GWIS (Graphing Water Information System) is a USGS-developed JavaScript library for embedding interactive time-series charts of water observations in web pages. It connects to USGS Instantaneous (Real-Time) and Daily Value services, and supports multiple data series, zooming, interactive legends, and dual y-axes.
What is the USGS GWIS JavaScript library?
The U.S. Geological Survey announced GWIS on February 8, 2017. Developed by the USGS Texas Water Science Center, it combines the open-source dygraphs charting library with USGS water services to plot observations from hydrologic data collection sites across the United States. The announcement described GWIS as a way to create time-series plots of information measured at those sites: USGS announcement.
What data can GWIS plot?
GWIS can use current or historical observations from the USGS Instantaneous (Real-Time) Service and Daily Value Service. That makes it suitable for plotting higher-frequency measurements as well as daily values, depending on the service and data available for the selected site. The library is intended to put those plots into a web page, rather than requiring a reader to view data only in a separate charting interface. See the USGS announcement for its description.
What chart interactions and features does it support?
- Zoom: Drag vertically or horizontally on the axes to zoom; double-click to restore the full range.
- Interactive legend: Hover over the axes to display values for each plotted series.
- Multiple series: Plot more than one measurement or data series in a chart.
- Double y-axes: Compare measurements that use different units on separate vertical axes.
- Optional controls: Add full-screen display and logarithmic scaling for the y-axis.
- Pop-up plots and styling: Use pop-up plots and customize chart appearance.
These capabilities are listed in the USGS feature description.
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What do the official examples show?
One USGS example plots streamflow alongside specific conductance at Jacobs Well near Wimberley, Texas. The two measurements use separate y-axes, illustrating how conductance changes as streamflow increases. Another plots daily mean streamflow with daily maximum and minimum streamflow for the Colorado River at Austin, Texas; a time slider narrows the view to a recent 180-day window. The announcement links to the GWIS homepage, where USGS points readers to examples, documentation, and source code.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How should you assess GWIS for a project?
Check whether the service types, data interval, and interactions fit your chart before choosing the library. In particular, verify that the relevant USGS service provides the observations your project needs, and decide whether your users need controls such as zoom, multi-series comparison, or a second y-axis. The official announcement establishes GWIS’s described capabilities, but it does not establish a current release number, maintenance status, or compatibility with modern JavaScript frameworks. Consult the GWIS homepage for available documentation and source code, and verify those project-specific details there before adopting it.
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