Twin Cities waterproofing. 5 Twin Cities counties served.

The water was here first.

Most Twin Cities neighborhoods were built on land that had to be modified to make it buildable. The lakes the cities are named for — Bde Maka Ska, Lake of the Isles, Powderhorn, Cedar — were dredged and lowered between roughly 1880 and 1920 to drain the wetlands around them. Tens of square miles of marsh, peat bog, and tamarack swamp got tile-drained, filled, and platted into the streetcar suburbs that still define the metro.

The water didn't disappear. It moved sideways into the new municipal storm sewers, downward into the soils, and laterally along the bedrock contacts that defined where the wetlands sat in the first place. A century later, every basement built on a former wetland still sits over a water table that remembers exactly where it used to be.

That's what “the soils we know” actually means. The geology is the same whether you're in a 1920s bungalow in South Minneapolis or a 2010s subdivision in Woodbury — late Wisconsin glacial till, scattered peat lenses, perched groundwater on Platteville and Decorah bedrock, and the persistent influence of the Mississippi and Minnesota River watersheds. The construction era changes. The water doesn't.