CPM Definitions

Authorized Annual Groundwater Withdrawal Right subject to CPM: The authorized annual groundwater withdrawal right subject to CPM is the total of groundwater rights assigned to your well(s) and associated place of use as defined in your initial regular permit(s). Your authorized annual groundwater withdrawal rights are available for use during CPM. However, they are also subject to percent reductions based on the Stages (I-IV) of CPM. In the San Antonio Pool, municipal, industrial and irrigation users become affected by reductions beginning at Stage I. In the Uvalde Pool, municipal, industrial and irrigation users are all subject to CPM reductions beginning at Stage II.

Percent Groundwater Withdrawal Right Reduction: The percent groundwater withdrawal right reduction is the amount of water that is to be subtracted from your total annual groundwater withdrawal rights due to CPM. The percent reduction is calculated based on the number of days CPM is in effect and the percent reduction is prorated if CPM is in effect for less than a year (365 days). If multiple stages occur through out the year, all prorated percentages for each stage will be totaled then subtracted from your Authorized Annual Groundwater Withdrawal Rights. The result from your percent groundwater withdrawal right reduction will be your adjusted authorized annual groundwater withdrawal amount.

CPM Trigger Levels by Pool

In the San Antonio Pool, Stage I begins when the J-17 index well level is below 660 feet mean sea level (msl); or San Marcos Springs flow is below 96 cubic feet per second (cfs); or Comal Springs flow is below 225 cfs. Stage I is a 20% reduction for municipal, industrial and irrigation users in the San Antonio Pool. Stage II begins when the J-17 index well is below 650 feet msl; or the San Marcos Springs flow is below 80 cubic feet per second (cfs); or Comal Springs flow is below 200 cfs. Stage II is a 30% reduction for municipal, industrial and irrigation users in the San Antonio Pool. Stage III begins when the J-17 index well is below 640 feet msl; or Comal Springs flow is below 150 cfs. Stage III is a 35% reduction for municipal, industrial and irrigation users in the San Antonio Pool. Stage IV begins when the J-17 index well is below 630 feet msl; or the Comal Springs flow is below 100 cfs. Stage IV is a 40% reduction for municipal, industrial and irrigation users in the San Antonio Pool.

Note: Implementation of Stage I is based on a 10-day average. A change to a critical period stage with higher withdrawal reduction percentages is triggered if the 10-day average of daily springflows at the Comal Springs or the San Marcos Springs or the 10-day average of the daily aquifer levels at the J-17 Index Well drops below the lowest number of any of the trigger levels. A change to a critical period stage with lower withdrawal reduction percentages is triggered only when the 10-day average of daily springflows at the Comal Springs and the San Marcos Springs and the 10-day average of daily aquifer levels at the J-17 Index Well are all above the same stage trigger level.

In the Uvalde Pool, municipal, industrial and irrigation users are not affected by CPM until Stage II when the J-27 index well is below 850 feet msl. Stage II is a 5% reduction for municipal, industrial and irrigation users in the Uvalde Pool. Stage III begins when the J-27 index well is below 845 feet msl. Stage III is a 20% reduction for municipal, industrial and irrigation users in the Uvalde Pool. Stage III begins when the J-27 index well is below 845 feet msl. Stage IV is a 35% reduction for municipal, industrial and irrigation users in the Uvalde Pool.

Note: Implementation of Stage II is based on a 10-day average. A change to a critical period stage with higher withdrawal reduction percentages is triggered if the 10-day average of the daily aquifer levels at the J-27 Index Well drops below the next lowest stage trigger level. A change to a critical period stage with lower withdrawal reduction percentages is triggered only when the 10-day average of daily aquifer levels at the J-27 Index Well are above the next highest stage trigger level.

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