Hey there Carl.... I was there a few years back when the train derailed on the Cantara Loop and went into the Upper Sacramento. The Cantara Loop is an Infamous stretch of track just north of Dunsmuir, CA. Hunt up the Dunsmuir website, and you can probably get all the details from their local newspaper there. It was a BIG deal. It killed every fish downstream of the spill for many miles. They did a very thorough cleanup, and now, about 15 years later, the stream has fully recovered. I believe there were catchable trout there in about five years. I fished the river there a lot before the spill and it was a very good trout stream. I was back there fishing about seven years after the spill, and caught fish, but the streamside vegetation was still not back fully at that time. The spill wiped that out as well for a for miles. That spill was not chlorine, but some other more nasty chemical, and the derailed train laid there in the river for several days before they got it dragged out.
There was diesel fuel and other stuff involved as well. Good news is, the upper Sac. is back in spades, and has been for some time now. Your stream will recover too, faster if it gets proper help..........................................Modo cDan