Search criteria and codes
Site Criteria | Site Inventory Codes | Groundwater Codes | Surface Water Codes | Water Quality Codes
Definitive list of USGS parameters
Site Criteria
Site criteria let you find sites of interest. Site criteria pages exist for current conditions, site information, surface water, groundwater and water quality data. Not all criteria listed below can be used for all data categories.
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The agency that is reporting the data. Agency codes are fixed values assigned by the National Water Information System (NWIS). A list of agency codes is available. [ Tab-separated -- saved to file || HTML ]
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Altitude of the site referenced to the specified Vertical Datum.
- 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 to as unconfined (or water-table) aquifers. Where water completely fills an aquifer that is overlain by a confining bed, the aquifer is referred to as a confined (or artesian) aquifer. When a confined aquifer is penetrated by a well, the water level in the well will rise above the top of the aquifer (but not necessarily above land surface). Additional information is available.
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CAS Registry Number is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM.
- Date the well was completed.
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The name of the county or county equivalent (parish, borough, etc.) in which the site is located. A list of codes is available. [ Tab-separated -- saved to file || HTML ]
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All USGS data falls into one or more of these categories
Any Data type Matches data for any available options Current Conditions and Recent Daily Data Current condition data is any data down to the 15 minute interval that has been transmitted in the last 120 days. Recent Daily-Value Data is the average daily value for a site and it is usually for the past year and a half of recorded values. Surface Water Water flow and levels in streams, lakes and springs. Water Quality Chemical and physical data for streams, lakes, springs, and wells. Groundwater Water levels in wells.
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The area enclosed by a topographic divide from which direct surface runoff from precipitation normally drains by gravity into the stream above that point.
- The code indicating the type of site to which these data apply. The codes and their meanings are available.
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The total depth to which the hole was initially drilled, in feet below land surface datum.
- Note: Not all groundwater sites have information on Hole Depth. Such sites will not be retrieved using this search criteria.
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The contiguous United States is broken into 18 different major watersheds. Alaska, Hawaii, and Puerto Rico each have a separate watershed. Additional information is available.
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Hydrologic units are geographic areas representing part or all of a surface drainage basin or distinct hydrologic feature and are delineated on the State Hydrologic Unit Maps. Each hydrologic unit is identified by a unique number (HUC), and a name. Additional information is available.
- Note: Not all groundwater sites have been associated with a Hydrologic Unit. Such sites will not be retrieved using this search criteria.
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A previously saved file of USGS site identification numbers. This option should only appear on displays if the user is inside the USGS network.
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When looking at a map, consider a rectangle that encloses the area of interest to you. The maximum latitude and longitude define the upper-left corner, and the minimum latitude and longitude define the lower-right corner of that box. To find the approximate latitude and longitude try the USGS MapFinder. For the best results define the smallest practical latitude-longitude box that includes the area of interest; retrievals from unnecessarily large latitude-longitude boxes (1x1 degree, for example) may yield many undesired sites.
Examples Degrees-
Minutes-
SecondsDecimal
Degrees100 59 01 100.91 45 09 34 45.11
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Local aquifers in the USGS water resources data base are identified by a geohydrologic unit code (a three-digit number related to the age of the formation, followed by a 4 or 5 character abbreviation for the geologic unit or aquifer name). Additional information is available. [ Tab-separated -- saved to file || HTML ]
- Note: Not all groundwater sites have been associated with a Local Aquifer. Such sites will not be retrieved using this search criteria.
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Name of the aquifer. Also known as the geohydrologic unit. Additional information is available.
- Note: Not all groundwater sites have been associated with a Local Aquifer. Such sites will not be retrieved using this search criteria.
- Local aquifer codes and names are fixed values assigned by the National Water Information System (NWIS). A list of aquifer codes and names is available. [ Tab-separated -- saved to file || HTML ]
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A list of multiple site numbers separated by carriage returns (generated by pressing the ENTER key on your keyboard) are used to display many sites simultaneously. Each site in the USGS data base has a unique 2 to 15-digit identification number. You can search using an exact match or match using a partial number. To use an exact match you must include all of the digits including any leading zeros (0) that make up the complete site number. A site will not be found if the site number has a leading zero and it is not included in the string tested using an exact match.
- Note: The speed of the search using site numbers (and site names) is very fast using exact matches. The next fastest is matching from the beginning. Searches that match any part of the number (or name) are much slower.
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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 used as a source of potable water.
- Most of the national aquifers were published on the map sheet Principal Aquifers, part of the National Atlas of the United States of America. A few additional national aquifers were added from descriptions in the Groundwater Atlas of the United States. The aquifer names are regional names, and may not reflect local names used to refer to an aquifer. National aquifers are identified in the USGS water resources database using the codes available here.
- Note: Not all groundwater sites can be associated with a National Aquifer. Such sites will not be retrieved using this search criteria.
- A list of National aquifer codes and names is available. [ Tab-separated -- saved to file || HTML ]
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Number of records found meeting a given criteria.
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5-digit number used in the US Geological Survey computerized data system, National Water Information System (NWIS), to uniquely identify a specific constituent. List of parameter code names, and help finding a code.
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Parameters are grouped into major categories of water-quality data. Each parameter belongs to one group only. Parameter codes associated with each group.
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Period of record for the data selected. You can enter either or both of the first date or end date to restrict search. The search is done against the first and last date of record for the given type of data, not against the actual data values. Thus, if a site has one sample collected on 1910-01-01 and all following samples collected between 1980-01-01 and 1990-01-01, and the search "first date" is 1950-01-01, this site will pass the test since the period of record for the site would be from 1910-01-01 to 1990-01-01. (NOTE: checking data values explicitly, and not using a summary of the data is time consuming and is not supported currently. )
Dates can be entered in any of the following formats: FORMAT EXAMPLE YYYY-MM-DD 2000-05-12 YYYY-M-D 2000-5-12 M/D/YYYY 5/12/2000 M D YYYY 5 12 2000 YYYYMMDD 20000512 YYYY.M.D 2000.5.12
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Medium type refers to the specific environmental medium that was sampled and analyzed. Medium type differs from site type because one site type, such as surface water, could have data for several media, such as water, bottom sediment, fish tissue, and others. For a listing of the medium types look in the [Codes Help Section]
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This is the official name of the site in the database. For well information this can be a district-assigned local number. Do NOT include "river", "lake", "creek" or other hydrological term. Search for "trinity" not "trinity river", or a complete or partial local number. All name searches are NOT case sensitive.
- Note: Site name searches are the slowest way to find sites, and take 5 to 10 times longer than searches using the site number. The fastest site name search is matching from the beginning. Searches that match any part of the name are much slower.
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Each site in the USGS data base has a unique 2- to 15-digit identification number. Site numbers are assigned based on this logic. You can search using an exact match or match using a partial site number. To use an exact match you must include all of the digits including any leading zeros (0) that make up the complete site number. A site will not be found if the site number has a leading zero and it is not included in the string tested using an exact match.
- Note: The speed of the search using site numbers (and site names) is very fast using exact matches. The next fastest is matching from the beginning. Searches that match any part of the number (or name) are much slower.
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The hydrologic setting of the site. This is not equivalent to the type of data collected at the site.
A list of the codes are available. [ Tab-separated -- saved to file || HTML ]
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The name of the state or territory in which the site is located.
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The Update time option provides the ability to select sites that have been updated within the last x minutes (or other interval). The available intervals are dependent on the data being queried - Current condition inventory data intervals are minutes, while Site inventory and Streamflow measurements intervals are minutes, days, weeks, months, or years. It should be kept in mind that while most current condition sites record data onsite every 15 minutes, they only transmit those data to the web database every 1 to 4 hours.
- Water Quality method codes are associated with one or many parameter codes. The method codes and associated parameters used in NWIS are available. [ Tab-separated -- saved to file || HTML ]
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The depth of the finished well, in feet below land surface datum.
- Note: Not all groundwater sites have information on Well Depth. Such sites will not be retrieved using this search criteria.
Site Inventory Codes
These codes document attributes of sites in the system.
- Agency codes (agency_cd) - The agency that is reporting the data. Agency codes are fixed values assigned by the National Water Information System (NWIS). [ Tab-separated -- saved to file || HTML ]
- Aquifer type code (aqfr_type_cd) - Describes the type of aquifer(s) encountered by a site type of well (groundwater). [ Tab-separated -- saved to file || HTML ]
- Basin codes (basin_cd) - The Basin Code or "drainage basin code" is a two-digit code that further subdivides the 8-digit hydrologic-unit code. The drainage basin code is defined by the USGS State Office where the site is located.
- Hydrologic unit codes (huc_cd) - 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.
- Lat/Long coordinate accuracy codes (coord_acy_cd) - Indicates the accuracy of the latitude longitude values.
- Lat/Long coordinate method codes (coord_meth_cd) - Indicates the method used to determine latitude longitude values.
- Lat/Long in DMS coordinate datum code (coord_datum_cd) - Latitude/longitude (horizontal) coordinate datum.
- Local aquifer codes (aqfr) - The eight-character string identifying an aquifer. Codes are defined by the "Catalog of Aquifer Names and Geologic Unit Codes used by the Water Resources Division."
- Local standard time flag (local_time_fg) - Y for yes or an N for no to indicate whether the site is in an area that switches to Local Standard Time (Daylight Savings Time) for a part of the year.
- National aquifer codes - 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 used as a source of potable water. [ Tab-separated -- saved to file || HTML ]
- Site-Type Codes (site_tp_cd) - A list of primary and secondary site types that can be associated with data collection sites. A site type is a generalized location in the hydrologic cycle, or a man-made feature thought to affect the hydrologic conditions measured at a site. All sites are associated with a primary site type, and may additionally be associated with a secondary site type that further describes the location. The exception to this rule is the Facility primary site type, which must always be associated with a secondary site type. The site type code incorporates these hierarchial distinctions. [ Tab-separated -- saved to file || HTML ]
- State and county Codes (state_cd, county_cd) - State code. A two-digit ANSI code (formerly FIPS code) as defined by the American National Standards Institute, to define States and equivalents. A three-digit ANSI code is used to define counties and county equivalents. A lookup table is available.
- Time zone codes (tz) - Time zone offset from GMT. An ANSI SQL/92 time zone offset string. Some examples are '-05:00' (Eastern), '+02:00' (Eastern Europe), and '+03:30' (India). [ Tab-separated -- saved to file || HTML ]
- Topographic setting code (topo_cd) - Refers to the geomorphic features in the vicinity of the site.
- Type of data collected (data_types_cd) - This is a legacy field from the old WATSTORE days therefore the national consistency of the information/values stored in this field will vary. This field is actually a 30-POSITION ARRAY of characters.
Groundwater Codes
These codes document attributes unique to groundwater sites in the system.
- Daily value qualification code
- Depth and water level source codes - Source of water level measurement.
- Instantaneous value qualification code
- Instantaneous and daily value status codes
- Water level method codes (siwlmt.edi) - Code indicating how the water level was measured.
- Water level site status codes
(lev_status_cd) - A code indicating the status of the site at the time the water level was measured. If the water level measured represents a static level, this field is blank.
Surface Water Codes
These codes document attributes unique to surface water sites in the system.
- Channel evenness - The code identifying the evenness of the channel. [ Tab-separated -- saved to file || HTML ]
- Channel location code - The code describing the relative location of the channel measurement section in comparison with the gaging station. [ Tab-separated -- saved to file || HTML ]
- Channel material - The code identifying the material of the channel (sand, gravel, silt, etc.) [ Tab-separated -- saved to file || HTML ]
- Channel stability - The code identifying the stability of the channel (firm, soft, etc.) [ Tab-separated -- saved to file || HTML ]
- Daily value qualification code
- Discharge measurement quality code - The code identifying a stream discharge measurement quality qualifier.
- Flow adjustment code - Describes how the sum of the channel discharges was adjusted to get the measurement discharge. [ Tab-separated -- saved to file || HTML ]
- Horizontal velocity description - Describes the velocity distribution across the channel. [ Tab-separated -- saved to file || HTML ]
- Instantaneous value qualification code
- Instantaneous and daily value status codes
- Longitudinal velocity - Describes the flow down the channel. [ Tab-separated -- saved to file || HTML ]
- Measurement yype - Describes the method used to suspend or place the instrumentation into the water. [ Tab-separated -- saved to file || HTML ]
- Peak streamflow special conditions
- Rating control condition code - Describes the condition of the rating control at the time of the measurement.
- Stat codes - The statistic code of all the unit values for the DD (data descriptor). Most common is 00011 (instantaneous), but some recorders sample the stream on some very frequent interval and report things like the minimums, maximums, and means of all the samples taken for a longer interval. So, for example, the recorder would output a set of values every 15 minutes that are the min., max., and mean of the values taken every 30 seconds during those 15 monites. Data from recorders like those would use a statistic code such as 00001 (max), 00002 (min), or 00003 (mean) in the DD. [ Tab-separated -- saved to file || HTML ]
- Streamflow method - Describes the method used to measure the discharge. [ Tab-separated -- saved to file || HTML ]
- Velocity method - Describes the method used to measure the velocity, and is only applicable to certain streamflow methods. [ Tab-separated -- saved to file || HTML ]
- Vertical velocity description - Describes the vertical velocity distribution within the cross-section. That is, whether the vertical distribution of velocity within the cross-section is mostly uniform, standard profile, or non-standard profile. [ Tab-separated -- saved to file || HTML ]
- Use incomplete data for statistics calculation - Compute statistics for months where data for some days of that month are missing.
Water Quality Codes
These codes document attributes unique to water quality sites in the system.
- Body part codes (body_part) - A part of the body of an organism. [ Tab-separated -- saved to file || HTML ]
- Data quality indicator codes (dqi_cd) - Indicates the review status of a result, controls whether the batch-update programs can overwrite a result, and affects the inclusion of a result in retrievals. [ Tab-separated -- saved to file || HTML ]
- Fixed parameter codes (fxd) - [ Tab-separated -- saved to file || HTML ]
- Hydrologic condition codes (hyd_cond_cd) - A single alphanumeric character that identifies the height and change of the river or aquifer during a sampling. The codes and descriptions are: "A" Not determined, "4" Stable, low stage, "5" Falling stage, "6" Stable, high stage, "7" Peak stage, "8" Rising stage, and "9" Stable, normal stage. [ Tab-separated -- saved to file || HTML ]
- Hydrologic event code (hyd_event_cd) - A single alphanumeric character that identifies a weather event or other environmental event which may affect the quantity or quality of water in a river or aquifer during sampling. [ Tab-separated -- saved to file || HTML ]
- Instantaneous and daily value status codes
- Medium codes, descriptions, and definitions (medium_cd) - The 3-character alpha code that identifies the material type and quality-assurance type of the sample. The first character of the code is the "super" medium, which describes the primary matrix of the sample. The second character is the sub-medium, which characterizes the sample type as a unique entity within the "super" medium category. The third character is used to designate whether a sample is an environmental or QC sample. A blank in position three denotes an environmental sample; a "Q" in position three denotes a QC sample. [ Tab-separated -- saved to file || HTML ]
- Method codes (meth, parm_meth, cit_meth) - Water quality method codes. A method for calculating the value of a water quality parameter. [ Tab-separated -- saved to file || HTML ]
- Parameter codes
- Parameter groups - The definition of parameter groups was a collaborative effort between USGS and USEPA (Environmental Protection Agency). Some parameter groups have few or no entries stored by USGS, although these groups are used by USEPA.
- Protocol organization codes (proto_org) - Used to identify result-analyzing and sample-collecting organizations. [ Tab-separated -- saved to file || HTML ]
- Remark codes (remark_cd) qualify the result value. - [ Tab-separated -- saved to file || HTML ]
- Report level codes (rpt_lev_cd) - A string of alpha characters that identify the analytical reporting level appropriate for the analytical method. [ Tab-separated -- saved to file || HTML ]
- Sample type codes (sample_type_cd) - [ Tab-separated -- saved to file || HTML ]
- Taxonomic unit (tu) -http://www.itis.gov Legal taxon name and associated attributes for levels of taxonomic hierarchy structure from kingdom to genus. Genus, binomials/polynomials are identified.
- Time datum reliability codes (tm_datum_rlblty_cd) - Describes how well the time datum is known. For times entered prior to NWIS 4.3 (in 2003), there is no reliable means of determining the reliability, so the code is set to 'T'. For times entered after NWIS 4.3, the reliability should be known or estimated. [ Tab-separated -- saved to file || HTML ]
- Value qualifier codes (val_qual_cd) - Identifies specific exceptional or unusual characteristics of the measurement process used to determine a result. Value qualifiers provide additional information about the causes and possible direction of bias, and/or the magnitude of variability for the measurement. [ Tab-separated -- saved to file || HTML ]