Example Calculation:

Your reductions are calculated based on the number of days a CPM is in effect divided by the number of days in the year (365 days) multiplied by the reduction coefficient of each stage. For example, if the Authority declares Stage I (CPM) for 45 days and also declares Stage II for 35 days in the San Antonio Pool, the Stage I and II reduction for the year would be calculated as follows:

CPM Percent Reduction = (Stage I reduction coefficient x (number of days in Stage I/365 days)) + (Stage II reduction coefficient x (number of days in Stage II/365 days))

CPM Percent Reduction = (20% x (45/365)) + (30% x (35/365)) = 2.5% (Stage I prorated reduction) + 2.9% (Stage II prorated reduction) = 5.4% reduction from your total authorized annual groundwater withdrawal amount. Your total annual groundwater withdrawal reduction requirement due to CPM is 5.4%.

If you were a permit holder with 100 acre-ft. of authorized annual groundwater withdrawal rights, your adjusted authorized annual groundwater withdrawal amount will be calculated as follows.

Adjusted authorized groundwater withdrawal amount = 100 acre-ft. x (1 – 5.4%)

Adjusted authorized groundwater withdrawal amount = 94.6 acre-ft.

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