The argument focuses on US made dredges being uncompetitive and dirty (makes sense), but then the proposed changes to the law would prevent the EPA from performing environmental reviews!
My understanding is that, currently, both the US Army Corps of Engineers (USACE) and the EPA share jurisdiction over US federal environmental reviews for dredging. (I think other agencies may play some role in that process too, such as NOAA Fisheries.) Senator Mike Lee's "DEEP Act" proposal would remove the EPA's jurisdiction, but USACE would still be legally required to perform an environmental review. So it is not completely removing federal environmental reviews for dredging projects, just removing (or reducing) one federal regulatory agency's role in them.
That does seem likely to reduce bureaucracy, with likely reductions in project approval costs and potential speed-ups in environmental approval timelines. Would it have an environmental cost? I don't know. I suppose, it is possible (maybe) that USACE is more lenient than the EPA, and hence giving USACE exclusive federal environmental jurisdiction would result in more lenient environmental protection conditions and mitigations for dredging projects, resulting in greater environmental harm overall. But I don't know if that is actually true. And even if it is actually true, I'm not sure how big the quantum of additional environmental harm is going to be, or even how one could go about estimating that.
