Exactly how dry (or wet) has it been lately? To help answer that question, duration hydrographs have been added as a new option under the drought watch pick list on the USGS WaterWatch Web page for Ohio. You can input a stream name or gaging station number and also select a 7-, 14-, or 28-day averaging  period. An example for a streamflow gaging station (the Scioto River at Prospect, Ohio) is shown here. The plot shows a trace of the running 7-day average streamflow (the black line beginning on January 1 of the previous calendar year) as well as colored bands that represent historical percentile ranges of streamflow for each calendar day.

In the example, the 7-day average streamflow for August 29, 2008 (the point where the black line ends on the right), can be seen to fall in the low end of the range of “normal” streamflows (where normal is defined as a value that is greater than or equal to 25 percent of the historically observed values and less than or equal to a value that is greater than or equal to 75 percent of the historically observed value, both for that calendar day over the station’s period of record). In contrast, streamflow was “much above normal” (defined as a value that is greater than or equal to 90 percent of observed values for that calendar day) around the second week of February 2008.