NoVA Public Water System Atlas: Groundwater Islands, the Purchased-Water Network, and 47 Years of System Consolidation (SDWIS, 1979-2026)

Every public water system ever registered with EPA SDWIS in the nine Northern Virginia jurisdictions: 621 systems, 202 active and 409 deactivated between 1979 and 2026, with source-water type, 253 active wells, owner and system class, a 40-edge purchased-water dependency network, and 769 Safe Drinking Water Act violations spanning 1977-2026. 177 of the 202 active systems draw their own groundwater but serve only 47,221 people, while 2.58 million residents depend on 25 systems that trace back to the Potomac through Fairfax Water or the Washington Aqueduct. Includes the corrected VDH-to-FIPS PWSID locality crosswalk, FGDC CSDGM metadata for every GeoPackage, full data-lineage manifest, and the verification-gate record.Produced by the Keystone GIS Northern Virginia Autonomous GIS Research Program. Full methodology, interactive map, and FGDC metadata: https://keystonegis.com/datasets/nova-water-systems-day80.html