EFFECTS OF HYDRAULIC FRACTURING FLOWBACK FLUID DISPOSAL ON STREAM HEALTH

Assessing the impacts of hydraulic fracturing has been at the forefront of environmental concern. Hydraulic fracturing flowback fluid (HFFF) is sent to facilities to be treated and released into nearby waterways. Previously, elevated levels of Cl, Br, Sr, and Ba, have been found in streams near these facilities at concentrations above EPA maximum contaminant levels. We wanted to see if there was an impact on the biology tied to the discharge from the facilities. We evaluated the health of two freshwater streams in western Pennsylvania that are in proximity to facilities accepting HFFF, using biological assessments of macroinvertebrates. Benthic macroinvertebrates are used as an indicator of stream quality because many have limited migration capability and exhibit clustered distributions, which is helpful when looking at site-specific impacts. Using standard EPA procedure for biological assessments, we sampled multiple sites upstream, at the discharge, and downstream. We also measured the chemistry of the water at each point to correlate with our biology sample.

The salinities of the discharges measured at both facilities (Josephine and Hart) were within 140,000-170,000μS, consistent with that of HFFF, and were nearly 1000 times higher than background. Even with this drastically different input, both streams recovered by 1km downstream of the discharge. For our macroinvertebrate study, we applied common metrics to assess the water quality. The densities of the samples just downstream from the discharge increased slightly downstream of the discharge, but then returned to background levels (50-100 individuals/m²) by 1.5km downstream. Using a family-level biotic index, we determined no significant change from the pipe, as values were constant in the 4-6 range for both facilities. The EPT ratio decreases near the discharge and then recovers downstream. The mayfly ratio, which is sensitive to salinity, showed a decrease in mayfly populations at the discharge and then a recovery to 0.1-0.3 mayflies/non-mayflies. Our data suggests that there is a biological impact due to the high salinity of the HFFF discharge, but the streams recover well by 1-2km downstream. Other factors, such as existing acid mine drainage and poor background water quality, could be affecting trends in biological activity in the streams.