Sources of Shallow Saline Ground Water in Concho, Runnels, and Tom Green Counties

Soil and groundwater salinization, causing vegetative kill areas and water well contamination, are major concerns for farmers not only in Texas but also in many other states across the U.S. In various regions, a combination of natural processes and agricultural activities is primarily responsible for salinization. Moreover, in West Texas, pollution hazards associated with oil exploration and production further complicate the challenge of identifying the sources of soil and groundwater contamination.

This study focused on Concho, Runnels, and Tom Green Counties in west-central Texas (see Figure 1) due to the widespread occurrence of soil and groundwater salinization in these areas. Additionally, both natural and man-made sources of salinization could be active in this region.

The terrain in this area varies, with hilly terrain present in southern, western, and northern Tom Green County, where remnants of the Edwards Plateau rise to approximately 2,500 feet above sea level. Plains and river valleys dominate most of the remaining area, with the lowest surface elevations (approximately 1,500 feet) found in river valleys to the east. Major drainage systems in the region include the Colorado River in Runnels County, the Concho Rivers in Tom Green and Concho Counties, and several surface-water reservoirs just west of San Angelo.

The average annual rainfall in this area is approximately 21 inches, which is nearly one-third of the net lake evaporation.