This creek gets plenty of bad stuff dumped into it. Whenever it rains, all the oil and antifreeze is washed off the roads up stream and flows into the creek. I can see the oily film on the surface. In the winter time, the road salt and the sidewalk deicing chemicals wash into it as well. In the fall, the tree leaves clog the creek and the decaying leaves turns the water almost black. It's amazing the fish survive.
Even scarier is all this stuff flows into a large river a few miles away, and our water company uses that water for our area. Add in the foul smelling "treated" water from the 12 waste treatment plants up river from our town and it's amazing us humans survive.