Illegal Oil and Gas Wastewater Dumps Disrupt Foundations of Fragile Desert Ecosystems

The study sampled five sites, from a set of illegal dump sites identified by BLM in the Chihuahuan Desert, to assess the potential environmental effects resulting from illegal oil and gas wastewater dumping on desert soils.

"The effects of oil and gas wastewaters on desert ecosystems is quite poorly understood, and that's a challenge considering much of the world's oil and gas development occurs in desert ecosystems," said USGS scientist Denise Akob, one of the scientists who conducted the study. "In fact, the Permian Basin, where we did this research, is the largest producing oil and gas region in the United States, so if we want to understand how this industry may be affecting these ecosystems, this is an ideal place to start."

Since 2017, at least 39 separate releases of wastewater from oil and gas development in the Permian Basin have met the criteria for illegal dumping under federal and state regulations, totaling more than 150,000 gallons (600,000 liters) of fluids spilled onto the desert soils.

These wastewaters are derived from a variety of sources. Water naturally occurs in oil and gas formations and, when it is brought to the surface with oil and gas, the result is often referred to as produced waters. In addition, manufactured fluids are pumped down into the rock formations to help bring more oil and gas to the surface, some of which comes back with the oil and gas. What's more, some of the petroleum itself is mixed in with these wastewaters.

These wastewaters are typically salty, with a composition of ions, hydrocarbons, and characteristics that differ from the original fluids used to stimulate production. When the research team compared the chemical composition and microbial ecology of dump-affected soils, they confirmed elevated levels of sodium, chloride, and bromide that were consistent with produced waters from wells in the Permian Basin.

"Our results showed that there was not only a decrease in the bacteria we expect to find in desert soils, but also an increase in bacteria that feed on petroleum and that thrive in highly saline environments, like that in the oil and gas wastewaters," said Akob. "This shows that the wastewaters are having an effect on the microbial composition of desert soils."

Microbial composition in desert soils matters for things like cycling nutrients for plants to consume; retaining moisture which also benefits plants as well as soil stability; and increasing the fertility of arid soils. These factors make microbes essential to the survival of plants and fungi that serve as food for herbivores, who then serve as the food for predators on up the food chain. Disruptions to microbial communities in desert soils could cause further disruptions throughout the desert food chain.

The study, part of a larger research effort by the USGS and others looking at the effects of oil and gas wastewaters on desert ecosystems and water quality, was published in Applied and Environmental Microbiology.

More information on USGS research projects associated with oil and gas wastewaters can be found here.