There are lots of them all through the trout streams of Central Wisconsin like the Mecan, Pine, White and Tomorrow Rivers. You'll be fishing along and you'll see them along the stream margins, like little hot air poppers that keep a small column of sand in a state of perpetual percolation.
And while I know less about it, it would follow that a lot of the streams of Michigan's Lower Peninsula have them as well. Its the same geology.
I've also seen them, but considerably fewer, on smaller streams in portions of the ANF. Mostly in the upper Mill and Bear Creek watersheds in the Clarion drainage, but also on the SB Tionesta and a few in the Kinzua watershed.
Anywhere where the prevailing surface geology is sand and as a result, sand substrate dominates the streams.