Environmental Assessment Carlls River and Connetquot River Watersheds and Southwest Sewer District #3 Suffolk County, New York FEMA-4085-DR-NY March 2019 U.S. Department of Homeland Security Federal Emergency Management Agency Region II 26 Federal Plaza, NY, NY 10278 Environmental Assessment Carlls River and Connetquot River Watersheds and Southwest Sewer District #3 TABLE OF CONTENTS TABLE OF CONTENTS ................................................................................................................. I LIST OF TABLES ........................................................................................................................ III APPENDICES .............................................................................................................................. III LIST OF ACRONYMS ................................................................................................................ IV 1.0 INTRODUCTION ................................................................................................................. 1 1.1 SUFFOLK COUNTY COASTAL RESILIENCY INITIATIVE ................................................................................................ 1 1.2 CARLLS RIVER AND CONNETQUOT RIVER WATERSHEDS AND SOUTHWEST SEWER DISTRICT #3 SEWER EXTENSION PROJECT ENVIRONMENTAL REVIEW PROCESS ....................................................................................................... 1 2.0 PURPOSE AND NEED ......................................................................................................... 2 3.0 PROJECT BACKGROUND ................................................................................................. 2 3.1 CARLLS RIVER EXPANSION AREA ........................................................................................................................ 2 3.2 CONNETQUOT RIVER EXPANSION AREA ............................................................................................................... 3 3.3 SOUTHWEST SEWER DISTRICT #3 LATERALS AREA ................................................................................................. 3 3.4 SANITARY WASTEWATER DISPOSAL IN THE PROJECT AREA ...................................................................................... 3 4.0 ALTERNATIVES.................................................................................................................. 4 4.1 ALTERNATIVE 1: NO ACTION ............................................................................................................................. 4 4.2 ALTERNATIVE 2: PROPOSED ACTION ................................................................................................................... 4 4.2.1 Carlls River Expansion Area ......................................................................................................... 5 4.2.2 Connetquot River Expansion Area ............................................................................................... 6 4.2.3 Southwest Sewer District #3 Laterals Area .................................................................................. 7 4.2.4 Implementation and Construction ............................................................................................... 7 4.3 ALTERNATIVE 3: ON-SITE TREATMENT AND DISPOSAL – REPLACING EXISTING ON-SITE WASTEWATER TREATMENT AND DISPOSAL SYSTEMS WITH INNOVATIVE/ADVANCED ON-SITE WASTEWATER TREATMENT AND DISPOSAL SYSTEMS (I/A OWTS ALTERNATIVE) .................................................................................................... 8 4.3.1 Treatment Methods ..................................................................................................................... 8 4.3.2 Implementation and Construction ............................................................................................... 8 4.4 ALTERNATIVES CONSIDERED BUT DISMISSED ........................................................................................................ 9 5.0 AFFECTED ENVIRONMENT AND POTENTIAL IMPACTS .......................................... 9 5.1 RESOURCES DISMISSED FROM DETAILED ANALYSIS .............................................................................................. 10 5.2 SOILS .......................................................................................................................................................... 10 5.2.1 Existing Conditions ..................................................................................................................... 10 5.2.2 Potential Impacts ....................................................................................................................... 11 5.3 AIR QUALITY AND GREENHOUSE GASES ............................................................................................................. 14 5.3.1 Existing Conditions ..................................................................................................................... 14 5.3.2 Potential Impacts ....................................................................................................................... 15 5.4 WATER QUALITY ........................................................................................................................................... 18 5.4.1 Existing Conditions ..................................................................................................................... 18 i Environmental Assessment Carlls River and Connetquot River Watersheds and Southwest Sewer District #3 5.4.2 Potential Impacts ....................................................................................................................... 20 5.5 WETLANDS .................................................................................................................................................. 23 5.5.1 Existing Conditions ..................................................................................................................... 23 5.5.2 Potential Impacts ....................................................................................................................... 24 5.6 FLOODPLAINS, STORMS, AND SEA LEVEL RISE ..................................................................................................... 27 5.6.1 Existing Conditions ..................................................................................................................... 28 5.6.2 Potential Impacts ....................................................................................................................... 29 5.7 COASTAL RESOURCES ..................................................................................................................................... 32 5.7.1 Existing Conditions ..................................................................................................................... 32 5.7.2 Potential Impacts ....................................................................................................................... 33 5.8 VEGETATION ................................................................................................................................................ 35 5.8.1 Existing Conditions ..................................................................................................................... 35 5.8.2 Potential Impacts ....................................................................................................................... 36 5.9 WILDLIFE AND FISH ....................................................................................................................................... 39 5.9.1 Existing Conditions ..................................................................................................................... 39 5.9.2 Potential Impacts ....................................................................................................................... 42 5.10 THREATENED AND ENDANGERED SPECIES........................................................................................................... 45 5.10.1 Existing Conditions ..................................................................................................................... 45 5.10.2 Potential Impacts ....................................................................................................................... 48 5.11 CULTURAL RESOURCES ................................................................................................................................... 50 5.11.1 Existing Conditions ..................................................................................................................... 50 5.11.2 Potential Impacts ....................................................................................................................... 54 5.12 ENVIRONMENTAL JUSTICE ............................................................................................................................... 57 5.12.1 Existing Conditions ..................................................................................................................... 57 5.12.2 Potential Impacts ....................................................................................................................... 59 5.13 LAND USE AND PLANNING .............................................................................................................................. 62 5.13.1 Existing Conditions ....................................................................................................................