores, Regional Inventory Report, 1971. 33. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Insurance Study, Jefferson County, Texas, by Turner, Collie and Braden, Inc., March 1972. 34. Federal Emergency Management Agency, Federal Insurance Administration, Flood Insurance Study, City of Beaumont, Texas, by Tetra Tech, July 1980. 35. Pyburn and Odom, Flood Insurance Study, Cameron Parish, Louisiana, for Cameron Parish Police Jury, May 1970. 36. U.S. Army Corps of Engineers, New Orleans District, Flood Insurance Study for Calcasieu Parish, Louisiana, March 1978. 37. U.S. Army Corps of Engineers, New Orleans District, Flood Insurance Study for Calcasieu Parish, Louisiana, February 1996. 38. U.S. Army Corps of Engineers, Coastal Engineering Research Center, Hurricane Surge Frequency Estimates for the Gulf Coast of Texas, B. Bodine, CERC Technical Memorandum No. 26, February 1969. 39. Rady and Associates, Inc., Background and Commentary on the Review Draft Flood Study of Bridge City, Orange County, Texas, January 1977. 40. U.S. Department of Housing and Urban Development, Federal Insurance Administration, Flood Hazard Boundary Map, Prepared by City of Bridge City Chamber of Commerce, Scale 1" = 100", May 1974. 41. U.S. Army Corps of Engineers, Galveston District, Floods in the Vidor, Texas Area, pamphlet, December 1971. 42. U.S. Department of Housing and Urban Development, Flood Hazard Boundary Map, City of Rose City, Texas, July 12, 1977. 51