Millstone River Watershed Flood Damage and Mitigation Analysis Report Hurricane Floyd Flooding, September 17, 1999 Griggstown Causeway Looking Toward the Millstone River with Muletenders’ Barracks on right USDA Natural Resources Conservation Service Assisting Hunterdon County Mercer County Middlesex County Monmouth County Somerset County and Respective Soil Conservation Districts December 2004 USDA, Natural Resources Conservation Service 220 Davidson Ave. 4th Floor, Somerset NJ 08873 (732) 537-6040 http://www.nj.nrcs.usda.gov/ Mission Statement The Natural Resources Conservation Service provides leadership in a partnership effort to help people to conserve, maintain, and improve our natural resources and environment. 2 USDA Natural Resources Conservation Service Millstone River Watershed Flood Damage and Mitigation Analysis Report December 2004 TABLE OF CONTENTS TABLE OF CONTENTS .................................................................................................................................................................. 3 List of Tables .................................................................................................................................................................................... 4 List of Figures ................................................................................................................................................................................... 4 List of Photos.................................................................................................................................................................................... 5 ACKNOWLEDGEMENTS .............................................................................................................................................................. 6 EXECUTIVE SUMMARY............................................................................................................................................................... 7 INTRODUCTION ............................................................................................................................................................................. 9 WATERSHED SETTING................................................................................................................................................................. 9 HISTORY OF FLOODING............................................................................................................................................................. 25 PREVIOUS STUDIES ..................................................................................................................................................................... 29 HISTORY OF THIS STUDY.......................................................................................................................................................... 30 Public Participation.................................................................................................................................................................... 32 Methodology of Study ............................................................................................................................................................. 33 PHASE 1 – WATERSHED – WIDE ANALYSIS....................................................................................................................... 33 Municipal Interviews................................................................................................................................................................. 33 Federal Emergency Management Agency National Flood Insurance Claims .................................................................. 53 Flood Damage Priority Study Areas ....................................................................................................................................... 58 Agricultural Issues .................................................................................................................................................................... 58 PHASE 2 – MILLSTONE MAINSTEM ANALYSIS................................................................................................................. 63 Study Area.................................................................................................................................................................................. 63 Methodology for Flood Damage Evaluation......................................................................................................................... 63 Hydrology and Hydraulics .................................................................................................................................................. 63 Structure Elevation Survey.................................................................................................................................................. 64 Economic ................................................................................................................................................................................ 65 Minimum Standards to be Met for Flood Protection....................................................................................................... 69 PHASE 3 – MILLSTONE BOROUGH ANALYSIS.................................................................................................................... 81 Structural Measure .................................................................................................................................................................... 81 Floodwall ................................................................................................................................................................................ 81 Nonstructural Measures ........................................................................................................................................................... 85 Elevation................................................................................................................................................................................. 85 Flood Proofing....................................................................................................................................................................... 85 Relocation............................................................................................................................................................................... 85 Buyout .................................................................................................................................................................................... 86 Enhancement and Expansion of Existing Flood Warning System................................................................................. 86 No Action Alternative.......................................................................................................................................................... 89 HARRYS BROOK........................................................................................................................................................................... 89 Conclusions and Recommendations........................................................................................................................................... 92 Conclusions................................................................................................................................................................................ 92 Recommendations...................................................................................................................................................................... 93 REFERENCES.................................................................................................................................................................................. 97 APPENDICES................................................................................................................................................................................ 101 APPENDIX A - Millstone River Watershed (PL 566) Public Participation Plan............................................................. 103 APPENDIX B - Summary of Millstone River Watershed Public Meeting December 6, 2000....................................... 107 APPENDIX C - Notes from March 22, 200l Public Meeting in Montgomery Township............................................... 113 APPENDIX D - September 18, 2001 Public Meeting in Franklin Township .................................................................... 119 APPENDIX E – Figure 8 - Municipal Interview-Reported Flood Damages .................................................................... 125 APPENDIX F – Summary of Hydraulics Analysis .............................................................................................................. 129 APPENDIX G - Recreation Committee Meeting Minutes September 26, 2001 ............................................................... 131 3 USDA, Natural Resources Conservation Service Millstone River Watershed Flood Damage and Mitigation Analysis Report December 2004 List of Tables Table 1 - Present Land Use........................................................................................................................................................... 21 Table 2 – Past, Present and Projected Population*