The USGS Water Data OGC API — a conformant OGC API - Features implementation over the national water observation network, exposing 36 collections (monitoring locations, continuous and daily values, field and channel measurements, peaks, time-series metadata, and the full USGS reference-code vocabulary) as GeoJSON with CQL2 filtering. Verified anonymously on 2026-08-20: the landing page, /conformance and /collections each returned HTTP 200, and the first-party OpenAPI 3.0.2 (184 paths, 220 operations, "USGS Water Data APIs" v0.71.7) is served live and without a key at /openapi?f=json. The conformance declaration names 18 classes across OGC API - Common parts 1-3, OGC API - Features parts 1-4, and CQL2. This replaces an earlier catalog entry that described these OGC operations but pointed at earthquake.usgs.gov/fdsnws/event/1, where /collections soft-404s to an HTML documentation page.
USGS Water Data OGC API is one of 11 APIs that U.S. Geological Survey publishes on the APIs.io network, described by a machine-readable OpenAPI specification.
This API exposes 3 JSON Schema definitions.
Tagged areas include OGC, OGC API, OGC API Features, CQL2, and GeoJSON. The published artifact set on APIs.io includes an OpenAPI specification, API documentation, a getting-started guide, a JSON-LD context, authentication docs, and 3 JSON Schemas.
This API exposes
292 operations
across 184 paths,
organized into 37 resource areas,
and defines 77 schemas.
It is described by OpenAPI 3.0.2, at version 0.71.7.
Requests are made against a single base URL, https://api.waterdata.usgs.gov/ogcapi/v0.
292 operations184 paths77 schemas184 GET72 OPTIONS36 POST
Metadata
The identity and technical contract details declared by the specification.
USGS Water Data OGC API declares
2 security schemes
for authenticating requests.
An API key is passed in the header as api_key (ApiKeyHeader).
An API key is passed in the query as api_key (ApiKeyQuery).
ApiKeyHeader — Providing your API key gives you higher rate limits when querying our APIs. You can obtain an API key at https://api.waterdata.usgs.gov/signup
ApiKeyQuery — Providing your API key gives you higher rate limits when querying our APIs. You can obtain an API key at https://api.waterdata.usgs.gov/signup
Paths & Operations 292
Across 184 paths, the API surfaces 292 operations — 184 GET, 72 OPTIONS, 36 POST. They span 37 resource areas, including server, agency-codes, altitude-datums, aquifer-codes, aquifer-types, channel-measurements, citations, combined-metadata, and 29 more. Each is listed below with its method, path, parameters, and response codes.
server 4
The United States Geological Survey (USGS) collects water data at monitoring locations across the United States using both automated sensors and manual data collection. These APIs…
Code identifying the agency or organization used for site information, data sources, and permitting agencies. Agency codes are fixed values assigned by the National Water Informat…
The recommended vertical datum is NAVD88 (North American Vertical Datum of 1988) where applicable as stated in Office of Information Technical Memo 2002.01. NGVD29 (National Geode…
Local aquifers in USGS data are identified by an aquifer name and geohydrologic unit code (a three-digit number related to the age of the formation, followed by a 4 or 5 character…
Groundwater occurs in aquifers under two different conditions. Where water only partly fills an aquifer, the upper surface is free to rise and decline. These aquifers are referred…
Continuous data are collected via automated sensors installed at a monitoring location. They are collected at a high frequency and often at a fixed 15-minute interval. Depending o…
The name of the county or county equivalent (parish, borough, planning reagion, etc.) in which the site is located. List includes Census Bureau FIPS county codes, names and associ…
Daily data provide one data value to represent water conditions for the day. Throughout much of the history of the USGS, the primary water data available was daily data collected…
Field measurements are physically measured values collected during a visit to the monitoring location. Field measurements consist of measurements of gage height and discharge, and…
This endpoint provides metadata about field measurement collections, including when the earliest and most recent observations for a parameter occurred at a monitoring location and…
Hydrologic units are geographic areas representing part or all of a surface drainage basin or distinct hydrologic feature identified by a unique number (HUC), and a name. The Unit…
This endpoint provides the most recent observation for each time series of continuous data. Continuous data are collected via automated sensors installed at a monitoring location.…
Daily data provide one data value to represent water conditions for the day. Throughout much of the history of the USGS, the primary water data available was daily data collected…
Field measurements are physically measured values collected during a visit to the monitoring location. Field measurements consist of measurements of gage height and discharge, and…
Medium refers to the specific environmental medium from which the sample was collected. Medium type differs from site type because one site type, such as surface water, could have…
Water measurement or water-quality analytical methods. Codes and descriptions defining a method for calculating or measuring the value of a water quality or quantity parameter. Me…
Location information is basic information about the monitoring location including the name, identifier, agency responsible for data collection, and the date the location was estab…
National aquifers are the principal aquifers or aquifer systems in the United States, defined as regionally extensive aquifers or aquifer systems that have the potential to be use…
Parameter codes are 5-digit codes and associated descriptions used to identify the constituent measured and the units of measure. Some parameter code definitions include informati…
Annual peak flow values are the maximum instantaneous streamflow values recorded at a particular site for the entire water year from October 1 to September 30. Note that the annua…
The hydrologic cycle setting or a man-made feature thought to affect the hydrologic conditions measured at a site. Primary and secondary site types associated with data collection…
Daily data and continuous measurements are grouped into time series, which represent a collection of observations of a single parameter, potentially aggregated using a standard st…
Approved water data are considered published record, but on occasion changes or deletions (revisions) must be made to data after they are approved. Data revisions are rare because…
The ISO 8601 standard defines time zone offsets as a numerical value added to a local time to convert it to Coordinated Universal Time (UTC), either as +hh:mm or -hh:mm, or repres…
The code that best describes the topographic setting in which the site is located. Topographic setting refers to the geomorphic features in the vicinity of the site.
The contract defines 77 schemas that model the data the API accepts and returns. The most detailed are ChannelMeasurementsFeatureCollection (6 properties), TimeSeriesRevisionsFeatureCollection (6 properties), TimeSeriesMetadataFeatureCollection (6 properties), LatestDailyFeatureCollection (6 properties). Each schema is shown below with its type and property counts.
AgencyCodesFeature
object
4 properties2 required
AgencyCodesFeatureCollection
object
5 properties2 required
AltitudeDatumsFeature
object
4 properties2 required
AltitudeDatumsFeatureCollection
object
5 properties2 required
AquiferCodesFeature
object
4 properties2 required
AquiferCodesFeatureCollection
object
5 properties2 required
AquiferTypesFeature
object
4 properties2 required
AquiferTypesFeatureCollection
object
5 properties2 required
ChannelMeasurementsFeature
object
4 properties2 required
ChannelMeasurementsFeatureCollection
object
6 properties2 required
CitationsFeature
object
4 properties2 required
CitationsFeatureCollection
object
5 properties2 required
CombinedMetadataFeature
object
4 properties2 required
CombinedMetadataFeatureCollection
object
6 properties2 required
ContinuousFeature
object
4 properties2 required
ContinuousFeatureCollection
object
6 properties2 required
CoordinateAccuracyCodesFeature
object
4 properties2 required
CoordinateAccuracyCodesFeatureCollection
object
5 properties2 required
CoordinateDatumCodesFeature
object
4 properties2 required
CoordinateDatumCodesFeatureCollection
object
5 properties2 required
CoordinateMethodCodesFeature
object
4 properties2 required
CoordinateMethodCodesFeatureCollection
object
5 properties2 required
CountiesFeature
object
4 properties2 required
CountiesFeatureCollection
object
5 properties2 required
CountriesFeature
object
4 properties2 required
CountriesFeatureCollection
object
5 properties2 required
DailyFeature
object
4 properties2 required
DailyFeatureCollection
object
6 properties2 required
Error
object
1 property
FieldMeasurementsFeature
object
4 properties2 required
FieldMeasurementsFeatureCollection
object
6 properties2 required
FieldMeasurementsMetadataFeature
object
4 properties2 required
FieldMeasurementsMetadataFeatureCollection
object
6 properties2 required
HydrologicUnitCodesFeature
object
4 properties2 required
HydrologicUnitCodesFeatureCollection
object
5 properties2 required
LatestContinuousFeature
object
4 properties2 required
LatestContinuousFeatureCollection
object
6 properties2 required
LatestDailyFeature
object
4 properties2 required
LatestDailyFeatureCollection
object
6 properties2 required
LatestFieldMeasurementsFeature
object
4 properties2 required
LatestFieldMeasurementsFeatureCollection
object
6 properties2 required
MediumCodesFeature
object
4 properties2 required
MediumCodesFeatureCollection
object
5 properties2 required
MethodCategoriesFeature
object
4 properties2 required
MethodCategoriesFeatureCollection
object
5 properties2 required
MethodCitationsFeature
object
4 properties2 required
MethodCitationsFeatureCollection
object
5 properties2 required
MethodsFeature
object
4 properties2 required
MethodsFeatureCollection
object
5 properties2 required
MonitoringLocationsFeature
object
4 properties2 required
MonitoringLocationsFeatureCollection
object
6 properties2 required
NationalAquiferCodesFeature
object
4 properties2 required
NationalAquiferCodesFeatureCollection
object
5 properties2 required
ParameterCodesFeature
object
4 properties2 required
ParameterCodesFeatureCollection
object
5 properties2 required
PeaksFeature
object
4 properties2 required
PeaksFeatureCollection
object
6 properties2 required
ReliabilityCodesFeature
object
4 properties2 required
ReliabilityCodesFeatureCollection
object
5 properties2 required
SiteTypesFeature
object
4 properties2 required
SiteTypesFeatureCollection
object
5 properties2 required
StatesFeature
object
4 properties2 required
StatesFeatureCollection
object
5 properties2 required
StatisticCodesFeature
object
4 properties2 required
StatisticCodesFeatureCollection
object
5 properties2 required
TimeSeriesMetadataFeature
object
4 properties2 required
TimeSeriesMetadataFeatureCollection
object
6 properties2 required
TimeSeriesRevisionsFeature
object
4 properties2 required
TimeSeriesRevisionsFeatureCollection
object
6 properties2 required
TimeZoneCodesFeature
object
4 properties2 required
TimeZoneCodesFeatureCollection
object
5 properties2 required
TopographicCodesFeature
object
4 properties2 required
TopographicCodesFeatureCollection
object
5 properties2 required
queryable
object
6 properties2 required
queryables
object
1 property1 required
tilematrixsetlink
object
2 properties1 required
tiles
object
2 properties2 required
Specification
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