Big Stone Plant has 15 groundwater monitoring wells, 15 of which have been polluted above federal advisory levels based on samples collected between September 07, 2016 and August 14, 2017. Groundwater at this site contains unsafe levels of lithium, sulfate, boron, cobalt, molybdenum, arsenic, lead and radium.Site description
Otter Tail Power's Big Stone Plant opened in 1975 and is located on the banks of the Big Stone Lake, South Dakota. It has one coal-fired generating unit that is capable of producing 450-MW of electricity. The plant has two units regulated under the CCR rule: Slag Pond Area and Ash Disposal Area. CCR is also temporarily stored on-site in the Temporary Storage Area, located right next to the Slag Pond Area. . Big Stone Plant is among the U.S. Environmental Protection Agency's list of potential damage cases, indicating that coal ash disposal at the site has potentially polluted groundwater or surface water at levels which threaten human health and the environment.