(180as) Investigating the Possible Factors Causing the Increase of Salinity Levels in the Carrizo-Wilcox Aquifer, Winter Garden Region.

The Carrizo-Wilcox aquifer is one of the most prolific groundwater sources found within Texas, spanning 66 Texas counties between the border of Mexico and Louisiana. The aquifer yields are fresh to slightly saline water, so the aquifer is the primary groundwater source for meeting irrigation, public supply, and industrial needs. Groundwater development within the Carrizo-Wilcox aquifer began in the early 1900s, when irrigation pumpage was widespread in the southern region of the aquifer, with the first flowing artesian well drilled in Dimmit County in 1884. Over the years, groundwater pumpage depleted the aquifer, most notably in the south region of the aquifer, due to pumpage being far more common in the Winter Garden region. In recent years, oil and gas (O&G) operations have increased in the Winter Garden region of the aquifer as the Eagle Ford Shale has become one of the primary producers of O&G in Texas. As a result, O&G wells have been constructed near many groundwater water wells used for irrigation, industrial, stock, domestic, or public supply needs. The growing concern is that if any accidents occur where an O&G well casing becomes compromised or begins to leak oil production fluids, these water wells may be contaminated and render the water unusable or unsafe for consumption. Furthermore, if continuous accidents occur, the effects on the Carrizo-Wilcox aquifer would be an increase in salinity and contamination levels throughout the Carrizo-Wilcox aquifer located in the Winter Garden region. One of the primary objectives of this project is to simulate the effects of compromised/leaking O&G wells using GroundWater Vistas V8 (GWV8) to create a model that provides hydraulic information as well as a fate and transport model of the Carrizo-Wilcox aquifer. The model would encompass the entirety of La Salle County, TX, one of the four Texas counties comprising the Winter Garden region. In addition to GWV8, QGIS will be used to create a shapefile to help provide a visual of current well activity in La Salle County. Overall, the model developed will be used to analyze the effects of the casing leak, how the contamination spreads through the study area, and how the contamination affects irrigation/drinking water wells for current and future use.