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The Montana Bureau of Mines and Geology (MBMG) conducted water sampling in the area as a part of their groundwater investigation of the Upper Jefferson Valley. They discovered elevated concentrations of arsenic in the pond and an adjacent monitoring well. The concentrations of arsenic found in the pond exceeded the Montana Department of Environmental Quality’s (DEQ) numeric water quality threshold for human health, while the adjacent well had concentrations just below the human health threshold.


FWP collected fish from the pond this past spring and analyzed them for metals. Results confirmed levels of arsenic in the westslope cutthroat trout in Piedmont Pond.


Women of child-bearing age and children younger than 7 years old should limit consumption of trout from Piedmont Pond to one meal per month for fish 6 to 10 inches long and avoid consuming trout longer than 14 inches. Other adults and children 7 years or older should limit consumption to two meals per month for fish 6 to 10 inches long, and one meal per month for fish longer than 14 inches.


FWP will be posting signs at the pond to notify anglers of the fish consumption advisory. The arsenic in the groundwater and pond is likely due to natural hydrothermal activity in the area. Evaporation of groundwater from the pond further concentrates the arsenic and contributes to higher levels than in the groundwater, according to officials at MBMG.

DEQ recommends people avoid drinking the water while recreating at Piedmont Pond.

Similar fish consumption advisories exist for other waters throughout Montana. For more information, visit: