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EnviroAtlas - 303(d) Impairments by 12-digit HUC for the Conterminous United States

Published by U.S. EPA Office of Research & Development (ORD) - National Exposure Research Laboratory (NERL) | U.S. Environmental Protection Agency | Metadata Last Checked: January 27, 2026 | Last Modified: 2016-04-27T00:00:00.000+00:00
This EnviroAtlas dataset depicts the total length of stream or river flowlines that have impairments submitted to the EPA by states under section 303(d) of the Clean Water Act. It also contains the total lengths of streams, rivers, and canals, total waterbody area, and stream density (stream length per area) from the US Geological Survey's high-resolution National Hydrography Dataset (NHD). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

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