“Engineers and planners don’t actually know what the worst case scenario drought will be over the lifetime of a reservoir.”
Optima Lake Dam in Oklahoma was finished in 1978 and never got past 5 percent full, because groundwater pumping dried up the river feeding it. Lake Mead hit a record low in June at 175 feet below full. Reservoirs are sized against the worst drought anyone has recorded. The worst one is the one we haven’t had yet.