Find NHDPlus Stream Gages
hydro_find_gagesFind NHDPlus stream gages intersecting a watershed, bounding box, or river reach. Returns gage details and drainage area for USGS hydrology analysis.
Instructions
Find NHDPlus stream gages intersecting a geometry (NHDPlusGage, layer 0).
Each gage links to NWIS via sourceid + sourceagency and reports the monitored drainage area (dasqmi, in SQUARE MILES) and reach location.
Use when: "What stream gages are in this watershed / bounding box?", "Which gage monitors this river reach?"
Because gages are point features, supply a Polygon or BoundingBox to find gages within an area (a bare point rarely coincides exactly with a gage).
Returns: { "finding": str, "count": int, "truncated": bool, "features": [...], # station_nm, sourceid, sourceagency, dasqmi (SQ MILES), ... "provenance": {...}, "query_geometry": {"type": str, "crs_epsg": int} }
NOTE: dasqmi is drainage area in SQUARE MILES (not sq km).
Error responses:
"Error: supply either lat+lon or geometry, not both (or neither)"
"Error: unsupported geometry type ..."
"Error: NHDPlus HR request failed: ..."
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| lat | No | Latitude in decimal degrees (WGS84). Use with 'lon'. Omit when supplying 'geometry'. | |
| lon | No | Longitude in decimal degrees (WGS84). Use with 'lat'. Omit when supplying 'geometry'. | |
| geometry | No | GeoJSON geometry object as a JSON string. Supported types: Point, MultiPoint, LineString, MultiLineString, Polygon, MultiPolygon, or BoundingBox shorthand {"type": "BoundingBox", "bbox": [minLon, minLat, maxLon, maxLat]}. All coordinates must be WGS84 decimal degrees. Supply either this OR lat+lon, not both. Gages are points, so use a Polygon or BoundingBox to capture nearby gages. |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||