Wetlands and Watercourses Viewer

Overview This map displays wetland and watercourse areas at the parcel level across Connecticut. It offers a high‑level overview of where these wetlands and watercourses are located and the portion of each parcel they occupy, providing a helpful general reference. For those developing a Housing Growth Plan under C.G.S. §§ 8-13bb and 8-13cc, this map can help inform the Developable Land Inventory process, specifically the evaluation of the exclusion of wetlands and watercourses as outlined in the Developable Land Inventory Technical Guidance. Note that a detailed GIS analysis should still be completed for that purpose, as this map is intended as an overview only. Definitions Wetland and Watercourse Definitions: Click here to view definitions Inland Wetland Soils Area: The total area of Inland Wetland features (in acres), as defined by hydric soils in the Inland Wetlands and Watercourse Act, within the selected parcel NHD Watercourse Area: The total area of Watercourse features (in acres) within the selected parcel NWI Wetlands Area: The total area of NWI Wetland features (in acres) within the selected parcel Aggregate Area: The aggregate area of Inland Wetland Soils, NHD Watercourses, and NWI Wetlands* features (in acres) within the selected parcel. This metric only sums areas where Inland Wetland Soils, NHD Watercourses, and NWI Wetlands features overlap each other once. As such, the Aggregate Area can be less than the sum of the Inland Wetland Soils, NHD Watercourses, and NWI Wetlands Areas. *If the NWI Wetlands layer is toggled off so that it is hidden in the map, NWI Wetlands areas are not calculated in the parcel pop-ups and are not included in the aggregate area calculations. Datasets NHD Watercourses: This layer displays hydrography polygon features from the USGS National Hydrography Dataset (NHD) within the state of Connecticut. The full dataset from which this layer is derived contains several waterbody categories; however, in this viewer it is filtered for open water features (Where AV_LEGEND = "Water"). This dataset is maintained by the Connecticut Department of Energy and Environment (CT DEEP). See Connecticut Hydrography Set for more details. Inland Wetland Soils: This dataset contains statutorily defined Inland Wetland Soils Areas (See Inland Wetlands and Watercourse Act) and is maintained by CT DEEP. See Inland Wetland Soils for more details. NWI Wetlands: This dataset contains wetland features from the 2024 United State Fish and Wildlife Service National Wetlands Inventory (NWI) clipped to the Connecticut state boundary. This clipped version of the national dataset is maintained by the CT DEEP. The federally classified wetland features contained in this dataset may differ from the Connecticut statutory definition, which is based on hydric soils, but can serve as a useful supplemental reference when analyzing wetland coverage. Instructions To review parcel wetland and watercourse areas, zoom to your target area. The NHD Watercourses, Inland Wetland Soils, and NWI Wetlands layers will appear when the map is zoomed in past a zoom scale of less than 1:289,000. The Parcel layer will appear when the map is zoomed in past a zoom scale of less than 1:36,000. Click on a parcel to view the Inland Wetland and Watercourse areas (in acres) that fall within the parcel. Use the filters in the top right header bar to query the map by Municipality or Council of Government (COG). Use the filter in the top right of the map to toggle the NWI Wetlands layer on or off.