I should have used a different term, for clarity. By overflow I meant that the estimated amount of water in the reservoir exceeded its total storage capacity an

I should have used a different term, for clarity. By overflow I meant that the estimated amount of water in the reservoir exceeded its total storage capacity and they had to use spillways to drain the excess. We have a geo engineer on our team and he's saying that while primary spillways are made of concrete, the secondary (emergency) spillways are made of soil and materials and can deteriorate quickly.