Merriam-Webster defines a steelhead as: "an anadromous rainbow trout ". Merriam-Webster defines anadromous as: "ascending rivers from the sea for breeding". Merriam-Webster defines sea as: "a great body of salt water that covers much of the earth" (among other definitions).
I propose we call our big-lake-run, bigger-than-some-of-the-great-lakes'-steelhead rainbow trout "steelhead" as well.
And without a dime of taxpayers' money, Montana could boast some delightful "new" fishing opportunities.