The Arizona Department of Environmental Quality (ADEQ) surface water and soil test results of orange water and soil in the area surrounding the former Sheldon Mine in Walker, Arizona, indicate the orange coloration is due to naturally-occurring iron.
As iron is exposed to air, it forms iron oxide, which is orange or red in color. Based on the heavily mineralized geology in this former mining district, ADEQ tested the samples (surface water and soil) for metals (barium, cadmium, chromium, lead, mercury, selenium, silver, iron), arsenic, cyanide, and pH. Test results confirm that surface water and soil in the area do not pose an immediate threat to public health and that no remediation activities are warranted.
“Within 24 hours of receiving information from a resident about concerns related to the orange liquid and soil, ADEQ had an inspector on-site to investigate,” said ADEQ Water Quality Division Director Trevor Baggiore. “Once we confirmed the orange liquid, we immediately coordinated with our local, county and state partners and worked with Yavapai County Emergency Management to post signs to inform the public to avoid the area, while we made arrangements to conduct environmental sampling.”
On April 1, 2023, ADEQ collected four surface water samples – two from the area where the orange water was pooling and two where the orange water was entering a nearby creek. ADEQ also collected three soil samples from the area with the orange color.
- Surface Water Results: ADEQ test results show that water in the nearby creek met applicable state surface water quality standards that protect people’s health if they recreate in the creek. For the orange water samples taken prior to reaching the creek, most elements met the standards; the elements that measured higher than the standards were arsenic and lead. The orange water is also weakly acidic, which is common in this area due to the geology and consistent with data from other streams in the Bradshaw Mountains.
- Soil Results: ADEQ’s soil test results show all elements were well below the most conservative state cleanup standards, which are for residential areas, with the exception of arsenic. The arsenic results are consistent with levels that naturally occur in this highly mineralized area and across Arizona, do not present a concern for public health, and do not warrant cleanup action.
As a precautionary measure, ADEQ continues to advise people near the Sheldon Mine to avoid contact with orange water and orange stained soil in the area.
The Bradshaw Mountains include miles of underground mine workings and dozens of historic waste rock and tailings piles that date back many decades. Groundwater upwelling along with runoff from the historic waste rock and tailings piles contribute to the mineral content of surface water. Due to recent above-average precipitation in the region, orange water may be surfacing in other nearby areas.
On March 31, 2023, out of an abundance of caution, ADEQ advised the public to stay away from orange water or orange stained soils in the area surrounding the former Sheldon Mine in Walker, Arizona. While surface water and soil conditions in the area of the former Sheldon Mine do not pose an immediate health risk, ADEQ reminds Arizonans to always stay away from discolored soil, discolored surface water, and stormwater runoff in both urban and rural areas. In addition to metal pollutants, stormwater surface water flows can carry bacteria and pathogens.
ADEQ also reminds and encourages private well owners to regularly test their well water according to guidance provided by the Arizona Department of Health Services.