Let’s start thinking about water!

Radioactive and stable isotopes reveal variations in nearshore submarine groundwater discharge composition and magnitude across low inflow northwestern Gulf of Mexico estuaries

The bays of Texas are flooded valleys from the last ice age when the sea level was much lower. Therefore, our land geology and hydrogeology extends out into the Gulf of Mexico where groundwater from our aquifers discharge (if groundwater flow paths haven’t been disrupted by production). Murgulet and co-authors used radon, radium, and water isotopes to assess how much groundwater is discharging into the Nueces, Upper Laguna Madre, and Mission Aransas estuaries. They found much more groundwater inflow rates into the Nueces Estuary (average inflow rates of 120, 83, and 44 centimeters per day in the Nueces, Corpus Christi, and Oso bays, respectively) than into the Upper Laguna Madre Estuary (21 and 18 centimeters per day in Upper Laguna Madre and Baffin Bay, respectively) and the Mission Aransas Estuary (23 centimeters per day in Aransas Bay). Higher groundwater inflow rates for the Nueces Estuary are probably due to human disturbance of the bottom (dredging?) and growth faults.

Recent water disposal and pore pressure evolution in the Delaware Mountain Group, Delaware Basin, Southeast New Mexico and West Texas, USA

The production of oil and gas in the Permian Basin through fracking is well known as is the need for the disposal of flowback fluids from fracking as well as produced water derived from the production of oil and gas. Although some of this flowback and produced water is recycled, most of it is injected into deep formations in the same area. For the Delaware Basin, this water is injected into the Delaware Mountain Group through more than 1,000 disposal wells. The result has been an increase of pressure of 100 to 400 pounds per square inch. This pressurization, combined with abandoned wells, could connect the disposal zone with fresh-water aquifers and create seismicity.

Groundwater Withdrawals Associated with Oil and Gas Production from Water Supply Aquifers in Texas: Implications for Water Management Practices

We hear a lot about produced water in the Permian Basin, but produced water is also, well, produced from the deeper parts of the Carrizo-Wilcox formations. Coeckelenbergh and friends mined the files of the Railroad Commission for information on produced water disposal by the industry. They found that about 4,300 acre-feet per year of Carrizo-Wilcox produced water is permitted for discharge to surface waters for “agricultural” purposes (their quotes [but also my quotes]). The authors also found that 44% of the discharges have total dissolved solids greater than 1,000 milligrams per liter, which is also the secondary drinking water standard. Some of the discharged water had total dissolved solids approaching 4,000 milligrams per liter, which would be acceptable for certain agricultural and industrial uses. Despite produced water coming from where oil and gas can be produced from the Carrizo-Wilcox, the production of the water could have sustainability consequences on the aquifer as a whole.