Geologic Advisory Unit

The primary purpose of the Geologic Advisory Unit (GAU) is to conduct geologic and hydrogeologic analysis, issue GW-2 determination letters also known as “Water Board letters” or “surface casing letters”, which contain descriptions of protected water zones, and determinations of confinement called “Confinement Statements”.  For Class II, V, and VI Injection activities GAU also issues an “Endangerment” letter which are statements of the suitability of a zone for injection and are required for most Class II, Class V, and Class VI injection activities.  The most common endangerment statements are “Will Not Endanger”, “May Endanger”, “Will Endanger”, or “Is Endangering”.  While these statements are included in the GW-2 Letter (Water Board Letter).  Previously “Endangerment” letters were issued as separate documents and were often called “No Harm” or “May Harm” letters.  One or more of these letters are required in the state of Texas for most permitted oil and gas activities including: SWR 9, 13, 46, 99, 100 and 16 TAC 5.203.

Additional GAU functions include geophysical and data acquisition, hydrogeologic and geologic mapping, and the ability to respond on short notice to special projects that require geologic analysis and advice. 

Pursuant to NRC Section 91.0115(c) GAU also publishes and maintains a web enabled GIS Drilling Insight and Casing Estimator (DICE) Site to share hydrogeologic, geophysical, and drilling alert information. 

The GAU maintains and improves its general geologic knowledge and understanding in large part through coordination with peers engaged in similar geologic and hydrogeologic work including BEG, TWDB, TCEQ, USGS, and industry.

The GAU also administers the severance tax incentives in 16 TAC 3.101 and 3.103 and issues certificates of severance tax eligibility.

Geologic Advisory Unit Teams:

Groundwater Advisory Unit Issues groundwater letters of determination (GW-2) and provides isolation analysis for Underground Injection Control UIC (No-Harm Letters).

Geologic Investigative Unit Research, analysis, and management decision support consistent with Rules 9, 13, 14, 46 and maintenance and updates the Drilling Insight and Casing Estimator (DICE) Site.

Severance Tax and Administrative Services Unit Oversees the processing of SWR 101 and SWR 103 Severance Tax Applications and provides clerical support.