This case study illustrates advanced data provision using WaterML 2.0 and other methods by the USGS, providing a freely available instantaneous values service providing access to streamflow and other real-time data from thousands of US monitoring stations, as well as a daily values service and groundwater levels service over the Internet. In March 2014, support for provision of time series data in the WaterML 2.0 format was added to these services.
This data is used for water resource management, monitoring floods and droughts, bridge design and for many recreational activities. Through its National Water Information Service (NWIS - USGS Water Data for the Nation. http://waterdata.usgs.gov/nwis), USGS provides summary reports, maps, statistics and other information via the Internet as well as the data services designed for machine-to-machine access via automated tools. These 24/7/365 operational services provide access to streamflow, water level and other data from over 50,000 surface water and 800,000 groundwater monitoring stations across the USA.  More than 15,000 of the monitoring stations report in near real-time. 
As automated approaches to data access become more common, use of USGS water data services is increasing at a faster rate than more conventional web page access through as shown in the figure.
Data provision by USGS represents the current state of the art in real-time access to discharge and water level data encoded in WaterML 2.0. Using the USGS service, it is easy to create a persistent URL (web address) that provides a link to the latest discharge data for any site.