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Orange, iron-rich precipitate (ochre)
Orange, iron-rich precipitate (ochre) from outflow of Lead Queen mine tunnel, after late September 2014 monsoon storm. Photo by Glen E. "Gooch" Goodwin, Photographer - used with permission.

In late September, 2014, unusually heavy monsoonal rains were followed by citizen observations of bright orange "sludge" flowing in streams in the vicinity of the Lead Queen and Trench Camp Mines in the Patagonia Mountains. Lead Queen is an abandoned mine located on U.S. Forest Service land, and Trench Camp is a mine site that was remediated in the 1970s and is currently managed by Asarco Multistate Environmental Custodial Trust. At Lead Queen, flushing of adits and shafts by rapid inflow of rainwater apparently led to the mobilization of iron- and aluminum-rich sludge, which has mostly settled in the upper canyons near the mine site. Similar flow occurred at the Trench Camp site due to the failure of a sediment dam and overflow of the wetlands area established as part of the remediation.

Critical issues include how these other contaminants have dispersed through the watershed, the extent to which they have been deposited in sediments that can be remobilized in future events, the potential for future contaminant outflows from these two sites as well as other sites in the selected southeast Arizona mountain regions, and developing a plan for future USGS response to this and similar events in other areas. With the USGS's experience with rapid response, unbiased science, and the nationally and internationally recognized quality of its data and protocols, the USGS is in a unique position in the current situation to aid with and conduct sampling, monitoring, and modeling to provide a comprehensive perspective on the ongoing environmental hazards posed by the legacy of mining in the Patagonia Mountains and, in general, predict surface and groundwater potential vulnerably in new start-up areas.


  1. Determine the immediate extent, levels, and fate of contaminants released from the Lead Queen and Trench Camp mine site spills; characterize current and long term fluxes/impacts of the events to sensitive areas such as Harshaw and Sonoita Creeks downstream of the recent spill.
  2. Determine the fate of contaminants within the Sonoita Creek and Peña Blanca, AZ watersheds and their associated ecosystems.
  3. Identify contaminant risk potential of legacy and proposed mine sites in the Santa Rita, Atacosa, and Patagonia Mountains and develop classification criteria for predicting vulnerabilities and targeted sinks of metal contaminants.
  4. Compile geo-hydrologic data on pertinent lithologies, faults and associated fracture networks that might transmit groundwater from the naturally occurring pyrite wall rock of the deposit, or leaking discharges from the mine's tailings impoundment.
  5. Develop guidelines for future responses that effectively leverage the limited finances of the Mineral Resources Program, State, and other federal agency response mechanisms. Response guidelines will include financing considerations of deploying a 'Response-Ready' team and equipment, developing sampling protocols and objectives, and delivering fast, efficient, reviewed communication of data to land management and regulatory partners as well as the general public.
  6. Develop communications protocols for quick release of pertinent preliminary information to the collaborating agencies and public.

Project Activities

This pilot project will undertake efforts to:

  • Retrieve, compile and synthesize both historical and current surface and groundwater geochemical data from relevant wells, stream, and spring arrays in and around legacy, active and proposed porphyry copper systems
  • Develop descriptive, environmental, geo-hydrologic framework and, if possible, predictive models for trend analysis to address relevant water use dynamics and the broader ecological response of these deposits in semi-arid to arid settings
  • Identify the most appropriate best management practices for:
    • organizing sampling/monitoring groundwater well networks
    • determining the critical analytical methods needed for predicting/understanding surface water metal pathways
    • establish useful thresholds levels of potential ecological impacts outside of the area of the natural baseline conditions of the target deposit environment
  • Communicate the data and resulting interpretations in a transparent and consistent manner to land management agencies, mine management, local municipalities, and concerned citizens groups.


Journal Articles

Norman, L.M., Brinkerhoff, F., Gwillliam, E., Guertin, D.P., Callegary, J., Goodrich, D.C., Nagler, P.L., and Gray, F., 2016, Hydrologic Response of Streams Restored with Check Dams in the Chiricahua Mountains, Arizona: River Research and Applications, 32(4), p. 519-527, doi:10.1002/rra.2895.


Callegary, J., Gray, F., Norman, L., Bultman, M., and Heilman, J., 2016, Hydrologic Functioning of a Fractured-Rock Aquifer Containing Extensive Mining Tunnels and Open Drill Holes: 2016 National Groundwater Association (NGWA) Conference on Fractured Rock and Groundwater, Burlington, VT.

Callegary, J., Gray, F., Norman, L., Bultman, M., and Heilman, J., 2015, Hydrology and Water-budget Components of an Extensively Mined Area Using Geophysics, Geochemistry, Rainfall-runoff- and Sediment Transport Modeling: 2015 National Groundwater Association (NGWA) Conference on Groundwater in Fractured Rock, September 28-29, 2015, Burlington, VT.

Callegary, J., Norman, L.M., Eastoe, C., Wilson, N., Fandel, C., Gray, F., and Wiele, S., 2017, Multidisciplinary Modeling and Monitoring to Study Hydrologic, Geomorphologic, and Biogeochemical Effects of Restoration: 7th World Conference on Ecological Restoration, August 27-September 1, 2017, Iguazu, Brazil.

Gray, F., Page, W.R., Bultlman, M., and Menges, C.M., 2014, Hydrogeologic characteristics of the Miocene Nogales Formation: Potential new deeper source of groundwater in the upper Santa Cruze basin, southern Arizona: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 118. View Gray 2014 GSA abstract.

Project Contact

Floyd Gray
Phone: 520-670-5582
Geology, Minerals, Energy and Geophysics Science Center

Related Link

Mineral Resources Program Science Priority

The use of firm, trade, and brand names is for identification purposes only and does not constitute endorsement by the U.S. government.

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