One way we look at the issue ...

One way we look at the issue of below normal or above normal streamflow is to prepare a cumulative departure hydrograph in the SW USA.  First determine the long-term mean.  Subtract this from each years flow and then accumulate the difference.  The result is a graph the ascends then descends.  This will show periods od draught and fluvial periods.  It will also indicate what period would be appropriate for determining the mean.  This is important since the wrong period will mislead, and this has happened with the Colorado River.

Gary L. Guymon