Jefferson County

JEFFERSON COUNTY, NEW YORK (ALL JURISDICTIONS) Community Name ADAMS, TOWN OF* ADAMS, VILLAGE OF* ALEXANDRIA, TOWN OF* ALEXANDRIA BAY, VILLAGE OF* ANTWERP, TOWN OF* 1 ANTWERP, VILLAGE OF * BLACK RIVER, VILLAGE OF BROWNVILLE, TOWN OF* BROWNVILLE, VILLAGE OF* CAPE VINCENT, TOWN OF* CAPE VINCENT, VILLAGE OF* CARTHAGE, VILLAGE OF* CHAMPION, TOWN OF* CHAUMONT, VILLAGE OF*

Community Number 360324 360325 360326 360327 361560 361554 361525 361063 361576 361062 361574 360995 360328 360329

Community Name CLAYTON, TOWN OF* CLAYTON, VILLAGE OF* 1 DEFERIET, VILLAGE OF * DEXTER, VILLAGE OF* ELLISBURG, TOWN OF* ELLISBURG, VILLAGE OF* EVANS MILLS, VILLAGE OF* 1 GLEN PARK, VILLAGE OF * HENDERSON, TOWN OF* HERRINGS, VILLAGE OF* HOUNSFIELD, TOWN OF* 2 LERAY, TOWN OF 1 LORRAINE, TOWN OF * LYME, TOWN OF* 1 MANNSVILLE, VILLAGE OF *

Community Number 360330 360331 360332 360333 360334 360335 360337 360336 360338 360339 360340 360341 360342 360343 360344

Community Name

Community Number

ORLEANS, TOWN OF* PAMELIA, TOWN OF* PHILADELPHIA, TOWN OF* PHILADELPHIA, VILLAGE OF* RODMAN, TOWN OF* RUTLAND, TOWN OF* SACKETS HARBOR, VILLAGE OF* THERESA, TOWN OF* THERESA, VILLAGE OF* WATERTOWN, CITY OF* WATERTOWN, TOWN OF* WEST CARTHAGE, VILLAGE OF* WILNA, TOWN OF* 1 WORTH, TOWN OF *

1

360345 360346 360347 360348 360349 360350 360351 360352 360353 360354 360355 360356 360357 361409

No Special Flood Hazard Areas Identified Please see Flood Insurance Rate Map Index for current Effective Map Panel * Community is not included in this partial countywide Flood Insurance Study (FIS) and will retain its existing, separately published FIS and/or FIRM 2

Preliminary: April 30, 2012

FLOOD INSURANCE STUDY NUMBER 36045CV000A

NOTICE TO FLOOD INSURANCE STUDY USERS Communities participating in the National Flood Insurance Program have established repositories of flood hazard data for floodplain management and flood insurance purposes. This Flood Insurance Study (FIS) report may not contain all data available within the Community Map Repository. Please contact the Community Map Repository for any additional data. The Federal Emergency Management Agency (FEMA) may revise and republish part or all of this FIS report at any time. In addition, FEMA may revise part of this FIS report by the Letter of Map Revision process, which does not involve republication or redistribution of the FIS report. Therefore, users should consult with community officials and check the Community Map Repository to obtain the most current FIS report components. This preliminary partial countywide FIS report includes only Floodway Data Tables and Flood Profiles for detailed studied flooding sources within the village of Black River and town of LeRay. Flood Hazard data for other jurisdictions within Jefferson County can be found by consulting the FIS and/or FIRM (if published) for each community. Initial Countywide Effective Date:

To Be Determined

TABLE OF CONTENTS 1.0 

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

2.0 

AREA STUDIED .................................................................................................................. 3  2.1  Scope of Study ................................................................................................................ 3  2.2  Community Description .................................................................................................. 4  2.3  Principal Flood Problems................................................................................................ 5  2.4  Flood Protection Measures ............................................................................................. 5 

3.0 

ENGINEERING METHODS .............................................................................................. 6  3.1  Hydrologic Analyses....................................................................................................... 6  3.2  Hydraulic Analyses ......................................................................................................... 9  3.3  Vertical Datum .............................................................................................................. 11 

4.0 

FLOODPLAIN MANAGEMENT APPLICATIONS ..................................................... 15  4.1  Floodplain Boundaries .................................................................................................. 15  4.2  Floodways ..................................................................................................................... 16 

5.0 

INSURANCE APPLICATIONS ....................................................................................... 22 

6.0 

FLOOD INSURANCE RATE MAP ................................................................................. 23 

7.0 

OTHER STUDIES .............................................................................................................. 23 

8.0 

LOCATION OF DATA ...................................................................................................... 23 

9.0 

BIBLIOGRAPHY AND REFERENCES ......................................................................... 25 

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TABLE OF CONTENTS (Continued)

FIGURES Figure 1 - Floodway Schematic ........................................................................................................ 22 TABLES Table 1 - Summary of Discharges ...................................................................................................... 8 Table 2 - Manning's "n" Values ........................................................................................................ 11 Table 3 - Vertical Datum Used..........................................................................................................12 Table 4 - Verical Datum Conversion ................................................................................................ 12 Table 5 - Qualifying NGS Bench Marks Near the Town of LeRay ................................................. 14 Table 6 - Floodway Data................................................................................................................... 18 Table 7 - Community Map History ................................................................................................... 24 EXHIBITS Exhibit 1 - Flood Profiles Black River Black River Split Flow Indian River Pleasant Creek West Creek Exhibit 2

Panels 01P-05P Panel 06P Panels 07-09P Panels 10P-12P Panel 13P

Flood Insurance Rate Map Index Flood Insurance Rate Map Panels*: *Please note, the Town of LeRay will be shown on community-based panels 3603410020E, 3603410040E, 3603410043E, 3603410044E, 3603410056E, 3603410057E, 3603410058E, 3603410059E & 3603410065E and on countywide-based panels 36045C0543G, 36045C0544G, 36045C0561G, 36045C0562G, 36045C0563G, 36045C0751G, 36045C0752G & 36045C0756G

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FLOOD INSURANCE STUDY JEFFERSON COUNTY, NEW YORK (ALL JURISDICTIONS)

1.0

INTRODUCTION 1.1

Purpose of Study This Flood Insurance Study (FIS) revises and updates information on the existence and severity of flood hazards in portions of the geographic area of Jefferson County for the following selected communities: the Town of LeRay and Village of Black River (referred to collectively herein as Jefferson County). The remaining portions of Jefferson County will be shown at a later date. Effective Flood Insurance Rate Maps (FIRMs) (including the FIRM panels for that portion of the town of LeRay outside of the Black River watershed) and FISs for communities not included in this partial countywide are not superseded by this study. Therefore, please refer to the current FIRM and/or FIS (if published) for each of those jurisdictions. This FIS aids in the administration of the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973. This study has developed flood-risk data for various areas of the community that will be used to establish actuarial flood insurance rates and to assist the community in its efforts to promote sound floodplain management. Minimum floodplain management requirements for participation in the National Flood Insurance Program (NFIP) are set forth in the Code of Federal Regulations at 44 CFR, 60.3. In some states or communities, floodplain management criteria or regulations may exist that are more restrictive or comprehensive than the minimum Federal requirements. In such cases, the more restrictive criteria take precedence and the State (or other jurisdictional agency) will be able to explain them. The FIRM and FIS report for this countywide study have been produced in digital format. Flood hazard information was converted to meet the Federal Emergency Management Agency (FEMA) FIRM database specifications and Geographic Information System (GIS) format requirements. The flood hazard information was created and is provided in a digital format so that it can be incorporated into a local GIS and be accessed more easily by the community.

1.2

Authority and Acknowledgments The sources of authority for this FIS are the National Flood Insurance Act of 1968 and the Flood Disaster Protection Act of 1973.

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Precountywide Analyses Information on the authority and acknowledgements for each jurisdiction included in this countywide FIS, as compiled from their previously printed FIS reports, is shown below: LeRay, Town of:

In the January 16, 1992, FIS, the hydrologic and hydraulic analyses for Black River and Pleasant Creek were prepared by Kozma Associates Consulting Engineers, P.C., for the FEMA, under Contract No. EMW-88-C-2601. That work was completed in May 1990 (FEMA, 1992). In the February 2, 2002 revision, the hydrologic and hydraulic analyses for the Indian River and West Creek were prepared by Kozma Associates and Medina Consultants, P.C. for FEMA, under Contract No. EMN-98-CO-0013. This work was completed in September 1999 (FEMA, 2002). The base map information for the Indian River, Pleasant Creek and West Creek was derived from U.S. Geological Survey (USGS) Digital Orthophoto Quadrangles produced at a scale of 1:12,000 from photography dated 1994 or later. The coordinate system used for the production of the digital FIRM is Universal Transverse Mercator (UTM) Zone 18. The horizontal datum is NAD 83, Geodetic Reference System 1980 (GRS80) spheroid.

The Village of Black River has no previously printed FIS report; therefore, the previous authority and acknowledgment information for this community is not included in this partial countywide FIS. Month Date, 201x Partial Countywide FIS Report The hydrologic and hydraulic analyses for this study were performed by Bergmann Associates for FEMA, under Project Order No. 11-02-1472S. The work was completed in February 2012. Base map information shown on this FIRM was provided in digital format by the New York State Office of Cyber Security and Critical Infrastructure Coordination.

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This information was derived from 1- and 2-foot resolution digital orthophotography dated April 2006. The projection used in the preparation of this map is UTM zone 18, and the horizontal datum used is NAD83 GRS80 spheroid. 1.3

Coordination An initial meeting is held with representatives from FEMA, the community, and the study contractor to explain the nature and purpose of a FIS, and to identify the streams to be studied or restudied. A final meeting is held with representatives from FEMA, the community, and the study contractor to review the results of the study. Precountywide Analyses The initial and final meeting dates for previous FIS reports for Jefferson County and its communities are listed in the following table: Community

FIS Date

Initial Meeting

Final Meeting

LeRay, Town of

January 16, 1992 February 2, 2002

October 11, 1990* **

February 26, 1991 November 1, 2000

*Notified by letter **Data not available

Month Date, 201x Partial Countywide FIS Report The initial meeting was held on October 26, 2010, and attended by representatives of the New York State Department of Conservation (NYSDEC), Jefferson County, the Town of LeRay and the Village of Black River. The results of the study were reviewed at the final meeting held on Month Day, 201x, and attended by representatives of list all communities and parties that were in attendance. All issues and/or concerns raised at that meeting have been addressed.

2.0

AREA STUDIED 2.1

Scope of Study This FIS covers the geographic area of Jefferson County, New York, listed in Section 1.1. The areas studied by detailed methods were selected with priority given to all known flood hazards and areas of projected development or proposed construction through June 2011.

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The following streams were studied by detailed methods in this FIS report: Black River Black River Split Flow Indian River

Pleasant Creek West Creek

For this partial countywide FIS report, the Black River and Black River Split Flow were restudied by detailed methods from 5,200 feet upstream of the Delano Island Dam upstream to approximately 1,050 feet upstream of New York State Route 26. The limits of detailed study are indicated on the Flood Profiles (Exhibit 1) and on the FIRM (Exhibit 2). Approximate analyses were used to study those areas having low development potential or minimal flood hazards. The scope and methods of study were proposed to and agreed upon by FEMA and Jefferson County. No Letters of Map Revision were incorporated into this partial countywide. 2.2

Community Description Jefferson County is located in northern New York and is divided into 41 communities, only two of which are included within this study. The Town of LeRay and the Village of Black River are located near the center of the county, northeast of the county seat of the City of Watertown. Jefferson County is bordered to the northeast by St. Lawrence County; to the east by Lewis County; to the south by Oswego County; and to the west by Lake Ontario and the St. Lawrence River which forms the international border with Canada. According to the 2010 Census, the population of Jefferson County is 116,229. This figure represents an approximately 0.7% increase of population over the county’s 2000 population (U.S. Census Bureau, 2011). The climate of the county is greatly influenced by Lake Ontario and is characterized by long, cold winters and cool, short summers. During the winter, temperatures are frequently below zero degrees Fahrenheit (°F), while the summer temperatures rarely reach 90°F. The average high temperature is 28°F in January and 79°F in July. Precipitation averages 42.6 inches annually, and the average snowfall is over 100 inches (The Weather Channel, 2011). The Black River, a major aquifer in the region, runs along the southern border of the Town of LeRay and lies in the Lake Ontario Drainage Basin. Between Carthage and Lake Ontario, it flows through a rocky gorge and falls 480 feet in

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30 miles (U.S. Army Corps of Engineers (USACE), 1977a). Because of this topographic feature, numerous dams have been constructed across the river and several electric power generating plants have been built along its banks. However, a major portion of the town is drained by the Indian River, which flows northerly into the St. Lawrence River. Its drainage area is 238 square miles at its entry to LeRay, whereas it is 283 square miles at its exit. Pleasant Creek, a tributary of West Creek, lies within the drainage system. Fort Drum, a U.S. Military Reservation, where Pleasant Creek has its origin, occupies the southeastern part of the town. West Creek, a major tributary of the Indian River, has a drainage area of 31.8 square miles at its confluence with Indian River. It flows generally north and drains the southeastern portion of the town. 2.3

Principal Flood Problems Flooding can occur in the community during any season of the year, but it is most likely to occur in the late winter-early spring months when the melting snow may combine with intense rainfall to produce increased runoff. Ice jams and debris have often contributed to increasing the flood heights by impeding water flow at bridges and culverts. The largest flood of record on the Black River occurred on April 12, 1993. Its estimated peak discharge at the City of Watertown gaging station No. 04260500 was 42,600 cubic feet per second (cfs) (USGS Surface Water website http://nwis.waterdata.usgs.gov/usa/nwis/peak).

2.4

Flood Protection Measures There are no known structural flood control measures in existence within the study area of this report. However, in 1987 the Town of LeRay adopted a local law known as the "Flood Damage Prevention Local Law" (Town of LeRay, undated).

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3.0

ENGINEERING METHODS For the flooding sources studied by detailed methods in the community, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude that are expected to be equaled or exceeded once on the average during any 10-, 50-, 100-, or 500-year period (recurrence interval) have been selected as having special significance for floodplain management and for flood insurance rates. These events, commonly termed the 10-, 50-, 100-, and 500-year floods, have a 10-, 2-, 1-, and 0.2-percent chance, respectively, of being equaled or exceeded during any year. Although the recurrence interval represents the long-term, average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood that equals or exceeds the 1-percent-annual-chance (100-year) flood in any 50-year period is approximately 40 percent (4 in 10); for any 90-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes.

3.1

Hydrologic Analyses Hydrologic analyses were carried out to establish peak discharge-frequency relationships for each flooding source studied by detailed methods affecting the community. Precountywide Analyses Peak discharges for the Black River contained in the February 2, 2002 FIS for the Town of LeRay were based on the USACE 1977 Report of the Flood 14-18 March 1977 Black River Basin, New York (USACE, 1977a) and USACE, 1977, Floodplain Information Report Deferiet Dam to Confluence Deer River (USACE, 1977b), which provided 100-year peak discharges at USGS gaging station No. 04260500. Also in the February 2, 2002 FIS for the Town of LeRay, for Pleasant Creek, the peak discharge of the selected recurrence interval was determined using the procedures and regression equations outlined in "USGS Water Investigations 79-83," for ungaged sites on gaged streams (U.S. Department of the Interior, 1979 and Water Resources Council, 1977). For the western region of New York, the following equation was used: Q = K(DA)x(St +10)-y(P – 20)z where Q is the stream discharge; DA is the drainage area; St is the percentage of total drainage area shown as lakes, ponds, and swamps; P is the mean annual precipitation; K, x, y, and z are functions of the frequency. A value of 864 was used for K, 0.759 for x, 1.27 for y, and 0.67 for z, for the 100-year flood 6

discharge. In the February 2, 2002 revision, for Indian River and West Creek, the peak discharges of the selected recurrence intervals were determined using the procedures and regression equations outlined in "USGS Water Resources Investigations Report 90-4197," for ungaged streams (U.S. Department of the Interior, 1991 and Water Resources Council, 1977). For Hydrologic Region No.1 of New York State, the following equation was used: Q = K(DA)W(ST + 5)X(P - 20)Y(F + 10)Z where Q is the stream discharge; DA is the drainage area in square miles; ST is the basin storage in percent of the total basin drainage area; P is the mean annual precipitation in inches; and F is the percentage of the total basin area with forest cover; whereas K, w, x, y, and z are functions of the frequency. The values used for K, w, x, y, and z were as follows: FREQUENCY 10-percent-annual-chance 2-percent-annual-chance 1-percent-annual-chance 0.2-percent-annual-chance

K 130.0 250.0 306.0 441.0

w 0.881 0.868 0.864 0.858

x -0.526 -0.544 -0.548 -0.553

y 0.961 0.919 0.899 0.853

z -0.490 -0.510 -0.508 -0.496

Month Date, 201x Partial Countywide FIS Report As part of this revised study, discharges for points along the Black River were calculated by gage analysis, weighted with the 2006 (document Scientific Investigations Report (SIR)2006-5112) published USGS regression estimates, and transferred to ungaged sites upstream and downstream of the gage. Nomination locations, for this revision, were selected to coincide with nominations published in the previously published FIS reports and at hydrologically significant locations such as large changes in drainage area or at structures. The Black River is monitored by USGS gaging station, No. 04260500, with a drainage area of 1,864 square miles, located in the City of Watertown. The gage record contains annual peak estimates for the period from April 1869 to January 2010, the most recent year for which records were published. This revised study benefits from twenty-one additional observed annual peak discharges since the previous analysis. The annual peak stream flow values for the gage are notated as being subject to regulation and diversion. The Black River also has several run of river dams along its twenty-two mile reach within Jefferson County. However, these dams along the river were constructed to operate industrial mills or are now in use to generate hydroelectric power. None provide attenuation of peak flood events, nor is the amount of diversion considered significant in comparison to peak flood flows. Therefore, the period of record of the gage is considered to be homogeneous and unregulated for this analysis.

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The aforementioned gage record was analyzed using the USGS PeakFQ (v 5.2) software that uses the method of moments to fit the Pearson Type III distribution to the logarithms of annual flood peaks. This hydrologic analysis produces peak estimates for the 10-, 2-, 1-, and 0.2-percent-annual-chance frequency events. These results were weighted with the regional regression equation estimates in accordance with the procedures outlined in the SIR 2006-5112 Magnitude and Frequency of Floods in New York, (USGS, 2006). Therefore, the revised 1% annual chance estimate is 44,707 cfs at the City of Watertown gage station as compared to the value published in SIR2006-5112, Table 1 which provides a weighted peak estimate for the 1-percent-annual-chance event of 44,600 cfs based on the analysis of 99 records. Peak discharge-drainage area relationships for each flooding source studied in detail are shown in Table 1. Table 1 - Summary of Discharges Peak Discharges (cfs) Drainage Area (square miles)

10-PercentAnnual-Chance

2-PercentAnnual-Chance

1-PercentAnnual-Chance

0.2-PercentAnnual-Chance

BLACK RIVER At town of Wilna/town of LeRay corporate limit (Approximately 2.2 miles upstream of Great Bend Road bridge)

1,809.53

30,856

39,360

43,166

52,237

At town of Rutland/town of Champion corporate boundary (Approximately 4,000 feet downstream of Great Bend Road bridge)

1,813.88

31,032

39,591

43,420

52,550

At village of Black River/town of LeRay corporate boundary (Approximately 5,000 feet downstream of Black River Power Dam)

1,846.25

31,651

40,380

44,271

53,584

At town of Rutland/town of Watertown corporate boundary (Approximately 1.9 miles upstream of Eastern Boulevard bridge)

1,847.90

31,679

40,416

44,309

53,630

At town of LeRay/town of Pamela corporate boundary (Approximately 1.1 miles upstream of Eastern Boulevard bridge)

1,848.50

31,695

40,436

44,332

53,657

1,811

*

*

8,791

*

INDIAN RIVER At the downstream corporate limit of town of LeRay

283.6

9,350

12,900

14,530

18,390

Upstream from the confluence with West Creek

238.0

7,570

10,450

11,770

14,910

Flooding Source and Location

BLACK RIVER SPLIT FLOW At Kamargo Dam

*Data not available

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Table 1 - Summary of Discharges – con’t Peak Discharges (cfs) Drainage Area (square miles)

10-PercentAnnual-Chance

2-PercentAnnual-Chance

1-PercentAnnual-Chance

0.2-PercentAnnual-Chance

20.2

*

*

2,961

*

Approximately 2,400 feet upstream from US Route 11 and State Route 26

17.2

*

*

2,621

*

Approximately 3,000 feet downstream from Simonet Road

12.6

*

*

2,069

*

31.8

2,220

3,210

3,670

4,730

Flooding Source and Location PLEASANT CREEK At the town of LeRay/town of Philadelphia corporate boundary

WEST CREEK At the confluence with Indian River *Data not available

3.2

Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. Users should be aware that flood elevations shown on the FIRM represent rounded whole-foot elevations and may not exactly reflect the elevations shown on the Flood Profiles or in the Floodway Data Table in the FIS report. Flood elevations shown on the FIRM are primarily intended for flood insurance rating purposes. For construction and/or floodplain management purposes, users are cautioned to use the flood elevation data presented in this FIS report in conjunction with the data shown on the FIRM. Precountywide Analyses In the January 16, 1992, FIS, for the Black River, the cross-sectional data for the backwater analyses of the Black River were obtained from maps at a scale of 1:2,400 by the Niagara Mohawk Power Corporation from aerial photographs (Niagara Mohawk Power Corporation, undated). For Pleasant Creek the crosssectional data for the backwater analyses were obtained from topographic maps at a scale of 1:24,000 which were enlarged to 1:4,800 (USGS, 1982). The belowwater sections were obtained by field measurements. All bridges, dams, and culverts were field surveyed to obtain elevation data and structural geometry. Water-surface elevations of floods of the selected recurrence intervals were computed using the USACE HEC-2 step-backwater computer program (USACE, 1976). Starting water-surface elevations were calculated using the slope/area method. Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence intervals.

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For Indian River, Pleasant Creek, and West Creek, water-surface elevations of floods of the selected recurrence intervals were computed using the USACE HEC-2 step-backwater computer program (USACE, 1976). Starting watersurface elevations were calculated using the slope/area method. Flood profiles were drawn showing computed water-surface elevations for floods of the selected recurrence intervals. For the February 2, 2002 revision, cross sections for the Indian River and West Creek were obtained from field surveys. All bridges, dams, and culverts were field surveyed to obtain elevation data and structural geometry. Month Date, 201x Partial Countywide FIS Report For Black River water-surface elevations for floods of the selected recurrence intervals were computed using the USACE HEC-RAS version 4.1.0 river modeling computer program (HEC, 2010). The HEC-RAS model for each flooding source is based on cross-section geometry generated using both field survey and semi-automated methods derived from GIS techniques and data. For that portion of the Black River studied using approximate methods, cross-section elevations were obtained from a Digital Elevation Model (DEM). The DEM was generated by combining overbank elevation data from a grid derived from an aerial Light Detection and Ranging (LiDAR) survey with data from traditional field survey of the stream channel and its immediate overbank areas to produce a GIS grid. All bridges, culverts, dams, and other hydraulic obstructions were field surveyed to provide data on elevation, orientation, and structural geometry. With data used from the pre-countywide FIS’s, at selected locations along Black River, an overbank "n" value of 10 was used to eliminate conveyance in areas of ineffective flow. The channel bottom of the Black River is comprised mainly of fractured rock and shale and remains consistent throughout the study reach. Hence, a consistent manning’s roughness was deemed appropriate for use in this study. The Black River flow is divided into two channels at Poors Island in the Village of Black River. The division of flow is controlled by the gates and spillway of the Kamargo Dam. Flow is diverted into the southerly channel via a set of inlet gates to provide flow to a hydropower dam located downstream of South Main Street. Flow into the northerly channel, the primary channel, is controlled by the dams crest. For this revision, a split flow analysis was performed for the southerly and northerly channels based on the hydraulic capacity of the gates and dam crest resulting in independent 1% annual chance floodplain and Floodways. The southerly channel analysis only considered flooding effects for the 1% annual chance event due to the intake gates design.

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For Indian River, Pleasant Creek, and West Creek, channel roughness factors (Mannings “n”) used in the hydraulic computations were chosen by engineering judgment. The Manning’s “n” values for all detailed studied streams are shown in Table 2 – Mannings “n” Values:

TABLE 2 - Manning's "n" Values Stream Black River Indian River Pleasant Creek West Creek

Channel “n” 0.035 – 0.045 0.030-0.035 0.040 0.030-0.035

Overbank “n” 0.050 0.060-0.085 0.070-0.080 0.060-0.085

An approximate stream centerline was derived using geographically rectified aerial photography and the DEM. This serves as a base line to define distances along the stream channel as indicated on the Flood Profile and the Floodway Data Tables. Locations of selected cross sections used in the hydraulic analyses are shown on the Flood Profiles (Exhibit 1). For stream segments for which a floodway was computed (Section 4.2), selected cross section locations are also shown on the FIRM (Exhibit 2). The hydraulic analyses for this study were based on unobstructed flow. The flood elevations shown on the Flood Profiles (Exhibit 1) are thus considered valid only if hydraulic structures remain unobstructed, operate properly, and do not fail. 3.3

Vertical Datum IMPORTANT NOTICE: This FIS and FIRM use two vertical datums to reference elevation. A vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared. All flood elevations shown in this FIS report and on the FIRM within the town of LeRay are referenced to either the National Geodetic Vertical Datum of 1929 (NGVD 29) or the North American Vertical Datum of 1988 (NAVD 88), based on the specific flooding source and panel. All elevations in the village of Black River are referenced to NAVD 88. Table 3 – Vertical Datum Used, identifies the vertical datum used for each flooding source and printed FIRM panel within the town of LeRay.

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TABLE 3 - Vertical Datum Used Vertical Datum

Flooding Source

NGVD 29

Indian River Pleasant Creek West Creek

NAVD 88

Black River

Printed FIRM Panels 3603410020E, 3603410040E, 3603410043E, 3603410044E, 3603410056E, 3603410057E, 3603410058E, 3603410059E, 3603410065E 36045C0543G, 36045C0544G, 36045C0561G, 36045C0562G, 36045C0563G, 36045C0751G, 36045C0752G, 36045C0756G

Structure and ground elevations affected by a particular flooding source or located on a printed FIRM panel as shown above must be referenced to the correct vertical datum. It is important to note that communities adjacent to the town of LeRay or village of Black River may be referenced to either NGVD 29 or NAVD 88. This may result in differences in Base Flood Elevations (BFEs) across the corporate limits between the communities and watersheds. As noted above, the elevations shown in the FIS report and on the FIRM for Jefferson County are referenced to NGVD 29 or NAVD 88. Ground, structure, and flood elevations may be compared and/or referenced to either datum by applying a standard conversion factor. The conversion between the datums may be expressed as the following equation: NGVD 29 = NAVD 88 + 0.446 foot The average conversion factor that was used in this FIS report to determine NAVD88 was calculated using the National Geodetic Survey’s (NGS) VERTCON online utility (NGS, 2012). The data points used to determine the conversion are listed in Table 4. TABLE 4 – Vertical Datum Conversion Quadrangle Corner

Latitude

Longitude

Conversion from NGVD 29 to NAVD 88 (feet)

Adams

NE

-76.000

43.875

-0.435

Alexandria Bay

NE

-75.875

44.375

-0.447

Antwerp

NE

-75.500

44.250

-0.476

Barnes Corners

NE

-75.750

43.875

-0.323

Black River

NE

-75.750

44.125

-0.439

Boylston Center

NE

-75.875

43.750

-0.354

Brownville

NE

-75.875

44.125

-0.452

Cape Vincent South

NE

-76.250

44.125

-0.473

Cape Vincent South OE W

NE

-76.375

44.125

-0.485

Quadrangle Name

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TABLE 4 – Vertical Datum Conversion – con’t

Quadrangle Corner

Latitude

Longitude

Conversion from NGVD 29 to NAVD 88 (feet)

Carthage

NE

-75.500

44.000

-0.374

Chaumont

NE

-76.125

44.125

-0.458

Clayton

NE

-76.000

44.250

-0.467

Copenhagen

NE

-75.625

44.000

-0.379

Deferiet

NE

-75.625

44.125

-0.456

Dexter

NE

-76.000

44.125

-0.448

Ellisburg

NE

-76.125

43.750

-0.488

Galloo Island

NE

-76.375

44.000

-0.504

Henderson

NE

-76.125

43.875

-0.481

Henderson Bay

NE

-76.125

44.000

-0.467

La Fargeville

NE

-75.875

44.250

-0.461

North Wilna

NE

-75.500

44.125

-0.465

Philadelphia

NE

-75.625

44.250

-0.490

Point Peninsula

NE

-76.250

44.000

-0.489

Redwood

NE

-75.750

44.375

-0.458

Rodman

NE

-75.875

43.875

-0.384

Rutland Center

NE

-75.750

44.000

-0.382

Sackets Harbor

NE

-76.000

44.000

-0.449

Saint Lawrence

NE

-76.125

44.250

-0.472

Sandy Creek

NE

-76.000

43.750

-0.425

Stony Point

NE

-76.250

43.875

-0.512

Theresa

NE

-75.750

44.250

-0.493

Thousand Island Park

NE

-76.000

44.375

-0.366

Watertown

NE

-75.875

44.000

-0.433

Worth Center

NE

-75.750

43.750

-0.324

Henderson

SW

-76.250

43.750

-0.523

Point Peninsula

SW

-76.375

43.875

-0.526

Quadrangle Name

Average Conversion from NGVD 29 to NAVD 88 = -0.446 (feet)

13

For additional information regarding conversion between NGVD 29 and NAVD 88, visit the NGS website at www.ngs.noaa.gov, or contact the NGS at the following address: Vertical Network Branch, N/CG13 National Geodetic Survey, NOAA SSMC-3 #9202 1315 East-West Highway Silver Spring, Maryland 20910 (301) 713-3242 The following list of qualifying bench marks are those that are catalogued by the NGS in the National Spatial Reference System (NSRS) as first or second order vertical with a stability classification of A, B, or C. For purposes of establishing vertical control to determine the elevation of structures relative to the 1-percent-annual-chance flood elevations, bench marks located outside the community may be required. Table 5, "Qualifying NGS Bench Marks Near the Town of LeRay," identifies several bench marks that are located on panels not printed as well as those outside of the corporate limits of the Town of LeRay. It is important to note that vertical elevations of the bench marks listed below are expressed relative to NAVD 88 on the NGS website. Standard conversion programs such as VERTCON (www.ngs.noaa.gov/TOOLS/Vertcon/vertcon.html) may be used to translate the NAVD 88 elevations to the NGVD 29. TABLE 5 - Qualifying NGS Bench Marks Near the Town of LeRay Bench Mark NSRS Permanent Identifier PH1390 PH1204 OE1252 OE1250 PH1206 PH1387 PH1388 PH1389 PH1392 PH1393 PH1366 PH1365 PH1363 PH1353 PH1352 PH1351

Location Latitude 44.08583 44.07167 43.95361 43.97750 44.08139 44.08670 44.08639 44.08250 44.09000 44.09361 44.19444 44.20083 44.20861 44.18111 44.17056 44.16333

Longitude 75.86056 75.82028 75.81056 75.80250 75.81417 75.84425 75.84389 75.86111 75.88111 75.89528 75.86250 75.84917 75.83861 75.73833 75.72556 75.71028

Vertical Order

Stability Classification

Second Second Second Second Second Second Second Second Second Second Second Second Second Second Second Second

C C C C B C C C A B C A A C A A

Temporary vertical monuments are often established during the preparation of a flood hazard analysis for the purpose of establishing local vertical control. 14

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. Therefore, each FIS provides 1-percent-annual-chance (100-year) flood elevations and delineations of the 1- and 0.2-percent-annual-chance (500-year) floodplain boundaries and 1-percent-annual-chance floodway to assist communities in developing floodplain management measures. This information is presented on the FIRM and in many components of the FIS report, including Flood Profiles, Floodway Data Table, and Summary of Stillwater Elevations Table. Users should reference the data presented in the FIS report as well as additional information that may be available at the local map repository before making flood elevation and/or floodplain boundary determinations. 4.1

Floodplain Boundaries To provide a national standard without regional discrimination, the 1-percentannual-chance flood has been adopted by FEMA as the base flood for floodplain management purposes. The 0.2-percent-annual-chance flood is employed to indicate additional areas of flood risk in the community. For each stream studied by detailed methods, the 1- and 0.2-percent-annual-chance floodplain boundaries have been delineated using the flood elevations determined at each cross section. In the January 16, 1992 FIS, the boundaries were interpolated between cross sections using topographic maps at a scale of 1:2,400 with a contour interval of 5 feet for the Black River and topographic maps at a scale of 1:4,800 with a contour interval of 10 feet for Pleasant Creek (Niagara Mohawk Power Corporation, undated and USGS, 1982). For the February 2, 2002 FIS, between cross sections, the boundaries were interpolated using topographic maps at a scale of 1:4,800, with a contour interval of 4 feet for Indian River and West Creek (FEMA, 2002). For the February 2, 2002 revision, for the Indian River and West Creek, the boundaries were interpolated between cross- sections using topographic maps at a scale of 1:4,800, with a contour interval of 4 feet (Atlantis Aerial Survey Co., Inc., 1998).

15

For this partial countywide revision, for the Black River, the boundaries were delineated using the flood elevations at each cross section. Between cross sections the boundaries were interpolated using a DEM derived from LiDAR data. The DEM had a grid cell size of 3-meters, roughly equivalent to 2-foot contour lines. For the streams other than the Black River studied by approximate methods, the 1percent-annual-chance floodplain boundaries were taken from the previously printed FIS for the town of LeRay (FEMA, 1992). The 1- and 0.2-percent-annual-chance floodplain boundaries are shown on the FIRM (Exhibit 2). On this map, the 1-percent-annual-chance floodplain boundary corresponds to the boundary of the areas of special flood hazards (Zones A and AE), and the 0.2-percent-annual-chance floodplain boundary corresponds to the boundary of areas of moderate flood hazards. In cases where the 1- and 0.2percent-annual-chance floodplain boundaries are close together, only the 1-percentannual-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 (Exhibit 2). 4.2

Floodways Encroachment on floodplains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itself. One aspect of floodplain management involves balancing the economic gain from floodplain development against the resulting increase in flood hazard. For purposes of the NFIP, a floodway is used as a tool to assist local communities in this aspect of floodplain management. Under this concept, the area of the 1-percent-annual-chance floodplain is divided into a floodway and a floodway fringe. The floodway is the channel of a stream, plus any adjacent floodplain areas, that must be kept free of encroachment so that the 1percent-annual-chance flood can be carried without substantial increases in flood heights. Minimum Federal standards limit such increases to 1 foot, provided that hazardous velocities are not produced. The floodways in this study are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway studies. The floodway presented in this FIS report and on the FIRM was computed for certain stream segments on the basis of equal-conveyance reduction from each side of the floodplain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. The results of the floodway computations have been tabulated for selected cross sections (Table 6). In cases where the floodway and 1-percent-annual-chance floodplain boundaries are

16

either close together or collinear, only the floodway boundary has been shown. A portion of the floodway width for the Black River extends beyond the corporate limits. In the January 16, 1992 FIS, floodwaters from the Black River and Pleasant Creek were found to have hazardous velocities. Encroachment into areas subject to inundation by floodwaters having hazardous velocities aggravates the risk of flood damage, and heightens potential flood hazards by further increasing velocities. A listing of stream velocities at selected cross sections is provided in Table 6, "Floodway Data." Near the mouths of streams studied in detail, floodway computations are made without regard to flood elevations on the receiving water body. Therefore, "Without Floodway" elevations presented in Table 6 for certain downstream cross sections of West Creek are lower than the regulatory flood elevations in that area, which must take into account the 1-percent-annual-chance flooding due to backwater from other sources.

17

FLOODING SOURCE

CROSS SECTION

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (NAVD)1

FLOODWAY

DISTANCE

WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY (FEET NAVD)

WITH FLOODWAY (FEET NAVD)

INCREASE (FEET)

6,905 9,051 11,498 13,691 16,245 18,881 21,805 22,849 25,439 26,573 28,389 28,982 29,819 30,914 32,834 34,696 36,670 38,161 39,272

351 / 2573 756 / 6513 593 / 5453 259 / 1903 356 / 2713 276 213 277 270 216 305 164 367 231 235 / 1143 266 / 893 253 / 833 220 / 993 437 / 3203

7,813 10,752 10,722 4,231 6,253 7,950 3,480 4,483 5,792 3,077 4,636 1,820 5,544 3,723 3,876 3,839 4,729 4,381 7,481

5.6 4.1 4.1 10.4 7.0 5.5 12.6 9.8 7.6 14.3 9.5 19.0 6.9 9.7 11.3 11.5 9.3 10.0 5.9

507.8 508.6 509.1 509.1 512.5 513.6 526.5 541.5 548.5 548.5 552.7 560.4 567.4 568.0 569.0 572.6 575.7 577.0 578.9

507.8 508.6 509.1 509.1 512.5 513.6 526.5 541.5 548.5 548.5 552.7 560.4 567.4 568.0 569.0 572.6 575.7 577.0 578.9

507.9 508.7 509.2 509.3 512.6 513.8 527.5 542.5 548.8 548.9 553.0 560.4 567.6 568.0 569.3 572.8 576.0 577.4 579.5

0.1 0.1 0.1 0.2 0.1 0.2 1.0 1.0 0.3 0.4 0.3 0.0 0.2 0.0 0.3 0.2 0.3 0.4 0.6

2

Black River A B C D E F G H I J K L M N O P Q R S 1 2

3

North American Vertical Datum of 1988 Feet above Delano Island Dam

Width of floodway within the Town of LeRay/Total width of floodway

TABLE 6

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

JEFFERSON COUNTY, NY (ALL JURISDICTIONS)

BLACK RIVER

Table 2 - Floodway Data

18

1-PERCENT-ANNUAL-CHANCE FLOOD FLOODING SOURCE

FLOODWAY WATER SURFACE ELEVATION (NAVD)1

CROSS SECTION

DISTANCE

WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NAVD)

WITHOUT FLOODWAY (FEET NAVD)

WITH FLOODWAY (FEET NAVD)

INCREASE (FEET)

40,240 41,384 43,013 44,648 46,427 47,253 49,553 51,497 52,985 53,551 54,253

466 / 7733 508 / 7873 705 / 4383 415 / 2613 462 / 2353 305 / 1453 364 / 1643 148 / 613 137 / 803 356 / 2533 443 / 3143

7,609 5,094 9,534 3,314 7,189 4,023 5,437 3,494 2,115 5,497 5,755

5.8 8.6 4.6 13.3 6.1 10.9 8.1 12.3 20.4 7.9 7.5

580.1 580.8 583.2 584.6 596.4 596.4 600.1 600.7 607.8 619.6 620.6

580.1 580.8 583.2 584.6 596.4 596.4 600.1 600.7 607.8 619.6 620.6

580.7 581.4 583.5 584.7 596.6 596.6 600.2 601.0 607.8 619.6 620.6

0.6 0.6 0.3 0.1 0.2 0.2 0.1 0.3 0.0 0.0 0.0

100 125 185

1,569 1,977 2,233

5.6 4.4 3.9

2

Black River T U V W X Y Z AA AB AC AD Black River Split Flow A 28,844 B 30,339 C 32,363 1 North American Vertical Datum of 1988 2 Feet above Delano Island Dam

564.2 564.2 565.0 0.8 564.9 564.9 565.7 0.8 566.5 566.5 567.4 0.9 3 Width of floodway within the Town of LeRay/Total width of floodway

TABLE 6

FEDERAL EMERGENCY MANAGEMENT AGENCY

JEFFERSON COUNTY, NY (ALL JURISDICTIONS)

FLOODWAY DATA BLACK RIVER – BLACK RIVER SPLIT FLOW 19

FLOODING SOURCE

CROSS SECTION

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (NGVD)1

FLOODWAY

DISTANCE

WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NGVD)

90 3,120 5,565 8,180 10,285 12,975 14,840 16,660 18,485 20,090 21,185 23,090 25,345 27,550

160 867 250 153 158 159 190 104 161 143 105 121 136 109

2,857 8,618 3,598 2,976 2,981 3,057 3,380 2,418 3,192 2,694 2,744 2,815 2,970 2,545

5.1 1.7 4.0 4.9 4.9 4.8 4.3 4.9 3.7 4.4 4.3 4.2 4.0 4.6

405.8 407.4 407.6 408.1 408.6 409.3 409.8 410.4 411.0 411.2 412.4 412.6 412.9 413.2

2

WITHOUT WITH FLOODWAY FLOODWAY (FEET NGVD) (FEET NGVD)

INCREASE (FEET)

Indian River A B C D E F G H I J K L M N

1 2

405.8 407.4 407.6 408.1 408.6 409.3 409.8 410.4 411.0 411.2 412.4 412.6 412.9 413.2

406.8 408.3 408.5 409.0 409.5 410.2 410.7 411.4 411.9 412.1 413.3 413.6 413.9 414.2

National Geodetic Vertical Datum of 1929 Feet above Town of Philadelphia/Town of LeRay corporate limits

TABLE 6

FEDERAL EMERGENCY MANAGEMENT AGENCY

FLOODWAY DATA

JEFFERSON COUNTY, NY (ALL JURISDICTIONS)

INDIAN RIVER 20

1.0 0.9 0.9 0.9 0.9 0.9 0.9 1.0 0.9 0.9 0.9 1.0 1.0 1.0

FLOODING SOURCE

CROSS SECTION

1-PERCENT-ANNUAL-CHANCE FLOOD WATER SURFACE ELEVATION (NGVD)1

FLOODWAY WIDTH (FEET)

SECTION AREA (SQUARE FEET)

MEAN VELOCITY (FEET PER SECOND)

REGULATORY (FEET NGVD)

1102 1,4502 2,4302 5,4602 9,6802 12,8262

125 110 140 150 159 101

400 547 1,319 905 898 1,384

7.4 5.4 2.2 2.9 2.9 1.5

433.9 443.1 451.5 452.4 459.0 475.8

433.9 443.1 451.5 452.4 459.0 475.8

434.0 444.0 451.5 453.1 459.8 476.8

1.0 0.9 0.0 0.7 0.8 1.0

8103 2,9903 4,5303

83 80 71

715 935 808

5.1 3.9 4.5

409.9 409.9 409.9

402.74 405.44 406.84

403.7 406.4 407.8

1.0 1.0 1.0

DISTANCE

WITHOUT WITH FLOODWAY FLOODWAY (FEET NGVD) (FEET NGVD)

INCREASE (FEET)

Pleasant Creek A B C D E F West Creek A B C

1

National Geodetic Vertical Datum of 1929 Feet above Village of Evans Mills corporate limits 3 Feet above confluence with Indian River 2

4

Elevation computed without consideration of backwater effects from Indian River

TABLE 6

FEDERAL EMERGENCY MANAGEMENT AGENCY

JEFFERSON COUNTY, NY

FLOODWAY DATA

(ALL JURISDICTIONS) PLEASANT CREEK – WEST CREEK

The area between the floodway and 1-percent-annual-chance floodplain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the floodplain that could be completely obstructed without increasing the water surface elevation of the 1-percent-annual-chance flood more than 1 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to floodplain development are shown in Figure 1.

Figure 1 - Floodway Schematic 5.0

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

22

Zone AE Zone AE is the flood insurance risk zone that corresponds to the 1-percent-annual-chance floodplains that are determined in the FIS by detailed methods. In most instances, 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 risk zone that corresponds to areas outside the 0.2-percentannual-chance floodplain, areas within the 0.2-percent-annual-chance floodplain, areas of 1-percent-annual-chance flooding where average depths are less than 1 foot, areas of 1-percent-annual-chance flooding where the contributing drainage area is less than 1 square mile, and areas protected from the 1-percent-annual-chance flood by levees. No BFEs or base flood depths are shown within this zone. 6.0

FLOOD INSURANCE RATE MAP The FIRM is designed for flood insurance and floodplain management applications. For flood insurance applications, the map designates flood insurance risk zones as described in Section 5.0 and, in the 1-percent-annual-chance floodplains that were studied by detailed methods, shows selected whole-foot BFEs or average depths. Insurance agents use the zones and BFEs in conjunction with information on structures and their contents to assign premium rates for flood insurance policies. For floodplain management applications, the map shows by tints, screens, and symbols, the 1- and 0.2-percent-annual-chance floodplains, floodways, and the locations of selected cross sections used in the hydraulic analyses and floodway computations. The countywide FIRM presents flooding information for the selected geographic area of Jefferson County. Previously, FIRMs were prepared for each incorporated community and the unincorporated areas of the County identified as flood-prone. Historical data relating to the maps prepared for each community prior to this partial countywide are presented in Table 7.

7.0

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

8.0

LOCATION OF DATA Information concerning the pertinent data used in the preparation of this study can be obtained by contacting FEMA, Federal Insurance and Mitigation Division, 26 Federal Plaza, Room 1337, New York, New York 10278. 23

COMMUNITY NAME

Black River, Village of

LeRay, Town of

INITIAL NFIP MAP DATE

FLOOD HAZARD BOUNDARY MAP REVISION DATE

FIRM FIRM DATE

January 3, 1975

January 30, 1976 September 17, 1976

June 5, 1989

June 28, 1974

December 12, 1975 October 8, 1976

July 3, 1985

FIRM REVISION DATE

None

January 16, 1992 February 2, 2002

TABLE 7

FEDERAL EMERGENCY MANAGEMENT AGENCY

JEFFERSON COUNTY, NY (ALL JURISDICTIONS) Table 3 - Community Map History

COMMUNITY MAP HISTORY

9.0

BIBLIOGRAPHY AND REFERENCES Atlantis Aerial Survey Co., Inc., Topographic Maps, Scale 1:4,800, Contour Interval 4 feet, prepared from Aerial Photography, Bud Lake, New Jersey, 1998. Hydrologic Engineering Center, HEC-RAS River Analysis System, Version 4.1.0, U.S. Army Corp of Engineers, Davis, CA, January 2010. Federal Emergency Management Agency, Flood Insurance Study, Town of LeRay, January 16, 1992. Federal Emergency Management Agency, Flood Insurance Study, Town of LeRay, February 2, 2002. National Geodetic Survey, VERTCON - North American Vertical Datum Conversion Utility. Retrieved on March 7, 2012 from http://www.ngs.noaa.gov. Niagara Mohawk Power Corporation, Topographic Maps, Scale 1:2,400, Contour Interval 5 Feet, Syracuse, New York. Town of LeRay, Local Law No. 5: A Local Law Flood Damage Prevention, Town Board of the Town of LeRay, LeRay, New York. U.S. Army Corps of Engineers, Hydrologic Engineering Center, HEC-2 Water Surface Profiles Generalized Computer Program, Davis, California, 1976. U.S. Army Corps of Engineers, Report of Flood 14-18 March 1977. Black River Basin, New York, Buffalo, New York, 1977a. U.S. Army Corps of Engineers, Floodplain Information Report, Black River. New York. Deferiet Dam to Confluence with Deer River, Buffalo, New York, 1977b. U.S. Census Bureau, American FactFinder, Jefferson County, New York, 2010. Retrieved September 2, 2011, from http://factfinder2.census.gov. U.S. Geological Survey, 7.5-Minute Series Topographic Maps, Scale 1:24,000, Contour Interval 20 Feet: Black River, U.S. Department of the Interior, 1982. U.S. Geological Survey, Scientific Investigations Report 2006-5112, Magnitude and Frequency of Floods in New York, 2006. U.S. Department of the Interior, Geological Survey, Water Resources Investigations 70-83, Techniques for Estimating the Magnitude and Frequency of Floods on Rural Unregulated Streams in New York State Excluding Long Island, 1979.

25

U.S. Department of the Interior, Geological Survey, Water Resources Investigations Report 90-4197, Regionalization of Flood Discharges for Rural Unregulated Streams in New York State Excluding Long Island, Albany, New York, 1991. Water Resources Council, Bulletin 17A, Guidelines for Determining Flood Flow Frequency, June 1977. The Weather Channel, Monthly Averages for Watertown, NY. September 2, 2011, from http://www.weather.com.

26

Retrieved

530

520

520

510

510

500

500

490

490

480

480

470

470

460

450

0

1000

2000

3000

4000

5000

6000

7000

STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

8000

9000

10,000

11,000

BLACK RIVER

530

JEFFERSON COUNTY, NY

540

FLOOD PROFILES

ELEVATION IN FEET (NAVD 88)

540

12,000

01P

540

530

530

520

520

510

510

500

500

H

490

490

480

D

470 12,000

13,000

E

14,000

15,000

16,000

F

17,000

18,000

19,000

G

20,000

STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

21,000

22,000

23,000

24,000

JEFFERSON COUNTY, NY

540

BLACK RIVER

550

FLOOD PROFILES

ELEVATION IN FEET (NAVD 88)

550

560

BLACK RIVER POWER DAM

NYS ROUTE 3

560

25,000

02P

570

560

560

550

550

540

540

530

530

CONVERGENCE OF BLACK RIVER SPLIT FLOW

ELEVATION IN FEET (NAVD 88)

570

520

510

I

500 25,000

J

26,000

520

K

27,000

28,000

29,000

30,000

31,000

32,000

33000

STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

34,000

35,000

36,000

37,000

BLACK RIVER

580

JEFFERSON COUNTY, NY

580

FLOOD PROFILES

590

S. MAIN STREET

590

38,000

03P

LEFEBVRE MILL UPPER DAM

590

590

580

580

570

570

560

560

Z

550

550

540

R

530 38,000

S

39,000

T

40,000

U

41,000

V

42,000

43,000

W

44,000

X

45,000

46,000

STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

Y

47,000

48,000

49,000

50,000

JEFFERSON COUNTY, NY

600

BLACK RIVER

610

FLOOD PROFILES

ELEVATION IN FEET (NAVD 88)

600

FELTS MILLS DAM

610

LEFEBVRE MILL LOWER DAM

620

FIRST STREET WEST

620

51,000

04P

650

LIMIT OF DETAILED STUDY

ELEVATION IN FEET (NAVD 88)

630

620

620

610

610

600

600

590

590

580

580

570

AA

560 51,000

AB

52,000

53,000

AC

AD

54,000

55,000

BLACK RIVER

630

640

JEFFERSON COUNTY, NY

DAM

640

FLOOD PROFILES

NYS RTE 26

650

56,000 STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

05P

580

560

560

555

550

DIVERGENCE WITH BLACK RIVER

565

CONVERGENCE WITH BLACK RIVER

ELEVATION IN FEET (NAVD 88)

565

545

A

535 28,000

555

550

545

540

28,500

B

29,000

29,500

30,000

C

30,500

31,000

31,500

32,000

STREAM DISTANCE IN FEET ABOVE DELANO ISLAND DAM

32,500

33,000

BLACK RIVER SPLIT FLOW

570

DAM

570

575

JEFFERSON COUNTY, NY

575

FLOOD PROFILES

ST. REGIS STREET

KAMARGO DAM

580

33,500

06P

415

.

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