EPA Impaired Waters presence and causes for HUC12 watersheds across the Conterminous U.S.

This dataset summarizes impairment status for HUC12 watersheds at the CONUS scale using the EPA publicly available Assessment, Total Maximum Daily Load (TMDL) Tracking and Implementation System (ATTAINS) geospatial package and the USGS Watershed Boundary Dataset (WBD). ATTAINS is an online system maintained by the EPA containing information about the condition of the Nation’s surface waters, as reported by individual states. These data were downloaded in October 2023 and primarily reflect 2022 stream conditions. Because of the varying data types that exist in the database, an independent methodology was developed for summarizing impairment status for HUC12 watersheds using the USGS WBD as detailed in this metadata record. These process steps ensured consistency, standardization, and transparency of various spatial attributes. HUC12 watersheds flagged as “Impaired” indicate there are impaired waters within the HUC12 watershed, but does not imply all waters within the HUC12 are listed as impaired. A supplemental table indicating the cause of impairment at the HUC12 scale, where known, is also provided.

[
  "010:12"
]

[
  "geospatial"
]