Pima County challenges Hudbay’s efforts to reduce significance of desert streams near proposed Rosemont Mine

Pima County is challenging Hudbay Minerals attempts to have federal regulators reclassify two desert streams that will be impacted by its proposed Rosemont Mine as fleeting, short-lived, watercourses rather than as intermittent waterways that have continuous water for extended periods.

The distinction is crucial as the U.S. Army Corps of Engineers reviews Hudbay’s application for a Clean Water Act (CWA) permit for the massive open pit copper mine planned in the Santa Rita Mountains on the Coronado National Forest southeast of Tucson.

Reducing the amount of water in Barrel Canyon and Davidson Canyon could potentially allow Hudbay to reduce the amount of mitigation it must provide in order to obtain the CWA permit. The $1.9 billion mine cannot be constructed without the permit.

Hudbay’s efforts to obtain the permit have run into opposition from the Army Corps because its mitigation plans have not fully compensated for the loss of desert waterways. In July 2016, the Army Corps Los Angeles district office recommended denying Hudbay’s permit application. The Corps regional office is currently reviewing Hudbay’s application.

Rather than fully mitigate the damage it will cause to desert aquatic resources, Hudbay and its contractors are attempting to reduce the significance of the desert waterways by classifying them as “ephemeral”, which means they only have water for brief periods of time.

To accomplish this, Hudbay focused on the amount of water flowing in the waterways in 2010, which is one of the driest years in the ongoing long-term drought.

“By relying on an extremely dry period for estimating Barrel Canyon stormflow and baseflow, Hudbay appears to be hoping to minimize their needs for mitigating impacts on Waters of the United States,” Pima County Administrator Chuck Huckelberry states in a Nov. 7 letter to the Army Corps.

“Yet despite the extreme drought — and contrary to Hudbay’s assertions — intermittent surface water conditions have persisted in Barrel and Davidson canyons,” Huckelberry states.

Huckelberry’s states that biologist found a species of stonefly in Barrel Canyon in 2010 that requires at least 42 days of continuous stream flow in order to mature. “This is clearly a species that relies on intermittent surface water conditions for survival,” Huckelberry states.

The scientific evidence, Huckelberry states, clearly shows that “Barrel and Davidson canyons must be considered intermittent and not be repeatedly referred to as ‘ephemeral’ water bodies” by Hudbay and its contractors including Westland Resources Inc., and Earth Technologies.

“Water quality standards, impact analysis and mitigation must take into consideration these aquatic resources, and the long-term impacts of the mine on the resources during operation, as well as closure,” Huckelberry’s letter concludes.