Trinity Wells and Data

A great amount of data and information are available for the aquifers of Texas, however it can be difficult and time-consuming to access such data.  This webpage provides information about the Trinity aquifer in graphs, maps and charts to address general questions that pertain to the aquifer and uses of groundwater. 

The primary groundwater data source is the Texas Water Development Board’s well records database, available to download or to access through the Water Information Integration & Dissemination (WIID) System.  These data records are public and can be downloaded at any time, however the system is updated on a regular basis and therefore discrepancies between different dates of downloads are possible.

Source LM Parchman, The Meadows Center

Source TWDB WIIB Database, April 2011

Wells in the Trinity are found across the county, but particularly along the more productive areas of major fault zones.  A land surface expression of such a fault zone in the Hill Country can be seen in the map below.  Trending generally north-south, a linear clustering of wells along a fault zone is found in the central portions of Travis and Hays counties.  Estimates of over 6000 wells have been used in preparing groundwater models in the Hays Trinity Groundwater Conservation District (GCD). 

A search through the TWDB online database shows over 11,000 recorded wells.  Using the database requires some knowledge of the major and minor aquifers found in Texas and their associated water-bearing zones.  An example table of aquifer codes is shown below:

Water Well Number Grid for Hill Country Counties

Wells in Texas are identified through the TWDB statewide monitoring program.  Each well that is logged and recorded is given a specific number, based on the state well grid.  The following shows an example large-scale grid for 3 Hill Country counties:

Water levels within the Trinity vary greatly.  A summary chart of wells in the Hays County from March 2010 shows this variation. Source: TWDB WIID database, Hays County monitoring wells

The following table also shows the variability in water levels (2009 highest water levels in wells categorized as being in the Glen Rose Formation).

Well data are also meaningful when connected to population centers and population growth corridors:

Trinity Aquifer and Urban Areas

Trinity Aquifer and Population Projections. Source: LM Parchman, The Meadows Center

While the maps help to understand growth in the Hill Country, a comparison between 2000 and 2010 population data by county clearly shows the increases in population:

 Source: US Census 2010 Data

 Waste Sites within the Trinity Aquifer of Central Texas:

Waste Sites in the Trhinity Aquifer. Source: LM Parchman, The Meadows Center

Water uses are different across Texas as are the dominant well categories.  In the Hill Country Trinity, a region of rural landowners and ranches with small cities, domestic use is the top category, followed by public supply wells.

Note:  As the data sets were not generated by The Meadows Center for Water and the Environment, the data  in this webpage are not under quality assurance/quality control measures.