Interesting that you think grading the stream bank would violate federal law. Not saying you're right or wrong, personally I don't care about federal law and we've contacted state EPA recently without any response so enforcement is laughable at best depending upon location.
Our conservation office did a public event on our farm years ago and recommended grading stream banks for areas on our farm and said cost sharing was available if we wanted to do that. We didn't care to incur costs for non revenue generating projects, as any business should, but were open to pursuing if they wanted a demo site--didn't end up happening.
The head of my township also recently texted me saying landowners are allowed to move dirt on their property without permit/approval 🤷 ... Holding on to that text 😏