Groundwater Advisory Unit


Effective March 16, 2015, the Form GW-1, Groundwater Protection Determination Request Form, can now be completed and submitted online. The online payment process has been moved within the filing system and will process payment through, the official website of the State of Texas. For additional information, see Groundwater Advisory Unit Form GW-1 Payments.

The Groundwater Advisory Unit (GAU) provides three types of letters of groundwater determination 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 Survey

  • This type of groundwater protection determination letter provides a range of depths for the base of usable-quality groundwater across the seismic survey.


  1. Expedited processing is available for the Form GW-1. A surcharge of 150% is required for the $75 Groundwater Advisory Unit Expedite Fee, which is a total cost of $187.50 in accordance with Statewide Rule 78 (16 Texas Administrative Code §3.78).
  2. Expedited processing is not available for Saltwater Disposal or Seismic Survey determination letter requests.
  3. A scaled map showing the well location and surrounding survey lines can be created and printed using the Railroad Commission of Texas' Public GIS Viewer. This viewer will allow you to locate and retrieve details for an existing well and determine the coordinates for a proposed well.


Last Updated: 7/20/2015 10:42:35 PM