Decommissioning Legacy gwlevels and SensorThings APIs – Fall 2025

We are releasing new, modernized Water Data APIs this year and are beginning the process to decommission legacy APIs. This blog discusses the decommissioning of the "gwlevels" and “SensorThings” APIs. The gwlevels API will be decommissioned beginning November 1st, 2025. The SensorThings service will be decommissioned on December 9th, 2025.

Background

For over 15 years, the USGS has provided machine-readable and automated access to water data via the WaterServices family of application programming interfaces (APIs), which are hosted at https://waterservices.usgs.gov/ . These APIs underpin all other USGS web delivery products – including products such as the National Water Dashboard and Water Data for the Nation (WDFN) – and have been incredibly effective at delivering water data to the public. Between October 2024 and March 2025 alone, these legacy APIs have handled more than 1.6 billion requests from almost 3.5 million distinct IP addresses.

Unfortunately, maintaining these legacy APIs has become more challenging over the years. WaterServices depends upon both hardware and software components which are reaching their end of life, and it has become increasingly difficult to add features or otherwise maintain as time goes on.

As such, we are releasing new, modernized API endpoints throughout rest of 2025 which will provide the same data that you’re used to but with a new API interface and response format. We have already written about what you can expect from these new APIs , and have provided several webinars about the upcoming changes .

As part of this modernization effort, we are beginning to decommission legacy APIs, beginning with the “gwlevels” and “SensorThings” APIs.

gwlevels

The gwlevels API provided discrete field measurements of groundwater levels. Queries to this API begin with https://waterdata.usgs.gov/nwis/gwlevels/ .

Data provided by the gwlevels API will be frozen on November 1st, 2025. After this date, the endpoint will no longer publish new observations or any updates to existing observations. Documentation about the gwlevels endpoint will be replaced at this time with links to this blog post.

Beginning on February 1, 2026, the gwlevels API will be decommissioned. Instead of returning data, calls to the gwlevels API will return a 301 redirect to this blog post. After June 1st, 2026 these redirects will also be discontinued and requests to the API will return errors.

Users looking to obtain field measurements of groundwater levels via API should use the new field-measurements API on api.waterdata.usgs.gov , which provides these observations alongside field measurements of stream discharge and gage height.

Additional documentation can be found on our API documentation website . A migration guide, outlining where each field in the gwlevels response can now be found, is available in our documentation .

Users looking for browser-based downloads of groundwater levels should use the “Download Data ” form on api.waterdata.usgs.gov.

SensorThings

The SensorThings API was an experimental interface providing access to location metadata and provisional measurements from the last 10 days. After an evaluation period, we’ve decided that we won’t be promoting our SensorThings implementation to production status, and instead will be decommissioning this service. Queries to this API begin with https://labs.waterdata.usgs.gov/sta/v1.1/ .

Beginning on December 9th, 2025, all requests to the SensorThings API will return a 301 redirect to this blog post. After February 1st, 2026 these redirects will be removed and requests to this API will error.

Users looking to obtain this data should migrate to use the new latest-continuous endpoint to access the most recent sensor observations, the new monitoring-locations endpoint for monitoring location metadata, and the new time-series-metadata endpoint for time series metadata. A modernized endpoint for historical sensor data is expected to be released in the coming months. Additional documentation can be found on our API documentation website .

Stay up-to-date

These decommissions are happening as part of our broader modernization efforts, which include the modernization of a number of pages on NWISWeb. You can stay up to date with this modernization effort by subscribing to the Water Data for the Nation newsletter .

At this time, there are no announced dates for the decommissioning of other APIs (including the /iv and /dv endpoints available on WaterServices). We expect to announce these dates later in 2026, with the remaining legacy APIs decommissioned in late 2026 or early 2027.

We understand that change is hard, and some of these changes might feel sudden. We’re here to help. We have staff ready to help you make the transition should you need it. Please reach out to us at gs-w_waterdata_support@usgs.gov with any questions.