you wanna talk about sludge and liquid waste from industry take a look at the oil sands in Alberta. To extract the oil out of the sand they have to use 5 barrels of water to get 1 barrel of oil. The leftover sludge is extremely watered down clay which will take many many decades to settle. So not only is all of this water being taken out of the river system, it will be sitting in man-made pools for many a-decades to come. Just one of these pools is the size of downtown Vancouver.
Let's hope that the damns never break and all that sludge doesn't end up back in the Athabasca River... that could shut down the river completely, and that's probably the least of our worries. (I talked about the oil sands in Alberta in a past blog if you choose to look into it some more)