Not sure what the Federal regulations are/were. However, Lake Tahoe, which is about 20 miles from us, prohibits any carbureted two strokes. IIRC, some of the manufacturers are offering direct injection 2 strokes on larger motors which apparently meet the emission requirements as shown on the link.
It was said that the 2 stroke ban on Tahoe was merely a backdoor attempt to ban Jet Skis. Along came 4 stroke and direct injection 2 stroke jet skis, which are still with us.
Some years back there was proposed legislation, which was narrowly defeated, in California, to ban 2 strokes on any body of water that eventually drained into any drinking water supply. That would have effected almost all fresh water lakes in the state. It seems likely, to me, anyway, that the EPA will do that, and not allow existing 2 strokes to be grandfathered.
I have owned 8 - 2 stroke outboards, both large & small, plus 2 -4 strokes which are considerately heavier than comparable 4 strokes. 2 strokes are much easier to start manually, and when properly jetted & run hard, smoke very little, just at low speed & when first started. I was forced to buy a 4 stroke to fish on Lake Tahoe, but no doubt 2 strokes will be banned on all fresh water sources, followed by coastal salt water & bays.