Remediation is always more expensive and less effective when treating across a diffuse area (which happens when moving the toxic sediment downstream) than in a single contained area.<p>As a civilization we&#x27;re gradually getting better over time at remediation of large-scale &quot;waste&quot; like this, but still primitive considering our state of the art capabilities; we still don&#x27;t recognize at a systemic, industrial design level that waste is materiel that we don&#x27;t understand an economic use for yet, or understand how to transform into materiel we want at a thermodynamically desirable cost.