USGS Home Contact USGS Search USGS National Water Information System: Web Interface
USGS Water Resources		Data Category: Home Real-time Site Information Surface Water Ground Water Water Quality Mapper	Geographic Area: United States Alabama Alaska American Samoa Arizona Arkansas California Colorado Connecticut Delaware Dist. of Columbia Florida Georgia Guam Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Northern Mariana Islands Ohio Oklahoma Oregon Pennsylvania Puerto Rico Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virgin Islands Virginia Washington West Virginia Wisconsin Wyoming

NWISWeb Help System

All Data Times In MD-DE-DC Are Eastern Standard Time

Site Selection Criteria: Explanations

Agency Code

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 file || [Tab-separated --saved to compressed file || [Tab-separated --saved to file || Pre || Table].

Site number

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.

Site Name/Local Number

The official name of the site in our database. For well information this can be a district-assigned local number. Do NOT include "river", "lake", "creek" or other hydrologic 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.

File of Site numbers

A previously saved file of USGS site identification numbers, in the format:

USGS 11447650
USGS 394523084582301

The file may contain the agency code.

County

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 file || [Tab-separated --saved to compressed file || [Tab-separated --saved to file || Pre || Table].

Hydrologic Region

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.

Hydrologic Unit Code (HUC)

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 ground-water sites have been associated with a Hydrologic Unit. Such sites will not be retrieved using this search criteria.

Latitude-Longitude (Lat-Long) box

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- Seconds	Decimal Degrees
100 59 01	100.91
45 09 34	45.11

Site type

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.

Ground-water site type

The code indicating the type of site to which these data apply. The codes and their meanings are available.

Altitude

Height of the site referenced to sea level.

Drainage area

The area enclosed by a topographic divide from which direct surface runoff from precipitation normally drains by gravity into the stream above that point.

Data type

All USGS data falls into one or more of these categories

Any Data Type	Matches data for any available options
Real-time and Recent Daily-Value Data	Real-time Data is any data down to the 15 minute interval that has been transmitted in the last 31 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.
Ground Water	Water levels in wells.

Well depth

The depth of the finished well, in feet below land surface datum.

Note: Not all ground-water sites have information on Well Depth. Such sites will not be retrieved using this search criteria.

Hole Depth

The total depth to which the hole was initially drilled, in feet below land surface datum.

Note: Not all ground-water sites have information on Hole Depth. Such sites will not be retrieved using this search criteria.

Construction date

Date the well was completed

National aquifers

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 Ground-Water 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 ground-water 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 file || [Tab-separated --saved to compressed file || [Tab-separated --saved to file || Pre || Table].

Local aquifer (by code)

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

Note: Not all ground-water sites have been associated with a Local Aquifer. Such sites will not be retrieved using this search criteria.

Local aquifer (by name)

Name of the aquifer. Also known as the geohydrologic unit. Additional information is available.

Note: Not all ground-water 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 file || [Tab-separated --saved to compressed file || [Tab-separated --saved to file || Pre || Table].

Aquifer type

Ground water 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.

Number of observations

Number of records found meeting a given criteria

Period of record

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 in NwisWeb 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

Sample medium type

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]

Parameter groupings

Parameters are grouped into major categories of water-quality data. Each parameter belongs to one group only. Parameter codes associated with each group.

Parameter code/name

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.

File of Parameter Codes

A previously saved file of parameter codes, in the following format:

01130	Minor and Trace Inorganics	Lithium, water, filtered, micrograms per liter
01131	Minor and Trace Inorganics	Lithium, suspended sediment, recoverable, micrograms per liter
01132	Minor and Trace Inorganics	Lithium, water, unfiltered, recoverable, micrograms per liter

List of parameter code names, and help finding a code.

CASRN

CAS Registry NumberŪ is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM.)

USEPA SRS

http://www.epa.gov/srs/

Water Quality Method Codes

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 file || [Tab-separated --saved to compressed file || [Tab-separated --saved to file || Table].