Hydraulic fracturing fluids from nearby natural gas wells probably harmed endangered fish in a Kentucky creek, according to two federal agencies.
In a joint study, the U.S. Geological Survey and the Fish and Wildlife Service said fracturing fluid — a mixture of water, sand and chemicals that is pumped underground to unlock oil and gas — created conditions that likely caused the threatened Blackside dace minnow and other fish to die off when it was spilled in a small Appalachian creek in 2007.
London, Ky.-based Nami Resources Co. pleaded guilty to violating federal endangered species and clean water laws in 2009 in connection with the incident, when subcontractors working at four of the company’s wells failed to properly dispose of fracturing fluids used at the sites. According to the Fish and Wildlife Service, the fluids discharged into the upper reaches of Acorn Fork, a small Appalachian creek, contaminating it with hydrochloric acid and other chemicals.
The fish developed gill lesions and suffered liver and spleen damage consistent with exposure to acidic water and toxic concentrations of heavy metals, according to water and fish samples collected immediately after the incident and analyzed by the two Interior Department agencies.
Survey scientist Diana Papoulias, the lead author of the study, said the episode “is a precautionary tale of how entire populations could be put at risk even with small-scale fluid spills.”
The study is published in a special edition of Southeastern Naturalist.
According to the report, water in Acorn Fork became more acidic, with the pH level dropping from 7.5 to 5.6, after the fracturing fluids entered the creek. Water samples also showed higher levels of iron, aluminum and other dissolved elements.
The research comes amid a growing nationwide debate over the use of hydraulic fracturing and horizontal drilling to tap newly accessible oil and gas reserves nationwide.
The oil and gas industry insists that there have been no documented cases of fracturing fluid contaminating underground drinking water supplies. But surface spills of fracturing fluids can cause damage, and natural gas can migrate from poorly cemented and designed wells.
The new government study notes that contamination can compound existing environmental problems, particularly in areas such as the Appalachian Highlands, where mining, logging, agriculture and development have already degraded aquatic ecosystems and fragmented freshwater fish populations.
“As efforts accelerate to unleash new energy sources, application of technolo- gies such as hydraulic fracturing can, if not carefully developed, compound the effects of ecosystem degradation caused by past resource extraction,” the study’s authors write.
The Blackside dace are a minnow found in just three states: Kentucky, Tennessee and Virginia. The ray-finned fish has been listed as a federally threatened species since 1987. The main threat to the fish, which the Fish and Wildlife Service says generally lives in small, isolated groups, is loss of habitat.
The timing of the 2007 spill may have been particularly rough for the Blackside dace, the study authors note, because it occurred during the spawning season. Because it is unclear how many dace were killed after the 2007 spill, the study sought to examine whether fracturing-related degradation of Acorn Fork’s water quality could have harmed the minnow.
Although a fish kill was reported by a resident of the area, researchers arrived at least a month after two wells had been fractured. They observed “one dead, one moribund and several living but distressed Blackside dace, along with three distressed (Creek Chub).”
That limited the scope of the study, the researchers said:
“It is not known how many dace were killed during the 2007 event because two wells had already been fracked, and peak mortality was likely missed before researchers arrived to document the incident,” the authors said. “Therefore, the objective of this opportunistic study was to assess whether (fracturing)-related degradation in Acorn Fork water quality could have harmed or resulted in mortality of the federally protected Blackside Dace.”