Does anyone have any experience with the effects of copper sulfate being used to treat medium sized impoundments ( 500,000,000 gallons ) It seems that fishing is poor for several days after a treatment , but it could be my fishing ability 

I would imagine they are doing this to control some sort of algae bloom thats going on.  I would imagine that this would impact the fishing.  Im sure the fish need time to react to this chemical being put in their habitat.  Copper Sulfate also kills off invertebrates that bay be beneficial to the forage in the impoundment.  The forage could dye off because of the lack of invertebrates that they used to feed on, which could also negatively impact fishing given that the bass have less forage.  Im not scientist, but this is just my best guess.

Blue stone (copper sulfate) is used to treat algae blooms, very common practice. It can affect fishing for a few days, not a major impact if done properly.

Tom