The Gowanus Canal just sort of sprawls, slack and flat and brown and grease-slicked and awash in pesticides, PCBs and metals, across 1.8 miles in South Brooklyn. It is one of the most polluted waterways in the United States, which is a fact that essentially no one disputes. So in one sense, it’s not a surprise to read that the Gowanus Canal was tagged a Superfund site by the EPA on Tuesday. If there has ever been a more deserving Superfund site it… well, it would’ve had to have been pretty freaking nightmarish. But while the Gowanus is certainly apocalyptic enough in its noxiousness to deserve the Superfund label, there were some in New York City — including Mayor Bloomberg and several big real estate developers — who fought against that designation. Some of this is easily explained — the Toll Brothers at one point planned a 600,000-square-foot mixed-use development (with a freaking esplanade) along the Gowanus; Michael Bloomberg has almost certainly never been to Brooklyn — but what’s the debate, here?