Real-time sites - Data from automated equipment and represent the most current hydrologic conditions. Measurements are commonly recorded at 5-60 minute intervals and transmitted to the NWIS database every 1-4 hours. Values in pop-up bubbles are updated hourly from NWIS. Additional data for real-time sites.
Daily-value sites - Data are summarized from time-series data for each day for the period of record and may represent the daily mean, median, maximum, minimum, and/or other derived value. Daily values include approved, quality-assured data that may be published, and more recent provisional data, whose accuracy has not been verified. Example.
Field measured streamflow and lake sites - Periodic manual measurements of streamflow and gage height at streamflow and lake sites. These measurements are often used to supplement and (or) verify the accuracy of the time-series measurements. The last value available is shown in the pop-up bubble for each site. Additional data for surface-water sites.
Data are provisional and subject to revision.