Originally Posted by bobys
So by spilling does that mean the state is letting water out, or Is the reservoir overflowing, what is exactly happening?
Over flowing. Basically, dams all have a spillway built in for when there is just too much water to be released by normal means.
"Spilling" refers to the reservoir being so full that water is coming out of the spillway (as designed). "Overtopping" is a very bad thing which is when the water is going over the reservoir at places other than the spillway. Spilling is okay and the reservoirs are designed to handle it. Overtopping is bad and can lead to catastrophic damage such as the damn crumbling.
Cheesman has a very cool spillway that uses natural rocks:
Strontia Springs dam spilling:
An overtopped dam looks like this and is very bad news:
That is pretty much everything I know about dams and spilling.
My question, what does it do to fishing?