Groundwater Advisory Unit
The Groundwater Advisory Unit (GAU) provides groundwater protection determination letters. There are three types of letters:
Groundwater Protection Determination
- This type of groundwater protection determination letter, where possible, provides top and bottom of fresh water (less than 1,000 mg/L total dissolved solids (TDS)) and
- Base of usable-quality groundwater (3,000 mg/L TDS and other waters known to be used or identified as sources of desalinization water).
- This type of groundwater protection determination is used for new drills, cathodic protection, re-entry, well integrity test, microseismic boreholes, injection into a producing zone, plug and abandon, and conversion of an oil and gas well to a water well.
Groundwater Protection Determination for Saltwater Disposal Wells
- This type of groundwater protection determination letter provides the base of the underground source of drinking water (less than 10,000 mg/L TDS) and
- Verifies geologic isolation from the base of usable-quality groundwater.
Groundwater Protection Determination for Seismic SurveyThis type of groundwater protection determination letter provides a range of depths for the base of usable-quality groundwater across the seismic survey.