OK, the guy hosting the website I linked has an excerpt about US Army in recent times still having bluewater boats around in landing support roles:
There are still Army transport vessels. They are little known, but apparently that was the case back when the world was at war and the great Army fleet got little notice. They plug along doing those necessary jobs without a great deal of publicity and recognition. They carried cargo, troops and fought in Vietnam. They are prepared to support rapid deployment today. I suspect even other soldiers are often surprised to find exactly what an 88K does. I wonder if they are still the only troops with authorized footgear of "tennis shoes" or today's equivalent. Today's fleet is limited in scope, but still interesting. Link
In 1999 I spent a dampish October morning looking at traffic leaving the Chesapeake for the Atlantic from my motel balcony in Virginia Beach. I saw a line of small Navy vessels that looked a bit odd. When I got my glasses on them I realized they were not Navy. They were some of the newer landing craft that are much more ship like. I then noticed the Army insignia and realized I was seeing Army vessels at sea. They were all flying a brilliant red flag with some sort of gold device that I realized had to be that of the Transportation Corps. These were probably operating out of Fort Eustis.
And a contemporary novelist (Christian Bauman) has used Army boats in his novels and has a small page on them here
(with a photograph depicting a old looking LCM-8 craft loading up what looks like Army/Marine infantrymen).