 idea that that streams themselves are just moving water but the truth of the matter to the layman is that streams are also moving sediment with them and when we put dams up that's stopping that sediment transport you know we can still pass water over we can send it through chutes or spillways or send it over you know a portion of a dam but you're never passing sediments fully and that's where you really get a huge maintenance impact the backside rapid and dan had 100 years of sediments