Sometimes. Usually they are for completely different design criteria than this example. Review the Big Glen Canyon Daminside the state of Arizona and find out why they are considering taking it out of service. Locally, along the Missouri River right here in South Dakota, these large dams were projected to have a useable life span of near 200 years. This has been updated and found that these dams could possibly be silted shut in less than 75 years. What if smaller structures were placed in the watershed on the tributaries feeding the Missouri? Maybe it’s not too late to start improvement projects. What if every third or fourth tributary along the Sioux River between Watertown and Sioux City was modeled this way? There would appear to be very little chance of the Big Sioux going into flood mode. Dirt, sediment and nutrients could be left behind for the agricultural producer to use.and did cleaner water get mentioned?