60-some miles south of the Twin Cities, the Mississippi River widens into a large body of water that has come to be known as Lake Pepin. (Readers of Laura Ingalls Wilder may recall her girlhood crossing of the river ice there, just before its thunderous spring break-up, in Little House on the Prairie.) Two miles wide and 22 long, with a total surface area of about 40 miles, it's about the same size (and shape) as the famed Loch Ness.
Like Loch Ness, it has its own water-horse. Well, that's what they say.
“Pepie,” they call him, predictably. (Her? It? Them?)
Keep an eye on any sufficiently large body of water for long enough, and you'll be bound to see some strange things, for sure. Just how long folks have been seeing Pepie isn't entirely clear.
Predictably, there are stories ascribed to “Native American” times. Since a number of the local Indigenous peoples knew of “water panthers” that lived in lakes of a sufficient size, that's maybe not surprising.
(Water panthers are water-spirits who have an ongoing feud with the Thunderbirds. A number of 1000-year old effigy mounds in the area apparently represent these water panthers, powers of the Great Below.)
Some have dismissed Pepie as a “20th”-century publicity stunt to draw tourists. Well, people do love monsters, and monster tourism does indeed bring in money. Ask anyone in Roswell, New Mexico.
Admittedly, on the face of it, the prospect seems zoologically dubious. You can't, of course, have just one Pepie, since not even monsters are immortal. You need a breeding population of Pepies, which is another matter entirely. Pepin's a big lake, but it's not that big.
Publicity stunt or not, I suspect something deeper going on here. There's a witch in every woods, a monster in every lake. The language of the Good Folk, of those Others with whom we share the Land, gives us a very real, if nonliteral, way to talk about our relationship with the Great nonhuman Out There.
If you're looking for naturalistic explanations here—leaving aside wakes and floating logs—I'd personally suspect sturgeon. There used to be so many sturgeon in the Mississippi that there was actually a thriving domestic caviar industry, until—predictably—overfishing put paid to it. Sturgeon, which in the Mississippi sometimes grow to a length of nearly three feet, have been around since the Upper Cretaceous period—about 100 million years ago. So maybe, just maybe, there are prehistoric monsters in Lake Pepin after all.