And when you put it in your trash at home, depending on where you live
there's a good chance it'll end up right back offshore again.

In some cases this may be true. In some cases if you separate your recycle
it gets thrown into the landfill anyway for any number of reasons.

There are lots of things that go on "upstream" of our garbage that
"shouldn't" in an ideal situation, but at that level you're dealing with
municipal/provincial (or state in your case) inertia and priority
balancing -- ie very slow and cumbersome with big financial limitations.

But we can immediately affect our water quality by not throwing stuff in it.
It doesn't remove the upstream problem (or should that be downstream?), but
at least it doesn't add to it.

Like Clams I can't bring myself to throw stuff overboard, just don't have it
in my DNA to do it. If I spy something floating I'll reach it out with my
boathook if possible. It may be completely useless in the grand scheme of
things, especially considering the fuel I burn ... but it's the best I can
offer.