USGS Water Monitoring
USGS water monitoring provides real-time and historical stream gauge data — water levels, flow rates, flood stages, groundwater levels across 1.5M+ monitoring sites. Data includes instantaneous values, daily values, and site metadata. Parameter codes: 00060=discharge, 00065=gauge height, 72019=groundwater level.
Data Model
- Instantaneous values — real-time readings updated every 15 minutes from active gauges. Includes discharge (cfs), gauge height (ft), water temperature, dissolved oxygen.
- Daily values — approved daily statistics (mean, min, max) for streamflow, gauge height, and other parameters over calendar date ranges. Unlike instantaneous values (15-min intervals), daily values are quality-assured and suitable for historical analysis.
- Sites — monitoring stations identified by USGS site number (8-15 digits). Metadata includes lat/lon, county, state, HUC watershed, drainage area, datum.
- Parameter codes — standardized codes for measured quantities: 00060 (discharge/streamflow in cfs), 00065 (gauge height in ft), 00010 (water temperature), 72019 (groundwater level).
- Statistics — daily, monthly, annual statistics including mean, min, max, percentiles.
Gotchas
- Legacy WaterServices API: Uses the established NWIS WaterServices REST API, not the newer OGC API.
- Format parameter: Must specify format=json to get JSON responses; default is WaterML.
- State codes: Use two-letter state abbreviations (e.g. WA, CA, NY).
- Site status: Use siteStatus=active to filter for currently operating gauges only.
- Rate limits: No authentication required but excessive requests may be throttled.
Typical workflow
- List active monitoring stations for a state (and optional site type) to obtain site numbers.
- Fetch instantaneous (15-minute) readings for a site and parameter code, or daily approved statistics for historical analysis.
