How TrueTopo Maps Every River in Alaska
NHD Hydrography, flowlines, and watersheds—the dataset that powers river intelligence on the map.
Rivers are the backbone of Alaska—fishing, navigation, water supply, flood risk. Mapping them accurately requires a robust hydrography dataset. We use the National Hydrography Dataset (NHD)—the USGS standard for surface water features.
The Dataset
NHD provides:
- Flowlines: Streams, rivers, canals
- Water bodies: Lakes, reservoirs, estuaries
- Watershed boundaries: HUC8, HUC12
- Connectivity: How water flows from source to sea
For Alaska, we pull from the NHD High Resolution dataset, processed and tiled for web display. Flowlines are styled by stream order (Strahler)—major rivers stand out.
How We Use It
- Fish Pack integration: River names and IDs link to USGS gauges and ADF&G count sites.
- Gazetteer: Every named stream is searchable.
- Routing: Future—snap waypoints to flowlines for river trip planning.
- Flood layers: NHD + elevation = potential inundation modeling (future).
The Pipeline
NHD data flows through our standard pipeline: source → transform → tile/vectorize → R2. We maintain Alaska-specific subsets to keep tile size manageable. Updates follow USGS release cadence.
If you're building river-focused tools for Alaska, NHD is the foundation. TrueTopo gives you a ready-to-use layer; we can also expose the raw connection strings for power users.