Iowa 31 project in NW Iowa provides more than just a stable roadside

Bank stablization along Iowa 31We exist to make lives better through transportation, but what happens when transportation improvements and the desire to preserve part of our history intersect?

Our mission is to provide a safe and efficient transportation system, and as we deliver the projects that achieve that mission, we also follow federal and state laws that ensure environmental stewardship. As planning progressed for a bank stabilization along the Little Sioux River and Iowa 31, Iowa DOT Location and Environment Bureau staff realized early on that this particular project would be very different than most. Archaeologist Brennan Dolan shared “we recognized from day one that this project would be mostly contained within the boundaries of a large prehistoric village site.” Following months of planning, archaeological excavation, and construction, in June the State Historical Society of Iowa awarded the Iowa DOT the 2021 Excellence in Archaeology and Historic Preservation Award. 

Dr. John Doershuk, State Archaeologist of Iowa, said From the onset, it was clear this would be a remarkable opportunity to investigate one of Iowa’s richest archaeological sites and curate a collection of materials and data with near-limitless future research value.”
Collaboration on Iowa 31 project
Several groups collaborated on the excavation phase of this project.


The large historical preservation element of the Little Sioux River project, brought together the Iowa Department of Transportation, several Native American tribal representatives, the Office of the State Archeologist, U.S Army Corps of Engineers, the local landowner, and a consultant. The significance of a large number of collaborating entities and the care and consideration of the archeology project were the elements that raised this project to the top overall others that were nominated.

In his nomination of the project, Doershuk said,, “Seeing this complex project to its successful conclusion required significant collaborative planning and research efforts, particularly because it involved fulfilling the requirements of multiple state and federal preservation laws involving several organizations having project oversight. This project demonstrates the high level of preservation and data recovery that can be achieved through concerted preservation-minded foresight, creative engineering to minimize impacts, and continual collaboration amongst project partners.”

Doershuk further noted that this collaboration went beyond the typical approach to compliance stating some of the project details were “not a standard aspect of most agreement documents and represents a clear-eyed and respectful consideration of the archaeological site data and more importantly the wishes of the Tribal partners.”  Doershuk continued “In addition to standard lithic, faunal, botanical, and ceramic analyses the team embraced the implementation of advanced technologies to enhance the efficiency of archaeological excavation and allowed for data to be collected with much greater detail than previous Oneota excavations in Iowa.”

Brenan Dolan
Iowa DOT Archaeologist Brennan Dolan identifying a prehistoric storage feature in the cutbank of the Little Sioux River.

Dolan said, “Like many undertakings, it had its twists and turns but in the end, we delivered a project that balanced the transportation needs of the public while respecting the village site and the principles of historic preservation. The success we saw with this project would not have been possible without the tremendous efforts of many at the Iowa DOT and the collaboration of many, many partners from our consultation Tribes and Nations.”

You may remember seeing details of the project on our blog in 2017. This video tells the story of the collaboration between the Iowa DOT and the groups interested in the preservation of the site -

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