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Areas of Drilling Concern

Areas of Drilling Concern (ADC) are designated by the Director in response to known occurrences of waste or contamination of the state’s water resources and are established to protect public health and the state’s water resources.

Any person drilling a new well or deepening/modifying an existing well for any purpose in an area of drilling concern must comply with additional requirements. These additional well drilling and well construction requirements are based on geologic and hydrologic conditions specific to the ADC and are designed to reduce the potential for spreading contamination to other aquifers.

Currently, Idaho has two active ADCs: Bunker Hill and West Boise. Both are the result of groundwater being contaminated by chemicals or heavy metals introduced by industrial and commercial operations.

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AreaDate DesignatedReason and Related DocumentsMap
Soda SpringsProposedHydrometrics, on behalf of Greenfield Environmental Multistate Trust, petitioned the Idaho Department of Water Resources to designate an Area of Drilling Concern (ADC) near the city of Soda Springs in Caribou County, Idaho. The proposed ADC has been identified by the United States Environmental Protection Agency (EPA) as the most appropriate institutional control available to address potential off-site risk from exposure to contaminated groundwater resulting from past industrial processes at the site. Long term monitoring of groundwater levels and water quality document south-southwest trending plumes of molybdenum and vanadium in ground water at concentrations exceeding EPA tap water regional screening levels (“RSL”), 100 ug/L and 86 ug/L respectively. Long term monitoring confirms the vanadium plume extends approximately 1.5 miles south-southwest from the site while the molybdenum plume extends approximately 3 miles south-southwest to the Bear River.
West AdaProposedThe City of Meridian submitted a petition for the designation of a West Ada ADC (WAADC). The proposed ADC is intended to protect the groundwater resources by preventing the co-mingling of groundwater from different aquifers and sub-aquifers (production zones) which have different groundwater chemistries and hydraulic pressures. The petition for the WAADC provides a detailed report prepared by Hydro Logic, Inc. documenting the hydrogeologic conditions in the Meridian area. The report documents both natural and anthropogenic contamination in the aquifers near Meridian.

The public comment period will remain open through the close of business on Friday, July 15, 2016. Comments should be directed to Jeff Peppersack, IDWR Hearing officer. Comments can be submitted by email to or by postal mail to IDWR, PO BOX 83720, BOISE ID 83720-0098.
West BoiseMay 21, 2001The West Boise ADC order was signed into effect on May 21, 2001 in response to a request from Vopak USA Inc. and the Idaho Department of Environmental Quality to prevent spreading of a groundwater contaminant plume containing the cleaning agent Perchloroethylene (PERC) above Idaho's groundwater quality standards.

Bunker HillJune 3, 1994The Bunker Hill ADC order was signed into effect on June 3, 1994 and was the first ADC to be designated by IDWR. The order was in response to a request from the U.S. Environmental Protection Agency, the Idaho Department of Environmental Quality, the Idaho Department of Health and Welfare, and the Panhandle Health District because of concerns for public health in the Bunker Hill Superfund site. Groundwater contamination resulted from leaching of heavy metals from mine tailings and mine processing wastes.

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