Most urban waterways have seen their share of abuse. Having acted as lifelines of industry and commerce long before anyone ever paused to consider environmental consequences, these rivers, streams, and canals have absorbed decades worth of industrial waste, chemical runoff, and untreated sewage, most of which was eventually carried into the ocean, thereby accounting for the mercury content of much of the fish we eat today.

But what if that waste hadn't been carried away? What if, instead of being swept out to sea, all those chemicals and byproducts remained right where they were dumped, festering for decades in the middle of a busy city?