From the site: "The Real Time Groundwater Level Network contains water levels and well information from wells with "real time" data transmission instrumentation. This network includes all of these wells, regardless of the aquifer monitored or the monitoring objective.

Real-time data typically are recorded at 15-60 minute intervals, stored onsite, and then transmitted to USGS offices every 1 to 4 hours, depending on the data relay technique used. Recording and transmission times may be more frequent during critical events. Data from real-time sites are relayed to USGS offices via satellite, telephone, and/or radio and are available for viewing within minutes of arrival.

All real-time data are provisional and subject to revision."