HB 2017 (2017) requires DEQ, by no later than the last day of the month immediately following the month for which the calculation is completed, to calculate the volume-weighted average price of credits. The following chart represents the volume of credits traded and the average price:
If you click on the graph, the spreadsheet with the underlying data is available. DEQ is also required to post the formula for the calculation.
The volume-weighted average price is calculated as the sum of the value (credit price * number of credits traded) of all transactions, divided by the total volume of credits traded over the month.