Adding to the confusion is the nearby township named Four Mile. I chose to use the USGS name since that's the one that seemed to work best when searching official documents. Not being a local I was hesitant about changing the name since the government has made errors in the past. Naming convention here probably should be to use whatever makes it easiest for people to find things, so common usage should trump "official" as the primary name. If locals use two words for this creek the "official" nomenclature can go in the AKA field.
Apparently the official USGS name for the waterway is Fourmile Creek.
However, I'd wager that it's one of those "It really doesn't matter" sort of situations about the waterway's nomenclature. Ergo, does not matter whether we spell it "Fourmile" "Four-Mile" or "Four Mile", as it's gone by all of those variations in nomenclature.
However, for specificity's sake, we should leave it as Fourmile.
Just like to point it out Clark, Polk county refers to the creek as "Four Mile Creek" and other sources refer to it as "Four-Mile Creek"
The more common name is probably Four Mile Creek, not fourmile creek.