Hanover’s historical dam site surveyed and renamed
It was a raw, windy mid-November day last year when Ann Merriman, PhD and co-owner Christopher Olson, MA of Maritime Heritage Minnesota (MHM), donning dry suits, waded waist deep into the frigid 40-degree Crow River to investigate the original Hanover dam remains. Members of the Hanover Historical Society first documented the site back in 2003 and have kept close tabs on it ever since, revisiting the site when water levels were low to continue chronicling the remains.
Background Information
According to information passed down from Vollbrecht family members over the decades, brothers Jacob and William Vollbrecht, the town founders, built a dam and sawmill along the Crow River. “They reportedly had the mill operational by December 1856. On February 8, 1857, that dam broke, and the mill and part of a residence washed down river,” stated a handwritten letter written by Luella Marie Vollbrecht Smith, which now is part of the historical society archives.
The Hanover Historical Society applied for a Legacy grant through the Minnesota Historical Society in 2025 with the grant period recently ending. MHM was awarded the bid to perform an underwater archaeological survey of the historic log dam remains in the Crow River. With the heavy rains, high water levels, and swift current throughout the spring and summer, the team was finally able to safely get into the water in November having completed pre-disturbance work in June along the river banks and via boat. The SONAR work was a remote-sensing survey, and the entire project was a Phase 1 pre-disturbance survey.
Battling a stiff current and deep water in June during the first site visit, the team utilized their sonar equipment to search for timbers that were not visible above water.
“Interesting stuff in here,” she remarked after a third pass on the river by boat, “there’s more down here than we thought. It looks good. The integrity of remains will help determine if it is eligible for listing on the National Register of Historic Places (NRHP).”
About 100 yards west upstream from the concrete Highway 19 bridge toward Rockford, SONAR indicated what may be three sizeable pieces of the dam. “It’s right along the shoreline on the Wright County side,” she told me. “The Hennepin County side is different because there are more weeds. The SONAR will stop at the weed line, so that side is much less defined. It makes sense that most of the ruins would be on the Wright County side because of the way the river winds in and out; it’s going to go faster around that corner. Just from Google Earth pictures, I can tell you that the dam is there. The remains you have are the dam; I have no issue with that at all.”
Now in November 2025, with the dropped water levels, the duo conducted final pre-disturbance documentation (measuring exposed and submerged timbers, noting the rocky shoreline and location of where the logs jut into the rocks, brushing leaves and muck away from the logs and rocks). They noted the water depth of about four feet on the Wright County side and 4.5 feet in the middle of the channel where the dislodged longitudinal timber was sticking out of the water, and a swift current on this November afternoon. Visually, timbers now protruded on both sides of the river.
“Rocky bottom,” Olson called out as he stood in the frigid water and began stretching his tape measure across a log with Merriman securing it to her end.
“The logs look to be in good shape,” Ann noted as she and Olson measured and drew. “The visibility is not as great. If we can get what’s visible here and on the other side of the river, we can get on the site plan of what’s above and below water. It’s going to be interesting.”
I learned that the logs will continue to deteriorate from their ends in the water until they are gone. “There is a way, however, to prevent that,” Merriman explained. “You would have to build up an artificial “dam.” It would be like filling up and placing sandbags around the timbers because the sandbags would never move. You wouldn’t necessarily have to bury them in the water, just protect them from the very strong current around the logs. It’s an option and a preservation suggestion we can make a part of the report.”
When I asked if the German Vollbrecht brothers who built the dam may have had knowledge of various aspects related to construction like this, such as how strong of a current and the use of rocks, Merriman wasn’t sure how much they may have understood. But after investigating the ruins on the Wright County side where more logs were exposed, she confidently concluded: “These guys who built this were good. For this to still be here, they knew what they were doing. They certainly would not have wanted to spend the time to build a dam and then have it wash away. Did they understand this root system here prevents erosion?” she said, gesturing to an old tree whose exposed roots trailed down toward the shoreline. “I don’t know. Maybe after it washed out they still used it to pool logs. Who knows,” she added, “it definitely wasn’t a hindrance to navigation as the river was never that navigable for larger boats, although smaller vessels could use the river most of the time.”
She clarified my question about landowners on the Wright County side. “The shoreline is owned by the State of Minnesota,” she explained. “The Office of State Archaeologist (OSA) manages archaeological sites, but the State of Minnesota owns the greater body of land/water. The site is on state land – the entire thing is on state land, no private land.”
The two archaeologists discovered the bottom base of the timbers on the Wright County side were still in situ (intact) on this late fall afternoon. They located multiple layers and counted more than 130 timbers still underwater. “We’ve got timbers going transversely/horizontally and then longitudinally. Two layers survived; maybe more are incorporated within the rocks and sand or whatever else is holding it in place. This is amazing so much has survived; I never imagined there would be that many surviving layers,” Merriman admitted.
Grant Goals
Project goals under the grant included analyzing and documenting the structural and historical features of the site. The collected data was then used to determine if the site qualified for nomination to the National Register of Historic Places in collaboration with Minnesota’s National Register Archaeologist.
With the fieldwork completed in November, MHM then conducted extensive historical research to place the site into Crow River transportation, manufacturing, and economical contexts. Of particular interest was background history of the dam construction and use on the Crow River in other communities, such as nearby Rockford. Research indicated that the Vollbrecht brothers were sought out to build area bridges, not just the Hanover bridge, due to their expertise. Thus, the archaeological data produced during the fieldwork portion was then enhanced with historical research.
Collectively, after analyzing the archaeological fieldwork data and their historical research, a Minnesota Archaeology Site Form for the dam site was created. The site received two numbers – one for Wright County and another for Hennepin County.
Final Survey Report
The site was officially renamed the Vollbrecht Dam Site and will be reflected as such on the Minnesota Archaeology Site Form.
Finally, a comprehensive archaeological and historical report analyzed and described the archaeology and related history of the Vollbrecht Dam. Minnesota has three classifications of dams: logging dams, mill dams, and WPA (Works Progress Administration) dams. “The Vollbrecht dam is a logging dam because it was designed to create a pool of water on its upriver side to collect logs for processing,” MHM’s report stated. “The Vollbrecht Dam Site is a significant archaeological site that is intrinsically valuable due to its unlikely 170-year survival in the dynamic and flood-prone Crow River. The dam site’s extensive in situ timber components, at least 12 layers thick at its northern end, have retained their integrity as archaeological attributes of a timber crib dam,” continued the report.
“The Vollbrecht Dam Site, determined through Minnesota State Archaeological records, is the best preserved and oldest known post-contact archaeological timber crib dam site in Minnesota,” continued the report findings.
Now that the site is documented as a unique maritime archeological site, the next step is to determine if it is warranted for National Register of Historic Places nomination. NRHP evaluation guidelines consist of four criteria, but not all four need to be attained. The archaeological report suggests that perhaps two of the four criteria may be met.
History plays an integral part in our community’s past and its impact on daily lives, both past, present, and future. Regardless if the site is designated on the NRHP or not, history matters. Learning more of the history of the Vollbrecht brothers and their economic contributions to Hanover via their dam and bridge construction, as well as their mills, is an important and rich legacy.
NOTE: This project has been financed in part with funds provided by the State of Minnesota through the Minnesota Historical Society from the Arts & Cultural Heritage Fund.
Merriman and Olson are the only Underwater Archaeologists working in Minnesota and licensed by the Office of the State Archaeologist.
