Daily Values Service Details
You can use this service to retrieve daily statistical data about the hundreds of thousands of hydrologic sites served by the USGS. This service provides USGS water data in WaterML 1.1 (an XML schema) as well as the legacy RDB (tab-delimited) format and a JSON (Javascript-friendly) format.
How the service works
- This is a REST-friendly service, which means it is URL accessible and can be run from a browser
- The service can return daily values for one or more sites in one request
- Data for historical, as well as currently active sites are available.
With hundreds of thousands of qualifying sites across the nation, the amount of data available is very large. No one user is allowed to download all of the data with a single call. The service has consequently been engineered to facilitate common mass queries, defaulting to returning a narrower set of data. You are encouraged to make your queries efficient too, mindful that many others need access to the data at the same time. Always specify the minimum amount of data you need in your request, using built in filters and date ranges to the maximum extent possible.
Testing the service
Probably the best way to learn how to use the service is to try it out!
The USGS provides this tool that allows you to generate syntactically correct calls to the service. You can even run the query live in your browser. The XML output may look somewhat strange if you are new to XML. When you have perfected your query you can copy and paste the URL into your application to get the precise data you need.
Enabling gzip compression
Typically data is downloaded as plain text via Hypertext Transfer Protocol (HTTP). However, gzip compression
is supported by this service. Use of gzip compression may markedly speed up acquisition of data, particularly on large queries. It also is a more efficient use of USGS servers, so we appreciate when you are thoughtful enough to use it. Whether you can receive the data in gzip compressed formats depends on the capabilities of your client. Web browsers support gzip compression natively, but most regular users will use specialized utility programs like wget
and curl
to acquire data. If you can handle gzip compression, please place the following string into your HTTP request headers: Accept-Encoding: gzip, compress
curl and wget are typically used to download data. They may be configured to use gzip compression if the server will accept it. You may also explicitly have to tell it to use gzip compression. If so these tips should work:
- curl: try adding the argument:
-H 'Accept-Encoding: gzip,deflate'
- wget: try adding the argument:
--header="Accept-Encoding: gzip"
gzip files are typically returned as a file with a .gz file suffix unless you instruct your program to uncompress it. See the gzip man page for instructions on uncompressing .gz files.
Output
Please note that most recent data are marked provisional, so these data should be interpreted with caution as it is possible (although unlikely) to be incorrect. See the USGS Provisional Data Disclaimer page for more information.
When using format=waterml
(the default format), data are returned in XML
using the WaterML 1.1 schema
. WaterML
is a schema that has recently been adopted by the Open Geospatial Consortium
. The crucial data are the instantaneous values, which can be found inside the <value>
tag, which is nested inside the <timeSeries>
tag, such as in this example:
<ns1:values>
<ns1:value qualifiers="P" dateTime="2011-05-02">14.8</ns1:value>
<ns1:qualifier qualifierID="0" ns1:network="NWIS" ns1:vocabulary="uv_rmk_cd">
<ns1:qualifierCode>P</ns1:qualifierCode>
<ns1:qualifierDescription>Provisional data subject to revision.</ns1:qualifierDescription>
</ns1:qualifier>
<ns1:method methodID="0">
<ns1:methodDescription>sensor:null:7</ns1:methodDescription>
</ns1:method>
</ns1:values>
By itself this imparts no information as to what the daily value represents, other than the statistic is provisional because qualifiers=“P”. We do know the value is 14.8 and it represents a daily value for May 2, 2011. We also need to know what was measured. The key to figuring this out is to examine the outer <timeSeries>
tag, which contains some important information, shown below in bold:
<ns1:timeSeries name="USGS:01646500:00010:00002">
...
</ns1:timeSeries>
The name attribute contains a sequence of useful information with key fields delimited by colons. The pattern is <agencyCd>:<siteNo>:<parameterCd>:<statisticsCd>
.
So this node contains data about site number 01646500 (Little Falls Pumping Station on the Potomac River) monitored by the USGS. Specifically it has a calculated daily statistic for USGS parameter 00010, which is water temperature in degrees Celsius. How do we know this? It is made clear inside the <variable>
node within the <timeSeries>
node.
<ns1:variable ns1:oid="45807042">
<ns1:variableCode network="NWIS" vocabulary="NWIS:UnitValues" default="true" variableID="45807042">00010</ns1:variableCode>
<ns1:variableName>Temperature, water, °C</ns1:variableName>
<ns1:variableDescription>Temperature, water, degrees Celsius</ns1:variableDescription>
<ns1:valueType>Derived Value</ns1:valueType>
<ns1:unit>
<ns1:unitAbbreviation>deg C</ns1:unitAbbreviation>
</ns1:unit>
<ns1:options>
<ns1:option name="Statistic" optionCode="00002">Minimum</ns1:option>
</ns1:options><ns1:noDataValue>-999999.0</ns1:noDataValue>
</ns1:variable>
Since a daily value is a computation of many regular timeseries measurements, the next question is what statistic is being measured? A mean temperature? Maximum temperature? Minimum temperature? The statistics code is 00002, which the <options>
tag nested inside the <variable>
tag tells us is minimum (see above).
Putting it altogether, this means that for this site, the provisional minimum water temperature on May 2, 2011 was 14.8 degrees Celsius, or about 59 degrees Fahrenheit.
With other output formats, the location of the data will depend on the syntax of the format. You will need to inspect the format to locate the relevant data.
Error codes
Since this system uses Hypertext Transfer Protocol (HTTP), any application errors are reported in the HTTP headers. This means that when writing applications, it is important to first examine the HTTP status code that is returned in the HTTP response. The application server will return the error code along with a message describing the error in the event there is a problem. Programmers should always check the HTTP response code and if not a 200 handle the response as an exception. Among the status codes you may see:
HTTP Error Code | HTTP Error Code Description | Explanation |
---|---|---|
200 | OK | The request was successfully executed and some data should have been returned. |
304 | Not_Modified | This indicates your request was redirected using the proper URL. This may occur if the "path" of your URL is not fully qualified. Ideally a / is placed before the ? in the URL. Adding in this slash may make this go away. However, the request should still be processed. If this becomes annoying, you may also be able to tell your client program to automatically follow redirects. |
400 | Bad_Request | This often occurs if the URL arguments are inconsistent. An accompanying error should describe why the request was bad. Reasons include:
|
403 | Access_Forbidden | This should only occur if for some reason the USGS has blocked your Internet Protocol (IP) address from using the service. This can happen if we believe that your use of the service is so excessive that it is seriously impacting others using the service. To get unblocked, send us the URL you are using along with your client's IP using this form. We may require changes to your query and frequency of use in order to give you access to the service again. |
404 | Not_Found | Returned if and only if the query expresses a combination of elements where data do not exist. For multi-site queries, if any data are found, it is returned for those site/parameters/date ranges where there are data. Conditions that would return a 404 Not Found include:
|
500 | Internal_Server_Error | If you see this, it means there is a problem with the web service itself. It usually means the application server is down unexpectedly. This could be caused by a host of conditions but changing your query will not solve this problem. The application support team has to fix it. Most of these errors are quickly detected and the support team is notified if they occur. |
503 | Service_Unavailable | The server is currently unable to handle the request due to a temporary overloading or maintenance of the server. The implication is that this is a temporary condition which will be alleviated after some delay. |
Using the Web Service with Adobe Flex or the Flex API
Adobe Flex requires our server have a crossdomain.xml file indicating those domains that can access our web service using Adobe Flex. We are adding these on a case by case basis. If you need to access the service using Adobe Flex or the Flex API, please contact us using this form and indicate the domain of the server that will access the service.
CORS Support
This service supports the Cross-Origin Resource Sharing (CORS) specification. CORS permits browser-based asynchronous access to the service even though content originates from a server different than the one serving the web page. Otherwise the browser’s security controls would not allow content to come from USGS servers. Most, but not all browsers, support CORS. Some frameworks, like jQuery through the Ajax crossDomain setting, support CORS automatically.
URL Format
The URL must always be in this format:
https://waterservices.usgs.gov/nwis/dv/?<arguments>
where <arguments>
are one or more HTTP GET parameter names and values based on the information below.
Specifying the URL Arguments
You specify the arguments that go in <arguments>
.
- Each URL argument name is followed by an equal sign followed by one or more values for that argument. Where multiple values are allowed for the same argument, you can separate values with commas.
- URL arguments are separated by ampersands (&)
- The order of the URL arguments does not matter
- If a URL argument name does not match one of the names below, a HTTP 400 error code is returned
Here is an example of a valid URL that should return data:
URL argument names and argument values can be in upper, lower or mixed case. They will all be handled correctly. All of the following will yield the same result:
- https://waterservices.usgs.gov/nwis/dv/?stateCd=ny
- https://waterservices.usgs.gov/nwis/dv/?statecd=ny
- https://waterservices.usgs.gov/nwis/dv/?STATECD=ny
- https://waterservices.usgs.gov/nwis/dv/?stateCd=NY
- https://waterservices.usgs.gov/nwis/dv/?STATECD=NY
- https://waterservices.usgs.gov/nwis/dv/?stateCd=Ny
URL argument conventions
The following conventions are used below to document URL argument values:
arg1=[ a {,x | ,y} | b | c,d,...]
- square brackets
[]
are used to show a set of possible choices, with the pipe symbol|
delineating exclusive choices. You must select one and only one of these choices. - curved brackets
{}
are used to show optional elements. They also may be delineated with|
indicating exclusive choices. If used, you may select one and only one of these choices. ...
indicates more than item may be specified if items are delineated by commas. Note the limitation on the maximum number of argument values allowed below.
In the above example, these would be the allowed legal values:
arg1=a
arg1=a,x
arg1=a,y
arg1=b
arg1=c
arg1=c,d,e,f
arg1=e,f
Major Filters
Single Site Queries
Want to only query one site? Use site (or sites) as your major filter, and put only one site number in the list! Example:
Multiple Site Queries
- Every multiple site query requires a major filter. Pick the major filter (sites, stateCd, huc, bBox or counties) that best retrieves the data for the sites that you are interested in.
- Further refine the query with minor filters, if needed.
Major Filter (select one of the following) | Meaning | Minimum Number of Argument Values | Maximum Number of Argument Values | Examples |
---|---|---|---|---|
sites(aliases: site, location) | A list of site numbers. You can specify unlimited sites, up to any limit imposed by the application server or your client. Sites are comma separated. Sites may be prefixed with an optional agency code followed by a colon. If you don't know the site numbers you need, you can find relevant sites with the NWIS Mapper or on the USGS Water Data for the Nation site. | 1 | Unlimited (see caveat) | &site=01646500 &sites=USGS:01646500 &sites=01646500,06306300 |
stateCd (alias: stateCds) | U.S. postal service (2-digit) state code. USPS List of State Codes. | 1 | 1 | &stateCd=NY |
huc (alias: hucs) | A list of hydrologic unit codes (HUC) or aggregated watersheds. Only 1 major HUC can be specified per request. A major HUC has two digits. Minor HUCs must be eight digits in length. Not all sites are associated with a HUC. List of HUCs. | 1 | 1 Major, 10 Minor | &huc=01,02070010 |
bBox | A contiguous range of decimal latitude and longitude, starting with the west longitude, then the south latitude, then the east longitude, and then the north latitude with each value separated by a comma. The product of the range of latitude and longitude cannot exceed 25 degrees. Whole or decimal degrees must be specified, up to six digits of precision. Minutes and seconds are not allowed. Remember: western longitude (which includes almost all of the United States) is specified in negative degrees. Caution: many sites outside the continental US do not have latitude and longitude referenced to NAD83 and therefore can not be found using these arguments. Certain sites are not associated with latitude and longitude due to homeland security concerns and cannot be found using this filter. | 1 | 1 | &bBox=-83,36.5,-81,38.5 |
countyCd (alias: countyCds) | A list of county numbers, in a 5 digit numeric format. The first two digits of a county's code are the FIPS State Code. List of county codes. Some updates were made to the FIPS code standards in 2021. NIST has provided replacement standards. | 1 | 20 | &countyCd=51059,51061 |
Specifying Date Ranges
Many sites have periods of record that can be measured in decades, sometimes fifty years or more. Some sites have been measuring common parameters like streamflow continuously, others are seasonal in nature, and others have had periods when no funding was available to maintain the site so no data are available. Since daily values are by definition daily calculations, it makes no sense to request time periods in less than day increments. Please follow these rules for expressing dates with this service:
I want to... | Do this... | Syntax Rules | Examples |
---|---|---|---|
Get the latest daily values only | Nothing. Only the latest value is returned by default for each requested site, parameter and statistic. |
| &stateCd=ny¶meterCd=00060 // Get the latest discharge daily values for all sites in New York state |
Get a range of daily values from now | Specify the period argument |
| &period=P7D // Retrieve last seven days up from now to most recent instantaneous value) |
Get a range of daily values from an explicit begin or end date | Use the startDT and endDT arguments |
| &startDT=2010-11-22&endDT=2010-11-22 // One day of daily values only |
Format (format)
URL Argument Name | format |
---|---|
Description | Used to specify the output format of the data returned.
|
Syntax | format=[waterml{,1.1} | waterml,2.0 | rdb{,1.0} | json{,1.1}] |
Default | waterml |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
indent
URL Argument Name | indent |
---|---|
Description | Used to specify whether block structured data formats (&format=waterml|json only) should include indentation for easy viewing. Four space characters are inserted for every level of indentation. Otherwise the parameter is ignored. |
Syntax | indent=[on|off] |
Default | off |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Minor Filters
Additional filters can be applied after specifying a major filter. This further reduces the set of expected results. Users are encouraged to use minor filters because it allows more efficient use of this service.
Parameter Code (parameterCd)
URL Argument Name | parameterCd (aliases: variable, parameterCds, variables, var, vars, parmCd) |
---|---|
Description |
|
Syntax | parameterCd|variable={parameterCd1,parameterCd2,...} |
Default | returns all regular time-series parameters for the requested sites |
Minimum argument values required | 1 |
Maximum argument values allowed | 100 |
Examples |
|
Statistics Code (statCd)
URL Argument Name | statCd (alias: statisticCd) |
---|---|
Description |
|
Syntax | statCd=[ all | { statCd1,statCd2,... } ] |
Default | all - all statistics codes served for the sites and parameters requested |
Minimum argument values required | 1 |
Maximum argument values allowed | 20 |
Examples |
|
Site Status (siteStatus)
URL Argument Name | siteStatus |
---|---|
Description |
|
Syntax | siteStatus=[ all | active | inactive ] |
Default | all - sites of any activity status are returned |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Site Type (siteType)
URL Argument Name | siteType (aliases: siteTypes, siteTypeCd, siteTypeCds) |
---|---|
Description |
|
Syntax | siteType={siteType1,siteType2,...} |
Default | All site types are returned |
Minimum argument values required | 1 |
Maximum argument values allowed | No limit |
Examples |
|
Site was modified since (modifiedSince)
URL Argument Name | modifiedSince |
---|---|
Description |
|
Syntax | modifiedSince=ISO-8601-duration |
Default | None |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Agency Code (agencyCd)
URL Argument Name | agencyCd |
---|---|
Description |
|
Syntax | agencyCd=agencyCd1 |
Default | All sites regardless of agency code are retrieved |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Altitude (altMin and altMax)
URL Argument Name |
|
---|---|
Description |
|
Syntax |
|
Default | All sites are retrieved, regardless of their altitude |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Surface water filters
Drainage Area (drainAreaMin and drainAreaMax)
URL Argument Names |
|
---|---|
Description |
|
Syntax |
|
Default | All sites are retrieved, regardless of their drainage area |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Groundwater Filters
Aquifer Code (aquiferCd)
URL Argument Names |
|
---|---|
Description |
|
Syntax |
|
Default | all |
Minimum argument values required | 0 |
Maximum argument values allowed | 1000 |
Examples |
|
Local Aquifer Code (localAquiferCd)
URL Argument Names |
|
---|---|
Description |
|
Syntax |
|
Default | all |
Minimum argument values required | 0 |
Maximum argument values allowed | 1000 |
Examples |
|
Well Depth (wellDepthMin and wellDepthMax)
URL Argument Names |
|
---|---|
Description |
|
Syntax |
|
Default | All sites are retrieved, regardless of their well depth |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Hole Depth (holeDepthMin and holeDepthMax)
URL Argument Names |
|
---|---|
Description |
|
Syntax |
|
Default | All sites are retrieved, regardless of their hole depth |
Minimum argument values required | 1 |
Maximum argument values allowed | 1 |
Examples |
|
Feedback
Please provide any feedback you have on this service using this form .