by Fred Tahse, retired geologist

Watch Fred explain the rock types and acid mine drainage

Augusta Resource, the Canadian company that wants to develop a copper deposit in the Rosemont Valley of the northeastern Santa Rita Mountains , has stated recently that it may explore and possibly mine on the northwestern side of the mountains as well. This would have a huge effect on Green Valley , Quail Creek, Sahuarita and Corona de Tucson. In view of the depressing and harmful effects caused by the existing copper mines at Green Valley and Sahuarita, people from these communities deserve to know some facts* about the Rosemont mine:

  • how it came about;
  • whether or not it is the large mine Augusta claims it is;
  • what it could do to the environment all Arizonans treasure, and
  • what huge amounts of our forest land could be lost forever.

The Rosemont copper deposit is located within the old Helvetia mining district, once the site of several small underground mines. Since these mines closed down in 1951, the district has experienced exploration efforts by some of the largest mining companies in the United States—Banner Mining Company, American Exploration and Mining Company, Anaconda Mining Company, Anamax Mining Company, and ASARCO. These companies have drilled hundreds of exploration holes throughout the district and made several boisterous estimates of copper resources. None of them attempted a mine in this area. Augusta, too, launched an exploration program, focusing on the Rosemont area. Where large, experienced U.S. mining companies had failed, Augusta, an unproven Canadian mining company, now tells us they have drilled out a “world class” copper deposit.

Augusta's website states that they have about 617 million tons of reserves, but only 134 million tons—22 percent—are proven. The rest—78 percent—are only estimated. It seems very risky for the U. S. Forest Service to approve a Plan of Operations for an unproven mining company mining mostly unproven reserves, when the consequences of the mining process could be so devastating. Here is what probably would happen:

1. The Forest Service could grant Augusta the right to mine and dump waste onto as many as 850 unpatented mining claims that may ultimately total an area in excess of 25 square miles—more than twice the size of the entire communities of Green Valley and Quail Creek combined.

2. The mine would have an impact on the hydrology and water quality of the Davidson Canyon drainage system, important to the City of Tucson . If Augusta mines or dumps waste onto the northern tier of unpatented mining claims, this probably would alter the hydrology and water quality of the Sycamore Canyon drainage system too, thus affecting Corona de Tucson also.

3. The mine would use enormous amounts of water from the Santa Cruz River aquifers—an estimated 5,000 to 7,000 acre-feet per year, an amount equal to that used annually by 20,000 to nearly 30,000 household members. Augusta claims that the water they use will be replaced by CAP water, though they do not have a CAP guarantee for the full life of the mine. Furthermore, CAP water, with its very high content of dissolved solids, is not the same fresh, potable water that Augusta would pump from the Santa Cruz River aquifers. The trade-off of CAP water for ground water is a bad deal.

4. The nearly pristine beauty of the Santa Rita Mountains would be destroyed forever. Mine reclamation procedures, though promised by Augusta , can never restore such beauty. One simply needs to look at the mine dumps at Green Valley to see this. Will real estate values be the same if large mining operations are carried on at residents' back doors, with night-time lights, rock blasting and truck noise?

5. Mining profits would flow to Augusta investors and at least some of the copper concentrates may be shipped overseas—Augusta is talking about shipping concentrates by rail to the deep-water port at Guaymas, Mexico. Sumitomo Corporation, one of the three largest trading companies in Japan and a major stockholder of Augusta, may dictate where the concentrates go.

These are some of the facts about mining operations in the Santa Rita Mountains. Is it worth allowing Augusta to proceed when there are so many potentially devastating consequences? We Arizonans could be left with one or more huge holes in the ground, a ravaged and possibly contaminated countryside, and contaminated groundwater. Our tourists would certainly shun the areas they used to love for hiking, camping and other soul-enriching activities.

* The facts cited are from documents published by Augusta Resource or their consultants to satisfy information requests by the U. S. Forest Service or are from Augusta 's reports to its stockholders, both written and verbal.


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