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Hydrographic and Impairment Statistics Database: NPS-wide Impairment GIS Coverage

Published by National Park Service | Department of the Interior | Metadata Last Checked: January 25, 2026 | Last Modified: 2017-09-01T00:00:00Z
The National Park Service (NPS) Water Resources Division (WRD) compiles the Hydrographic and Impairment Statistics (HIS) Database for all park units. One of the goals of HIS is to track surface water impairments as defined by the Clean Water Act (CWA). Waters within or adjacent to park units that were identified by states as Category 5 (CWA Section 303d) or Category 4a, 4b, or 4c (CWA Section 305b) were included in this NPS-wide impairment GIS coverage. The GIS coverage of CWA impairments within the National Park System is updated on a monthly basis. Updates to this file in IRMA are made annually. Should you require a more updated version between annual updates, please contact Jia Ling at Jia_Ling@contractor.nps.gov or Dean Tucker at Dean_Tucker@nps.gov. Alternatively, you can also view more updated information on the NPS WRD Hydrographic and Impairment Statistics Database website (https://nature.nps.gov/water/HIS/index.cfm).

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