Scoping of Flood Hazard Mapping Needs for Androscoggin County, Maine

Open-File Report 2007-1131

Published 2007
Online Only

Scoping of Flood Hazard Mapping Needs for Androscoggin County, Maine

By Charles W. Schalk and Robert W. Dudley

Prepared in cooperation with the Federal Emergency Management Agency, Region I and the Maine Floodplain Management Program, State Planning Office.

Background

The Federal Emergency Management Agency (FEMA) developed a plan in 1997 to modernize the FEMA flood mapping program. FEMA flood maps delineate flood hazard areas in support of the National Flood Insurance Program (NFIP). FEMA's plan outlined the steps necessary to update FEMA's flood maps for the nation to a seamless digital format and streamline FEMA's operations in raising public awareness of the importance of the maps and responding to requests to revise them. The modernization of flood maps involves conversion of existing information to digital format and integration of improved flood hazard data as needed and as funds allow. To determine flood mapping modernization needs, FEMA has established specific scoping activities to be done on a county-by-county basis for identifying and prioritizing requisite flood-mapping activities for map modernization. The U.S. Geological Survey (USGS), in cooperation with FEMA and the Maine Floodplain Management Program (MFMP) State Planning Office, began scoping work in 2006 for Androscoggin County. Scoping activities included assembling existing data and map needs information for communities in Androscoggin County, documentation of data, contacts, community meetings, and prioritized mapping needs in a final scoping report (this document), and updating the Mapping Needs Update Support System (MNUSS) Database with information gathered during the scoping process.

The average age of the FEMA floodplain maps in Androscoggin County, Maine, is at least 17 years. Most studies were published in the early 1990s, and some towns have partial maps that are more recent than their study date. Since the studies were done, development has occurred in many of the watersheds and the characteristics of the watersheds have changed with time. Therefore, many of the older studies may not depict current conditions nor accurately estimate risk in terms of flood heights or flood mapping.

Report

Download the report in Portable Document Format (PDF).

Open-File Report 2007-1131 (PDF–708KB)

Section 1. Introduction
- Background
- Scope of Work
- Description of Androscoggin County
Section 2. Available Flood-Mapping Data and Mapping Needs
- Community FISs and FIRMs
- State of Maine Best Available Data (BAD) for Unnumbered A-Zones
- Letters of Map Change (LOMCs)
- LOMCs in Androscoggin County
- Community Flood Ordinances
- Mapping Needs Update Support System (MNUSS)
- Community Assistance Visits (CAVs) and Community Assistance Contacts (CACs)
- GIS Data
- Base Map Data
- Topographic Data
- Hydrography Data
- Community GIS Contact Information
- Community Meetings and Contacts
- Scope and Prioritization of Mapping Needs in Androscoggin County
  - Prioritization of Towns in Androscoggin County
  - Prioritization of Waterbodies in Androscoggin County
- Project Time and Costs for Identified Mapping Needs
- Project Alternatives
Section 3. Options for Future Mapping and DTM Preparation
- Mapping Requirements
- Base Map
- Digital Terrain Models (DTMs)
- Flood-Insurance Risk Zones
Section 4. References Cited
Appendices
Appendix A: Community Contacts and Best Available Data: Androscoggin County
Appendix B: Community Scoping Interview Data: Androscoggin County
Appendix C: Existing MNUSS Data Entries: Androscoggin County
Appendix D: Attachments
Appendix E: Census Block-Group Data

Tables

Table 1. Organized communities in Androscoggin County, Maine

Table 2. Summary of letters of map change (LOMCs) in Androscoggin County, Maine

Table 3. Summary of entries in the Mapping Needs Update Support System (MNUSS) for Androscoggin County, Maine

Table 4. Summary of Community Assistance Visits (CAVs) and Community Assistance Contacts (CACs) in Androscoggin County, Maine

Table 5. Maine Department of Transportation mapped projects that intersect streams in Androscoggin County identified as needing updated flood-insurance studies

Table 6. Maine Floodplain Management Program criteria for prioritization of community-based flood mapping needs in Androscoggin County (FIA, Federal Insurance Administration)

Table 7. Maine Floodplain Management Program criteria for prioritization of community-based flood mapping needs in Androscoggin County (CID, community identification number; CBG, census block group)

Table 8. Maine Floodplain Management Program criteria and qualitative weight for prioritization of waterbody-based flood mapping needs in Androscoggin County

Table 9. Prioritized waterbody-based flood mapping needs in Androscoggin County requiring redelineation, limited detail study, or detailed study

Table 10. Flood Insurance Rate Map (FIRM) Horizontal Accuracy

Table 11. National Standard for Spatial Data Accuracy (NSSDA)

Figures

Figure 1. Map showing communities in Androscoggin County, Maine

Figure 2. Map showing hydrology of Androscoggin County, Maine

Figure 3. Map showing orthophotography indices for Androscoggin County, Maine. Indices indicate coverage of 0.5-foot (each image pixel representing a planimetric square 0.5 foot on a side, shaded green), 1-foot (pink), and 2-foot (yellow) orthophotography archived and served through the internet by the Maine Office of Geographic Information Systems (MEGIS)

Figure 4. Map showing types of waterbody studies needed by communities in Androscoggin County

Figure 5. Map showing proposed digital flood insurance rate map panels for Androscoggin County

Contact

For questions or comments, please send inquiries to:
Robert Lent, Director
U.S. Geological Survey
Maine Water Science Center
196 Whitten Road
Augusta, Maine 04330

E-mail: dc_me@usgs.gov

For more information, visit our Web site at:
U.S. Geological Survey
Maine Water Science Center
http://me.water.usgs.gov/

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Published 2007 Online Only