Colstrip Steam Electric Station

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Colstrip Steam Electric Station has 609 groundwater monitoring wells, 596 of which have been polluted above federal advisory levels based on samples collected between February 03, 2010 and May 20, 2015. Groundwater at this site contains unsafe levels of sulfate, boron, selenium, nitrate, fluoride and manganese.

Site description

The Colstrip Steam Electric Station consists of four coal-fired units and operates a network of nine coal ash impoundments. It is the second largest coal-fired plant in the Western U.S. In 2003, residents of the town of Colstrip filed a lawsuit alleging that Colstrip’s impoundments and waste ponds had contributed to groundwater pollution. In May of 2008, the five utility companies that jointly owned and operated the Colstrip power plant finalized a $25 million settlement with the 57 plaintiffs who blame the utilities for contaminating their groundwater and causing structural damage to some properties.

In August 2012, the operators of the facility entered into an "Administrative Order on Consent" with the Montana Department of Environmental Quality to study the effectiveness of potential remediation strategies. Another legal settlement in 2016 requires the closure of Colstrip's two older units by 2022.

The Environmental Protection Agency has identified Colstrip as a location where coal ash disposal activities have been proven to contaminate ground and surface water.

The Colstrip Power Plant’s Bottom Ash Ponds 1&2, Fly Ash Ponds 1&2, Step D Cell 1&2, Step E Cell 1&2, Old Clearwell, EHP 3&4, Scrubber Pond, and Temporary Storage Area are all regulated under the CCR rule. You can find the industry reported data here. For more information on the Colstrip Steam Electric Station, see EIP’s 2019 National Coal Ash Report, Coal’s Poisonous Legacy.

Monitoring Wells Wells reporting one or more exceedances for at least one pollutant.
596 / 609
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No exceedances
One or more exeedances
No data available
Other designation
Well "halo" size corresponds to mean concentration. Please note that some wells may not be visible on the map due to overlapping locations.
Pollutants monitored and above guidelines
Tip: Click on a contaminant to view wells that have recorded exceedances. Click again to remove the filter. boron fluoride manganese nitrate selenium sulfate
Pollutants monitored and below guidelines
ammonia arsenic chromium lead mercury nitrite
Pollutants not monitored
antimony, barium, beryllium, cadmium, cobalt, copper, cyanide, gross alpha particle, gross beta particle, hexavalent chromium, lithium, molybdenum, nickel, radium, silver, strontium, thallium, tritium, uranium

Facility last updated on Tuesday, July 23, 2019 10:20:37 AM EDT