Mallard Dam project completed

Construction work to repair damage that occurred on Mallard Dam in Lyman County was completed in October of last year

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Photo © Dan Svingen

Mallard Dam was one of the very first DU projects in South Dakota, originally completed in the fall of 1986. This 30-acre impoundment is located within the Fort Pierre National Grasslands and has served as an oasis in a vast sea of grass to waterfowl, shorebirds, deer, antelope, livestock and outdoorsmen for the past three decades.


In June of 2009 a high water event caused extensive damage to the water control structure and spillway and the dam was breached. DU engineers and biologists surveyed the damage and developed a plan to repair the dam. The repairs included replacing the damaged water control structure with a larger and sturdier structure and surrounding it with rock rip rap for better long-term stability. The damaged spillway was repaired and reshaped with soil. Then it was lined with a sheet of polymesh fabric covered in a layer of rock to prevent future soil erosion during peak water flows through the spillway.


DU worked with other conservation partners to ensure the Mallard Dam repair plan was implemented. The US Forest Service, the South Dakota Game Fish and Parks Department and the South Dakota Habitat Conservation Fund Board provided funding and support for completion of this project. The US Forest Service will monitor and manage the dam and associated impoundment to ensure continued beneficial use for fish and wildlife habitat, recreational opportunities and livestock water.