The Fight to Tame a Swelling River With Dams That May Be Outmatched by Climate Change

There were no good choices for John Remus, yet he had to choose. Should he try to hold back the surging Missouri River but risk destroying a major dam, potentially releasing a 45-foot wall of water? Or should he relieve the pressure by opening the spillway, purposely adding to the flooding of towns, homes and farmland for hundreds of miles.Mr. Remus controls an extraordinary machine — the dams built decades ago to tame a river system that drains parts of 10 states and two Canadian provinces. But it was designed for a different era, a time before climate change and the extreme weather it can bring. And early last Thursday, the Niobrara River smashed through the nearly century-old Spencer Dam while pushing huge chunks of ice downriver. By the end of the day, the Niobrara and other tributaries had filled the reservoir behind the Gavins Point Dam, near Yankton, South Dakota, and Mr. Remus faced his decision.Gavins Point is relatively small, not designed to hold back that kind of inflow. But losing the dam would be catastrophic.To save Gavins Point, he ordered its spillways opened. At its peak, 100,000 cubic feet of water per second, the same as Niagara Falls, poured into a river already surging toward record heights.“Scientists say that, in the Missouri Basin, we’ll be spending more time at each end of the spectrum — longer and more severe floods, longer and more severe droughts,” Mr. Remus said. And this year, he had “nothing but bad options.”