We already suffer from dead zones in the gulf of Mexico every summer because of fertilizer run off - this could be really bad for the gulf. The wet lands in Louisiana play some part in 90% of all life in the gulf so if it becomes contaminated, that's a huge loss of various seafood.
I read an article - sorry no sauce - that said Resident can do this and not require Senate approval and SCOTUS has supposedly in the past upheld "treaties" signed by presidents and not approved by Senate as binding on all states also.