It happens every day with no issues.
Can't quote the specific law, but just for the knowledge I'm going
to look into it. I do have to admit, at this point, that you could very
well be correct.
I live on a section of river that has been declared as "Wild and Scenic"
by the federal gov't. We get runs of five different salmon species, and
a yearly run of wild steelhead, many of which move up into another river
that runs into the Skagit, and it is also legendary for it's wild steelhead fishing.
When you bring dirt from a far away, unknown location and introduce
it into a creek, stream, river, etc., you also introduce all of the foreign
bacteria, and possibly vegetation (seeds) into that watershed. In some
cases, especially when invasive plants take root, this can have a devastating
effect on the local fish and wildlife.
FWIW, although I want to be sure to do my part in protecting wildlife, I'm not
some rabid environmentalist. I do try to think ahead and consider the impact
my actions may have before acting.
Curiosity has gotten to me, so I'll be looking into this soon and will let
ya all know what I find out.