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USGS Water Data Collection Categories

Introduction

USGS water data is collected at monitoring locations either by automated sensors or manual data collection.

Each monitoring location has location information that details the location name and identifier, the agency responsible for data collection, and geographic information about the location. Additionally, most monitoring locations have data available online in WDFN in one or more of the following categories: continuous data, daily data, field measurements, and discrete sample data.

Location information

Location information is basic information about the monitoring location including the name, identifier, agency responsible for data collection, and the date the location was established. It also includes information about the type of location, such as stream, lake, or groundwater, and geographic information about the location, such as state, county, latitude and longitude, and hydrologic unit code (HUC).

Continuous data

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 on the specific monitoring location, the data may be transmitted automatically via telemetry and be available on WDFN within minutes of collection, while other times the delivery of data may be delayed if the monitoring location does not have the capacity to automatically transmit data. Continuous data are described by parameter name and parameter code (pcode). These data might also be referred to as "instantaneous values" or "IV"

Daily data

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 were daily data. These data were originally collected manually at the monitoring location each day, then transitioned to being recorded at the location. With improved availability of computer storage and automated transmission of data, the daily data published today are generally a summary statistic or single metric of the continuous data collected each day. Daily data are automatically calculated from the continuous data of the same parameter code and are described by parameter name and parameter code (pcode) and a statistic code. These data have also been referred to as “daily values” or “DV”.

Field measurements

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 readings of groundwater levels, and are primarily used as calibration readings for the automated sensors collecting continuous data. They are collected at a low frequency, and delivery of the data in WDFN may be delayed due to data processing time.

Discrete sample data

Discrete sample data are derived from manual field collection and laboratory analysis of physically collected samples collected during a visit to the monitoring location. These samples can be of water quality, sediment, biological tissue, air, and soil. They are collected at a low frequency, and delivery of the data in WDFN may be delayed due to laboratory processing time. Discrete sample data are described by observed property (OP).