Other U.S. laws regulate both safety and environmental issues, but you seem to be assuming that foreign vessels are more likely to break them than the Jones Act.
As far as I can tell, though, the Jones Act doesn't regulate country of manufacture or require exclusive U.S. operation; it only requires U.S. flagging and crews. A foreign-flagged vessel is not really more or less likely than a domestic-flagged one to have been constructed in the U.S., or to have been transported here from elsewhere, or to operate elsewhere.
It's entirely possible (if French law permits) to have a U.S. flagged ship built in France that does river cruises on the Seine but occasionally sails (or realistically gets transported) back to the Mississippi, bringing with it whatever is stuck to its hull. On the other hand it's theoretically possible without the law to have a French-flagged and crewed ship that is built in the U.S. and never operates anywhere but the Mississippi, which seems to still satisfy your requirements. The Jones Act is an employment and profit law, not a health, safety, or environmental one.
> The Jones Act is an employment and profit law, not a health, safety, or environmental one.
And yet this does not guarantee repealing the Jones Act will not introduce environmental issues, and I'm not sure why we'd have such strong sympathy for limited profit opportunities of foreign operators and vessels restricted by the Jones Act.
As far as I can tell, though, the Jones Act doesn't regulate country of manufacture or require exclusive U.S. operation; it only requires U.S. flagging and crews. A foreign-flagged vessel is not really more or less likely than a domestic-flagged one to have been constructed in the U.S., or to have been transported here from elsewhere, or to operate elsewhere.
It's entirely possible (if French law permits) to have a U.S. flagged ship built in France that does river cruises on the Seine but occasionally sails (or realistically gets transported) back to the Mississippi, bringing with it whatever is stuck to its hull. On the other hand it's theoretically possible without the law to have a French-flagged and crewed ship that is built in the U.S. and never operates anywhere but the Mississippi, which seems to still satisfy your requirements. The Jones Act is an employment and profit law, not a health, safety, or environmental one.