This project aims to characterize potential environmental and health impacts of produced water discharges on downstream water quality. Water samples were collected from a NPDES discharge point and the surrounding watershed in an oil field in Wyoming. Contaminants including polycyclic aromatic hydrocarbons, surfactants, and NORMS were identified in the produced water-impacted samples. Chemical concentrations generally decreased with increasing distance from the discharge. However, as a holistic assessment of water quality based on select chemical indicator compounds alone may be insufficient, bioassays were used to quantify toxicity. These included Ames tests, yeast bioassays (measuring both point and chromosomal mutations), daphnia toxicity, and zebrafish development studies. Results showed statistically significant increases in both point and chromosomal mutations in produced water-impacted samples right at the discharge as compared to upstream water samples, but decreased to background levels further downstream. Neither zebrafish studies nor Daphnia studies revealed toxicity. To put our findings into context, further tests will be conducted to compare these data to effluent from a municipal wastewater treatment plant (i.e., a “socially accepted” surface water discharge). Thus, the results of this study can be used to help industry and regulators to effectively and safely manage produced water discharges for agricultural beneficial reuse.

Primary Author / Conference Presenter:
Molly McLaughlin
PhD Candidate
Colorado State University
Fort Collins, CO, USA

Co-Authors:
Jens Blotevogel, Dept. of Civil and Environmental Engineering, Colorado State University
Luca Argueso, Dept. of Environmental and Radiological Health Sciences, Colorado State University
Thomas Borch, Depts. of Chemistry, Soil & Crop Sciences, Colorado State University