Answer:
There
may be occasional equipment or database problems where
erroneous data are reported for short periods of time
until corrections can be made. This is why it is important
to look at a record of streamflow such as the 7-day
hydrograph plots rather than a single point in time.
However, most of the time USGS has a high level of
confidence in its real-time stage data.
During
low streamflow conditions, aquatic grasses may produce
increases in stream water level near gages. On smaller
streams, debris or rocks on flow control structures may
also produce increases in water level. Stage values
reported on these pages are believed to be reasonably
accurate, but the higher stage readings may produce
estimates of discharge that are higher than actual. These
higher stage readings at stream gages may be localized and
may not be good indicators of stream stage at other
locations on the river.
During extreme cold weather, ice can affect stage and
discharge determinations at some stream-gaging stations.
Data values reported by USGS may be significantly higher
or lower than actual streamflow. Adjustment of data for
ice effects can only be done after detailed analysis.
