# properties.id.description
A unique identifier representing a single time series. This corresponds to the "time_series_id" field in other endpoints.

# properties.unit_of_measure.description
A human-readable description of the units of measurement associated with an observation.

# properties.parameter_code.description
Parameter codes are 5-digit codes used to identify the constituent measured and the units of measure. A complete list of parameter codes and associated groupings can be found at [https://api.waterdata.usgs.gov/ogcapi/v0/collections/parameter-codes/items](https://api.waterdata.usgs.gov/ogcapi/v0/collections/parameter-codes/items).

# properties.statistic_id.description
A code corresponding to the statistic an observation represents. Example codes include 00001 (max), 00002 (min), and 00003 (mean). A complete list of codes and their descriptions can be found at [https://api.waterdata.usgs.gov/ogcapi/v0/collections/statistic-codes/items](https://api.waterdata.usgs.gov/ogcapi/v0/collections/statistic-codes/items).

# properties.hydrologic_unit_code.description
The United States is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, sub-regions, accounting units, and cataloging units. The hydrologic units are arranged within each other, from the smallest (cataloging units) to the largest (regions). Each hydrologic unit is identified by a unique hydrologic unit code (HUC) consisting of two to eight digits based on the four levels of classification in the hydrologic unit system.

# properties.state_name.description
The name of the state or state equivalent in which the monitoring location is located.

# properties.last_modified.description
The last time a record was refreshed in our database. This may happen due to regular operational processes and does not necessarily indicate anything about the measurement has changed.
You can query this field using date-times or intervals, adhering to RFC 3339, or using ISO 8601 duration objects. Intervals may be bounded or half-bounded (double-dots at start or end).
Examples:

  - A date-time: "2018-02-12T23:20:50Z"
  - A bounded interval: "2018-02-12T00:00:00Z/2018-03-18T12:31:12Z"
  - Half-bounded intervals: "2018-02-12T00:00:00Z/.." or "../2018-03-18T12:31:12Z"
  - Duration objects: "P1M" for data from the past month or "PT36H" for the last 36 hours

Only features that have a `last_modified` that intersects the value of datetime are selected.

# properties.begin.title
Time series first observation timestamp - local time

# properties.begin.description
This field contains the same information as "begin_utc", but in the local time of the monitoring location. It is retained for backwards compatibility, but will be removed in V1 of these APIs.

# properties.end.title
Time series most recent observation timestamp - local time

# properties.end.description
This field contains the same information as "end_utc", but in the local time of the monitoring location. It is retained for backwards compatibility, but will be removed in V1 of these APIs.

# properties.begin_utc.title
Time series first observation timestamp - UTC

# properties.begin_utc.description
The datetime of the earliest observation in the time series. Together with `end_utc`, this field represents the period of record of a time series. Note that some time series may have large gaps in their collection record.
You can query this field using date-times or intervals, adhering to RFC 3339, or using ISO 8601 duration objects. Intervals may be bounded or half-bounded (double-dots at start or end).
Examples:

  - A date-time: "2018-02-12T23:20:50Z"
  - A bounded interval: "2018-02-12T00:00:00Z/2018-03-18T12:31:12Z"
  - Half-bounded intervals: "2018-02-12T00:00:00Z/.." or "../2018-03-18T12:31:12Z"
  - Duration objects: "P1M" for data from the past month or "PT36H" for the last 36 hours

Only features that have a `begin_utc` that intersects the value of datetime are selected.

# properties.end_utc.title
Time series most recent observation timestamp - UTC

# properties.end_utc.description
The datetime of the most recent observation in the time series. Data returned by this endpoint updates at most once per day, and potentially less frequently than that, and as such there may be more recent observations within a time series than the time series `end_utc` value reflects. Together with `begin_utc`, this field represents the period of record of a time series. It is additionally used to determine whether a time series is "active".
You can query this field using date-times or intervals, adhering to RFC 3339, or using ISO 8601 duration objects. Intervals may be bounded or half-bounded (double-dots at start or end).
Examples:

  - A date-time: "2018-02-12T23:20:50Z"
  - A bounded interval: "2018-02-12T00:00:00Z/2018-03-18T12:31:12Z"
  - Half-bounded intervals: "2018-02-12T00:00:00Z/.." or "../2018-03-18T12:31:12Z"
  - Duration objects: "P1M" for data from the past month or "PT36H" for the last 36 hours

Only features that have a `end_utc` that intersects the value of datetime are selected.

# properties.computation_period_identifier.description
Indicates the period of data used for any statistical computations.

# properties.computation_identifier.description
Indicates the computation performed to calculate this time series. Values of "Instantaneous" reflect point measurements.

# properties.thresholds.description
Thresholds represent known numeric limits for a time series, for example the historic maximum value for a parameter or a level below which a sensor is non-operative. These thresholds are sometimes used to automatically determine if an observation is erroneous due to sensor error, and therefore shouldn't be included in the time series.

# properties.sublocation_identifier.description
An optional human-readable identifier used to specify where measurements are recorded at a monitoring location.

# properties.primary.description
A flag identifying if the time series is a "primary" time series. "Primary" time series (which have this flag) are standard observations which undergo [Bureau review and approval processes](https://www.usgs.gov/survey-manual/5028-fundamental-science-practices-review-and-approval-scientific-data-release). Non-primary time series, which will have missing values for "primary", are provisional datasets made available to meet the need for timely best science and to assist with daily operations which need real-time information. Non-primary time series data are only retained by this system for 120 days. See the [USGS Provisional Data Statement](https://waterdata.usgs.gov/provisional-data-statement/) for more information.

# properties.monitoring_location_id.description
A unique identifier representing a single monitoring location. This corresponds to the `id` field in the `monitoring-locations` endpoint. Monitoring location IDs are created by combining the agency code of the agency responsible for the monitoring location (e.g. USGS) with the ID number of the monitoring location (e.g. 02238500), separated by a hyphen (e.g. USGS-02238500).

# properties.web_description.description
An optional description of the time series. WDFN and other USGS data dissemination products use this field, in combination with sublocation_identifier, to distinguish the differences between multiple time series for the same parameter code, statistic code, and monitoring location.

# properties.parameter_description.description
A description of what the parameter code represents, as used by WDFN and other USGS data dissemination products.

# properties.parent_time_series_id.description
The unique identifier representing the parent or "upchain" time series that a daily values time series is generated from. Daily values time series have one and only one parent time series.