The Buckeye mine site is located in the Boulder River watershed along Basin Creek,
in northern Jefferson County, Montana. This project is part of the Boulder River watershed
Abandoned Mine Lands Initiative, and is a collaborative effort between the U.S. Geological
Survey and Bureau of Land Management in the U.S. Department of the Interior, and the U.S.
Forest Service in the U.S. Department of Agriculture. The site includes a large flotation milltailing
deposit, which extends to the stream and meadows below the mine. These tailings contain
elevated levels of metals, such as silver, cadmium, copper, lead, and zinc. Metal-rich fluvial
tailings containing these metals, are possible sources of ground and surface water contamination.
Geophysical methods were used to characterize the sediments at the Buckeye mine site. Ground
geophysical surveys, including electromagnetics, DC resistivity, and total field magnetic methods,
were used to delineate anomalies that probably correlate with subsurface metal contamination.
Subsurface conductivity was mapped using EM-31 and EM-34 terrain conductivity
measuring systems. The conductivity maps represent variation of concentration of dissolved
solids in the subsurface from a few meters, to an approximate depth of 30 meters. Conductive
sulfides several centimeters thick were encountered in a shallow trench, dug in an area of very
high conductivity, at a depth of approximately 1 to1.5 meters. Laboratory measurements of
samples of the sulfide layers show the conductivity is on the order of 1000 millisiemens. DC
resistivity soundings were used to quantify subsurface conductivity variations and to estimate the
depth to bedrock. Total field magnetic measurements were used to identify magnetic metals in the
subsurface. The EM surveys identified several areas of relatively high conductivity and detected
a conductive plume extending to the southwest, toward the stream. This plume correlates well
with the potentiometric surface and direction of ground water flow, and with water quality data
from monitoring wells in and around the tailings. The electrical geophysical data suggests there
has been vertical migration of high dissolved solids. A DC sounding made on a nearby granite
outcrop to the north of the mine showed that the shallow conductivity is on the order of 5
millisiemens/m. Granite underlying the mine tailings, with similar electrical properties as the
outcropping area, may be more than 30 meters deep.
Additional publication details
USGS Numbered Series
Ground geophysical study of the Buckeye Mine Tailings, Boulder watershed, Montana
U.S. Department of the Interior, U.S. Geological Survey,