I live near Boston, and every winter the city needs to deal with tons and tons of snow removed from the streets. The easiest solution is to dump it in Boston Harbor, but the Massachusetts Department of Environmental Protection banned that in 1997 (as part of cleaning up the Harbor). The solution: pile the snow up in vacant lots and let it melt into the Harbor. What's the difference? Dunno...

There's a significant difference in that solids picked up with the snow (gravel, dirt, dog shit, human...) mostly won't end up in the harbor.

The solution to pollution is dilution.

It might not always be true, but it is here.

crude oil is also just organic solids. err... liquids.