A creek is defined as smaller than a river and bigger than a brook, so that's a lot of leeway. (It's clearly smaller than the Mississippi or the Amazon, for example.)
At any rate, it is explicitly labeled Breach Creek in the map of the town on the inside cover of Hellknight Hill.
If it's a big enough disconnect for a table, renaming it Breach River is fine.
We went with Breach Creek because it sounds neater when you say it out loud, and because the word "creek" helps to make the settlement feel smaller and more remote.