U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3221

Prepared in cooperation with the New Jersey Department of Environmental Protection

Flood-Inundation Maps for the Saddle River 

from Rochelle Park to Lodi, New Jersey, 2012

Pamphlet to accompany
Cover. The August 2011 flood event on the Saddle River in Lodi, New Jersey. (Photograph by John J. Trainor, U.S. Geological Survey)
Flood-Inundation Maps for the Saddle River 

from Rochelle Park to Lodi, New Jersey, 2012

By Heidi L. Hoppe and Kara M. Watson

Prepared in cooperation with 

New Jersey Department of Environmental Protection

Scientific Investigations Map 3221

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, 

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Hoppe, H.L. and Watson, K.M., 2012, Flood-inundation maps for the Saddle River from Rochelle Park to Lodi, 

New Jersey, 2012: U.S. Geological Survey Scientific Investigations Map 3221, 7 p., 11 sheets, scale 1:12,000. 

Available online at http://pubs.usgs.gov/sim/3221.
iii

Acknowledgments

The authors wish to thank the many local, State, and Federal agencies that have cooperated in the funding for the operation and maintenance of the streamgage used for this study, 

especially the New Jersey Department of Environmental Protection and the U.S. Army Corps 

of Engineers, New York District. Special thanks are given to National Technological Hazards 

Management Consulting, Inc., for their cooperation in providing the hydrologic model for this 

study and to the National Weather Service for their continued support of the U.S. Geological 

Survey flood-inundation mapping initiative.
iv

Contents

Acknowledgments........................................................................................................................................iii

Abstract...........................................................................................................................................................1

Introduction.....................................................................................................................................................1

Purpose and Scope ..............................................................................................................................2

Study Area Description........................................................................................................................2

Previous Studies ...................................................................................................................................4

Constructing Water-Surface Profiles.........................................................................................................4

Hydrologic and Steady Flow Data......................................................................................................4

Topographic/Bathymetric Data ..........................................................................................................4

Energy Loss Factors .............................................................................................................................4

Model Calibration and Performance .................................................................................................4

Development of Water-Surface Profiles...........................................................................................5

Inundation Mapping ......................................................................................................................................5

Saddle River, New Jersey, Flood-Inundation Maps on the Internet............................................5

Disclaimer for Flood-Inundation Maps .............................................................................................6

Uncertainties and Limitations Regarding Use of Flood-Inundation Maps ..................................6

Summary..........................................................................................................................................................6

References Cited............................................................................................................................................6

Figures

1. Map showing location of study reach for the Saddle River at Lodi, New Jersey, 

and location of U.S. Geological Survey streamgage and National Weather service 

forecast point ................................................................................................................................3

Tables

1. U.S. Geological Survey streamgage and miscellaneous site information 

for study basin, Saddle River, New Jersey...............................................................................2

2. 1.0-percent annual exceedance probability peak-discharge estimates, 

drainage areas, and percentage of total discharge for selected locations 

on the Saddle River, New Jersey...............................................................................................4

3. Stages and water-surface elevations for the Saddle River at Lodi, New Jersey, 

streamgage with corresponding discharge estimates at 0.5 mile downstream from 

Interstate 80 along the Saddle River, New Jersey, for selected simulated 

water-surface profiles. ................................................................................................................5
v

Sheets

1. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 5.0 feet and an elevation of 29.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

2. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 6.0 feet and an elevation of 30.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

3. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 7.0 feet and an elevation of 31.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

4. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 8.0 feet and an elevation of 32.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

5. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 9.0 feet and an elevation of 33.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

6. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 10.0 feet and an elevation of 34.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

7. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 11.0 feet and an elevation of 35.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

8. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 12.0 feet and an elevation of 36.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

9. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 13.0 feet and an elevation of 37.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

10. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 14.0 feet and an elevation of 38.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.

11. Flood-inundation map for the Saddle River from Rochelle Park to Lodi, New Jersey 

corresponding to a gage height of 15.0 feet and an elevation of 39.0 feet at the U.S. 

Geological Survey streamgage 01391500 Saddle River at Lodi, New Jersey.
vi

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

Hydraulic gradient

foot per mile (ft/mi) 0.1894 meter per kilometer (m/km)

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).
Abstract

Digital flood-inundation maps for a 2.75-mile reach of 

the Saddle River from 0.2 mile upstream from the Interstate 

80 bridge in Rochelle Park to 1.5 miles downstream from the 

U.S. Route 46 bridge in Lodi, New Jersey, were created by the 

U.S. Geological Survey (USGS) in cooperation with the New 

Jersey Department of Environmental Protection (NJDEP). The 

inundation maps, which can be accessed through the USGS 

Flood Inundation Mapping Science Web site at http://water.

usgs.gov/osw/flood_inundation/, depict estimates of the areal 

extent and depth of flooding corresponding to selected water 

levels (stages) at the USGS streamgage at Saddle River at 

Lodi, New Jersey (station 01391500). Current conditions for 

estimating near real-time areas of inundation using USGS 

streamgage information may be obtained on the Internet at 

http://waterdata.usgs.gov/nwis/uv?site_no=01391500. The 

National Weather Service (NWS) forecasts flood hydrographs at many places that are often collocated with USGS 

streamgages. NWS-forecasted peak-stage information may be 

used in conjunction with the maps developed in this study to 

show predicted areas of flood inundation. 

In this study, flood profiles were computed for the stream 

reach by means of a one-dimensional step-backwater model. 

The model was calibrated using the most current stagedischarge relations at the Saddle River at Lodi, New Jersey 

streamgage and documented high-water marks from recent 

floods. The hydraulic model was then used to determine 11 

water-surface profiles for flood stages at the Saddle River 

streamgage at 1-ft intervals referenced to the streamgage 

datum, North American Vertical Datum of 1988 (NAVD 88), 

and ranging from bankfull, 0.5 ft below NWS Action Stage, 

to the extent of the stage-discharge rating, which is approximately 1 ft higher than the highest recorded water level at the 

streamgage. Action Stage is the stage which when reached by 

a rising stream the NWS or a partner needs to take some type 

of mitigation action in preparation for possible significant 

hydrologic activity. The simulated water-surface profiles were 

then combined with a geographic information system 3-meter 

(9.84-ft) digital elevation model (derived from Light Detection and Ranging (LiDAR) data) in order to delineate the area 

flooded at each water level.

The availability of these maps, along with Internet information regarding current stage from USGS streamgages and 

forecasted stream stages from the NWS, provide emergency 

management personnel and residents with information that is 

critical for flood response activities, such as evacuations and 

road closures, as well as for post-flood recovery efforts.

Introduction

The Borough of Lodi is an urban community with an 

estimated population of 24,136 and a population density of 

10,657.6 persons per square mile (U.S. Bureau of Census, 

2012). Lodi has experienced severe flooding numerous times, 

most notably in 2011 (Hurricane Irene), 1999 (Tropical Storm 

Floyd), and 1971. Damage costs not adjusted for inflation 

within Lodi for these floods were reported to be $6,599,425 

in 2011 and $4,049,052 in 1999 (New Jersey Department of 

Environmental Protection, State National Flood Insurance 

Program Coordinators Office, written commun., 2012). Damage costs for the 1971 flood are not available because Lodi 

Borough did not join the National Flood Insurance Program 

(NFIP) until February 15, 1978. Most of the flood damages 

have occurred along the Saddle River and the Stink Creek 

tributary, both of which flow through the Borough of Lodi. 

Floodplains within Lodi are highly developed and contain a 

mix of residential and commercial structures.

Prior to this study, Lodi officials relied on several information sources (all of which are available on the Internet) to 

make decisions on how to best alert the public and mitigate 

flood damages. One source is the Federal Emergency Management Agency (FEMA) Flood Insurance Study (FIS) for Bergen 

County dated September 30, 2005 (Federal Emergency Management Agency, 2005). A second source of information is the 

U.S. Geological Survey (USGS) Saddle River at Lodi, New 

Jersey, streamgage (station 01391500), from which current or 

Flood-Inundation Maps for the Saddle River from Rochelle 

Park to Lodi, New Jersey, 2012

By Heidi L. Hoppe and Kara M. Watson 
2 Flood-Inundation Maps for the Saddle River from Rochelle Park to Lodi, New Jersey, 2012

historical water levels (stage) can be obtained. A third source 

is the National Weather Service (NWS) forecast of peak stage 

at the USGS streamgage through the Advanced Hydrologic 

Prediction Service (AHPS) site. Although information on 

USGS current stage and NWS forecast stage is particularly 

useful for residents in the immediate vicinity of a streamgage, 

it is of limited use to residents farther upstream or downstream 

because the water-surface elevation is not constant along the 

entire stream channel. Also, FEMA and State emergency management mitigation teams or property owners typically lack 

information related to how deep the water is at locations other 

than near USGS streamgage or NWS flood-forecast points. 

Purpose and Scope

The purpose of this report is to describe the development 

of a series of estimated flood-inundation maps for the Saddle 

River from Rochelle Park to Lodi, New Jersey. The maps 

and other useful flood information are available on the USGS 

Flood Inundation Mapping Science Web site at http://water.

usgs.gov/osw/flood_inundation/. Internet users can select estimated inundation maps that correspond to (1) current stages at 

the USGS streamgage, (2) the NWS forecasted peak stage, or 

(3) other desired stream stages.

The scope of the study was limited to a 2.75-mile reach 

of the Saddle River from 0.2 mile upstream from the Interstate 

80 bridge in Rochelle Park to 1.5 miles downstream from 

the U.S. Route 46 bridge in Lodi (fig. 1). Tasks specific to 

development of the maps were (1) analysis of data from the 

Saddle River at Lodi streamgage (table 1), (2) collection of 

topographic data and geometric data (for structures/bridges) 

throughout the study reach, (3) verification of energy-loss 

factors (roughness coefficients) in the stream channel and 

floodplain and steady-flow data from previous studies (4) computation of water-surface profiles using the U.S. Army Corps 

of Engineer’s HEC–RAS computer program (U.S. Army 

Corps of Engineers, 2010), (5) production of estimated floodinundation maps at various stream stages using the U.S. Army 

Corps of Engineer’s HEC–GeoRAS computer program (U.S. 

Army Corps of Engineers, 2009) and a geographic information system (GIS), and (6) development of a Web interface that 

links to USGS real-time streamgage information and NWS 

forecasted peak stage to facilitate the display of user-selected 

flood-inundation maps on the Internet.

Methods used are generally cited from previously 

published reports. If techniques varied substantially from 

previously documented methods owing to local hydrologic 

conditions or available data, they are described in detail in 

this report. Maps were produced for water levels referenced 

to the stage at Saddle River at Lodi, New Jersey, and ranging 

from approximately bankfull, 0.5 foot (ft) below NWS Action 

Stage, to the extent of the stage-discharge rating, approximately 1 ft higher than the maximum observed water level at 

the streamgage. Action Stage is the stage which when reached 

by a rising stream, lake, or reservoir represents the level 

where the NWS or a partner/user needs to take some type of 

mitigation action in preparation for possible significant hydrologic activity (National Weather Service, 2010).

Study Area Description

The Saddle River is in northeast New Jersey in the 

Piedmont physiographic province. The drainage area ranges 

from 54.6 square miles (mi2) at the Saddle River at Lodi 

streamgage to 59.8 mi2 at the downstream extent of the 

study reach. The headwaters originate in Rockland County, 

in southern New York State, and the stream flows generally southward before entering the borough limits of Lodi in 

Bergen County, New Jersey. Stink Creek is a major tributary to the Saddle River that joins the main stem as it flows 

through Lodi. The Saddle River drains into the Passaic River 

1.1 miles downstream from Lodi, New Jersey. The basin 

terrain is moderately hilly. The study reach is approximately 

2.75 miles long and has an average top-of-bank channel width 

of 109 ft and an average channel slope of 8.5 feet per mile 

(ft/mi). About 81.2 percent of the land contiguous to the study 

reach is classified as urban or developed, 11.2 percent as 

forest, and 0.5 percent as cropland (New Jersey Department 

of Environmental Protection, 2010). The basin is still under 

development, and population has increased 0.7 percent from 

23,971 to 24,136 during the period 2000 to 2010 (U.S. Census 

Bureau, 2012). Six major road crossings or other structures 

are located within the main channel of the study reach or the 

adjacent floodplain. 

Table 1. U.S. Geological Survey streamgage and miscellaneous site information for study basin, Saddle River, New Jersey.

Station name Station 

number

Drainage area 

(square miles) Latitude Longitude Period of record Maximum recorded stage at gage (feet) and date

Saddle River at Lodi, NJ 01391500 54.6 40°53′25′′ 74°04′50′′ Oct 1923 to 2012 

(current year)

13.94

Sep 17, 1999
Introduction 3

Lodi Borough

Rochelle Park 

Township

Saddle Brook

Township

Garfield City

OUTWATER LANE

01391500

74°06' 5'30" 5' 74°04'30"

40°53'30"

53'

52'30"

40°52'

Study

area

NEW JERSEY

0 0.25 0.5 MILE

0 0.25 0.5 KILOMETER

Base from U.S. Geological Survey digital data 

North American Datum of 1983 (NAD83)

46

80

S a

d d l e

R i

v

e

r

S a

d d l e

R i

v

e

r

Stink C r e e kStink C r e e k

PASSAIC STREET

17

MARKET STREET

EXPLANATION

Flood-inundation area

Study area extent

Township boundary

Flow arrow—Indicates direction of water flow

U.S. Geological Survey streamgage 

and number, collocated with National 

Weather Service forecast point

U.S. route marker

Interstate route marker

State route marker

01391500

46

80

17

Figure 1. Location of study reach for the Saddle River at Lodi, New Jersey, and location of U.S. Geological Survey streamgage 

and National Weather service forecast point.
4 Flood-Inundation Maps for the Saddle River from Rochelle Park to Lodi, New Jersey, 2012

Previous Studies

The current FIS for Lodi (Federal Emergency Management Agency, 2005) was completed by Natural and Technological Hazards Management Consulting, Inc., (NTHMC) in 

2004. That study provided information on the 1.0- and 0.2-percent annual exceedance probability water-surface profiles and 

associated floodplain maps for the Saddle River. Estimates 

of the peak discharges for the 1.0-percent annual exceedance 

probability flood along the Saddle River, as shown in table 2 

below for the study reach, were described by FEMA (2005). 

Constructing Water-Surface Profiles

The water-surface profiles used to produce the 11 floodinundation maps in this study were computed using HEC–

RAS, version 4.1.0 (U.S. Army Corps of Engineers, 2010). 

HEC–RAS is a one-dimensional step-backwater model for 

simulation of water-surface profiles with steady-state (gradually varied) or unsteady-state flow computation options. The 

HEC–RAS analysis for this study was done using the steadystate flow computation option.

Hydrologic and Steady Flow Data

The study area hydrologic network consists of one 

streamgage (fig. 1; table 1). This streamgage already existed 

prior to this study. Water level (stage) is measured continuously and continuous records of streamflow are computed 

at this site. All water-surface elevations are referenced to 

North American Vertical Datum of 1988 (NAVD 88). The 

streamgage is equipped with a satellite radio transmitter that 

allows data to be transmitted routinely on the Internet within 

an hour of collection. 

Steady-flow data consist of flow regime, boundary 

conditions (normal depth, as per the original model, with the 

rating curve added at the streamgage cross section), and peak 

discharge information. The peak discharge data for the study 

reach were obtained from field measurements and the stagedischarge relation that was developed by the USGS at the 

Saddle River at Lodi, New Jersey streamgage.

Topographic/Bathymetric Data

Channel cross sections were developed from NTHMC 

field surveys that were conducted in 2004; these cross sections 

provide detailed channel elevation data below the water surface and were collected using hydroacoustic instrumentation 

to measure depth and Differential Global Positioning System 

(DGPS) instrumentation to determine horizontal position. 

Light Detection and Ranging (LiDAR) data were used to 

provide 3-meter (9.84-ft) digital elevation data for the portions 

of the cross sections that were above the water surface at the 

time of the surveys. The LiDAR data were collected during 

2006–07, and post-processing of these data was completed by 

U.S. National Geospatial-Intelligence Agency (NGA) in 2007. 

Various man-made drainage structures (bridges, culverts, 

roadway embankments, levees, and dams) in and along the 

stream affect or have the potential to affect water-surface 

elevations during floods along the stream. To properly account 

for these features in the model, structural dimensions for six 

bridges were measured and surveyed in the field concurrently 

with the stream-channel surveys. A detailed description of 

the methods used to acquire and process the topographic and 

bathymetric data can be found in Bales and others (2007). 

Energy Loss Factors

Field observations and high-resolution aerial photographs 

were used to select initial (pre-calibration) Manning’s roughness coefficients (“n” values) for energy (friction) loss calculations. The final Manning’s n values used ranged from 0.025 to 

0.08 for the main channel and 0.020 to 0.10 for the overbank 

areas modeled in this analysis. 

Model Calibration and Performance

The hydraulic model was calibrated to the most current stage-discharge relation at the Saddle River at Lodi 

streamgage. The measured peak discharge for the 2011 flood 

was 5,740 cubic feet per second (ft3/s) at a stage of 13.50 

ft at the streamgage. The measured peak discharge for the 

1999 flood was 5,330 ft3/s (stage of 13.94 ft). Model calibration was accomplished by adjusting Manning’s n values and, 

Table 2. 1.0-percent annual exceedance probability peak-discharge estimates, drainage areas, and percentage of total discharge for 

selected locations on the Saddle River, New Jersey. (From Federal Emergency Management Agency, 2005)

Location on Saddle River Drainage area 

(square miles)

Peak-discharge estimate 

(cubic feet per second)

Percentage of 

total discharge

At Outwater Lane, Saddle River at Lodi, NJ, streamgage 54.6 5,440 100
Inundation Mapping 5

in some cases, changing the channel cross section or slope 

until the results of the hydraulic computations closely agreed 

with the known flood discharge and stage values. Differences 

between measured and simulated water levels for measured or 

rated flows at USGS streamgage Saddle River at Lodi (station 01391500) were equal to or less than 0.13 ft. The results 

demonstrate that the model is capable of simulating accurate 

water levels over a wide range of flows in the basin. Details on 

techniques used in model development and calibration can be 

found in Bales and others (2007).

Development of Water-Surface Profiles

Profiles were developed for a total of 11 stages at 1-ft 

intervals from 5.0 ft to 15.0 ft as referenced to the Saddle 

River at Lodi, New Jersey (station 01391500). Discharges 

corresponding to the various stages were obtained from the 

most current stage-discharge relation (rating no. 33) at the 

Saddle River streamgage. Discharges for all profiles (table 3) 

at locations upstream and downstream from station 01391500 

on the Saddle River were selected with the assumption that the 

percentage contribution to the total flow was the same as that 

assumed for the 2005 FIS (table 2).

Inundation Mapping

Flood-inundation maps were created for the USGS 

Saddle River at Lodi streamgage (station 01391500), which 

has been designated as a NWS flood-forecast point (as of 

December 1973). The maps were created in a geographic 

information system by combining the water-surface profiles 

and digital elevation model data. The 3-meter (9.84-ft) digital 

elevation model data were derived from LiDAR data obtained 

from the NGA (National Geospatial-Intelligence Agency, 

2007). Each digitized cross-section line used for the study 

area was attributed with a HEC-RAS calculated water-surface 

elevation for each of the 11 profiles (table 3). The flood 

surfaces were generated using an iterative finite-difference 

interpolation technique found in the ArcGIS, TopoToRaster 

tool. This tool is unique because it is the only ArcGIS interpolation routine designed to work intelligently with contour data, 

and it combines locally efficient interpolation methods with 

global surface-continuity routines (Environmental Systems 

Research Institute, Inc., 2009). Inputs into the tool are contour 

data using the digital cross sections attributed with the NAVD 

88 elevation, in feet, and boundary data using the study-area 

polygon. Depth of water grids were generated by subtracting 

the flood water-surface elevation from the study-area digital 

elevation model (DEM). (Roland and Hoffman, 2011) The 

map products show estimated flood-inundated areas overlaid 

on high-resolution, geo-referenced, aerial photographs of the 

study area for each of the water-surface profiles that were 

generated by the hydraulic model.

Saddle River, New Jersey, Flood-Inundation 

Maps on the Internet

The flood-inundation maps and current study documentation are available online at the U.S. Geological Survey 

Publications Warehouse (http://pubs.usgs.gov/sim/2012/3221). 

Also, a Flood Inundation Mapping Science Web site has been 

established to provide a portal for USGS flood-inundation 

study information for the public at http://water.usgs.gov/osw/

flood_inundation/. That Web portal has a link (http://wim.usgs.

gov/FIMI/FloodInundationMapper.html) to interactive online 

map libraries that can be downloaded in several commonly 

used electronic file formats. In the latter link, each stream 

reach displayed contains further links to the USGS National 

Water Information System (NWISWeb) graphs of the current stage and streamflow at the USGS Saddle River at Lodi 

streamgage (station 01391500) to which the inundation maps 

are referenced. A link also is provided to the NWS AHPS site 

(http:/water.weather.gov/ahps/) so that the user can obtain 

applicable information on forecasted peak stage. The estimated 

flood-inundation maps are displayed in sufficient detail to note 

the extent of flooding with respect to individual structures so 

Table 3. Stages and water-surface elevations for the Saddle 

River at Lodi, New Jersey, streamgage (station 01391500) with 

corresponding discharge estimates at 0.5 mile downstream from 

Interstate 80 along the Saddle River, New Jersey, for selected 

simulated water-surface profiles.

[NAVD 88, North American Vertical Datum of 1988]

Map 

sheet 

number

Stage, 

in feet above 

gage datum

Elevation, 

in feet above 

NAVD 88

Estimated discharge, 

in cubic feet 

per second

1 5 29 1,430

2 6 30 1,900

3 7 31 2,360

4 8 32 2,800

5 9 33 3,310

6 10 34 3,820

7 11 35 4,360

8 12 36 4,900

9 13 37 5,460

10 14 38 6,020

11 15 39 6,600
6 Flood-Inundation Maps for the Saddle River from Rochelle Park to Lodi, New Jersey, 2012

that preparations for flooding and decisions for emergency 

response can be performed efficiently. Roadways and bridges 

were closely reviewed and are shown as shaded (inundated 

and likely impassable) or not shaded (dry and passable) to 

facilitate emergency planning and use. However, buildings 

that are shaded do not reflect inundation but denote that bare 

earth surfaces in the vicinity of the buildings are inundated. 

When the water depth (as indicated in the Web Mapping 

Application by holding the cursor over an inundated area) in 

the vicinity of the building of interest exceeds that building’s 

height, the structure can be considered fully submerged.

Disclaimer for Flood-Inundation Maps

Inundated areas shown are not to be used for navigation, 

regulatory, permitting, or other legal purposes. The USGS 

provides these maps “as-is” for a quick reference, emergency 

planning tool but assumes no legal liability or responsibility 

resulting from the use of this information.

Uncertainties and Limitations Regarding Use of 

Flood-Inundation Maps

Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some uncertainty 

is associated with these maps. The flood boundaries shown 

were estimated on the basis of water stages and streamflows 

at the USGS streamgage station Saddle River at Lodi, New 

Jersey (01391500). Water-surface elevations along the stream 

reaches were estimated by steady-state hydraulic modeling, assuming unobstructed flow, and using streamflows and 

hydrologic conditions anticipated at the USGS streamgage. 

The hydraulic model reflects the land-cover characteristics and 

any bridge, dam, levee, or other hydraulic structures existing 

as of September 2004. Unique meteorological factors (timing 

and distribution of precipitation) may cause actual streamflows 

along the modeled reach to vary from those assumed during 

a flood, which may lead to deviations in the water-surface 

elevations and inundation boundaries shown. Additional areas 

may be flooded as a result of unanticipated conditions, such as 

changes in the streambed elevation or roughness, backwater 

into major tributaries along a main stem river, or backwater from localized debris or ice jams. The accuracy of the 

floodwater extent portrayed on these maps will vary with the 

accuracy of the digital elevation model used to simulate the 

land surface. Additional uncertainties and limitations pertinent 

to this study may be described elsewhere in this report.

If this series of flood-inundation maps will be used in 

conjunction with NWS river forecasts, the user should to be 

aware of additional uncertainties that may be inherent or factored into NWS forecast procedures. The NWS uses forecast 

models to estimate the quantity and timing of water flowing 

through selected stream reaches in the United States. These 

forecast models (1) estimate the amount of runoff generated 

by precipitation and snowmelt, (2) simulate the movement 

of floodwater as it proceeds downstream, and (3) predict the 

flow and stage (and water-surface elevation) for the stream at 

a given location (AHPS forecast point) throughout the forecast 

period (every 6 hours and 3 to 5 days out in many locations). 

For more information on AHPS forecasts, please see http://

water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. 

Summary

A series of estimated flood-inundation maps were developed in cooperation with the New Jersey Department of Environmental Protection for the Saddle River between Rochelle 

Park and Lodi, New Jersey. These maps, available at a USGS 

Web portal, in conjunction with the real-time stage data from 

the USGS streamgage at Saddle River at Lodi, New Jersey 

(station 01391500) and National Weather Service flood-stage 

forecasts, will help to guide the general public in taking individual safety precautions and will provide municipal officials 

with a tool to efficiently manage emergency flood operations 

and flood mitigation efforts.

The maps were developed using the U.S. Army Corps 

of Engineers’ HEC–RAS and HEC–GeoRAS programs to 

compute water-surface profiles and to delineate estimated 

flood-inundation areas for selected stream stages. The maps 

show estimated (shaded) flood-inundation areas overlaid on 

high-resolution, geo-referenced, aerial photographs of the 

study area for stream stages of 5 ft to 15 ft at 1-ft intervals at 

the Saddle River at Lodi streamgage. Interactive use of the 

maps using the mouse cursor to click within the shaded areas 

can give users a general indication of depth of water at any 

point. These maps can be accessed through the USGS Flood 

Inundation Mapping Science Web site at http://water.usgs.gov/

osw/flood_inundation/.

References Cited

Bales, J.D., Wagner, C.R., Tighe, K.C., and Terziotti, Silvia, 

2007, LiDAR-derived flood-inundation maps for realtime flood-mapping applications, Tar River Basin, North 

Carolina: U.S. Geological Survey Scientific Investigations 

Report 2007–5032, 42 p.

Environmental Systems Research Institute, Inc., 2009, Products—ArcGIS: accessed May 16, 2011, at http://www.esri.

com/products/index.html.

Federal Emergency Management Agency, 2005, Flood Insurance Study, Bergen County, New Jersey: Washington, D.C., 

September 30, 2005, 4 p.

National Geospatial-Intelligence Agency, 2007, LiDAR-Metro 

N. Jersey 2006–07: Springfield, Virginia.
References Cited 

7

National Weather Service, 2010, National Weather Service 

Manual 10-950, accessed May 31, 2012, at http://www.nws.

noaa.gov/directives/sym/pd01009050curr.pdf.

Natural and Technological Hazards Management Consulting, 

Inc., 2004, Final hydrology: Riverine flood insurance stud-

ies in FEMA Region II New Jersey FY-03: Saddle River, 

New Jersey, 107 p.

New Jersey Department of Environmental Protection, 2010, 

NJDEP 2007 landuse/landcover update, State of New Jer-

sey, accessed May 16, 2011, at http://www.nj.gov/dep/gis/

lulc07shp.html.

Roland, M.A., and Hoffman, S.A., 2011, Development of 

flood-inundation maps for the West Branch Susquehanna 

River near the Borough of Jersey Shore, Lycoming County, 

Pennsylvania: U.S. Geological Survey Scientific Investiga-

tions Report 2010–5057, 9 p.

U.S. Army Corps of Engineers, Hydrologic Engineering Cen-

ter, 2009, HEC-GeoRAS, GIS tools for support of HEC–

RAS using ArcGIS, User’s manual, version 4.2, [variously 

paged]. 

U.S. Army Corps of Engineers, Hydrologic Engineering 

Center, 2010, HEC–RAS River Analysis System, Hydraulic 

reference manual, version 4.1, [variously paged].

U.S. Bureau of Census, 2012, Census 2010 state and county 

quick facts, accessed April 23, 2012, at http://quickfacts.

census.gov/qfd/states/34/3441100.html.

For additional information, write to:

Director, 

New Jersey Water Science Center

U.S. Geological Survey

810 Bear Tavern Road, Suite 206

West Trenton, NJ 08628

or visit our Web site at:

http://nj.usgs.gov/

Document prepared by the West Trenton Publishing Service Center
Hoppe and Watson—Flood-Inundation Maps for the Saddle River from Rochelle Park to Lodi, New Jersey, 2012—Scientific Investigations Map 3221