This layer is a join of the NHD flowline features and the NY DEC Water Quality Classifications for streams. The Water Quality Classifications data set provides the water quality classifications of New York State's lakes, rivers, streams and ponds, collectively referred to as water bodies. All water bodies in the state are provided a water quality classification based on existing, or expected best usage, of each water body or water body segment. Under New York State's Environmental Conservation Law (ECL), Title 5 of Article 15, certain waters of the state are protected on the basis of their classification. Streams and small water bodies located in the course of a stream that are designated as C (T) or higher (i.e., C (TS), B, or A) are collectively referred to as "protected streams." NHDFlowline features are the lines that make up the linear surface water drainage network. They represent NHD features such as stream/rivers, canal/ditches, and pipelines, portrayed as single lines, or the artificial paths through open waters such as lake/ponds and wide stream/rivers. NHDFlowlines also represent coastlines along oceans and Great Lakes. These data are the subset of the National Hydrography Dataset (NHD) that comprise the surface water drainage system of NYS. NHD is a feature-based database that interconnects and uniquely identifies stream segments, or reaches. The NHD data structure was developed as a collaboration of the US Geological Survey (USGS) and the US Environmental Protection Agency. The NHD contains names from the USGS Geographic Names Information System, and a reach code address system for indexing related information. It also has centerlines through areal water features, with flow direction, to create a continuous, traceable network. The NHD is managed nationally by USGS, with state agencies acting as local Data Stewards. These Stewards are the designated authority on, and often perform, updates to the data. NYSDEC is the Steward for NHD data in NYS. Most NYS NHD was developed by NYSDEC. The original NYS NHD line work was based on the 1:24,000 scale USGS topographic quadrangles. Efforts to improve its spatial and attribute accuracy are ongoing. NYSDEC is currently updating much of the data to better align with the NYS Digital Orthoimagery. The NHD contains feature-level metadata. Each feature is part of a Digital Update Unit whose metadata is described in the NHDMetadata table. This metadata can also be accessed through the Identify Tool in ArcMap by expanding a feature's dropdown information (+) in the Identify Results window.