Printed on recycled paper

Flynn, R.H.—Scoping of Flood Hazard Mapping Needs for Merrimack County, New Hampshire—Open-File Report 2006

1127
Scoping of Flood Hazard Mapping Needs for 

Merrimack County, New Hampshire

By Robert H. Flynn

U.S. Department of the Interior

U.S. Geological Survey

In cooperation with the

Federal Emergency Management Agency, Region 1

Open-File Report 2006-1127
U.S. Department of the Interior

P. Lynn Scarlett, Acting Secretary

U.S. Geological Survey

P. Patrick Leahy, Acting Director

U.S. Geological Survey, Reston, Virginia: 2006

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

Any use of trade, product, or firm names in this publication 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.
 iii

Contents

Section 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Scope of Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Section 2. Data Collected from Merrimack County Communities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Community Flood Insurance Studies and Flood Insurance Rate Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Delineation of Detailed and Approximate Study Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Letters of Map Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Letters of Map Change in Merrimack County . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Mapping Needs Update Support System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Mapping Needs in Merrimack County, New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

State and Community Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Meeting with New Hampshire Office of Emergency Management (NHOEM) and 

Scoping Team Members . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Merrimack County Community Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Available Digital Mapping and Remotely Sensed Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Data-Collection Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

NH GRANIT Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Community Data Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Stream Final Coverage Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Section 3. Options for Future Mapping and Digital Terrain Model Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Mapping Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Base Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Digital Terrain Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Flood Insurance Risk Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Suitability of the Available Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

USGS of GRANIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Community Data Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

County Data Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Base Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Digital Terrain Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Flood Insurance Risk Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Mapping Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Base Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Digital Terrain Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Flood Insurance Risk Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Section 4. Hydrologic and Hydraulic Restudy Needs and Prioritization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Mapping Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Prioritization Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Prioritization Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Non-Participating Community - Dunbarton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Section 5. Recommendations and Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Mapping Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Mapping Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
 iv

Project Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Selected References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Appendixes:

Appendix A. Summary of Letters of Map Change (LOMC) Data in Merrimack County . . . . . . . . . . . . . . . . . . . . . . . 35

Appendix B. Mapping Needs Update Support System (MNUSS) Needs Assessment Reports . . . . . . . . . . . . . . 37

Appendix C. State and Community Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Appendix D. Prioritized Flooding Sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Figures

1. Merrimack County, New Hampshire, location map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Merrimack County, New Hampshire, hydrography and FEMA Digital Flood Insurance Rate Map 

(DFIRM) data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. Letter of Map Change (LOMC) and community location map in Merrimack County, New Hampshire. . . . . 9

4. Merrimack County, New Hampshire, stream final coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Tables

1. Merrimack County, New Hampshire, communities and populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. FIS and FIRM information for communities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3. Summary of specific mapping needs in Merrimack County, New Hampshire . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4. FIRM horizontal accuracy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5. National standard for spatial data accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

6. Currently available high resolution orthophotography for Merrimack County. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

7. Estimate of costs to obtain Digital Terrain Model data (2-ft contours). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8. Community flooding source prioritization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
v

CONVERSION FACTORS AND ABBREVIATIONS

Horizontal coordinate information is referenced to the insert datum name (and abbreviation) here for instance, “North 

American Datum of 1983 (NAD 83).”

OTHER ABBREVIATIONS USED IN REPORT

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 inch (in2) 6.452 square centimeter (cm2)

square mile (mi2) 2.590 square kilometer (km2)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3)

Slope

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

Velocity and Flow

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

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

APFO Aerial Photography Field Office

BFE Base Flood Elevation

CAC Community Assistance Contact

CAV Community Assistance Visit

cfs cubic feet per second

CID Community Identification

CIS Community Information System

COTR Contracting Officer’s Technical Representative

CTP Cooperating Technical Partner

DEM Digital Elevation Model

DFIRM Digital Flood Insurance Rate Map

DOQ Digital Orthophoto Quadrangle

DOQQ Digital Ortho Quarter Quadrangle

DTM Digital Terrain Model

FBFM Flood Boundary and Floodway Map

FEMA Federal Emergency Management Agency

FHBM Flood Hazard Boundary Map
 vi

FIRM Flood Insurance Rate Map

FIS Flood Insurance Study

GIS Geographic Information System

GRANIT Geographically Referenced ANalysis and Information Transfer system

GSP Ground Sample Distance

H&H Hydrologic and Hydraulic

LiDAR Light Detection and Ranging

LOMA Letter of Map Amendment

LOMC Letters of Map Change

LOMR Letter of Map Revision

LOMR-F Letter of Map Revision based on Fill

MNA Mapping Needs Assessment

MNUSS Mapping Needs Update Support System

MrSID Multi-resolution Seamless Image Database

NAIP National Agriculture Imagery Program

NDOP National Digital Ortho Program

NED National Elevation Dataset

NFIP National Flood Insurance Program

NHD National Hydrography Dataset

NHDOT New Hampshire Department of Transportation

NHOEM New Hampshire Office of Emergency Management

NHOEP New Hampshire Office of Energy and Planning

NSSDA National Standard for Spatial Data Accuracy

RMC Regional Management Center

SFHA Special Flood Hazard Area

TIN Triangulated Irregular Network

UNH University of New Hampshire

USACE United States Army Corps of Engineers

USDA United States Department of Agriculture

USEPA United States Environmental Protection Agency

USGS United States Geological Survey

UTM Universal Transverse Mercator

WISE Watershed Information System
 1

Scoping of Flood Hazard Mapping Needs for 

Merrimack County, New Hampshire

By Robert H. Flynn

Section 1. Introduction

This report was prepared by the U.S. Geological Survey (USGS) New Hampshire/VermontWater 

Science Center for scoping of flood-hazard mapping needs for Merrimack County, New Hampshire, under 

Federal Emergency Management Agency (FEMA) Inter-Agency agreement Number HSFE01-05X-0018. 

This section of the report explains the objective of the task and the purpose of the reports.

Background

FEMA is embarking on a map modernization program nationwide to:

1. Gather and develop updated data for all flood prone areas in support of floodplain management.

2. Provide maps and data in a digital format for the improvement in the efficiency and precision of the 

mapping program.

3. Integrate FEMA’s community and state partners into the mapping process.

One of the priorities for FEMA, Region 1, is to develop updated Digital Flood Insurance Rate Maps 

(DFIRMs) and Flood Insurance Studies (FIS) for Merrimack County, New Hampshire. The information 

provided in this report will be used to develop the scope for the first phase of a multiyear project that will 

ultimately result in the production of new DFIRMs and FIS for the communities and flooding sources in 

Merrimack County.

The average age of the FEMA floodplain maps in Merrimack County, New Hampshire is 18.5 years. 

Most of these studies were computed in the late 1970s to the mid 1980s. However, in the ensuing 20–

30 years, development has occurred in many of the watersheds, and the rivers and streams and their floodplains have changed as a result. In addition, as development has occurred, peak flooding has increased 

downstream of the development from increased flows across impervious surfaces. Therefore, many of the 

older studies may not depict current conditions nor accurately estimate risk in terms of flood heights.

Merrimack County gained 9,317 residents between 2000 and 2004. This represents a growth of 6.8 percent compared to 5.2 percent for the state as a whole. Merrimack County ranks third (from highest to lowest) 

out of New Hampshire’s 10 counties in terms of rate of population increase. Since 1990, Merrimack County 

has gained 25,537 residents (University of New Hampshire, 2005).
 2

Scope of Work

The following is the scope of work as defined in the FEMA/USGS Statement of Work:

Task 1: Collect data from a variety of sources including community surveys, other Federal and State 

Agencies, National Flood Insurance Program (NFIP) State Coordinators, Community Assistance Visits 

(CAVs) and FEMA archives. Lists of mapping needs will be obtained from the Mapping Needs Update 

Support System (MNUSS) database, community surveys, and CAVs, if available. FEMA archives will be 

inventoried for effective Flood Insurance Rate Maps (FIRM) panels, FIS reports, and other flood hazard 

data or existing study data. Best available base map information, topographic data, flood hazard data, and 

hydrologic and hydraulic (H&H) data will be identified and obtained. FEMA Letters of Map Change 

(LOMC) areas will also be identified.

Task 2: Contact communities in Merrimack County to notify them that FEMA and the State have 

selected them for a map update, and that a project scope will be developed with their input. Topics to be 

reviewed with the communities include (1) Purpose of the Flood Map Project (for example, the update needs 

that have prompted the map update); (2) The community's mapping needs; (3) The community’s available 

mapping, hydrologic, hydraulic, and flooding information; (4) Target schedule for completing the project; 

and (5) The community’s engineering, planning, and geographic information system (GIS) capabilities. 

When requested by the community, or when needed to obtain information on mapping needs and available 

information, the USGS will schedule meetings with individual communities. 

Based on the collected information from Task 1 and community contacts/meetings in Task 2, the USGS 

will develop a Draft Project Scope for the identified mapping needs of the communities in Merrimack 

County. The following items will be addressed in the Draft Project Scope: review of available information; 

determine if and how the currently effective FIS data can be used in new project; identify other data needed 

to complete the Project and its source; and the DFIRM format. The Draft Project Scope will establish priority levels for flooding sources to be analyzed and mapped, and estimate schedules for completion of the 

components of flood mapping.

The USGS is to supply the FEMA Contracting Officer’s Technical Representative (COTR) with a 

report summarizing the following:

1. Available data and collected information on mapping needs.

2. Documentation of meetings and contacts.

3. Suitability of existing data and options for future mapping.

4. Restudy needs and priorities.

5. Recommended project scope and influences on cost.

This report provides a summary of data-collection efforts conducted for this task, as well as information 

on available mapping/remote sensing data. The report includes recommendations for providing needed 

mapping/remote sensing data to accomplish the ultimate goal of producing new DFIRMs. It also provides 

options for accomplishing this goal within the context of FEMA’s Cooperating Technical Partner (CTP) 

Program. The report begins the process of establishing restudy priorities in Merrimack County. 

The communities of Merrimack County and their populations are listed in table 1, and the location of 

Merrimack County in New Hampshire is shown in figure 1. The Merrimack County Hydrography and 

FEMA DFIRM Data, county communities, rivers and streams and flood zones are shown in figure 2. 
Table 1. Merrimack County, New Hampshire, communities and populations.

County/Town Year 2000 

population

Land area 

(square mile)

Population per 

square mile

Merrimack County 136,225 954.7 142.7

Allenstown 4,843 20.6 235.1

Andover 2,109 41.0 51.4

Boscawen 3,672 25.4 144.6

Bow 7,138 28.5 250.5

Bradford 1,454 35.9 40.5

Canterbury 1,979 44.8 44.2

Chichester 2,236 21.3 105.0

Concord 40,687 67.2 605.5

Danbury 1,071 38.0 28.2

Dunbarton 2,226 31.3 71.1

Epsom 4,021 34.6 116.2

Franklin 8,405 29.2 287.8

Henniker 4,433 44.8 99.0

Hill 992 26.7 37.2

Hooksett 11,721 37.1 315.9

Hopkinton 5,399 45.1 119.7

Loudon 4,481 46.7 96.0

New London 4,116 25.4 162.0

Newbury 1,702 38.1 44.7

Northfield 4,548 28.9 157.4

Pembroke 6,897 22.8 302.5

Pittsfield 3,931 24.3 161.8

Salisbury 1,137 39.8 28.6

Sutton 1,544 43.3 35.7

Warner 2,760 55.5 49.7

Webster 1,579 28.8 54.8

Wilmot 1,144 29.6 38.6

 3
72°

71°

45°

44°

43°

0 10 20 30 40

Coos

Grafton

Hillsborough Rockingham

Belknap

Strafford

CarrolL

Sullivan

Cheshire

Merrimack

50 MILES

0 10 20 30 40 50 KILOMETERS

 4

Figure 1. Merrimack County, New Hampshire, location map.
A

AE

X

Hydrography

43o15'

71o15'

71o45'

71o30'

72o

EXPLANATION

Flood Insurance Rate zones

(See pages 7 and 8)

Newbury

Sutton

New London

Wilmot

Danbury Hill

Andover

Franklin

Northfield

Canterbury

Loudon

Chichester

Pittsfield

Epsom

Pembroke

Allenstown

Hooksett

Bow

Dunbarton

Hopkinton Henniker

Warner

Bradford

Webster

Boscawen

Salisbury

Concord

43o30'

0 5 10 MILES

0 5 10 KILOMETERS

Base from U.S. Geological Survey 

Digital Line Graphs, 1:24,000, 1990-94 and

National Hydrography Dataset, 1:24,000, 1999

5

Figure 2. Merrimack County, New Hampshire, hydrography and FEMA Digital Flood Insurance Rate Map (DFIRM) data.
6

Section 2. Data Collected from Merrimack County Communities

This section provides a summary of the data-collection efforts for communities in Merrimack County 

relating to the most recent community FISs and FIRMs; Letter of Map Amendments (LOMAs) and Letter 

of Map Revisions (LOMRs); information from the MNUSS database; and state and community meetings, 

and information on the location of existing remote-sensing data. 

The flood-hazard information obtained in the data-collection efforts are summarized in figure 2, and 

include:

• State, county, and community boundaries.

• Water features.

• Limits of existing detailed and approximate study within Merrimack County.

These maps can be continually updated in the future as new information becomes available.

Community Flood Insurance Studies and Flood Insurance Rate Maps

A summary of FIS and FIRM dates for the communities located in Merrimack County are listed in 

table 2.

Table 2. FIS and FIRM information for communities.—Continued

[FIS, Flood Insurance Studies; FIRM, Flood Insurance Rate Map; FHBM, Flood 

Hazard Boundary Map; --, no data]

Community Date of entry FIRM/FHBM date FIS date

Allenstown 4/2/1979 4/2/1979 10/1978

Andover 4/2/1986 4/2/1986 --

Boscawen 7/16/1979 7/16/1979 1/1979

Bow 4/16/1979 11/20/2000 11/20/2000

Bradford 4/15/1992 4/15/1992 4/15/1992

Canterbury 5/15/1979 5/15/1979 11/1978

Chichester 5/14/2004 9/1/1978 3/1978

Concord, City of 3/4/1980 8/23/1999 8/23/1999

Danbury 1/1/2003 1/1/2003 --

Dunbarton 3/28/2001 (NSFHA)1 --

Epsom 7/3/1978 7/3/1978 1/1978

Franklin, City of 9/28/1979 9/28/1979 3/1979

Henniker 3/14/1979 5/1/1978 11/1977

Hill 4/2/1986 2/26/2002 --

Hooksett 4/2/1979 3/12/1982 3/1982
 7

The effective map dates range from 1977 in the Town of Sutton to 2004 in the Town of Loudon. 

Fifty percent of the FIRMs were produced prior to 1986 and are 20 years old or older. The oldest FIRM is 

28 years old, the most recent is 1 year old, and the average is 18.5 years old. Most (over 

70 percent) of the FIS analyses were performed between 1977 and 1988 and have not been updated. 

Delineation of Detailed and Approximate Study Areas

Digital Q3 Flood Data have not been developed for Merrimack County to determine the areas of 

detailed study (zone AE) and areas of approximate study (zone A) within the communities. FEMA digital 

Q3 flood data is the electronically scanned currently effective map panels of an existing paper FIRM. Digital 

FIRM Data were created and provided by the University of New Hampshire Geographically Referenced 

ANalysis and Information Transfer system (UNH GRANIT) (Jenn Merriam, written commun., October 14, 

2005) for this report. These data had not been quality checked by FEMA’s contractors as of the date 

received. GRANIT, a collaborative effort between the University of New Hampshire and the New Hampshire Office of Energy and Planning (NHOEP), is a cooperative project to create, maintain, and make available a statewide geographic data base serving the information needs of state, regional, and local decisionmakers. Definitions of flood insurance rate zones A and AE are provided below:

• Zone AE: Zone AE is the flood insurance rate zone that corresponds to the 100-year floodplains 

that are determined in the FIS by detailed methods. In most instances, whole-foot base flood elevations (BFEs) derived from the detailed hydraulic analyses are shown at selected intervals within this 

zone.

• Zone A: Zone A is the flood insurance rate zone that corresponds to the 100-year floodplains that 

are determined in the FIS by approximate methods. Because detailed hydraulic analyses are not performed for these areas, no BFEs or depths are shown within this zone.

Hopkinton 5/17/1988 5/17/1988 5/17/1988

Loudon 8/1/2004 8/1/2004 --

New London 7/16/1991 7/16/1991 7/16/1991

Newbury 4/2/1986 4/2/1986 --

Northfield 6/15/1979 6/15/1979 12/1978

Pembroke 4/2/1979 4/2/1979 10/1978

Pittsfield 7/3/1978 7/3/1978 1/1978

Salisbury 4/15/1986 4/15/1986 --

Sutton 5/17/1977 5/17/1977 --

Warner 6/4/1987 6/4/1987 6/4/1987

Webster 4/15/1986 6/2/1993 6/2/1993

Wilmot 4/1/1986 4/1/1986 --

1

NSFHA, No Special Flood Hazard Area, All Zone C.

Table 2. FIS and FIRM information for communities.—Continued

[FIS, Flood Insurance Studies; FIRM, Flood Insurance Rate Map; FHBM, Flood 

Hazard Boundary Map; --, no data]

Community Date of entry FIRM/FHBM date FIS date
 8

• Zone X: The flood insurance rate zone that corresponds to areas outside of the 500-year floodplain, 

areas within the 500-year floodplain, and to areas of the 100-year floodplain where average depths 

are less than 1 foot, areas of the 100-year flooding where the contributing drainage area is less than 

1 square mile, and areas protected from the 100-year flood by levees. No BFEs or depths are shown 

in this zone.

Letters of Map Change

A LOMC is a letter issued by FEMA in response to a request to revise or amend an effective NFIP map 

to remove a property or reflect changed flooding conditions on the effective map. LOMCs may include 

LOMAs and LOMRs, as defined below:

• LOMAs: A LOMA is an official amendment, by letter, to an effective NFIP map. A LOMA establishes a property’s location in relation to the Special Flood Hazard Area (SFHA). There is no appeal 

period for LOMAs, and the letter becomes effective the date that it is sent.

• LOMRs: A LOMR is an official revision, by letter, to an effective NFIP map. A LOMR may 

change flood insurance risk zones, floodplain and(or) floodway boundary delineations, planimetric 

features, and(or) BFEs. The effective date of a LOMR depends on the type of change requested. For 

example, some LOMR’s are effective on the date that the letter is issued and others become effective 

following an appeal period (typically 30 to 90 days or 6 months).

• LOMR-F: A Letter of Map Revision based on Fill (LOMR-F) may be filed as a special case of the 

LOMR. A LOMR-F provides FEMA’s determination concerning whether a structure or parcel has 

been elevated on fill above the BFE and excluded from the SFHA. A LOMR-F is an official revision, by letter, to an effective NFIP map. The letter becomes effective on the date that it is sent.

In addition to the categories above, conditional LOMAs, LOMRs, and LOMR-Fs may be issued by 

FEMA to comment on a proposed project. The letter does not revise an effective NFIP map, but indicates 

whether the project, if built as proposed, would be recognized by FEMA.

Letters of Map Change in Merrimack County

LOMCs were collected for each of the communities.

A summary of the LOMCs obtained from FEMA (http://msc.fema.gov) and the NHOEM is provided 

in appendix A. The summary table in appendix A includes the LOMC case number, effective date, flooding 

source, location, area/structure removed from SFHA, and new flood zone. The location of each LOMC is 

shown in figure 3.
Newbury

Sutton

New London

Wilmot

Danbury Hill

Andover

Franklin

Northfield

Canterbury

Loudon

Chichester

Pittsfield

Epsom

Pembroke

Allenstown

Hooksett

Bow

Dunbarton

Hopkinton

Henniker

Warner

Bradford

Webster

Boscawen

Salisbury

Concord

EXPLANATION

Hydrography

LOMC

43o15'

43o30'

71o15'

71o45'

71o30'

72o

0 5 10 MILES

0 5 10 KILOMETERS

Base from U.S. Geological Survey 

Digital Line Graphs, 1:24,000, 1990-94 and

National Hydrography Dataset, 1:24,000, 1999

 9

Figure 3. Letter of Map Change (LOMC) and community location map in Merrimack County, New Hampshire.
 10

Mapping Needs Update Support System

In accordance with section 575 of the National Flood Insurance Reform Act of 1994, FEMA assesses 

“...the need to revise and update all floodplain areas and flood-risk zones identified, delineated, or established based on analysis of all natural hazards affecting flood risks.” FEMA initiated the Mapping Needs 

Assessment (MNA) process, which identifies and prioritizes flood-hazard mapping needs for communities 

nationwide. As part of this effort, FEMA developed the MNUSS, which is an interactive, web-based software application that maintains an inventory of needs for future map updates. In particular, MNUSS stores 

information on the following two types of update needs:

• Map Maintenance Needs: Includes changes to base map information, such as the addition of new 

roads, changes to corporate limits, and incorporation of LOMCs.

• Flood Data Update Needs: Includes changes to flood-hazard areas as a result of changes in H&H 

conditions, changes to BFEs, and(or) changes in the floodplain delineation.

Mapping needs may be viewed and entered into MNUSS by a variety of parties, including FEMA 

Headquarters and Regional offices, state NFIP coordinators, study contractors, CTPs, and other Federal 

agencies, such as the U.S. Army Corps of Engineers (USACE) and the USGS. All needs are reviewed and 

approved by the FEMA MNUSS controller prior to office entry into the system.

Mapping Needs in Merrimack County, New Hampshire

Information on mapping needs for the respective communities within Merrimack County was downloaded from MNUSS on August 17, 2005, and is included in appendix B. This information included a summary of those communities that had and had not responded to requests for information on MNUSS mapping 

needs, as well as a summary of the map maintenance and flood-data-update needs, as appropriate, for those 

communities where responses had been received. A summary of the response status for each community 

and the general mapping needs are listed in appendix table B-1.Information on the specific community mapping needs is provided in table 3.
Table 3. Summary of specific mapping needs in Merrimack County, New Hampshire.

[BFE, Base Flood Elevation]

Community Need 

identifier

Study 

category Comments

Andover 10603 Maintenance Add streets to panels (no panels were associated with need).

Bow 10565 Riverine Increase in BFE by between 1 and 5 ft on 5.87 mi stretch on the Merrimack 

River.

Epsom 10570 Riverine Changes to hydraulic analysis on Northwood Lake with an anticipated BFE 

decrease of less than 1 foot over 1.86 mi.

Henniker 10594 Maintenance Add streets to panel 0025B.

10595 Riverine Changes to hydrologic conditions with an anticipated BFE increase of greater 

than 5 ft along 2 mi of an unnamed zone A area.

Hooksett 29312 Maintenance Add streets to panels 0005C, 0010C, 0015C, and 0020C.

29315 Riverine Changes in hydrologic and hydraulic conditions with an anticipated BFE 

decrease of less than 1 foot over 1.4 mi of Maple Falls Brook (county boundary 

to Dubes Pond Dam).

29316 Riverine Changes in hydrologic conditions with an anticipated BFE decrease of less than 

1 foot over 0.75 mi of Dalton Brook (Benton Road to Berry Hill Road).

29313 Riverine Changes in hydrologic and hydraulic conditions with an anticipated BFE 

decrease of less than 1 foot over 1.7 mi of Heads Pond.

29314 Riverine Changes in hydrologic and hydraulic conditions with an anticipated BFE 

decrease of less than 1 foot over 1.2 mi of Dubes Pond.

Hopkinton 10631 Maintenance Align map panel 0009B.

Pembroke 10572 Maintenance Add streets to panel 0005A.

Salisbury 10632 Maintenance Add streets to panels (no panels were associated with need).

11

As shown in table 3, a total of 13 mapping update needs are listed in MNUSS throughout Merrimack 

County. These include six map maintenance needs and seven flood-data-update needs. Not all of the communities in the county responded to the FEMA request for information regarding mapping needs, so the 

actual number of mapping needs may be higher than what is currently reported in MNUSS. Additional information on mapping needs in the communities was established through state and community meetings, as 

discussed in the following sections.
 12

State and Community Meetings

As part of the scoping effort, the USGS conducted a series of meetings with the following State agencies and communities:

• NHOEM on August 24, 2005, to review LOMCs.

• Conference call kick-off meeting with NHOEM, FEMA, USGS, and Watershed Concepts on 

September 1, 2005.

The following section provides a summary of the key outcomes from each of the State and community 

meetings. Additional detail is given in appendix C, which provides copies of the meeting minutes and an 

example community interview form.

Meeting with New Hampshire Office of Emergency Management (NHOEM) and Scoping Team Members

USGS held a kick-off meeting with a conference call on September 1, 2005, that included representatives from NHOEM, FEMA, USGS, and Watershed Concepts (RMC - Regional Management Center). The 

meeting was used to introduce the scoping project team and review roles and responsibilities. The meeting 

agenda and minutes are included in appendix C. The following people were included in the meeting:

• Dean Savramis, representing FEMA, provided an overview of the Map Modernization Program and 

Scoping. He also provided a description of the countywide approach.

• Brent McCarthy (RMC) described the role of the RMC in assisting FEMA and the mapping contractors. He described the Watershed Information System (WISE) (Watershed Concepts, 2005) 

computer applications developed for FEMA to standardize the scoping process methodology, data 

collection, and storage for the map modernization program. Brent mentioned that it may be a good 

idea to set up a morning and evening meeting with each County in order to be able to talk to all of 

the representatives in each town (two meetings for each county). Brent also mentioned that Watershed Concepts could lead breakout sessions with towns during the meetings with the Counties.

• Jeff Burm (RMC) spoke about the WISE Scoping tool and various features of this tool including 

community contact information, available GIS data, stream data, statistical analysis, stream mile 

information to calculate costs for hydrology and hydraulics, LOMAs, CAVs and Community Assistance Contacts (CACs), creation of reports for each of the items.

• Fay Rubin (UNH GRANIT), Craig Johnston, Laura Hayes and Robert Flynn (USGS)—discussed 

available data and coverages within New Hampshire (for example, 2003 National Agriculture Imagery Program (NAIP) color Digital Orthophoto Quadrangles (DOQs)). Remote sensing, base map 

information, GIS data (for example, contour data, E911 data, Digital Elevation Model (DEMs), 

buildings layer, survey data available from the New Hampshire Department of Transportation 

(NHDOT). In addition, the county regional planning commissions were mentioned as possible 

sources of data.
 13

Merrimack County Community Meetings

Conference calls were conducted with representatives from all of the towns in Merrimack County. The 

following sections provide a brief summary of the key findings from each community interview, and in particular, identifying areas with increased development, areas with known flooding problems, and areas with 

changes to hydraulic structures. The applicable community contacts are also provided in each section.

The goals of these meetings were to:

• Inform the communities of the nature and the intent of the flood map update process.

• Solicit community input and discuss the flood-prone areas that communities would like to include 

as a part of the flood map update.

Community comments were captured on paper interview forms, FIRM panels, and on working maps 

of each community produced for this purpose. These comments were entered into the WISE scoping application. Notes from the working maps and FIRM panels are summarized on figure 3. For communities not 

represented at the meetings, information provided by NHOEM, and contained in the community business 

plan was relied upon.

Merrimack County:

Allenstown

The following list provides a summary of the key issues identified during the community interview 

(August 10, 2005, October 20, 2005, and October 21, 2005):

• No new studies needed.

Contact: Everett Stone, Building Inspector (603-485-4276); Kelly Collins, Administrative Assistant to the 

Board of Selectmen; and Penny Touchette, Assessing Clerk (603-485-4276)

Andover

The following list provides a summary of the key issues identified during the community interview 

(August 10, 2005, and October 17, 2005):

• Many road names are incorrect and roads are missing from the FIRM. E911 road data are available.

• On panels 4, 5, 8 and 9, a detailed study is needed along Sucker Brook from Highland Lake to the 

upstream corporate limit due to flooding and development issues. Zone A delineation is also incorrect for Sucker Brook in that the flow does not go over the railroad bed (panels 4, 5, 8 and 9) or over 

Hoyt Road (panel 5) and flow does not go over the road (name unknown) between Highland Lake 

and Maple Street. Flow does not go over the road at Route 11 or Last Street (panel 9). A town maintained dam is upstream on Maple Street (Tilton Brook Road) and a private dam is located approximately 200 ft. downstream of Maple Street.

• On panel 7, flow is not over the road west of Elbow Pond along Elbow Pond Road. This area needs 

to be re-delineated.

• On panel 8, an unnamed brook flowing from upstream of Maple Street (erroneously labeled as 

Taunton Hill Road on FIRM) to the southern end of Highland Lake needs to have a detailed study 
14

from approximately 1,000 ft upstream of West Shore Drive to 1,000 ft downstream of Route 11 due 

to regular flooding that is not delineated on the FIRM.

• On panel 8, a re-delineation of the flooding extent is needed across Flaghole Road (zone A) for an 

unnamed tributary (extent is thought to be too wide).

• On panel 9, there is no flow over Emery Road as shown for unnamed zone A tributary.

• On panel 10, there is no flow over Route 11 or Cilleyville Road as shown for the zone A delineated 

Blackwater River. 

• On panel 11, there is no flow over the railroad tracks south of Route 4 and perpendicular to Bridge 

Road. Flooding is more extensive than delineated to the south along Bridge Road. On panel 11, 

flooding from Mitchell Brook (coming from Ragged Mountain State Forest) is more extensive (to 

the west) between Route 11 and the railroad tracks from Mitchell Brook and south of the railroad 

tracks from the Blackwater River. Flooding does not occur over the railroad tracks south of Ragged 

Mountain State Forest nor over South Short Street, U.S. Route 4 or the railroad tracks north of 

Horseshoe Pond. 

• On panel 12, there is no flooding over the elevated bridge on Route 4 over the Blackwater River but 

there is to either side of the bridge. A detailed study is needed along the Blackwater River from the 

western to eastern corporate limits due to incorrectly delineated flood boundaries and development.

• On panel 12, detailed studies are needed along the two unnamed tributaries under Switch Road to 

their confluences with the Blackwater River.

Contact: Mark Stetson, Town Administrator (603-735-5332)

Boscawen

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005, September 16, 2005, and October 6, 2005):

• No new studies needed.

• Beaver Dam Brook is along the Town line with Webster. This brook needs a detailed study (according to Town of Webster official) from Walker Pond to Mutton Road due to two LOMAs issued on 

Long Street and Beaver Dam Drive.

Contact: Sherlene Fisher, Town Administrator (603-753-9188, ext. 303)

Bow

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005, and October 20, 2005):

• On panel 2, a detailed study is needed along Bow Bog Brook from I-93 to the Merrimack River. 

This area is currently zone A and is zoned as industrial by the town and has had a lot of development. 

• On panel 2, a detailed study is needed along the tributary to Bow Bog Brook from I-93 to Bow Bog 

Brook. This area is currently zone A and is zoned as industrial by the town and has had a lot of development. 

• Two-foot contour-interval data are available for purchase from Holden Engineering for the town.

Contact: Bill Klubben, Director of Planning and Economic Development (603-225-3008)
 15

Bradford

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• On panel 5, the Jones Road Bridge over Hoyt Brook will be replaced in 2007. This area is adjacent 

to a flood area designated as a Zone A and a detailed study is needed along Hoyt Brook for the extent 

of the current zone A.

• On panel 5, Lake Massaseekum is a Zone AE but there is dispute among the locals about elevation 

and a new detailed study is requested for this Lake.

• On panel 5, Lake Todd is a Zone AE and the dam is being repaired. No elevation change is supposed 

to occur to the dam but if the elevation does change, a new study would be required.

• On panel 5, the town of Warner has requested a restudy along the Warner River which joins Lake 

Massasecum at its southern end. A detailed study for the length of the Warner River from Lake Massasecum to the corporate limit with Warner, N.H., is needed.

Contact: Cheryl Behr, Town Administrator, (603-938-5900)

Canterbury

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005, August 31, 2005, September 8, 2005, September 16, 2005, and October 6, 2005):

• No new studies needed.

Contact: Jan Stout, Clerk to the Board of Selectmen (603-783-9955); Ben Bynum, Clerk to the Assessor 

(603-783-9955); Robert Fife, Member and former chairman of the Conservation Commission (603-783-

4416).

Chichester

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• No new studies needed.

Contact: John Martell, Chichester Emergency Management Director (603-798-4208) and Bob Mann, 

Conservation Commission Chairman (603-798-5371)

Concord

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• Burnham Brook: Brook does not run through city street.

• Delineation is incorrect for Contoocook and Suncook Rivers. The delineation was previously done 

with 10 ft contours but 2 ft contours are now available.

• Turkey River is a Zone A but a detailed study is now needed.

• Snow Pond and Turtle Pond are developing and need detailed studies.

Contact: Steve Henninger, Assistant City Planner (603-225-8580)
 16

The following list provides a summary of the key issues identified during the community interview 

(October 12, 2005):

• Due to development and improperly defined A zone along Ash Brook, a detailed study is needed 

from 1,500 ft above Currier Road (at confluence of two brooks) to Little Turkey Pond.

• Due to development along Millers Brook, a detailed study is needed along the entire length from the 

confluence with Turkey River to the headwaters (south of Little Pond Road).

• Due to development along Mill Brook, a detailed study is needed from its confluence with the 

Merrimack River to Batcher Mill Road.

• Due to development along Beaver Meadow Brook, a detailed study is needed from its headwaters 

at Chickory Court to its confluence with the Merrimack River.

• BFEs along “The Outlet” (east of Contoocook Park Dam on the Contoocook River) appear to be 

incorrect and a new hydraulic model is needed in this area. The 100-year flood elevation above 

Island Road (Section “F” along “The Outlet”) is 354 ft both in the Contoocook River and in “The 

Outlet.” Below Island Road, in “The Outlet,” the BFE is 348 ft, whereas above the Contoocook Park 

Dam, the BFE is 353 ft. The river can flow around Island Road, upstream of Contoocook Park Dam 

and so an elevation of 353 ft appears to be more likely downstream of Island Pond Road in “The 

Outlet” rather than 348 ft. BFE elevations need to be checked along the entire reach of “The Outlet” 

and a new hydraulic model needs to be created for this area.

• Due to development and flood delineation issues with the previous FIRM, a detailed study is needed 

along Hackett Brook from Hoit Road (south of Hoit Road Marsh) to its confluence with Hayward 

Brook.

• Due to development and flood delineation issues with the previous FIRM, a detailed study is needed 

along Hayward Brook from the upstream corporate limit to Hoit Road.

• Concord city officials have retained the Merrimack River 1972 USACE flood-hazard delineation 

rather than using the FEMA 1998 flood hazard delineation although the 1998 study has been 

adopted by the city for insurance purposes. City officials would like a restudy along the Merrimack 

River to determine new hydrology and hydraulics. City officials would like to incorporate the 

impact of the 1936 and 1938 flood events with the upstream flood control measures in place. The 

1998 FIS used the hydrology as determined in the 1980 FEMA FIS. The hydrology in the 1980 FIS 

references the discharges used in the 1972 USACE study. HEC-2 was used in the previous studies 

and HEC-RAS should be used for the revision according to the City of Concord, N.H. The 1980 

study did not do calibration runs for the 1936 and 1938 high-water marks because of changes that 

have occurred in the floodplain since the flood events occurred but, the original USACE study 

(1972) does account for Merrimack River flow gage data (including the 1936 and 1938 floods) and 

discharge values were modified to reflect the effect of the five existing flood control structures. 

Floods of the magnitude of the 1936 and 1938 floods would be much less likely to occur today 

because of the flood control structures on the Merrimack River. A verification of the hydrology is 

necessary and a new hydraulic model needs to be built to determine flood elevations on the Merrimack River in Concord, N.H.

Contact: Douglas Woodward, City Planner (603-225-8515) and Steve Henninger, Asst. City Planner 

(603-225-8515)—Meeting at Concord City Hall on October 12, 2005
 17

Danbury

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• No new studies needed.

Contact: Twila Cook, Chair of Selectmen (603-768-3313)

Dunbarton

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• No new studies needed.

Contact: Ken Swazy, Planning and Building (603-774-3541, ext. 3)

Epsom

The following list provides a summary of the key issues identified during the community interview 

(August 11, 2005):

• No new studies needed.

Contact: Barbara Pellegri, Town Clerk (603-736-9002) and Betsy Bosiak, Planning Board Chairman 

(603-736-4477)

Franklin

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, September 7, 2005, and October 6, 2005):

• No new studies needed but, Sucker Brook has been requested for restudy in Andover so detailed 

study needed from Webster Lake to corporate limit along Sucker Brook.

Contact: Richard Lewis, Planning Board (603-934-3900)

Henniker

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, August 26, 2005, September 7, 2005, and October 6, 2005):

• No new studies needed.

Contact: Peter Flynn, Town Administrator (603-428-3221)

Hill

The following list provides a summary of the key issues identified during the community interview 

(2005):

• No new studies needed.

Contact: Linda Henry, Administrative Assistant (603-934-1094)
 18

Hooksett

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, September 6, 2005, and October 7, 2005):

• On panel 5, the 500-year flood is shown as delineated across the former Bayside Airport runway; 

however, it is believed that flooding does not occur here and the delineation is incorrect.

• On panels 5 and 10, Heads Pond dam (privately owned by Manchester Sand and Gravel) is to be 

rebuilt to restore water level to historic levels. Development (Carriage Hill Subdivision) is planned 

in 2006 around Heads Pond (500–550 homes and a golf course). This Pond is currently designated 

as a zone A. The dam at the outlet is to be rebuilt to its former elevation. A detailed study is needed 

on this pond from the dam below Daniel Webster Highway to the southern end of the pond.

• On panel 10, a detailed study is needed to establish a BFE on Dubes Pond due to development 

(Farrwood subdivision) along the southwest side of the pond (approximately 1.2 mi). This area is 

currently designated as a zone A.

• On panel 15, flooding over Goonan Brook is thought not to occur (BFE = 186 ft) and it is believed 

that the delineation is incorrect.

• On panel 20, a detailed study is needed along Dalton Brook between Benton and Berry Hill Roads 

(approximately 0.75 mi). There is currently a detailed study in this area but the extent of flooding is 

thought to be inaccurate (floodplain too wide).

• Two-foot contour-interval data are available for purchase from Holden Engineering for the town.

• Many new roads in Hooksett need to be included on the flood maps. E911 roads data are available.

Contact: Charles Watson, Town Planner (603-268-0279)

Hopkinton

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005):

• No new studies needed.

Contact: Karen Robinson, Director of Planning (603-746-4487)

Loudon

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, and September 7, 2005):

• Two-foot contour-interval data are available for purchase from Holden Engineering for the town.

• On panel 3, a detailed study is needed along the Soucook River from Route 106 (near the Route 106 

and Route 129 intersection) to Route 106 (east of South Village Road)

Contact: Bob Fisk, Building Inspector (603-798-5584)

New London

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, September 8, 2005, and October 11, 2005):
 19

• On panels 10 and 15, development is occurring around the zone A designated Little Sunapee Lake, 

Pleasant Lake and Messer Pond and it is believed that the current zone A delineations are incorrect. 

A detailed study is needed to establish BFEs on these three bodies of water.

• On panel 10, it is believed that the hydrology is correct but the delineation is incorrect on Lake Sunapee.

Contact: Peter Stanley, Zoning Administrator (603-526-4821 ext. 16)

Newbury

The following list provides a summary of the key issues identified during the community interview 

(August 16, 2005, and October 6, 2005):

• On panels 5 and 10, a detailed study is needed along Ring Brook beginning at the John Stark Highway and Route 103, along Ring Brook at Sutton Drive to Chalk Pond Road at the eastern corporate 

limit (approximately 4.0 mi). This area is currently designated as a zone A or not designated.

• On panel 10, a detailed study is needed along Andrew Brook from the confluence with Ring Brook 

at Sutton Road to 2,000 ft upstream (approximately 0.4 mi).

• Many new roads in Newbury that need to be included on the flood maps.

Contact: Bill Weiler, Conservation Commission (603-938-2892) and Dennis Pavalicek, Town Administrator (603-763-4940, ext. 204).

Northfield

The following list provides a summary of the key issues identified during the community interview 

(August 19, 2005, and September 16, 2005):

• No new studies needed.

Contact: Dana Fullweiler, Code Enforcement Officer (603-848-0409)

Pembroke

The following list provides a summary of the key issues identified during the community interview 

(August 19, 2005, and October 12, 2005):

• New bridge on Route 3 with new abutments over Suncook River.

• Zone A incorrect at Bachelor Road on Suncook River (elevation of property is approximately 

20 ft above stream).

• Possibly an impact by the recent building of Associated Grocers Warehouse on Soucook River.

• A company called “Pembroke 600” (Dan Scott) has impacted the floodplain at Routes 6 and 103.

• Two-foot contour-interval data are available for purchase from Holden Engineering for the town.

Contact: Peter Rowell, Code Enforcement (603-485-4747, ext. 214) and Laura Scott, Town Planner 

(603-485-4747)
 20

Pittsfield

The following list provides a summary of the key issues identified during the community interview 

(August 19, 2005, and October 7, 2005):

• On panel 20, Whites Pond and Clarks Pond (just to the west of Whites Pond) need a detailed study 

due a subdivision built around these two ponds. The dam on Whites Pond is owned by the homeowners association (Winsunvale Homeowners Association) and work is being done to the dam.

• On panel 20, Gas House Brook runs through a lot of housing and a detailed study is needed from 

the outlet of Clarks Pond to the Suncook River.

• It is not clear as to whether the Town Hall and houses along Joy Street are within the floodplain of 

the Suncook River. 

Contact: Cara Marston, Assessor (603-435-6773)

Salisbury

The following list provides a summary of the key issues identified during the community interview 

(August 23, 2005, and October 19, 2005):

• No new studies needed.

• E911 roads data are available.

Contact: Margaret Warren, Administrative Assistant (603-648-2473) and Mr. Al Tanner, Planning Board 

member.

Sutton

The following list provides a summary of the key issues identified during the community interview 

(August 19, 2005):

• Many roads are not on the map.

• Many road names are incorrect.

Contact: Jennifer Call, Secretary to the Selectmen (603-927-4416) and Paul Parker, Highway Department 

(603-927-4411).

The following list provides a summary of the key issues identified during the follow-up community 

interview (October 17, 2005):

• Many Road names are incorrect and roads are missing from Flood Hazard Boundary map (FHBM). 

E911 road data are available.

• On panel 3, a LOMA was issued at Cascade Brook for French Road at the Morgan Acres subdivision. Due to development in this area, a detailed study is needed along Cascade Brook from Baker 

Road to just above French Road.

• On panel 11, a LOMA was issued at Lane River for Dodge Hill Road. Due to development, and 

flood delineation issues, a detailed study is needed for the Lane River from Dodge Hill Road (just 

above Route 114) to its confluence with the Warner River (panels 11 and 14).
 21

• On panel 14, a LOMA was issued at the Warner River for Roby Road. This area is currently designated as zone A on the 1977 town of Sutton FHBMs. A detailed study was done on the Warner River 

in Warner and this is shown on the 1987 FIRM for Warner. Elevations as determined in the Warner 

Flood Insurance Study need to be transferred to the Sutton flood maps. 

Contact: Jennifer Call, Secretary to the Selectmen (603-927-4416) and Paul Parker, Highway Department 

(603-927-4411).

Warner

The following list provides a summary of the key issues identified during the community interview 

(September 15, 2005, and October 17, 2005):

• Many road names are incorrect and roads are missing from the FIRM E911 road data are not available.

• The Town of Warner Emergency Management Director would like verification that flow from Lake 

Massasecum in Bradford, Lake Todd in Bradford and Newbury, and Blaisdell Lake in Sutton are all 

included in the determination of the hydrology for the Warner River.

• On panel 15, a detailed study is needed along Davis Brook from Newmarket Road to the Warner 

River due to development along Newmarket Road.

• On panel 15, due to flooding and development on Horne Street, a detailed study is needed along 

Slaughter Brook from the Harriman Chandler State Forest to the Warner River. 

• On panel 20, detailed study is needed along Stevens Brook from the confluence of Stevens and 

French Brooks to the Warner River due to development and flooding along North Road.

• On panel 20, a restudy is needed along the Warner River from section AP to section AK due to fill 

being placed in the floodplain the approximate location of sections AM and AN. 

• On panel 25, a detailed study is needed along an unnamed tributary from the outlet of Day Pond to 

the corporate limit along Route 114 due to flooding which has occurred along Route 114 near Lake 

Massasecum in Bradford.

• On panel 30, a detailed study is needed along Schoodac Brook from its confluence with Frazier 

Brook to the Warner River.

• On panel 30, a detailed study is needed along Bog Road (also known as Brook Meadow Lane) from 

Poverty Plains Road to Connors Mill Road due to flooding and development along Bog Road.

• On panel 30, the delineation of Tom Pond is questionable and needs top be verified with better contour data.

Contact: Edward Mical, Emergency Management Director for the Town of Warner (603-456-3350)

Webster

The following list provides a summary of the key issues identified during the community interview 

(August 23, 2005, and October 6, 2005):

• Beaver Dam Brook is along the Town line with Boscawen. This brook needs a detailed study 

(according to Town of Webster official) from Walker Pond to Mutton Road (panels 5 and 10) due 

to two LOMAs issued on Long Street and Beaver Dam Drive.
 22

• On panels 5 and 10, a detailed study is needed on Lake Winnepocket due to development 

(75 homes). The dam on Lake Winnepocket is privately owned.

• On panel 10, a detailed study is needed on Pillsbury Lake due to development around the lake 

(160 homes). This lake has a dam.

Contact: Judy Jones, selectwoman (603-648-2272)

Wilmot

The following list provides a summary of the key issues identified during the community interview 

(August 23, 2005, and October 12, 2005):

• The road over the Blackwater (Pleasant) River was updated from a 1-lane to a 2-lane road.

• Campground Road was made wider and has new abutments.

• On panel 11, Cannery Brook needs a detailed study from Shindagan Brook to the Tannery Pond 

(Stone Bridge Road).

• On panel 11, a detailed study is needed from Tannery Pond (Wilmot Flat) to the corporate limit.

• On panel 11, a detailed study is needed on Chase Pond due to development. A LOMA was issued 

on Quiet Cove Road.

• On panel 9, Eagle Pond needs a detailed study due to development.

• On panels 8 and 9, a detailed study is needed along Kimpton Brook from North Wilmot Road to 

Eagle Pond.

Contact: Ken Grossman, Conservation Committee Member (603-526-6390) and Rhonda Gauthier, Administrative Assistant (603-526-4802)
 23

Available Digital Mapping and Remotely Sensed Data

This section provides an inventory of the digital data available to support the production of DFIRMs 

for the study area. Basic information is provided on the content, lineage, and accuracy of the products.

Data-Collection Efforts

To determine the availability of digitally available data, the USGS contacted Lynn Bjorklund (New 

England Liaison to USGS National Mapping), Fay Rubin (GIS Manager, NH GRANIT, UNH Complex 

Systems Research Center), Central New Hampshire Regional Planning Commission (CNHRPC), Southern 

New Hampshire Regional Planning Commission (SNHRPC), Upper Valley Lake Sunapee Regional Planning Commission (UVLSRPC), and the communities themselves. The NH GRANIT has useful base mapping. 

NH GRANIT Data Sources

NH GRANIT is a cooperative project to create, maintain, and make available a statewide geographic 

database serving the information needs of state, regional, and local decision-makers. A collaborative effort 

between the UNH and the NHOEP, the core GRANIT system is housed at the UNH Institute for the Study 

of Earth, Oceans, and Space in Durham.

NH GRANIT maintains data layers (http://www.granit.sr.unh.edu) including features such as roads, 

streams, and political boundaries. Some of the base map data layers maintained by NH GRANIT have been 

derived from USGS data and represent many of the feature types found on USGS topographic maps. More 

recently developed data were derived from digital orthophotos providing improved base map accuracy.

NH GRANIT is presently converting the standard, paper FIRMs and Flood Boundary and Floodway 

maps (FBFMs) to DFIRMs by digitizing existing flood maps from the existing paper flood maps. The 

DFIRMs will depict flood risk information, and include 100- and 500-year floodplain boundaries as well as 

areas of minimal flood risk. NH GRANIT is using USGS 1998 DOQs as the base, and they are incorporating 

any LOMC that are on file with FEMA.

The Q3 flood-data product is a digital representation of certain features of FEMA’s FIRM product and 

are created by scanning the effective FIRM paper maps and digitizing selected features and lines. The digital 

Q3 flood data contain the following:

1. 1-percent (100-year) and 0.2-percent (500-year) annual chance floodplain boundaries (including 

velocity zones),

2. Flood insurance zone designations,

3. Floodway boundaries (where available),

4. Political boundaries (State, county, and community),

5. Community and map panel identification numbers,

6. FIRM panel neatlines,

7. USGS 7.5-minute (1:24,000 scale) series topographic map neatlines, and

8. Coastal Barrier Resources System areas.
 24

Community Data Resources

The USGS and NH GRANIT have digital base mapping data for Merrimack County that meet FEMA 

requirements for DFIRM production. Community data requests were limited to topographic data suitable 

for hydraulic modeling (for example, 4-ft contours).

Merrimack County has high resolution digital orthophotos (1:12,000). With the exception of select 

locations in Hooksett, Pembroke, Bow, and Loudon (Peter Holden, Holden Engineering and Surveying, 

Inc., oral commun., September 6, 2005), topographic data are limited to that found on USGS topographic 

maps with 10 or 20-ft contour intervals. These four towns have 2-ft contour-interval data available for purchase through Holden Engineering. The City of Concord also has 2-ft contour-interval data available. No 

other community sources of digital elevation data for FEMA flood mapping were located.

Stream Final Coverage Output

The WISE Scoping Tool organizes and stores data and assists in the prioritization of the community 

requests for floodplain studies. As the scoping process is completed, three coverages (maps) are created: 

Effective, Meeting, and Stream Final. 

• Effective Coverage: Q3 flood-hazard data are not available for Merrimack County. NH GRANIT 

has a contract with FEMA to digitize the FIRMs and they made these nearly completed DFIRMs 

available to the USGS for purposes of scoping. The DFIRM data for Merrimack County was 

received from NH GRANIT on October 15, 2005, although it had not been Quality Assurance/

Quality Control checked at that time. Users of the WISE tool should obtain an updated version of 

the DFIRM data when it becomes available in December of 2006. The DFIRM information was 

entered into the WISE scoping tool. The initial Scoping Tool database was set up using the U.S. 

Environmental Protection Agency (USEPA) National Hydrography Dataset (NHD) stream centerline coverage (http://nhd.usgs.gov/data.html) and digital flood boundary base mapping data provided by NH GRANIT. The NHD stream centerline coverage was used to build the Effective 

Coverage in the Scoping Tool. The digitized flood-hazard data were overlain onto the NHD stream 

centerline coverage. The Scoping Tool was used to enter each reach of the Effective Coverage one 

at a time by assigning the beginning and end of each reach and the current effective type of study. 

• Meeting Coverage: The Effective Coverage was used to prepare the work maps for recording mapping needs requested by the communities during the Scoping Meetings. These requests were also 

recorded in the Meeting Coverage of the Scoping Tool.

• Stream Final Coverage: The WISE Scoping Tool was used to create a Stream Final Coverage to 

document and highlight community meeting results. Community mapping needs based on community input are summarized in figure 4.
Detailed study request

Hydrography

43o15'

71o15'

71o45'

71o30'

72o

EXPLANATION

Newbury

Sutton

New London

Wilmot

Danbury Hill

Andover

Franklin

Northfield

Canterbury

Loudon

Chichester

Pittsfield

Epsom

Pembroke

Allenstown

Hooksett

Bow

Dunbarton

Hopkinton

Henniker

Warner

Bradford

Webster

Boscawen

Salisbury

Concord

0 5 10 MILES

0 5 10 KILOMETERS

Base from U.S. Geological Survey 

Digital Line Graphs, 1:24,000, 1990-94 and

National Hydrography Dataset, 1:24,000, 1999

 25

Figure 4. Merrimack County, New Hampshire, stream final coverage.
 26

Section 3. Options for Future Mapping and Digital Terrain Model Preparation

Mapping Requirements

This section provides an assessment of the costs and benefits of utilizing the data cataloged in the previous section for the preparation of DFIRMs for Merrimack County. Options are presented for using these 

data sets in various combinations and supplementing them with new data sets.

DFIRMs are produced from the following three broad categories of geospatial data: (1) Base Map, 

(2) Digital Terrain Model (DTM), and (3) Flood Insurance Risk Zones. The spatial accuracy of each of these 

three categories is fixed by the specifications contained in the “Guidelines and Specifications for Flood Hazard Mapping Partners,” April 2003 (Federal Emergency Management Agency, 2004).

• Base Maps: Base maps (1998 DOQs) are being acquired from NH GRANIT and will be used by 

FEMA as the background to the flood insurance risk zones shown on the DFIRMs. 

• DTMs: DTMs are used in conjunction with H&H models to interpret the limits of flood insurance 

risk zones. 

• Flood Insurance Risk Zones: Geographic boundaries produced by FEMA.

Base Map

Base maps are defined in the “Guidelines and Specifications” as the “map of the community that depicts 

cultural features (for example, roads, railroad, bridges, dams, and culverts), drainage features, and corporate 

limits.” Depending on the source of the base map, the specific features found on DFIRMs may include the 

following data and features:

• Roads: centerlines, edge-of-pavement, right-of-way, names.

• Railroads: names.

• Bridges: names.

• Flood Control Structures: headwall, dam, levee, names.

• Airport Boundaries: names.

• Rivers: centerlines, banks, names.

• Streams: names.

• Lakes: names.

• Political Boundaries: county, municipality, special districts, wards, military reservations, Native 

American lands, names.

• Land Use: parks, individual land parcels, names.

The “Guidelines and Specifications” specify “absolute horizontal accuracy” for base map features to 

establish horizontal accuracy for the position of the digital data set to its actual location on the earth’s surface. The horizontal accuracy is specified as a statistical error distribution at the 95-percent confidence level 

and is specified in the “Guidelines and Specifications” as a function of finished map scale, as shown in 

table 4:
Table 4. FIRM Horizontal Accuracy.

[FIRM, Flood Insurance Rate Map]

FIRM map scale

Absolute horizontal accuracy at 

the 95-percent confidence level, 

in feet

1 in = 500 ft 19.0

1 in = 1,000 ft 38.0

1 in = 2,000 ft 45.6

 27

Digital Terrain Models

FEMA typically develops DTMs for the production of DFIRMS as they are not widely available at the 

accuracies required by FEMA. The DTMs are used in conjunction with H&H models to interpret flood 

boundaries and can be used by the community for many purposes other than flood management. DTMs represent terrain with irregularly spaced spot elevations (x,y,z) and breaklines that indicate changes in ground 

slope at features such as the toe or top of channel banks or ridge lines. These data sets are generally photogrametrically compiled by a mapping contractor from stereo photos and utilized in the form of a Triangulated Irregular Network (TIN) or a DEM. A DEM uses a regular grid, or raster, spacing of (x,y,z) points to 

represent the land surface. Each grid cell is assigned an average elevation to represent the elevation of the 

ground that is covered by the grid cell. A DEM represents the terrain surface with a mesh of regularly spaced 

points, whereas a TIN uses contiguous triangular planes.

Federal Emergency Management Agency (2004) “Guidelines and Specifications” identify the following four types of DTMs: (1) Digital contours, (2) DEMs, (3) Mass points and breaklines, and (4) TIN. Each 

of these models can be created from the other and their use is application dependent.

Under FEMA guidelines, the allowable DTMs are as follows:

1. Digital contours: continuous, nonintersecting lines of equal elevation separated by a specified elevation interval.

2. DEM: x, y, and z coordinates of regularly spaced points that form a grid.

3. Mass Points and Breaklines: x, y, and z coordinates of irregularly spaced points.

4. TIN: contiguous triangles with x, y, and z values at the vertices and faces with slope and aspect.

The “Guidelines and Specifications” specify what is referred to as “absolute vertical accuracy” for 

DTMs, which relates the elevation of the land surface in the digital data set to its actual elevation relative to 

a specific vertical datum. The National Standard for Spatial Data Accuracy (NSSDA) is specified as a statistical error distribution at the 90- and 95-percent confidence level as a function of the specified contour 

interval as shown in table 5.
Table 5. National Standard for Spatial Data Accuracy.

[NSSDA, National Standard for Spatial Data Accuracy, all values are in feet]

Contour interval NSSDA

90-percent confidence interval

NSSDA

95-percent confidence interval

2 1 1.2 

4 2 2.4 

 28

Contouring and DEMs are not printed on DFIRMS so their vertical accuracy is not labeled on the 

DFIRMS, but it is recorded in the metadata of elevation datasets used for H&H modeling.

Flood Insurance Risk Zones

Flood insurance risk zones are created by FEMA to set insurance rates and manage the floodplain. 

Flood insurance risk zone accuracy requirements are not specified in the Guidelines and Specifications but 

can be described in terms of the combined accuracies of the base map, DTM, and the hydrology and hydraulic simulation models.

Suitability of the Available Data

The following section provides a summary of the suitability of the base map and DTM available for 

Merrimack County, N.H., from the appropriate community, county, and state resources. The USGS and NH 

GRANIT can provide digital data base mapping data for Merrimack County that meets FEMA requirements 

for DFIRM production. Neither USGS nor NH GRANIT has elevation data suitable for hydraulic modeling 

and communities were contacted to find topographic or elevation data suitable for hydraulic modeling (for 

example, 2-ft or 4-ft contours). 

Community Data Resources

The City of Hooksett, N.H., and towns of Pembroke, Bow and Loudon, N.H., have 2-foot contourinterval data available for purchase through Holden Engineering (Peter Holden, Holden Engineering and 

Surveying, Inc., oral commun., September 6, 2005). The City of Concord also has 2-ft contour data available. These data are believed to meet FEMA requirements. No other community sources of digital elevation 

data for hydraulic modeling or FEMA flood mapping were located. 

County Data Resources

Merrimack County does not contain suitable data for DFIRM use. Towns in Merrimack County are 

within the planning area of three planning commissions. These planning commissions include the Southern 

New Hampshire Regional Planning Commission, Central New Hampshire Regional Planning Commission, 

and Upper Valley Lake Sunapee Regional Planning Commission. The planning commissions did not have 

suitable data for DFIRM use.
 29

Base Map

NH GRANIT maintains data layers including features such as roads, streams, and political boundaries. 

Base map layers maintained by NH GRANIT include features such as roads, streams, and political boundaries. Base map data layers have been acquired from a variety of sources including the USGS data and represent many of the feature types found on USGS topographic maps. More recently developed data were 

derived from the digital orthophotos providing improved base map accuracy.

There are three base map sources available (table 6). These include the USGS DOQs (1:12,000; 1998, 

1992) and NAIP Aerial Photographs (1:40,000; 2003). Existing coverages maintained by NH GRANIT can 

be linked to or viewed at the following Web site: http://www.granit.sr.unh.edu

Table 6. Currently available high resolution orthophotography for Merrimack County.

[USGS, U.S. Geological Survey; DOQQ, Digital Orthophoto Quarter Quad; B&W, Black and White; NAIP, National Agricultural Imagery Program, NH GRANIT, New Hampshire Geographically Referenced Analysis and Information Transfer System]

Item Source Date Resolution Coverage

USGS DOQQ B&W USGS 1998, 1992 1.0 meter pixel Statewide

NAIP 2003 Color NH GRANIT, NAIP 2003 1.0 meter pixel Statewide

USGS Digital Ortho Quarter Quads (DOQQs) are available for all of Merrimack County. The DOQQs 

are FEMA’s default standard for the base map. The accuracy and quality of the DOQQs meets National Map 

Accuracy Standards at 1:12,000 scale for 3.75-minute quarter quadrangles, plus or minus 33.33 ft or 10 m. 

For Merrimack County, the DOQQ orthophotos are dated 1998 and are 1.0-m resolution.

The NAIP 2003 color orthophotos were created by the Aerial Photography Field Office (APFO) of 

the U.S. Department of Agriculture (USDA) and processed by NH GRANIT to (1) standardize the exterior 

“nodata” values; (2) re-project the data into New Hampshire State Plane Feet (North American Datum of 

1983 (NAD 83)); (3) tile the data to 15-minute quadrangles to facilitate distribution; and (4) re-compress 

the data to MrSID Generation 3 format. The source product is 1-m ground sample distance (GSD) DOQQs 

from the National Digital Ortho Program (NDOP). The imagery may contain as much as 10-percent cloud 

cover per source photograph.

Digital Terrain Model

NH GRANIT has the DEM USGS National Elevation Dataset (NED) available for download. NH 

GRANIT extracted the NED and re-projected the files into NAD 83. The data are based on USGS 7.5 minute 

DEMs (30m x 30m square grids). The DEMs were derived from USGS 1:24000 and 1:25000 quadrangle 

maps.

Flood Insurance Risk Zones

FEMA flood insurance rate 100- and 500-year flood zones are being converted to digital data layers by 

NH GRANIT for each community participating in the NFIP in New Hampshire. These datasets were developed by direct digitization of FIRM maps using data registration techniques that produced the best-fit registration to community boundaries or other suitable features.
 30

Mapping Options

The following section provides a summary of the potential options for developing base maps, DTMs, 

and flood insurance risk zones.

Base Map

Three base map options are presented for consideration:

1. Use existing USGS DOQQs from 1998 and 1992.

2. Use NAIP 2003, 1.0-m resolution color orthophotos.

3. Produce new vector data.

The recommended option for DFIRM production in Merrimack County is option #1

Digital Terrain Model

There are no DTM data available that meet FEMA requirements for Merrimack County with the exception of 2-ft contour interval for Concord, N.H., and data created by Holden Engineering in select areas of 

Hooksett, Pembroke, Bow, and Loudon (Peter Holden, Holden Engineering and Surveying, Inc., oral commun., September 6, 2005).

DTM development options include (1) obtaining countywide DTM data that covers all communities 

and (2) obtaining DTM data only for selected floodplain areas as needed to support a detailed study, limited 

detailed study, restudy or re-delineation of flood-hazard areas. 

The estimated costs of obtaining new DTM data is shown in table 7. These costs are based on the information determined by Camp, Dresser, and McKee, Inc. (2004) in their 2005 Scoping Report for Rutland 

County, Vermont. The estimates include the cost of the LiDAR (Light Detection and Ranging) imaging system work and the associated aerial photography work needed to create break line data.

Table 7. Estimate of costs to obtain Digital Terrain Model data (2-ft contours).

Area 

(square miles)

Unit cost 

($ per square mile) Estimated cost

20 5,000 $100,000

50 3,000 $150,000

75 2,250 $168,750

100 2,000 $200,000

935 

(All of Merrimack County)

1,250 $1,168,750

Obtaining DTM data on a countywide basis is expensive. Most of the acquired data would be outside 

of the floodplain and not needed for hydraulic analysis. Two-foot contour data are available for select locations in Hooksett, Pembroke, Bow, and Loudon, N.H., from Holden Engineering and Surveying, Inc. (Peter 

Holden, Holden Engineering and Surveying, Inc., oral commun., September 6, 2005). If FEMA obtains new 

DTM data for selected areas as needed, it would be most cost effective to consolidate areas, where possible, 

and optimize flights, to reduce the unit costs.
31

Flood Insurance Risk Zones

The response from communities in Merrimack County, New Hampshire was mixed regarding the accuracy of the flood insurance risk zones as shown on the existing panels. The most common comment by community representatives was that a better base map is needed to allow easier determination of where the risk 

zone boundaries are relative to the existing features such as roads and buildings. 

Section 4. Hydrologic and Hydraulic Restudy Needs and Prioritization

This section summarizes the mapping needs prioritization process and presents the prioritization results 

based on community input as well as data obtained from other sources including MNUSS and LOMCs.

Mapping Needs

Based on community input, mapping needs included comments that no new studies were needed, floodplain boundaries are delineated incorrectly, the existing detailed study area needs to be extended, and 

remapping is needed. 

Prioritization Process

DFIRM data are available for Merrimack County; however, the DFIRM data received on October 15, 

2005, and entered into WISE, has not been Quality Assurance/Quality Control checked. 

The data collected from the state and community meetings and MNUSS was entered into the WISE 

scoping tool. The data then were exported out of WISE and put into a spreadsheet to score each stream 

segment based on the relative importance of the following factors:

• Community population density.

• Population change (growth).

• Age of effective flood insurance study.

• Significant areas (as defined by the community).

• Existing or proposed development since the FIS.

• Presence of LOMAs/LOMRs.

• Priority (as assigned by community).

• Ranking of importance within the community (community defined).

The prioritization of the flooding sources was based on a number of factors specific to Merrimack 

County and is shown in table 8.
Table 8. Community flooding source prioritization.

[FIS, Flood Insurance Study; LOMCs, Letters of Map Changes]

Community population density 1990–2000 percent population growth Year since most recent FIS

Range Value Range Value Range Value

> 1,000 10 > 50 10 < 1980 10

90–999 8 40–49 8 1980–1984 8

80–89 6 30–39 6 1985–1989 6

60–79 4 20–29 4 1990–1994 4

30–59 2 10–19 2 1995–1999 2

10–29 1 5–9 1 2000–2004 1

< 9 0 < 4 0 2005 0

Significant areas 

(as defined by the community)

Existing or proposed development

since FIS Presence of LOMCs

Range Value Range Value Range Value

Yes 5 Yes 5 Yes 5

No 0 No 0 No 0

Community priority Community ranking

Range Value Range Value

High 20 1 10

Medium 10 2 8

Low 0 3 6

> 4 4

 32

Prioritization Results

The sum of the score for the parameters listed in table 8 was used to determine the final score for each 

stream and flooding source. The list of prioritized flooding sources is provided in appendix D.

Non-Participating Community - Dunbarton

The Town of Dunbarton is not currently in the NFIP. However, community representatives stated that 

the town has no flooding sources of concern.
 33

Section 5. Recommendations and Schedule

This section presents flood-mapping recommendations to meet the mapping needs described in previous sections.

Mapping Recommendations

FEMA’s goal is to develop updated DFIRMs and FISs for Merrimack County, New Hampshire. The 

County has an area of approximately 935 mi2

 and encompasses 27 cities and towns.

Mapping Options

Mapping can be categorized based on the level of detail and required study effort to create or update 

flood-hazard zones.

• Baseline–DFIRM only: The most economical method of creating a countywide DFIRM is through 

digitizing flood-hazard information from the effective FIRMs and FISs onto new mapping. This 

baseline option is currently being undertaken by NH GRANIT.

• Redelineation: Detailed topography (2-ft contour interval) is available in Hooksett, Pembroke, 

Bow, Loudon, and Concord. The flood-hazard information from the effective FIRMs and FISs can 

be redelineated onto new topography and base mapping as it becomes available.

• Limited Detailed Study: Automated tools are used to produce digital information. This assumes 

new field surveys for structures but, no new field surveys for cross-sections are needed and that the 

existing hydraulic model can be used.

• Detailed Study: Can be performed to develop the digital information, including field surveyed 

cross-sections and structures. Since this is the most expensive type of study that FEMA can perform, 

the extent of the detailed study may be limited.

Project Alternatives

Costs can be reduced by cutting back on the level of effort for the H&H analyses and(or) reducing the 

number of DFIRM panels. Alternative H&H options that would help FEMA to reduce costs include reducing the study scope from a detailed study to a limited detail study or redelineation of current flood information only. Reducing the number of DFIRM panels by altering the mix of panel scales would lower the total 

panel count and reduce the estimated DFIRM production cost.

Schedule

The project schedule will vary depending on the final scope of the work. Detailed and Limited Detail 

Restudy and DFIRM production can be completed in 24 months, plus the time required for post preliminary 

processing, which may be completed in about 6 months for a total of 30 months.
 34

Selected References

Camp, Dresser, and McKee, Inc., 2004, Flood insurance study needs in the Blackstone River basin in Providence County, Rhode Island and Worcester County, Massachusetts: Contract No. EME-2003-CO-0340, 

Task Order T001, Task 1, February 2004, variously paged.

Camp, Dresser, and McKee, Inc., 2005, Flood insurance study needs in Rutland County, Vermont: Contract 

No. EME-2003-CO-0340, variously paged.

Federal Emergency Management Agency, 2004, Guidelines and specifications for flood-hazard ampping 

partners, accessed online January 10, 2006, at http://www.fema.gov/plan/prevent/fhm/gs_main.shtm

New Hampshire GRANIT (Geographically Referenced ANalysis and Information Transfer system), 2006, 

accessed online January 12, 2006, at http://www.granit.sr.unh.edu/

University of New Hampshire, 2005, Carsey Institute, accessed online September 28, 2005, at 

http://www.nneindicators.unh.edu/ShowOneRegion.asp?IndicatorID=1&FIPS=33013.

Watershed Concepts, a Division of Hayes, Seay, Mattern and Mattern, Watershed Information System 

(WISE), version 2.0.9, 2005.
 35

Appendix A. Summary of Letters of Map Change (LOMC) 

Data in Merrimack County
36

Table A-1. Summary of LOMC data in Merrimack County.[LOMC, Letters of Map Changes; SFHA, Special Flood Hazard Area. The SFHA is an area that would be inundated by the flood having a 1-percent chance of being equaled 

LOMA, Letter of Map Amendment; LOMR-FW, Letter of Map Revision Floodway; LOMA-OAS, Letter of Map Amendment Out-As-Shown]

Community LOMC type Case number Effective date Flooding source Address Property latitude Property longi- tude Removed from SFHA (1) New 

zo

Concord, N.H. LOMA 02-01-0622A 6/26/2002 Bela Brook Birchdale Road 43.162 -71.583 Portion of property X Danbury, N.H. LOMA 00-01-0376A 6/20/2000 Unnamed tributary 

to Walker Brook

Walker Brook Road 43.502 -71.913 Structure C 

Epsom, N.H. LOMA 03-01-1318A 7/24/2003 Suncook River 12 Nixon Street 43.189 -71.381 Structure C Epsom, N.H. LOMRFW 04-01-1202A 11/1/2004 Suncook River 1188 Suncook Valley Highway 43.181 -71.391 Property C Franklin, N.H. LOMA 02-01-0886A 5/8/2002 Webster Lake 39 Lake Shore Drive 43.467 -71.695 Structure C Hill, N.H. LOMAOAS 02-01-0216A 3/22/2002 Pemigewaset River 22 Route 3A 43.516 -71.699 Factory/2 buildings C Hill, N.H. LOMA 02-01-0216A 3/22/2002 Pemigewaset River 22 Route 3A 43.516 -71.699 House/barn C Loudon, N.H. LOMA 03-01-0902A 4/21/2003 Soucook River 11 Route 129 43.287 -71.465 Residential structure C Loudon, N.H. LOMA 99-01-486A 3/16/1999 Soucook River 78 Goshen Drive 43.303 -71.465 Structure C Loudon, N.H. LOMA 99-01-1402A 2/17/2000 Soucook River 25 Staniels Road 43.257 -71.455 Portion of property C New London, N.H. LOMA 02-01-0842A 8/2/2002 Messer Pond 3 White Pine Lane 43.402 -72.008 Structure C New London, N.H. LOMA 03-01-1062A 5/8/2003 Unnamed flooding 

source

9 Scythe Shop Road 43.419 -71.932 Residential structure C 

Pembroke, N.H. LOMA 04-01-0584A 2/5/2004 Suncook River 730 Bachelder Road 43.171 -71.399 Residential structure C Pittsfield, N.H. LOMA 00-01-0774A 6/27/2000 Suncook River 1 Lyford Hill Road 43.307 -71.331 Structure C Sutton, N.H. LOMA 01-01-0052A 11/14/2000 Warner River Roby Road 43.29 -71.888 Residential structure C Sutton, N.H. LOMA 01-01-0144A 12/19/2000 Lane River 10 Dodge Hill Road 43.318 -71.934 Structure C Sutton, N.H. LOMA 01-01-0944A 7/25/2001 Cascade Brook 12 French Road 43.393 -71.912 Residential structure C Webster, N.H. LOMA 02-01-0354A 2/8/2002 Beaverdam Brook 1197 Long Street 43.333 -71.707 Structure C Webster, N.H. LOMA 02-01-0362A 2/8/2002 Beaverdam Brook 1178 Long Street 43.332 -71.707 Structure C Webster, N.H. LOMA 02-01-0364A 2/8/2002 Beaverdam Brook 50 Beaver Dam Drive 43.335 -71.708 Structure C Webster, N.H. LOMA 02-01-0350A 2/8/2002 Beaverdam Brook 40 Beaver Dam Drive 43.334 -71.708 Structure C Webster, N.H. LOMA 02-01-0358A 2/8/2002 Beaverdam Brook 30 Beaver Dam Drive 43.334 -71.707 Structure C Webster, N.H. LOMA 02-01-0738A 3/11/2002 Beaverdam Brook 29 Beaver Dam Drive 43.334 -71.708 Garage C Webster, N.H. LOMA 02-01-0360A 2/8/2002 Beaverdam Brook 20 Beaver Dam Drive 43.333 -71.707 Structure C Webster, N.H. LOMA 02-01-0356A 2/8/2002 Beaverdam Brook 29 Beaver Dam Drive 43.334 -71.708 Residential structure C Webster, N.H. LOMA 02-01-0344A 2/8/2002 Beaverdam Brook 17 Beaver Dam Drive 43.333 -71.708 Structure C Wilmot, N.H. LOMA 02-01-1238A 7/12/2002 Chase Pond 114 Quiet Cove Road 43.417 -71.913 Structure C Wilmot, N.H. LOMA 00-01-0224A 3/3/2000 Chase Pond Quiet Cove Road 43.417 -71.917 Structure C 
 37

Appendix B. Mapping Needs Update Support System 

(MNUSS) Needs Assessment Reports

Merrimack County, New Hampshire

MNUSS Needs Assessment Reports Summary Table

New Hampshire Mapping Needs in MNUSS

November 30, 2005
Table B-1. Mapping Needs Update Support System (MNUSS) needs assessment reports summary.

CID Community name Flood data update Map maintenance Pending Resolved

330103 Allenstown, Town of 0 0 0 0

330104 Andover, Town of 0 1 0 0

330105 Boscawen, Town of 0 0 0 0

330107 Bow, Town of 0 0 0 1

330106 Bradford, Town of 0 0 0 0

330108 Canterbury, Town of 0 0 0 0

330109 Chichester, Town of 0 0 0 0

330110 Concord, City of 0 0 0 0

330111 Danbury, Town of 0 0 0 0

330202 Dunbarton, Town of 0 0 0 0

330112 Epsom, Town of 1 0 0 0

330113 Franklin, City of 0 0 0 0

330114 Henniker, Town of 1 1 0 0

330214 Hill, Town of 0 0 0 0

330115 Hooksett, Town of 4 1 0 0

330116 Hopkinton, Town of 0 1 0 0

330117 Loudon, Town of 0 0 0 0

330230 New London, Town of 0 0 0 0

330226 Newbury, Town of 0 0 0 0

330118 Northfield, Town of 0 0 0 0

330119 Pembroke, Town of 0 1 0 0

330120 Pittsfield, Town of 0 0 0 0

330121 Salisbury, Town of 0 1 0 0

330122 Sutton, Town of 0 0 0 0

330123 Warner, Town of 0 0 0 0

330236 Webster, Town of 0 0 0 0

330124 Wilmot, Town of 0 0 0 0

Totals 6 6 0 0

 38
GENERAL COMMUNITY INFORMATION

Community: ANDOVER, TOWN OF CID: 330104

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010603 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 03/16/1998

Approved By: FEMA

Date: 3/16/98

Study Category: MAINTENANCE Need Types: Add streets to panel

Status: Existing

 39

mu

PANELS AFFECTED BY THE NEED

No panels have been associated with this need.

ORIGIN OF NEED INFORMATION

Entity: TOWN OF ANDOVER Phone: 6037355332 Ext: Unspecified

Last Name: STETSON First Name: MARK

Address 1: P.O. BOX 61 Title: TOWN ADMINISTRATOR

Address 2: Unspecified Email: Unspecified

City: ANDOVER Fax: Unspecified

State: NH Zip: 03216-0061

NEED NOTES AND COMMENTS

There are no notes for this need.
GENERAL COMMUNITY INFORMATION

Community: BOW, TOWN OF CID: 330107

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010565 Entered By: Chuck Wood

Source: FEMA Future File Date: 06/08/1999

Approved By: FEMA

Date: 6/8/99

Study Category: RIVERINE Need Types: Changes to BFEs

Flooding Source: MERRIMACK RIVER

Status: Resolved

Resolved Date: 11/20/00 Type of map action: T-19 (Contracted Study)

NEED FLOODPLAIN DATA

Anticipated BFE Change: Increased By Between 1 and 5 feet

Length of Study: 5.87 miles

Average Width of Floodplain: 2500 feet

Location of Floodplain:

PANELS AFFECTED BY THE NEED

3301070001D (11/20/2000) 3301070002D (11/20/2000)

ORIGIN OF NEED INFORMATION

Entity: D&D FUTURE FILE Phone: Unspecified Ext: Unspecified

Last Name: Unspecified First Name: Unspecified

Address 1: Unspecified Title: Unspecified

Address 2: Unspecified Email: Unspecified

City: Unspecified Fax: Unspecified

State: Unspecified Zip: Unspecified

NEED NOTES AND COMMENTS

Date Entered By Note 

06/08/1999 Chuck Wood NEW STUDY IS NEEDED, FIRM IS NOT ACCURATE AND AREA HAS SEEN 

A RECENT BOOM IN DEVELOPMENT. 

06/08/1999 Chuck Wood NEW STUDY IS NEEDED, FIRM IS NOT ACCURATE AND AREA HAS SEEN 

A RECENT BOOM IN DEVELOPMENT.

 40
GENERAL COMMUNITY INFORMATION

Community: EPSOM, TOWN OF CID: 330112

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010570 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 09/09/1997

Approved By: FEMA

Date: 9/9/97

Study Category: RIVERINE Need Types: Changes to hydraulic analysis

Flooding Source: NORTHWOOD LAKE

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Decreased By Less Than 1 foot

Length of Study: 1.86 miles

Average Width of Floodplain: 80 feet

Location of Floodplain:

PANELS AFFECTED BY THE NEED

3301120005B (07/03/1978)

ORIGIN OF NEED INFORMATION

Entity: EPSOM, TOWN OF [TOWN GOVERNMENT] Phone: 603736441 Ext: Unspecified

Last Name: BICKFORD First Name: ALFRED G.

Address 1: P.O. BOX 10 Title: ZONING OFFICER

Address 2: Unspecified Email: Unspecified

City: EPSOM Fax: 6037368539

State: NH Zip: 03234-

NEED NOTES AND COMMENTS

There are no notes for this need.

41
GENERAL COMMUNITY INFORMATION

Community: HENNIKER, TOWN OF CID: 330114

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010594 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 03/04/1998

Approved By: FEMA

Date: 3/4/98

Study Category: MAINTENANCE Need Types: Add streets to panel

Status: Existing

PANELS AFFECTED BY THE NEED

3301140025B (05/01/1978)

ORIGIN OF NEED INFORMATION

Entity: HENNIKER, TOWN OF [TOWN GOVERNMENT] Phone: 6034283221 Ext: Unspecified

Last Name: CLARK First Name: KELLY A.

Address 1: 2 DEPOT HILL ROAD Title: TOWN ADMINISTRATOR

Address 2: Unspecified Email: Unspecified

City: HENIKER Fax: 6034284366

State: NH Zip: 03242-

NEED NOTES AND COMMENTS

There are no notes for this need.

 42
GENERAL COMMUNITY INFORMATION

Community: HENNIKER, TOWN OF CID: 330114

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010595 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 03/04/1998

Approved By: FEMA

Date: 3/4/98

Study Category: RIVERINE Need Types: Changes to hydrologic conditions

Flooding Source: UNNAMED ZONE A AREA

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Increased By Greater Than 5 feet

Length of Study: 2 miles

Average Width of Floodplain: 680 feet

Location of Floodplain:

PANELS AFFECTED BY THE NEED

3301140025B (05/01/1978)

ORIGIN OF NEED INFORMATION

Entity: HENNIKER, TOWN OF [TOWN GOVERNMENT] Phone: 6034283221 Ext: Unspecified

Last Name: CLARK First Name: KELLY A.

Address 1: 2 DEPOT HILL ROAD Title: TOWN ADMINISTRATOR

Address 2: Unspecified Email: Unspecified

City: HENNIKER Fax: 6034284366

State: NH Zip: 03242-

NEED NOTES AND COMMENTS

There are no notes for this need.

 43
GENERAL COMMUNITY INFORMATION

Community: HOOKSETT, TOWN OF CID: 330115

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000029312 Entered By: Kara Deutsch

Source: State Implementation Plan Date: 09/30/2002

Approved By: Automatic (no FEMA validation)

Date: 11/14/02

Study Category: MAINTENANCE Need Types: Add streets to panel

Status: Existing

PANELS AFFECTED BY THE NEED

3301150005C (03/12/1982) 3301150010C (03/12/1982)

3301150015C (03/12/1982) 3301150020C (03/12/1982)

ORIGIN OF NEED INFORMATION

Entity: HOOKSETT PLANNING DEPARTMENT Phone: (603) 268-0279 Ext: 0

Last Name: WATSON First Name: CHARLES

Address 1: 16 MAIN STREET Title: TOWN PLANNER

Address 2: - Email: cwatson@hooksett.org

City: HOOKSETT Fax: (603) 485-4423

State: NH Zip: 03106

NEED NOTES AND COMMENTS

There are no notes for this need.

 44
GENERAL COMMUNITY INFORMATION

Community: HOOKSETT, TOWN OF CID: 330115

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000029315 Entered By: Kara Deutsch

Source: State Implementation Plan Date: 09/30/2002

Approved By: Automatic (no FEMA validation)

Date: 11/14/02

Study Category: RIVERINE Need Types: Changes to hydrologic conditions

Changes to hydraulic analysis

Flooding Source: MAPLE FALLS BROOK

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Decreased By Less Than 1 foot

Length of Study: 1.4 miles

Average Width of Floodplain: 500 feet

Location of Floodplain: County boundary to Dubes Pond Dam.

PANELS AFFECTED BY THE NEED

3301150010C (03/12/1982) 3301150020C (03/12/1982)

ORIGIN OF NEED INFORMATION

Entity: HOOKSETT PLANNING DEPARTMENT Phone: (603) 268-0279 Ext: 0

Last Name: WATSON First Name: CHARLES

Address 1: 16 MAIN STREET Title: TOWN PLANNER

Address 2: - Email: cwatson@hooksett.org

City: HOOKSETT Fax: (603) 485-4423

State: NH Zip: 03106

NEED NOTES AND COMMENTS

There are no notes for this need.

 45
GENERAL COMMUNITY INFORMATION

Community: HOOKSETT, TOWN OF CID: 330115

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000029316 Entered By: Kara Deutsch

Source: State Implementation Plan Date: 09/30/2002

Approved By: Automatic (no FEMA validation)

Date: 11/14/02

Study Category: RIVERINE Need Types: Changes to hydrologic conditions

Flooding Source: DALTON BROOK

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Decreased By Less Than 1 foot

Length of Study: 0.75 miles

Average Width of Floodplain: 600 feet

Location of Floodplain: Benton Road to Berry Hill Road.

PANELS AFFECTED BY THE NEED

3301150020C (03/12/1982)

ORIGIN OF NEED INFORMATION

Entity: HOOKSETT PLANNING DEPARTMENT Phone: (603) 268-0279 Ext: 0

Last Name: WATSON First Name: CHARLES

Address 1: 16 MAIN STREET Title: TOWN PLANNER

Address 2: - Email: cwatson@hooksett.org

City: HOOKSETT Fax: (603) 485-4423

State: NH Zip: 03106

NEED NOTES AND COMMENTS

Date Entered By Note

09/30/2002 Kara Deutsch Community believes flood boundary is inaccurate.

 46
GENERAL COMMUNITY INFORMATION

Community: HOOKSETT, TOWN OF CID: 330115

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000029313 Entered By: Kara Deutsch

Source: State Implementation Plan Date: 09/30/2002

Approved By: Automatic (no FEMA validation)

Date: 11/14/02

Study Category: RIVERINE Need Types: Changes to hydrologic conditions

Changes to hydraulic analysis

Flooding Source: HEADS POND

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Decreased By Less Than 1 foot

Length of Study: 1.7 miles

Average Width of Floodplain: 800 feet

Location of Floodplain:

PANELS AFFECTED BY THE NEED

3301150005C (03/12/1982) 3301150010C (03/12/1982)

ORIGIN OF NEED INFORMATION

Entity: HOOKSETT PLANNING DEPARTMENT Phone: (603) 268-0279 Ext: 0

Last Name: WATSON First Name: CHARLES

Address 1: 16 MAIN STREET Title: TOWN PLANNER

Address 2: - Email: cwatson@hooksett.org

City: HOOKSETT Fax: (603) 485-4423

State: NH Zip: 03106

NEED NOTES AND COMMENTS

Date Entered By Note

09/30/2002 Kara Deutsch Currently Zone A.

 47
GENERAL COMMUNITY INFORMATION

Community: HOOKSETT, TOWN OF CID: 330115

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000029314 Entered By: Kara Deutsch

Source: State Implementation Plan Date: 09/30/2002

Approved By: Automatic (no FEMA validation)

Date: 11/14/02

Study Category: RIVERINE Need Types: Changes to hydrologic conditions

Changes to hydraulic analysis

Flooding Source: DUBES POND

Status: Existing

NEED FLOODPLAIN DATA

Anticipated BFE Change: Decreased By Less Than 1 foot

Length of Study: 1.2 miles

Average Width of Floodplain: 1000 feet

Location of Floodplain:

PANELS AFFECTED BY THE NEED

3301150005C (03/12/1982) 3301150010C (03/12/1982)

ORIGIN OF NEED INFORMATION

Entity: HOOKSETT PLANNING DEPARTMENT Phone: (603) 268-0279 Ext: 0

Last Name: WATSON First Name: CHARLES

Address 1: 16 MAIN STREET Title: TOWN PLANNER

Address 2: - Email: cwatson@hooksett.org

City: HOOKSETT Fax: (603) 485-4423

State: NH Zip: 03106

NEED NOTES AND COMMENTS

Date Entered By Note

09/30/2002 Kara Deutsch Currently Zone A

 48
GENERAL COMMUNITY INFORMATION

Community: HOPKINTON, TOWN OF CID: 330116

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010631 Entered By: Chuck Wood

Source: FEMA Future File Date: 09/15/1998

Approved By: FEMA

Date: 9/15/98

Study Category: MAINTENANCE Need Types: Align map panels

Status: Existing

PANELS AFFECTED BY THE NEED

3301160009B (05/17/1988)

ORIGIN OF NEED INFORMATION

Entity: D&D FUTURE FILE Phone: Unspecified Ext: Unspecified

Last Name: Unspecified First Name: Unspecified

Address 1: Unspecified Title: Unspecified

Address 2: Unspecified Email: Unspecified

City: Unspecified Fax: Unspecified

State: Unspecified Zip: Unspecified

NEED NOTES AND COMMENTS

There are no notes for this need.

 49
GENERAL COMMUNITY INFORMATION

Community: PEMBROKE, TOWN OF CID: 330119

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010572 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 10/03/1997

Approved By: FEMA

Date: 10/3/97

Study Category: MAINTENANCE Need Types: Add streets to panel

Status: Existing

PANELS AFFECTED BY THE NEED

3301190005A (04/02/1979) 3301190010A (04/02/1979)

ORIGIN OF NEED INFORMATION

Entity: TOWN OF PEMBROKE Phone: 6034854747 Ext: Unspecified

Last Name: DOLLARD First Name: DONALD W.

Address 1: TONW HALL Title: ASSESSOR

Address 2: 311 PEMBROKE ST. Email: Unspecified

City: PEMBROKE Fax: Unspecified

State: NH Zip: 03275-

NEED NOTES AND COMMENTS

There are no notes for this need.

 50
GENERAL COMMUNITY INFORMATION

Community: SALISBURY, TOWN OF CID: 330121

County: MERRIMACK COUNTY State: New Hampshire

NEED DETAIL INFORMATION

Need ID: 100000000010632 Entered By: Chuck Wood

Source: FEMA 5-year letter Date: 11/25/1998

Approved By: FEMA

Date: 11/25/98

Study Category: MAINTENANCE Need Types: Add streets to panel

Status: Existing

PANELS AFFECTED BY THE NEED

No panels have been associated with this need.

ORIGIN OF NEED INFORMATION

Entity: SALISBURY, TOWN OF [TOWN GOVERNMENT] Phone: 6036482473 Ext: Unspecified

Last 

Name:

WARREN First Name: MARGARET

Address 1: SELECMAN'S OFFICE Title: ADMINISTRATIVE ASSISTANT

Address 2: P.O. BOX 214 Email: Unspecified

City: SALISBURY Fax: Unspecified

State: NH Zip: 03268-

NEED NOTES AND COMMENTS

There are no notes for this need.

51
 52

Appendix C. State and Community Meetings
53

FEMA Map Modernization Program

Merrimack County Scoping

Scoping Meeting Conference Call

Meeting Minutes

September 1, 2005

U.S. Geological Survey (USGS) held a kick-off meeting via conference call on September 1, 2005, with 

representatives from New Hampshire Office of Emergency Management (NHOEM), Federal Emergency 

Management Agency (FEMA), USGS, and Watershed Concepts (RMC - Regional Management Center) to 

introduce the scoping project team and review roles and responsibilities. 

As one of the scoping study process requirements, this conference call was held to review the USGS 

role in the scoping project process in four counties in New Hampshire (Merrimack, Coos, Belknap, and Carroll Counties) as well as to detail the data requirements of USGS in order to determine restudy needs and 

prioritization of restudies in these four counties. 

Attendance:

• Dean Savramis, FEMA Map Modernization Coordinator

• Brent McCarthy and Jeff Burm, Watershed Concepts (RMC)

• Fay Rubin, GIS Manager at Complex Systems Research Center, University of New Hampshire

• Robert Flynn, Craig Johnston, and Laura Hayes, USGS

• Joanne Cassulo and Jennifer DeLong, Map Modernization Coordinators, NHOEM

Minutes:

1. Dean Savramis (FEMA)—Provided an overview of the Map Modernization Program and Scoping. 

He also provided a description of the countywide approach.

2. Brent McCarthy (Watershed Concepts)—Describe the role of the RMC in assisting FEMA and the 

mapping contractors. Description of the WISE computer applications developed for FEMA to 

standardize the scoping process methodology, data collection, and storage for the map modernization 

program. Description of the DFIRM Production tool.

3. Joanne Cassulo and Jennifer DeLong (NHOEM)—Spoke about CAVs to collect information. 

NHOEM is providing copies of LOMAs. Joanne mentioned that the regional planning commissions 

have a lot of data available and can provide community contacts.
54

4. Jeff Burm (Watershed Concepts)—mentioned that FEMA’s Community Information System (CIS) 

has CAVs and CACs and access can be gotten from Mike Goetz at FEMA. He also spoke about the 

WISE scoping tool and various features of this tool including community contact information, 

available GIS data, stream data, statistical analysis, stream mile information to calculate costs for 

hydrology and hydraulics, LOMAs, CAVs and CACs, creation of reports for each of the items.

5. Fay Rubin (GRANIT, UNH Complex Systems)—Fay spoke about the Map Modernization work that 

is being done at FEMA and that she is using DOQs in her map modernization work. Fay mentioned 

that the Merrimack County digitization is complete, that the Belknap and Carroll County digitization 

will be complete by December and that the Coos County digitization will be complete next year (due 

by December of 2006). She stated that NHDOT is in the process of updating DOQs ion southeastern 

New Hampshire and that they are looking for a vendor to process the data. She mentioned that the 

2003 NAIP color DOQs may not meet FEMA specifications. She has the NAIP DOQs in New 

Hampshire State Plane coordinates (our NAIP DOQs are in UTM projection). 

6. Fay Rubin, Craig Johnston, Laura Hayes and Rob Flynn (GRANIT; USGS)—discussed available data 

and coverages within New Hampshire (for example, 2003 NAIP color DOQs). Remote sensing, base 

map information, GIS data (for example, contour data, E911 data, DEMs, buildings layer, survey 

data available from NHDOT). County Regional Planning Commissions may also have data.

7. USGS and NHOEM—Discuss follow-up meetings with communities to discuss prioritization. 

USGS will need to coordinate with NHOEM and Watershed Concepts to obtain mailing lists for 

communities and set a date to meet with representatives from each of the towns in each of the 

counties. Brent McCarthy mentioned that it may be a good idea to set up a morning and evening 

meeting with each county in order to be able to talk to all of the representatives in each town 

(two meetings for each county). Brent McCarthy also mentioned that Watershed Concepts could lead 

breakout sessions with towns during the meetings with the counties.
55

Merrimack County Interview Form

FEMA Map Modernization Program

________________________________________________________________________

Date: _________________________ Effective FIS/FIRM Date:______________________

Community:____________________ Form of Government:__________________________

CID#:_________________________ If Town Government, 

 Date of Annual Town Meeting:__________________

Community Representative:

Name:______________________________________________________________________

Title:________________________________________________________________________

Telephone #:___________________________Email:__________________________________

Fax:________________________________________________________________________

Other Appropriate Community Contacts:_________________________________________

1. Known problems with current FIRMs and FISs for the community (general details on next 

pages).

a. Base Map Issues (note FIRM panel numbers): (for example, poor/mixed map scales, panels 

not printed, change in corporate boundaries, etc.)

______________________________________________________________________________

______________________________________________________________________________

b. Floodplain Issues (note FIRM panel numbers): (for example, need flood elevations, disagree with floodplain boundaries, flood elevations too high/low, comments from MNUSS or 

best available data)

______________________________________________________________________________

______________________________________________________________________________

2. Areas of approximate study (for example, Zone A’s) where detailed re-studies should be 

considered:

______________________________________________________________________________

______________________________________________________________________________
 56

3. Areas not mapped/no floodplain where approximate or detailed studies should be considered:

______________________________________________________________________________

______________________________________________________________________________

4. Changes to structures within the town that may affect river hydraulics (for example, reconstruction or removal of dams, changes to bridges and culverts, etc.):

______________________________________________________________________________

______________________________________________________________________________

5. Areas of increased/proposed development within the floodplain since the effective FIS:

______________________________________________________________________________

______________________________________________________________________________

1. Availability of mapping at the town level:

a. Aerial Photography (flight date, scale, color/black and white): 

_________________________________________________________________________

_________________________________________________________________________

b. Topography (contour interval): 

_________________________________________________________________________

_________________________________________________________________________

c. Other: 

_________________________________________________________________________

_________________________________________________________________________

2. Future community data acquisition plans/wants/needs: 

_________________________________________________________________________

_________________________________________________________________________

3. Information on GIS programs in-place or GIS plans that may benefit from a new FIRM:

____________________________________________________________________

4. Other comments:

_________________________________________________________________________

_________________________________________________________________________

5. Action Items:

________________________________________________________________________

_________________________________________________________________________

 Additional Notes:

_________________________________________________________________________

_________________________________________________________________________
 57

Appendix D. Prioritized Flooding Sources
58

Appendix D. Prioritized flooding sources in Merrimack County.—Continued[CID, Community Identification; FIS, Flood Insurance Studies; LOMC, Letter of Map Change; --, no data]

Community CID Reach_ID Description

Current 

analysis 

effective 

date

Current 

effective 

zone

Study 

reach 

length

(ft)

Study type

Community 

priority 

range

Community 

priority

Population 

density 

score

Population 

growth 

score

Year 

since 

most 

recent 

FIS 

score

Sig

ica

are

sco

Hooksett 330115 {5D716BDA-16D5-41A1-

84A0-B1239A263C84}

Heads Pond(1047777.36, 214140.48)

3/12/1982 A 7,694.7 Detailed study/

Riverine

Medium High

1 8 6 8 5 

Pittsfield 330120 {6E213E5D-8FF3-4914-

B37D-67E6FE6994C7}

Whites Pond (1080578.26, 292282.24)

7/3/1978 -- 3,330.3 Detailed study/

Riverine

Medium High

1 8 1 10 5 

New London 330230 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Whitney Brook (911728.44, 335456.04) 7/16/1991 A 2,688.4 Detailed study/ Riverine Medium High 2 8 4 4 5 Concord 330110 {8991D004-A6FE-4ACEA086-A6A44B4340CA} The Outlet (998189.22, 279146.60) 8/23/1999 -- 7,451.7 Detailed study/ Riverine High 1 8 2 2 5 Concord 330110 {6B244ABB-71F7-4FE4-

A3BA-549201877C9C}

Contoocook River (996281.43, 277703.82)

8/23/1999 AE 10,215.1 Limited 

detailed study/Riverine

High 1 8 2 2 5 

Warner 330123 {58BB2B22-638A-4451-

A0AE-A7083F1FDAFA}

Warner River (934924.54, 287337.05)

6/4/1987 AE 12,850.9 Limited 

detailed study

High 1 2 4 6 5 

New London 330230 {B6FCFAD7-3717-4F8B9B3E-057ED9884DAB} Little Sunapee Lake (894235.75, 342124.56) 7/16/1991 A 10,758.5 Detailed study Medium High 1 8 4 4 5 Concord 330110 {8DDC9691-E6B6-4203-

AD33-01F9364DFB3D}

Merrimack River (1004823.77, 286828.77)

8/23/1999 AE 18,382.0 Limited 

detailed study/Riverine

Medium High

2 8 2 2 5 

Hooksett 330115 {2BDA4396-BF37-414D9FD0-C10A33F80BAE} Dubes Pond (1052041.26, 207899.35) 3/12/1982 A 5,735.8 Detailed study/ Riverine Medium 2 8 6 8 5 Loudon 330117 {3C2D2E6E-3845-4EBD8F4A-03A311212156} Soucook River (1037392.79, 295792.44) 9/28/1979 A 22,252.3 Detailed study/ Riverine Medium High 1 8 1 1 5 New London 330230 {C3AFBE53-192E-4DC7-

AB92-62F3E68DAA78}

Pleasant Lake (906852.93, 338498.45)

7/16/1991 A 2,120.2 Detailed study Medium 

High

2 8 4 4 5 

New London 330230 {C3AFBE53-192E-4DC7-

AB92-62F3E68DAA78}

Pleasant Lake (905697.35, 339078.18)

7/16/1991 A 1,334.5 Detailed study Medium 

High

2 8 4 4 5 

New London 330230 {C3AFBE53-192E-4DC7-

AB92-62F3E68DAA78}

Pleasant Lake (904813.96, 341395.11)

7/16/1991 A 2,599.0 Detailed study Medium 

High

2 8 4 4 5 

New London 330230 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Pleasant Lake (908606.35, 337337.79) 7/16/1991 A 3,718.2 Detailed study Medium High 2 8 4 4 5 Sutton 330122 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (918651.45, 325967.31)

5/17/1977 A 4,793.5 Detailed study/

Riverine

Medium 1 2 1 10 5 

Sutton 330122 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (919113.90, 326400.84)

5/17/1977 A 931.7 Detailed study/

Riverine

Medium 1 2 1 10 5 

Pittsfield 330120 {0F5FB324-FB18-4649-

9C0F-F56665D5F634}

Clarks Pond (1077169.39, 292453.44)

7/3/1978 -- 493.9 Detailed study/

Riverine

Medium 2 8 1 10 5 

Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Cascade Brook (921649.66, 334631.99) 11/19/1976 A 10,832.5 Detailed study/ Riverine Medium High 1 2 4 6 5 Newbury 330226 {E40D837F-79A5-47BDAE1C-D3946D0EC1A5} Ring Brook (900303.96, 302358.54) 4/2/1986 A 3,444.9 Detailed study/ Riverine Medium High 1 2 4 6 5 Newbury 330226 {E40D837F-79A5-47BDAE1C-D3946D0EC1A5} Ring Brook (900001.38, 295721.32) 4/2/1986 A 6,761.6 Detailed study/ Riverine Medium High 1 2 4 6 5 Newbury 330226 {E40D837F-79A5-47BDAE1C-D3946D0EC1A5} Ring Brook (900418.18, 299315.19) 4/2/1986 A 4,272.8 Detailed study/ Riverine Medium High 1 2 4 6 5 New London 330230 {8A83C96D-3FB4-48A5-

9AC5-F3E48070229F}

Messer Pond(892744.56, 330985.95)

7/16/1991 A 6,406.2 Detailed study Medium 

High

3 8 4 4 0 

Sutton 330122 {988185AE-8435-4C92-

8EB3-3800D744557F}

Lane River(911980.32, 298900.52)

5/17/1977 A 22,604.6 Detailed study/

Riverine

Medium High

2 2 1 10 5 
59

Andover 330104 {FEFA0970-D853-4F85-

B618-E951A2D83861}

Blackwater River (930608.33, 339351.61)

4/2/1986 A 24,953.4 Detailed study/

Riverine

Medium High

1 2 2 6 5 

Andover 330104 {FEFA0970-D853-4F85-

B618-E951A2D83861}

Blackwater River (950220.54, 339823.08)

4/2/1986 A 14,411.7 Detailed study/

Riverine

Medium High

1 2 2 6 5 

Bow 330107 {158AC221-D0B1-4DA0-

8675-BB88EFA47D5A}

Bow Bog Brook (1030374.10, 230410.68)

11/20/2000 A 17,834.4 Detailed study/

Riverine

Medium High

1 8 6 1 5 

Andover 330104 {F6E7B5EA-907F-4097-

88D8-04624251AD4F}

Sucker Brook (962298.64, 348324.40)

4/2/1986 A 24,594.0 Detailed study/

Riverine

Medium High

2 2 2 6 5 

Andover 330104 {F6E7B5EA-907F-4097-

88D8-04624251AD4F}

Sucker Brook (964567.04, 342014.42)

4/2/1986 A 5,866.2 Detailed study/

Riverine

Medium High

2 2 2 6 5 

Andover 330104 {FEFA0970-D853-4F85-

B618-E951A2D83861}

Blackwater River (930164.48, 340693.27)

4/2/1986 A 1,443.2 Detailed study/

Riverine

Medium High

2 2 2 6 5 

Webster 330236 {C2F195FD-02F6-4C8CA5D5-8A346EB5B4A7} Lake Winnepocket (965834.67, 294363.50) 6/2/1993 -- 4,546.1 Detailed study Medium High 1 2 2 4 5 Webster 330236 {25E6E49E-E135-451C9D38-E4C7F4106F5E} Pillsbury Lake (980353.82, 283709.07) 6/2/1993 -- 5,512.6 Detailed study Medium High 2 2 2 4 5 Pittsfield 330120 {156CA3B8-6AE1-4216-

AEF5-510EF4D2C117}

Berry Pond Brook (1076662.40, 292280.23)

7/3/1978 -- 5,098.9 Detailed study/

Riverine

Medium High

3 8 1 10 0 

Warner 330123 {6AE0B980-FEBE-4852-

B754-20382389510F}

Slaughter Brook (927755.12, 276870.31)

6/4/1987 -- 10,384.7 Detailed study/

Riverine

Medium High

2 2 4 6 5 

Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Cassey Brook (920358.82, 337359.44) 11/19/1976 A 3,638.6 Detailed study/ Riverine Medium High 2 2 4 6 5 Newbury 330226 {8B7B6BD5-EB4E-4082-

A264-D0FF0CC991F3}

Andrew Brook (897352.57, 290261.65)

4/2/1986 A 3,411.4 Detailed study/

Riverine

Medium 2 2 4 6 5 

Bow 330107 {C9DFB5EE-41F6-47A2-

93B8-DBE41D2106CF}

Bow Bog Brook Tributary(1030014.01, 232365.77)

11/20/2000 A 4,074.9 Detailed study Medium 2 8 6 1 5 

Hooksett 330115 {BEDE6865-839A-45C0-

B38E-0F2C7C68F480}

Dalton Brook (1048509.26, 201092.52)

3/12/1982 X 2,526.3 Detailed study/

Riverine

Medium 3 8 6 8 0 

Hooksett 330115 {BEDE6865-839A-45C0-

B38E-0F2C7C68F480}

Dalton Brook (1046328.59, 200630.97)

3/12/1982 AE 1,709.8 Limited 

detailed study/Riverine

Medium 3 8 6 8 0 

Warner 330123 {0A0E1E70-1637-4E78-

990F-E8ABC134833B}

Stevens Brook (935371.08, 296917.65)

6/4/1987 -- 12,414.1 Detailed study/

Riverine

Medium High

3 2 4 6 0 

Wilmot 330124 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (921838.07, 332642.17)

11/19/1976 A 4,210.5 Detailed study/

Riverine

Medium High

3 2 4 6 0 

Wilmot 330124 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (922205.87, 333891.08)

11/19/1976 A 1,564.3 Detailed study/

Riverine

Medium High

3 2 4 6 0 

Wilmot 330124 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (922831.30, 334442.62)

11/19/1976 A 878.9 Detailed study/

Riverine

Medium High

3 2 4 6 0 

Wilmot 330124 {73262940-3904-4129-

87F4-6CC1507A0763}

Cascade Brook (922792.64, 334718.01)

11/19/1976 A 140.7 Detailed study/

Riverine

Medium High

3 2 4 6 0 

Concord 330110 {63622084-C9E8-4653-

91C4-73D94CA201EA}

Hayward Brook (1016303.72, 292746.23)

8/23/1999 A 8,857.9 Detailed study/

Riverine

Medium High

4 8 2 2 0 

Concord 330110 {E5F75244-1971-4A19-

B0A6-4B257A10852B}

Bela Brook(1003259.87, 238475.89)

8/23/1999 A 9,204.7 Detailed study/

Riverine

Medium 7 8 2 2 0 

Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Whitney Brook (913817.00, 335241.95) 11/19/1976 A 753.6 Detailed study/ Riverine Medium 6 2 4 6 0 

Appendix D. Prioritized flooding sources in Merrimack County.—Continued[CID, Community Identification; FIS, Flood Insurance Studies; LOMC, Letter of Map Change; --, no data]

Community CID Reach_ID Description

Current 

analysis 

effective 

date

Current 

effective 

zone

Study 

reach 

length

(ft)

Study type

Community 

priority 

range

Community 

priority

Population 

density 

score

Population 

growth 

score

Year 

since 

most 

recent 

FIS 

score

Sig

ica

are

sco
60

Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Whitney Brook (914508.50, 335263.95) 11/19/1976 A 3,833.8 Detailed study/ Riverine Medium 6 2 4 6 0 Concord 330110 {77A413FE-0D41-4F1E9A35-30EFD5ACF503} Millers Brook (1007284.13, 257396.80) 8/23/1999 -- 162.6 Detailed study/ Riverine Medium 2 8 2 2 5 New London 330230 {18554505-9655-4F79-

A25F-640F329384F4}

Sunapee Lake (887453.75, 331692.37)

7/16/1991 AE 11,436.3 Redelineation Medium 4 8 4 4 0 

New London 330230 {F4D35C0E-0447-4324-

8298-14562F4C2AA6}

Sunapee Lake (885011.38, 324296.44)

7/16/1991 AE 2,326.6 Redelineation Medium 4 8 4 4 0 

New London 330230 {225194A9-9D2B-4879-

98DC-D5FF167A3FE3}

Sunapee Lake (884308.69, 322844.15)

7/16/1991 AE 1,964.3 Redelineation Medium 4 8 4 4 0 

New London 330230 {18554505-9655-4F79-

A25F-640F329384F4}

Sunapee Lake (882338.25, 333797.55)

7/16/1991 AE 1,602.9 Redelineation Medium 4 8 4 4 0 

New London 330230 {B20D7D36-7E3B-4C28-

BA08-1704164BF801}

Sunapee Lake (880321.74, 336504.88)

7/16/1991 AE 785.5 Redelineation Medium 4 8 4 4 0 

New London 330230 {034F2C79-E139-498AA260-F090A31FDF85} Sunapee Lake (881280.11, 335191.46) 7/16/1991 AE 1,495.9 Redelineation Medium 4 8 4 4 0 Andover 330104 {D35DCD4C-FB39-43D0-

95F6-73DEAD6EBA13}

Unnamed Brook (959616.56, 345402.02)

4/2/1986 A 328.5 Detailed study Medium 2 2 2 6 5 

Andover 330104 {D35DCD4C-FB39-43D0-

95F6-73DEAD6EBA13}

Unnamed Brook (958661.52, 346206.31)

4/2/1986 A 1,252.0 Detailed study/

Riverine

Medium 2 2 2 6 5 

Concord 330110 {726787D1-C679-454CA7F2-07CF38E3EE24} Beaver Meadow Brook (1006132.42, 274740.88) 8/23/1999 -- 12,911.9 Detailed study Medium 3 8 2 2 0 Concord 330110 {D5E36619-3BE3-4564-

B744-911BDA49344D}

Mill Brook (1022097.62, 269687.96)

8/23/1999 A 8,150.9 Detailed study Medium 3 8 2 2 0 

Concord 330110 {BC58336D-D8D6-4800-

B794-8F8142C92373}

Turee Brook (1010759.24, 241247.76)

8/23/1999 A 6,083.6 Detailed study Medium 10 8 2 2 0 

Concord 330110 {7E8EDC3E-05F8-42B6-

892F-6CD8F441B47B}

White Brook (1008954.71, 240312.38)

8/23/1999 A 2,104.3 Detailed study Medium 10 8 2 2 0 

Concord 330110 {4A287C3E-5E47-40F2-

A19C-854E0C208511}

Little Turkey Pond (1006937.34, 244471.99)

8/23/1999 A 880.8 Detailed study Medium 8 8 2 2 0 

Concord 330110 {4A287C3E-5E47-40F2-

A19C-854E0C208511}

Little Turkey Pond (1005922.31, 243671.13)

8/23/1999 A 6,412.5 Detailed study Medium 8 8 2 2 0 

Concord 330110 {CC16505B-7D93-49E1-

BB43-F049695AD0E0}

Turkey River (1003041.31, 252112.32)

8/23/1999 A 8,643.8 Detailed study/

Riverine

Medium 10 8 2 2 0 

Concord 330110 {4A287C3E-5E47-40F2-

A19C-854E0C208511}

Little Turkey Pond (1003600.63, 248790.68)

8/23/1999 A 3,826.1 Detailed study Medium 9 8 2 2 0 

Concord 330110 {4A287C3E-5E47-40F2-

A19C-854E0C208511}

Little Turkey Pond (1001448.19, 252033.43)

8/23/1999 A 1,854.2 Detailed study Medium 9 8 2 2 0 

Concord 330110 {CC16505B-7D93-49E1-

BB43-F049695AD0E0}

Turkey River (1013069.43, 248216.64)

8/23/1999 A 10,403.0 Detailed study/

Riverine

Medium 10 8 2 2 0 

Concord 330110 {CC16505B-7D93-49E1-

BB43-F049695AD0E0}

Turkey River (1011858.76, 249625.21)

8/23/1999 A 2,726.0 Detailed study/

Riverine

Medium 10 8 2 2 0 

Concord 330110 {CC16505B-7D93-49E1-

BB43-F049695AD0E0}

Turkey River (1008927.48, 252163.30)

8/23/1999 A 6,975.4 Detailed study/

Riverine

Medium 10 8 2 2 0 

Wilmot 330124 {DBE90B08-67A1-4A24-

B341-8C030B5F152E}

Kimpton Brook (924219.20, 345121.30)

11/19/1976 A 13,283.2 Detailed study/

Riverine

Medium 7 2 4 6 0 

Wilmot 330124 {DBE90B08-67A1-4A24-

B341-8C030B5F152E}

Kimpton Brook (913532.70, 349611.74)

11/19/1976 A 438.0 Detailed study/

Riverine

Medium 7 2 4 6 0 

Appendix D. Prioritized flooding sources in Merrimack County.—Continued[CID, Community Identification; FIS, Flood Insurance Studies; LOMC, Letter of Map Change; --, no data]

Community CID Reach_ID Description

Current 

analysis 

effective 

date

Current 

effective 

zone

Study 

reach 

length

(ft)

Study type

Community 

priority 

range

Community 

priority

Population 

density 

score

Population 

growth 

score

Year 

since 

most 

recent 

FIS 

score

Sig

ica

are

sco
61

Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Tannery Pond (919537.59, 334276.39) 11/19/1976 A 2,458.1 Detailed study Medium 4 2 4 6 0 Wilmot 330124 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Chase Pond (917226.62, 333705.68) 11/19/1976 A 2,774.7 Detailed study Medium 5 2 4 6 0 Andover 330104 {C8BF8B5C-73B4-4EABB4FA-57606DCC508A} Cascade Brook (927420.51, 337697.60) 4/2/1986 A 4,803.7 Detailed study/ Riverine Medium 3 2 2 6 0 Concord 330110 {06C906AF-755E-4E96-

AC53-1D86666A16AC}

Ash Brook(1001171.00, 252372.56)

8/23/1999 A 457.4 Detailed study/

Riverine

Medium 9 8 2 2 0 

Concord 330110 {77860711-B07B-4F9A8DA1-37B55956A092} Hackett Brook (1021414.90, 288314.69) 8/23/1999 A 7,277.5 Detailed study/ Riverine Medium 4 8 2 2 0 Concord 330110 {06C906AF-755E-4E96-

AC53-1D86666A16AC}

Ash Brook(996313.90, 256124.60)

8/23/1999 A 8,417.5 Detailed study/

Riverine

Medium 9 8 2 2 0 

Concord 330110 {77A413FE-0D41-4F1E9A35-30EFD5ACF503} Millers Brook (1008625.14, 254994.54) 8/23/1999 -- 4,174.2 Detailed study Medium 5 8 2 2 0 Concord 330110 {77A413FE-0D41-4F1E9A35-30EFD5ACF503} Millers Brook (1007384.32, 257268.73) 8/23/1999 -- 2,942.8 Detailed study/ Riverine Medium 5 8 2 2 0 Concord 330110 {0818A6D8-5ED7-4FEAA7C5-6499D313C6AD} Millers Brook (1007629.02, 259744.54) 8/23/1999 -- 3,502.2 Detailed study/ Riverine Medium 5 8 2 2 0 Concord 330110 {5F800174-80E7-42BBBE60-E21EFB8F3760} Hoit Road Marsh Outlet (1021390.62, 288883.17) 8/23/1999 -- 461.9 Detailed study Medium 4 8 2 2 0 Warner 330123 {C79DD47A-530D-41A3-

8F97-4E7621E7BB0B}

French Brook (937045.88, 298912.22)

6/4/1987 -- 4,544.0 Detailed study/

Riverine

Medium 4 2 4 6 0 

Andover 330104 {FB1811E6-F546-430D8B12-C2A59B946B0D} Punch Brook (964783.23, 339003.25) 4/2/1986 A 400.5 Detailed study Medium 6 2 2 6 0 Andover 330104 {711BC930-8E8E-48A3-

A612-92279891421E}

Unnamed Stream (955544.91, 339047.38)

4/2/1986 A 2,725.7 Detailed study Medium 5 2 2 6 0 

Andover 330104 {862D18CA-CD18-4F30-

8807-9D487D560F92}

Unnamed Stream (954402.44, 341235.01)

4/2/1986 A 2,802.5 Detailed study Medium 4 2 2 6 0 

Wilmot 330124 {BBC72434-6C88-4775-

B41B-9577F14C9504}

Eagle Pond(925436.13, 351138.87)

11/19/1976 A 3,957.9 Detailed study Medium 

Low

8 2 4 6 0 

Appendix D. Prioritized flooding sources in Merrimack County.—Continued[CID, Community Identification; FIS, Flood Insurance Studies; LOMC, Letter of Map Change; --, no data]

Community CID Reach_ID Description

Current 

analysis 

effective 

date

Current 

effective 

zone

Study 

reach 

length

(ft)

Study type

Community 

priority 

range

Community 

priority

Population 

density 

score

Population 

growth 

score

Year 

since 

most 

recent 

FIS 

score

Sig

ica

are

sco
Printed on recycled paper

Flynn, R.H.—Scoping of Flood Hazard Mapping Needs for Merrimack County, New Hampshire—Open-File Report 2006–1127