Naturally occurring groundwater contamination in Texas

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Groundwater accounts for approximately 60 percent of total water used in Texas. Estimates of future groundwater availability strongly depend on groundwater quality because of strong linkages and feedbacks between water quantity and quality. Groundwater quality impacts available fresh groundwater, and groundwater quantity affects the ability of aquifers to dilute or assimilate contaminants. Groundwater quality in the state is greatly impacted by naturally occurring contamination derived from meteoric sources (precipitation), soils, and/or geologic sources. These naturally occurring substances contrast with anthropogenic substances that are added to the system through human activities.

The objective of this study is to assess all naturally occurring and limiting chemical constituents that affect the quantity of fresh groundwater in Texas.

Impacts of naturally occurring chemical constituents on groundwater availability were evaluated by quantifying exceedances of U.S. Environmental Protection Agency (EPA) primary and secondary maximum contaminant levels (MCL) for drinking water in the state. The analysis was based on the most recent groundwater analysis from the TWDB water quality database using analyses from 1988 to 2010. The percent of wells that exceed each MCL was quantified for each of the nine major and 21 minor aquifers.


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