**GFWA** returns the flow weighted average in the date range specified by the Offset and Grouping for a concentration variable and flow variable.
__SYNTAX:__

**GFWA(ConcentrationVarNum,GroupOffset/StartDate,Grouping/EndDate, FlowVarNum) **

**ConcentrationVarNum:** The variable number to get the average for.

**GroupOffset/StartDate:** Used with the Grouping parameter to set the dates to calculate the stat for. Sets the number of Groups (set by the Grouping Parameter) to be added to set the dates. See examples below. If this field is a date string (i.e. "07/16/2004") or refers to a cell with a date in it, it is assumed to be the start date to calculate the stat for.

**Grouping/EndDate:** Used to set which dates to calculate the stat for. If the Grouping is a date literal string (i.e. "07/16/2004") or refers to a cell with a date in it, it is assumed to be the end date to calculate the stat for. Common Groupings are:

"D" Days

“M” Monthly

"R" Report Dates

Click here for available Grouping options

FlowVarNum: The variable number of the flow variable

__NOTES: __

Flow Weighted Average = SUM of (Flow * Conc) / SUM of the Flows.

The Flow and Concentration variables must be of the same frequency (e.g. daily, hourly). Only days (slots) that have both values are used in the calculation.

__EXAMPLES:__