Instructions to Geologists for Geologic Assessments on the Edwards Aquifer Recharge/Transition Zones

Access full-text files



Journal Title

Journal ISSN

Volume Title



The Edwards Rules (Title 30 Texas Administrative Code (TAC) Chapter 213) were revised on June 1, 1999. If you have not reviewed a copy of the revised Rules since that date, please obtain a copy of the current Rules. Some significant changes in the Rules include: The assessment of area geology is now called "geologic assessment." A downgradient geologic assessment is not required for Edwards Aquifer Protection Plans received on or after June 1, 1999. Some terms have been redefined and are included in the glossary.

This "Instructions to Geologists" has been revised as of August 31, 2001, to improve effectiveness without compromising the efficiency of the geologic assessment of sensitive features in the Edwards recharge zone.

The major changes to the instructions are:

  1. To eliminate the category "possibly sensitive". Geologists doing the assessment are not asked to express a high degree of certainty about flow characteristics and communication to the subsurface to rank features as sensitive, as uncertainty is already expressed in the language of the Edwards Rules.
  2. To simplify the assessment to include only three variables: a classification by feature type, orientation with respect to structure, and a field-based assessment of relative infiltration rate.
  3. To increase emphasis on matching appropriate engineering responses to sensitive features.
  4. To evaluate features encountered during sewer construction to identify those where flow should be maintained.
  5. To increase the guidance provided in the instructions.
  6. To reduce variability in assessment by better defining the criteria on which to evaluate relative infiltration rate.


LCSH Subject Headings