DRAFT Narrow River Watershed Plan Prepared by: Office of Water Resources Rhode Island Department of Environmental Management 235 Promenade Street Providence, RI 02908 Draft: December 24, 2019, clean for local review DRAFT Contents Executive Summary ........................................................................................................................ 1 I. Introduction ............................................................................................................................. 8 A) Purpose of Plan................................................................................................................. 8 B) Water Quality and Aquatic Habitat Goals for the Watershed ........................................ 12 1) Open Shellfishing Areas ............................................................................................. 12 2) Protect Drinking Water Supplies ................................................................................ 12 3) Protect and Restore Fish and Wildlife Habitat ........................................................... 12 4) Protect and Restore Wetlands and Their Buffers ....................................................... 13 5) Protect and Restore Recreational Opportunities ......................................................... 14 C) Approach for Developing the Plan/ How this Plan was Developed .............................. 15 II. Watershed Description .......................................................................................................... 16 A) Hydrology Overview ...................................................................................................... 16 1) Surface Water ............................................................................................................. 16 2) Groundwater ............................................................................................................... 19 B) Land Use ........................................................................................................................ 21 C) Drinking Water ............................................................................................................... 27 D) Wastewater ..................................................................................................................... 30 E) Wetlands ......................................................................................................................... 32 III. Water Quality ..................................................................................................................... 36 A) Surface Waters ............................................................................................................... 36 1) Impaired Water Quality Segments ............................................................................. 36 2) Pollutants and Stressors in the Narrow River Watershed ........................................... 42 3) Other Contaminants of Concern in the Watershed ..................................................... 47 B) Groundwater ................................................................................................................... 48 IV. Threats to Water Quality .................................................................................................... 49 A) Stormwater ..................................................................................................................... 49 1) Impervious Surfaces ................................................................................................... 51 2) Sediment ..................................................................................................................... 51 3) Stormwater Management Activities in the Watershed ............................................... 53 4) What Needs to be Done to Improve Stormwater Management in the Watershed? .... 55 B) Wastewater ..................................................................................................................... 61 i DRAFT 1) Sewers ......................................................................................................................... 61 2) Onsite Wastewater Treatment Systems (OWTSs) ...................................................... 62 3) Cesspools .................................................................................................................... 65 4) Illicit connections or direct discharges of wastewater to waterbodies ....................... 65 5) Wastewater Management: What Needs to be Done? ................................................ 66 C) Residential Land Use ..................................................................................................... 67 D) Pet Waste ........................................................................................................................ 68 E) Waterfowl and Wildlife .................................................................................................. 70 F) Commercial and Industrial Facilities- Facility Management ......................................... 72 1) RIPDES (RI Pollutant Discharge Elimination System) ............................................. 74 2) Storage Tanks ............................................................................................................. 74 3) Tier 2 Facilities ........................................................................................................... 74 4) Contaminated Sites ..................................................................................................... 75 G) Lawn and Turf/ Grounds Management .......................................................................... 75 H) Agriculture ..................................................................................................................... 77 I) Road Salt and Sand ......................................................................................................... 77 J) Marine and Riverine Debris ........................................................................................... 79 K) Boating and Marinas ...................................................................................................... 79 L) Atmospheric Deposition ................................................................................................. 80 V. Stressors to Aquatic Habitat.................................................................................................. 82 A) Wetland Disturbance ...................................................................................................... 82 B) Loss of Vegetated Buffers .............................................................................................. 85 C) Invasive Species ............................................................................................................. 88 D) Water Withdrawals ......................................................................................................... 91 E) Barriers to Stream Connectivity ..................................................................................... 92 F) Dredging and Dredge Material Management ................................................................. 98 VI. Climate Change ................................................................................................................ 100 A) Stormwater, Drinking Water, and Wastewater Infrastructure ...................................... 100 B) Aquatic Habitat ............................................................................................................ 100 C) Flooding ....................................................................................................................... 102 D) Managing Climate Change and Sea Level Rise in the Watershed ............................... 102 VII. Other Watershed Protection and Restoration Activities .................................................. 107 A) Narrow River Special Area Management Plan, CRMC, 1999, amended 2012 ........... 107 B) Comprehensive Planning.............................................................................................. 107 ii DRAFT C) Open Space Protection (“Conservation”) ..................................................................... 108 D) Individual Actions ........................................................................................................ 112 E) Support Watershed Organizations ................................................................................ 113 F) Public Outreach ............................................................................................................ 113 G) Recreation: Potential Effects on Water Quality and Aquatic Habitats ....................... 116 H) Lake Management Plans .............................................................................................. 116 I) Groundwater Protection ............................................................................................... 117 VIII. Implementation Table .................................................................................................. 120 IX. Implementation Tools ...................................................................................................... 140 A) Financial Support ......................................................................................................... 140 1) DEM Nonpoint Source Grant Program (319 funds) ................................................. 140 2) Clean Water