GLANSIS
Watershed Lookup

The NOAA GLANSIS HUC8 Lookup tool is a lightweight, public-facing web application that surfaces watershed boundary data for the Great Lakes Basin, covering all 178 watersheds across both the US and Canadian portions of the region. Users enter an address, city, ZIP, or HUC8 code, or simply click the map to identify which watershed they live in and download a labeled, print-ready PDF map.

Built for NOAA's Great Lakes Environmental Research Laboratory and integrated into the GLANSIS (Great Lakes Aquatic Nonindigenous Species Information System) ecosystem, the tool bridges scientific datasets and the general public through a clear, accessible interface. Crucially, the coverage extends across the US–Canada border, reflecting the basin's geography rather than stopping at a political boundary.

Accessing local watershed data through GLANSIS requires a HUC8 code — an eight-digit hierarchical identifier assigned to each watershed unit. While working alongside educators on a pilot project, the GLANSIS team discovered that both teachers and students were struggling to find their code: the USGS and EPA tools that used to provide this have either disappeared or reference older versions of the data layer.

An initial attempt to address this — a layer toggle on the existing zoomable map explorer — proved insufficient. The map was difficult to navigate to the right extent, the codes were hard to read at any zoom level, and printing a usable reference map was effectively impossible. The pilot classroom was served by hand-delivering custom maps, but that wasn't a solution — it was a workaround. What GLANSIS needed was a tool any teacher in the region could use independently, without support.

Recognizing that the same friction was likely limiting the database for a much broader set of users, they approached us to build it: a simple, public-facing lookup tool that could translate an address into a watershed — and put a print-ready map in anyone's hands in seconds.

A key constraint shaped every technical decision: NOAA has limited access to commercial software licenses and limited capacity to manage infrastructure once a tool is published. The system needed to be free to run, easy to hand off, and nearly maintenance-free.

The watershed boundary data was downloaded from the USGS National Hydrography Products repository and cleaned in QGIS — stripping the dataset down to just the Great Lakes Basin polygons and the properties needed at runtime: watershed name and HUC8 code. The result is a single lightweight GeoJSON that loads entirely in the browser, keeping the system simple and server-free.

Adjacent watershed relationships are pre-computed by a custom Node.js script that ingests the GeoJSON and uses Turf.js to detect which polygons share a boundary. The output is a JSON lookup dictionary bundled alongside the geometry file. Both scripts are designed to be re-run whenever USGS publishes an updated dataset — typically once a year — so the tool stays current without any ongoing maintenance burden.

Address lookup and autocomplete are handled by the LocationIQ API, which resolves typed input to coordinates in real time. Those coordinates are passed to a Turf.js point-in-polygon query to identify the matching HUC8 unit and highlight it on the map. The map layer itself is built with Leaflet.js, rendering all 178 basin watersheds as interactive overlays.

The print flow uses the browser's native print capabilities rather than a server-side renderer — the page layout is print-styled so the output is a clean, labeled watershed map the user can save as a PDF or send directly to a printer.

The tool is currently in active development. The data pipeline, adjacency script, and address lookup are complete. UI and print flow are in progress. Expected to hand off the project to the client in April 2026.