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For immigrants moving into the St. Croix River region in the 19th century, the river and its tributaries were priceless conveyances: transporting millions of logs downstream, and carrying settlers and their goods upriver.

Before railroads were established, water was by far the best mode to transport large amounts of people, equipment, and logs over long distances. The first train didn’t reach the St. Croix until 1871, and it took decades to cover the region. Before rails were laid, the only alternative to riding the river was laborious land travel along footpaths and wagon trails.

The St. Croix was the interstate highway of its day. Just like today, its maintenance was supported by both the state and federal government.

In an online presentation last month, three National Park Service historians shared the story of the construction of wing dams and other river modifications constructed between 1875 and the 1930s on the St. Croix River between Taylors Falls and Stillwater by the U.S. Army Corps of Engineers and local steamboat pilots and workers. The presentation was organized by the Minnesota Historic Preservation Office, and moderated by state archaeologist David Mather.

The years of river manipulation were undertaken so it could carry the most cargo and passengers possible. Not only are many of the structures still present today, but they still perform their intended function.

Historic diagrams of river navigation improvement structures, courtesy National Park Service

Wing dams extend into the river from the banks, pushing the water toward the middle to create a narrower main channel, which is faster and deeper and can carry more boats. Closing dams were built to keep water out of side channels and backwaters, again to improve main channel navigation. In other places, banks were reinforced with stone to prevent erosion.

What once made it possible for countless paddlewheelers to make their way along the river and to keep log drives moving, now help canoeists and kayakers from running aground, and have probably saved a few boat motors.

Over the past decade, the National Park Service has been studying the structures and seeking to understand their history. It has involved extensive research in federal archives, turning up original hand-drawn maps and figures, journals and reports, and underwater forays by specialized archaeologists who study submerged historic sites.

In 2015, the National Park Service’s Submerged Resources Center and Midwest Archeological Center collaborated with the St. Croix National Scenic Riverway to document the extensive United States Army Corps of Engineers improvements along the St. Croix River.

From 1879 to 1900, the Corps built 3.6 miles of wing dams, closing dams, jetties, revetments, and shoreline riprap to regulate the river and make it a predictable commercial highway for steamboats and log drives. As part of this investigation, fifty historic water control features were identified and studied between Taylors Falls and Afton, Minnesota.

These extant features continue to be observable in the river today. To the unsuspecting eye, they may appear to be natural islands, sandbars, or rock piles. In actuality, they are remnants of manmade infrastructure from the river’s days as a robust commercial thoroughfare. The study provides an opportunity to share this story with the public in hopes of provoking visitors’ appreciation of the complexity of past and present human interaction with nature.

– MN State Historic Preservation Office

The entire study began with now retired park cultural historian Jean Schaeppi-Anderson, who first began thinking about the structures when she noticed them during another low water year, in 2007. In 2012, she enlisted a seasonal worker who happened to be a graduate student in history, Dan Ott, to conduct research. Ott is now Cultural Resources Program Manager with the Mississippi National Riverway. His work led to the involvement of a nationwide team of National Park Service archaeologists who specialize in underwater work, led by David Conlin. The program is now under the purview of Jonathan Moore, Cultural Resources Program Manager with the St. Croix National Scenic Riverway.

Moore said during the question and answer session that the studies will very likely lead to nominating the navigation projects for the National Register of Historic Places.

Historic diagrams and maps of river navigation improvement structures, courtesy National Park Service

Some of the work included surveys around the Boom Site near Stillwater, which is already a registered National Historic Landmark. The presenters said the current designation focuses primarily on the bluff-top region where the logging boom’s buildings and support were, but the river study may help expand the designated area to include historic features in the river.

This summer, taking advantage of the low water, the Park Service brought in companies that specialize in underwater photography and mapping, to better document the existing structures.

A wing dam by itself can be a little “underwhelming,” says Moore, as they were simple structures of stone and logs — but looked at as a whole, they become charismatic. They have survived a century or more of freezing winters, spring thaws, and hot summer sun, he points out. Today, one of the biggest threats to these human artifacts is humans themselves. The Park Service has already seen several places where people have removed rocks from the historic structures, probably unaware of their signficance.

“Isn’t it awesome that 140 years, or 100 years later, [the structures] are still there to behold and some of them are influencing how the river behaves?” Moore said in closing. “Please, enjoy and celebrate them, but please don’t harm them or change them.”

St. Croix 360 observed the underwater archaeology in 2015 and published two articles about it at the time:

• Diving For Dams: Historic ‘Road Construction’ on the St. Croix River
• River Bum Blog: Covering Archaeology From A Kayak

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