LIST Hydrographic Area depicts all waterbody and associated polygon features in the hydrographic theme including lakes, estuaries, dams, mudflats, swamps and coastal flats. It contains attributes that allow area features to be delivered in separate layers and with attributes. The data set is held as regions which allow area features to overlap.

HYD_FLOWLINE_ARC: This dataset contains flowline features from the US Geologic Survey (USGS) High Resolution National Hydrography Dataset (NHD). NHD Flowline features are linear depictions of streams and centerlines of rivers. Additional attributes have been added from the Bureau of Land Management (BLM) hydrography event data. This dataset will be refreshed as-needed to reflect updates to the NHD and hydrography events.

The feature classes ESIL and ESIP contain vector lines and polygons representing shorelines and intertidal habitats of the St Lawrence River - 2021 ESI Geodatabase, classified by their susceptibility to oiling. The Environmental Sensitivity Index (ESI) classification system, developed by NOAA, considers several natural and biological factors including relative exposure to wave and tidal energy, shoreline slope, substrate type and biological productivity and sensitivity. The study area includes the St. Lawrence River from the headwaters of Lake Ontario, northeast to the western portion of L'Ile-Saint-Regis Island (CA). As a whole, the ESI data characterize the marine and coastal environments and wildlife by their sensitivity to spilled oil, and includes information for three main components: shoreline habitats, sensitive biological resources, and human-use resources.

This layer shows the locations of the United States Geological Survey sampling stations that are equipped with telemetry to transmit data on streamflow, temperature, and other parameters back to a data base for real-time viewing via the World Wide Web.

This streamgage boundary layers dataset consists of 512 USGS streamgage point locations and polygons delineated to show their drainage areas. The drainage areas were delineated from the streamgage points functioning as pour points, in addition to the Flow Accumulation Raster for Maine StreamStats and Flow Direction Raster for Maine StreamStats in from this data release.