These uniquely shaped rocks are from an area north of Mandan on Highway 1806. They’re part of the excavation and construction of the earthen dam of the Harmon Lake project. While they look pretty bizarre, they’re simply the result of normal geologic processes. They’re called “cannonballs” and are not all that uncommon in our area.

Just like a Tootsie Pop, they have a center that differs in composition from the outer layers. I don’t think their internal composition is what makes them stand out so much; rather, it’s their round or egg-shaped appearance. In the case of these particular rocks, their size is remarkable too.

I’d heard about the Harmon Lake project a while back, but never seen it for myself until recently. It’s not often that a guy finds himself traveling north on 1806…heck, it even turns to gravel just a stone’s throw north of here! If you do find yourself in the area, however, it’s not easy to miss the big piles of dirt to the left of the roadway. Originally the concrete tower of the overflow control unit stood out like a water tower; now it’s not even visible from the highway side of the dam any more.

This is the backside of the dam. Construction is still underway, but was halted on this particular day because of rain. Once it’s completed, this will be a recreational area for all to enjoy. The project actually began in 1969 (just like yours truly) when it was first designed, but is only now coming to fruition. Upon the groundbreaking back in 2003, it was expected to be completed in 2005. I guess they missed that mark.

This 2100-foot long, 67-foot tall dam and the 144 acre lake it will create are a joint effort between ND Game and Fish, the cities of Bismarck and Mandan, and the State Water Commission. The USDA’s NRCS (Resource Conservation Service) kicked in a grant for almost eighty percent of the project’s anticipated $11 million cost.