WaterLevels.org
Data disclosures

How we use agency water data

WaterLevels.org is an independent site that republishes selected public water monitoring data from the U.S. Geological Survey, curated reservoir elevations from the U.S. Bureau of Reclamation (RISE), the U.S. Army Corps of Engineers (CWMS), and the California Data Exchange Center (CDEC), selected National Weather Service NWPS gauges without a USGS site id, plus flood categories and stage thresholds from NWPS when available. This page explains where the data comes from, what we keep, how we display it, and what it is not.

Data sources

Nearly all stream and lake observation values shown on WaterLevels.org come from the USGS Water Data APIs (OGC API–Features services operated by the USGS). Site identity, coordinates, and official station pages for those gauges are likewise USGS products.

Selected Reclamation reservoirs (for example Lake Mead at Hoover Dam) use daily lake/reservoir elevation from the Bureau of Reclamation RISE APIs. Those stations are identified separately from USGS gauges and link to the official RISE location page for provenance and datum notes.

Selected Corps reservoirs and pools (for example Raystown Lake, Hartwell Dam, and Lake Okeechobee) use lake/reservoir elevation from the U.S. Army Corps of Engineers CWMS Data API. We curate Corps-owned series and skip USGS-revision mirrors published in CWMS. USACE pages do not use NWPS flood stages.

Selected National Weather Service NWPS gauges that publish no USGS site id (for example Alpowa Creek at Mouth) appear as first-class stations with observed stage from the NWPS API. We do not promote NWPS points that already join to a USGS gauge (those stay USGS stations with NWPS flood enrichment only), and we skip lids that would duplicate reservoirs already ingested from USBR.

Selected California reservoirs that USBR and USACE do not already cover (for example Lake Oroville, Lake Shasta, and Folsom Lake) use daily lake/reservoir elevation from the California Data Exchange Center. Shasta is USBR-operated, but it is not on the USBR RISE allowlist, so CDEC is the source. CDEC pages do not use NWPS flood stages.

Flood categories (action, minor, moderate, major) and stage thresholds, when shown on the map, Flood Alerts list, and station pages, come from the National Weather Service National Water Prediction Service (NWPS) via the NWPS API. We join NWPS forecast points to USGS gauges by site number when a match exists. Not every USGS site has an NWPS forecast point, so some stations will show USGS measurements without flood-stage context. USBR and USACE reservoir pages do not use NWPS flood stages.

USGS, USBR, USACE, and NWS products are U.S. government work. WaterLevels.org is not affiliated with, endorsed by, or operated by the USGS, the Bureau of Reclamation, the U.S. Army Corps of Engineers, the National Weather Service, NOAA, the Department of the Interior, or the Department of Defense. We are a private project that consumes public APIs and presents a subset of that data for browsing and reference.

For the authoritative hydrologic record at any station, use the official USGS monitoring-location page linked from each WaterLevels.org station (typically waterdata.usgs.gov). For official flood forecasts, impacts, and watches/warnings, use water.noaa.gov and local NWS products. Official pages may include additional parameters, cooperators, remarks, and quality notes that we do not show.

What we show

We focus on continuously monitored surface-water and related sites that currently report at least one of:

  • Water level / stage — including gage height (USGS parameter code 00065) and, where available, lake or reservoir elevation relative to a vertical datum such as NGVD 1929 (62614) or NAVD 1988 (62615), or height above a local datum (00062).
  • Streamflow / discharge — USGS parameter code 00060, typically in cubic feet per second.
  • Water temperature — USGS parameter code 00010, stored in Celsius and convertible to Fahrenheit in the interface.
  • NWS flood context — observed flood category and action/minor/moderate/major stage thresholds from NWPS when a gauge is matched, used for map coloring, the alerts directory, and station flood-stage markers.

When a site reports more than one water-level style parameter, we generally prefer gage height for map and default display, and still expose the other selected series on the station page so you can compare them. We do not attempt to host the full USGS groundwater-well archive or every historical field measurement.

How the data is used

In practical terms, WaterLevels.org:

  • Discovers active sites from USGS latest-continuous feeds for the parameter codes above.
  • Stores monitoring-location metadata (name, site number, coordinates, state/county when provided) and selected time-series metadata.
  • Caches the latest observation for map popups and station “current conditions.”
  • Syncs NWPS flood categories and stage thresholds for matched gauges and surfaces them on the map, Flood Alerts list, and station pages.
  • Backfills short continuous history (and related daily/peak series where available) so station graphs and tables can render without calling USGS on every page view.
  • Serves highly cached HTML and JSON responses so the site stays fast; cached pages can lag behind the live USGS and NWPS feeds by design.

We do not sell USGS or NWS data, resell raw API access, or claim ownership of those observations. Values are shown for informational browsing. Units, parameter descriptions, approval status, and timestamps are taken from the source fields when present.

Provisional data and limitations

USGS marks many real-time values as provisional. Provisional data can be revised, corrected, or removed after USGS review. Approved values are more stable but still subject to USGS publication practices. NWPS flood categories and thresholds can also change as conditions and forecasts update.

WaterLevels.org is not a warning system and is not suitable as the sole source for flood response, navigation, engineering design, legal disputes, or other safety-critical decisions. Always confirm against official USGS and NWS products and local emergency authorities when those decisions matter.

Gaps can appear when a sensor is offline, a parameter is discontinued, our sync lags, a station falls outside the site types we keep, an NWPS match is missing, or USGS/NWPS rate limits or API errors interrupt a refresh. “Stale” labels on the site mean our latest stored observation is older than our freshness threshold (currently one week), not necessarily that USGS has stopped collecting data.

Updates and caching

Catalog, latest-observation, and flood-stage syncs run on a schedule (and can be triggered operationally). Station history is filled on demand and by batch jobs. Public pages and map station payloads are cached at the application and, in production, often at the CDN edge. That means the number or flood category you see may be minutes to hours behind the USGS or NWPS source at peak, and occasionally longer if a sync has not completed.

Attribution

Hydrologic observation data: U.S. Geological Survey. Access via the USGS Water Data APIs (api.waterdata.usgs.gov). Prefer citing the specific monitoring location and observation time when you reuse a value from this site.

Flood categories and stage thresholds: National Weather Service, National Water Prediction Service (water.noaa.gov; API api.water.noaa.gov/nwps). Prefer citing the NWPS gauge (LID) and valid time when you reuse a flood-stage value from this site.

The interactive map uses CARTO Dark Matter vector basemaps, built on OpenStreetMap data; map credit appears in the map control itself.

Questions about a value

If something looks wrong on WaterLevels.org, first check the official USGS station page for hydrologic values, or NWPS for flood category and stage thresholds. If the official source and this site disagree, treat the official source as correct and contact us with the site number and approximate time so we can investigate our sync or display logic.