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History lesson alongside Iowa 31


DSC_0172On the surface, it looks like just another erosion control project. But under the surface, the project on Iowa 31 in Woodbury County is a dive back in time.

In December 2015, Dixie Nelson, now-retired Iowa Department of Transportation highway maintenance supervisor in Correctionville, noticed some erosion on the cutbank of the Little Sioux River running alongside Iowa 31 near Anthon. She contacted the Iowa DOT's District 3 Office in Sioux City to start the process to stabilize the area. As it turns out, there is much more to this story than a need to firm up the riverbank.

A little history on Iowa 31
IMG_1007This particular road provides a wealth of historical information about northwest Iowa. In 1913, the golden days of railroads, the Illinois Central Railroad channelized, or in essence moved, the Little Sioux River to allow for the construction of a straighter rail line. After the rail line was abandoned, the Iowa DOT bought the railbed in 1967 and built Iowa 31 more or less on top of it.

Over the years of building and repairing Iowa 31, several sites with historical significance have been found. By law, the Iowa DOT is required to protect these areas, but it's also the right thing to do. The Iowa DOT's cultural resources unit, a part of the Office of Location and Environment, is charged with overseeing projects that might impact historically significant sites. Annually, the unit is involved with approximately 500 to 600 projects, about a quarter of those require an identification effort or archeological survey of one kind or another. The Iowa 31 project uncovered a large Native American village documented to be occupied around A.D. 1350.

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

Brennan Dolan, one of the Iowa DOT's archeologists, is working on the Iowa 31 stabilization project. He said, "Back when the railroad channelized the river and then when we took over the railbed and built the road, preserving historical sites wasn't a focus. But we did have good information that there was a site in the current work area. We needed to come up with a plan to allow a contractor to get in and stabilize the riverbank, but at the same time preserve as much of the village as possible. We had to do this in a way that makes sense, balancing the construction needs and impacts to the river and the site."



Working with partners to find a workable solution
Dolan said one of the keys to the project’s success was early conversations with groups that would be working on or impacted by the project. He said, "Within the Iowa DOT, there was great communication between several offices. From Design to Bridges and Structures to the District 3 folks, everyone worked together to do what was best. Whenever there are many different groups involved, compromise is needed. But we all wanted the same thing, to stabilize this riverbank for the long term, but impact as little of the historically significant land as possible."

In developing the project, the Iowa DOT reached out to the landowners and Native American tribes to hear their concerns and work with them to preserve their history. Dolan said a unique partner on this project was the Army Corps of Engineers. "Since this project didn't require federal funds, we weren't working with the Federal Highway Administration as we would normally do," said Dolan. "But we were going to be working under the same federal guidelines with the Army Corps of Engineers as the lead. It's not typical to work with them in this way, but they were as dedicated as we were to deliver a quality project as quickly as possible."

Several groups collaborated on the excavation phase of this project.

The University of Iowa Office of the State Archeologist and impacted Native American tribes and nations all collaborated in the planning and execution of the project.

The solution all parties agreed to was to complete archeology on four select segments of the larger project area to give the contractor access to complete the riverbank stabilization without disrupting the majority of the village site. Dolan said, "We're working smarter. This village is larger than the highway project work area. If we had conducted this project using our standard method of archeology, excavating the entire historic site, it would not have been feasible to complete. We chose four smaller segments that would give the contractor the access they need without disturbing a majority of the site."

What was found at the site?
As is typical for the excavation of a historically significant site, the Iowa DOT contracted with an archeology company to complete the field work. Dolan said, "For this project, we worked with OSA. At various points along the process, a number of Native American representatives were on-site. Working in 10-day sessions, the group excavated four selected access points, identifying and collecting artifacts from the village that lies embedded in the riverbank."

Archaeological field crew
Archaeological field crew completing data recovery excavations

Dolan continued, "The preservation at this site is phenomenal. We study the people who lived here and the way they lived by analyzing what was left behind, from large stone tools to animal bones all the way down to microscopic residue on their pottery."

Based on information already known about the site and the pottery the team recovered, the likely inhabitants of this village were connected to what archeologists call the Oneota Tradition. Dolan explained, "In historical terms, that's the label we've given this people group based on the technology they used. It's not a name they would have called themselves. This archaeological culture included Siouxan-speaking tribes like the Ioway, Oto, Missouria, Omaha, Ponca, and Dakota bands that lived in the prairie-plains region."

Prehistoric pottery from the bank stabilization project near Anthon.


He continued, "This site, and sites with this kind of preservation, offers a truly remarkable glimpse of past life in Iowa. Because this site is so well preserved, we can get a look at the way these people lived at a household level. Some of the artifacts we found would not have been produced here, so we can infer that the people were involved in trade at some level. Some, not all, of the animal bones uncovered also suggest they either hunted long distances away or traded for animals native to distance areas."

While the Iowa 31 site is unique in its size and high level of preservation, the age of the artifacts is common in Iowa. Dolan said, "This time period is pretty typical in the projects we deal with every day."

What happens now?
The archeological excavations were completed in July 2017. The contractor has stabilized the cutbank. The recovered artifacts will be analyzed and studied by archaeologists. Long term, they will be retained in a secure, climate-controlled storage facility for future research. They may be made available at some point for educational programs or exhibits in museum displays.

Dolan said he is happy with the way the project was developed and carried out. He said, "The project’s outcome provided stability for a highway that Woodbury County travelers use daily; at the same time, we respectfully preserved a good portion of a really interesting place that documents how people lived in Iowa 700 years ago. It is a win-win."

A great summary of work on an important site. DOT is to be commended.

Nice writeup about a fantastic site!

Excellent article and Brennan deserves high praise for facilitating a challenging preservation project that is a true win-win: Hwy 31 will remain intact as will the irreplaceable Oneota village deposits.

Congratulations on successfully preserving the roadway into the future, and the pathway into the Past.

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Iowa highway in the evening