A major supplier of oil to the NWT is the Norman Wells Refinery from which we lifted many thousands of tons of various oil grades including Bunker C.
At the end of a shipping season, the refinery would drain its pipelines into the Mackenzie from which point it would float downstream into the delta through the bird sanctuaries to the coast.
I have followed a couple of these "flushes" down river and there was no sign of dead fish or tarred birds.
Then, there was a bunker spill in a place called Bar C aka Tununik. Being close to an ESSO camp all the boys toys came out and I had a chance to play with all of them. Slick-Lickers similar to what you see on TV today had a good but limited success in containment.
Straw and peat moss (Use a carbon base material to filter or soak up a carbon base spill) was the most effective and also the most manual labor. Garden rakes proved to be the most useful tool in collecting the mix into bags to be hauled away.
Oil spills in running water such as ditches can be contained with the use of straw. Put a straw bale below the offending spill and the oil will be stopped by the straw bail allowing only clear water to pass.
And now to the dispersant:
Still in Bar C, dispersant was added to the water/oil mixtures. Gone from sight; gone from mind.
I must say at this point there was no indication of dead fish of any kind while working with the mechanical clean up apparatus.
However after the dispersant applications dead fish littered the banks from Bar C to the Arctic ocean.
I am of the opinion after working in this, that dispersant is far more harmful than the oil and at the same time, the damages from the oil is grossly over blown!