In early January 2022, two appeals, one by PARA and one by Chris Werkhoven, of Sonoita, were heard by the Office of Administrative Hearings concerning a Significant Amendment to an Aquifer Protection Permit, granted by ADEQ in 2021, that would allow mining company South32 to dewater the Patagonia Mountains and start extracting underground minerals on an industrial scale. 

The contested amendment is piggybacked on an already completed, small-scale Trench Camp Mine remediation project. The new, high-volume groundwater pumping effluent will be discharged in Harshaw Creek, just downstream of where ADEQ stopped it’s 2003 pollution assessment showing that upstream from the discharge point, Harshaw Creek is impaired. ADEQ claimed that no pollution was “visible” in the lower reaches of Harshaw Creek when “walking Harshaw Creek streambed.” 

For its length as a perennial stream to Patagonia Lake, Sonoita Creek is impaired as well, and to demonstrate that both impairments are connected while avoiding the need to deal with ever changing surface water conditions, a USGS study of soil pollution along Sonoita Creek was shown to the court. Those results clearly reveal a significant accumulation of heavy metals, starting at the confluence with Harshaw Creek, and continuing in severity where other impaired creeks join Sonoita Creek. 

In this context it is not surprising that S32’s hydrology modeling, contracted to a third party, declares that all mine effluent water infiltrates the Harshaw Creek streambed about one mile upstream of its merger with the Sonoita Creek. The modelling was challenged during the hearing. This letter’s authors have analyzed water level recordings showing that almost all mine effluent will, in fact, reach Sonoita Creek in Patagonia. 

The USGS soil analysis results were included in a 2012 University of Arizona master’s thesis on “Bio-Accumulation of Heavy Metals from Soils to Plants” where soil pollution was correlated with acid drainage from legacy mines and naturally weathered, mineralized rock areas, both abundantly present in the Patagonia Mountains. In addition, USGS soil erosion studies were referenced during the hearing indicating that large amounts of soil can be transported via watersheds like Harshaw Creek due to the typical, seasonal rain events. Both studies can account for the metal accumulation found in sediments along the banks of Sonoita Creek and, presumably, at the bottom of Patagonia Lake as well. Prolonged consumption of plants growing from such soils is known to lead to health problems in livestock and in humans as well. 

These findings will hopefully lead to revocation of the permit by the court and provide guidelines for a more realistic way to protect public health and the environment, which is the mission statement entrusted to ADEQ by the people of Arizona.