data api · United States

USGS National Hydrography

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What's in it

Data offered docs-verified: NHD flowlines (NHDFlowline), all stream types · Strahler stream order (streams-by-order; nhdplus-hr/flowline) · Perennial stream subset (FCODE 46006) · NHDPlus HR network attributes: drainage area, slope, routing
Coverage docs-verified: Nationwide US: 50 states, DC, PR/VI and Pacific territories (base NHD-H); NHDPlus HR covers all 266 published hydrologic units, with partial Alaska coverage
Resolution docs-verified: NHD High Resolution vector flowlines (no numeric spatial accuracy stated)
Formats docs-verified: GeoParquet · PMTiles · Hive-partitioned Parquet (H3 res 8 hex)
Access docs-verified: Free, public, anonymous HTTPS/S3 access; public-domain licence (US federal work)

Useful for

Use cases llm-inferred: Flow-permanence screening of watercourses using perennial-streams (FCODE 46006) for FRA or constraint mapping · Catchment stream network and drainage-area attributes from nhdplus-hr/flowline for drainage strategy and hydrology inputs · Stream-order watercourse classification within a masked, verified HUC area (check per-HUC2 order coverage first) · Watercourse baseline for BNG or ecological habitat context in a specific catchment
Audience llm-inferred: hydrologists · flood consultants · drainage engineers · GIS analysts · ecologists

Limitations

Constraints docs-verified: streamorder is populated for only 11.1% of base NHD-H flowlines; 15 of 22 HUC2 regions are at 0.0% usable coverage · streamorder = 0 is a 'not computed' sentinel; filter streamorder > 0, and use nhdplus-hr/flowline for stream order · Source units are ingested whole and are not state extents; regional statistics must be masked to the area of interest · NHDPlus HR Alaska coverage is partial; base NHD-H remains the complete Alaska source · Base NHD-H and NHDPlus HR differ in ephemeral channel content and length, so they are not interchangeable · PMTiles drop features on dense tiles; compute quantities only from GeoParquet or hex data · Hex rows repeat per-feature lengths, so lengthkm must not be summed on hex data · No refresh cadence is stated

Licence: see product README
Authentication: Public; anonymous HTTPS/S3 access via data.source.coop
GitHub stars: Unknown
Last commit: Unknown
Last successful page check: 14/10/2026
Page health: page reachable
Package: Not recorded
Verification: Not independently verified

Provenance & evidence

Verified via Source Cooperative API /api/v1/products/cboettig (public product, updated 2026-07-25).

Metadata observed 14/10/2026 · research sweep: manual-2026-10-15 (source.coop)