Maritime Heritage Minnesota has finished a comprehensive sonar survey of Lake Minnetonka and released a final report on what was discovered.
Completion of the project makes Lake Minnetonka the only body of water in Minnesota to be surveyed in its entirety for submerged archaeological resources.
Led by researchers Ann Meriman and Christoper Olson, Maritime Heritage Minnesota conducted side and down sonar imaging surveys of Lake Minnetonka in two phases. The lower portion of the lake, as well as Crystal Bay, was surveyed last fall. A survey of the remaining portions of the upper lake was completed earlier this spring.
Maritime Heritage Minnesota's work was funded by two Minnesota Historical and Cultural Heritage Grants—part of the Clean Water, Land and Legacy Amendment approved by voters back in 2008.
Nine known Lake Minnetonka wrecks had been identified prior to the second phase of Maritime Heritage Minnesota's survey work—three of which were found during the Phase I sonar survey. Maritime Heritage Minnesota completed paperwork for eight of these wrecks, as well as several landmarks around Big Island, to be officially designated as nautical archaeological sites.
Several other identified sites are likely wrecks as well but will remain classified as "anomalies" until divers can complete further exploration.
Both state and federal law protect all officially designated wrecks. A wreck must be 50 years old in order to be designated a nautical archaeological site.
During Maritime Heritage Minnesota's second phase of sonar study, completed last month, an additional 54 objects that appear to be human made were identified. Researchers are confident two are wrecks, but they will remain "anomalies" until divers can provide further information on their age and specifications.
Another nine sites are being described by researchers as probable wrecks, and 24 sites have been designated possible wrecks. They, too, will remain anomalies until divers can provide additional information.
One such wreck in Spring Park Bay is described as being about 15 feet long and likely some sort of motorized runabout or possibly a speedboat.
Researchers have little doubt that another wreck, this one in West Arm Bay, is a pontoon. The sonar signatures of craft's two pontoons, which appear to be connected to a boat deck, pop off the monitor and were easily identifiable.
In all, Maritime Heritage Minnesota has identified well over 130 possible dive sites and prioritized its recommendations for exploration.
Topping the list is what could be a dugout canoe that may have been used by members of the Mdewakanton Dakota tribe. Sonar indicates the anomaly is about seven feet long and rests in the shallow waters of upper Lake Minnetonka.
Second on Maritime Heritage Minnesota's prioritized wreck exploration list is a site near Shady Island. It is the approximate size of a steamboat that was renamed several times over its lifetime (Governor Ramsey, Excelsior, Lady of the Lake, Minnetonka, Mermaid) and could be
Third on the list is what Maritime Heritage Minnesota says is almost certainly a dredge boat on the bottom of St. Albans Bay.
But a wreck in Wayzata Bay has perhaps the most questions surrounding it. Further exploration is needed, but the size of the wreck raised the eyebrow of researchers, and there are no reports of such large craft sinking or having been scuttled in Wayzata Bay.
About two dozen other sites located throughout Lake Minnetonka are on the prioritized list of exploration locations.
Investigation of the newly-identified Lake Minnetonka archaeological sites will be coordinated and organized in the coming weeks and months utilizing what Maritime Heritage Minnesota says will be interested and volunteer divers.
Completion of the study sets the stage for what could be the state's first National Historic Shipwreck District and potentially an underwater archeological park.
Editor's note: All information contained in this post was provided by Maritime Heritage Minnesota. The complete LMS-2 Report can be viewed and downloaded for free by clicking here.