Around California, the country and the world, reservoirs are silently filling with sediment, and only a few people are thinking about it. Among them is Tim Randle, a civil engineer with the United States Bureau of Reclamation’s Sedimentation and River Hydraulics Group. “We used to be gaining water storage capacity with dam building,” said Randle, who is based in Denver. “Now, around the world, the pace is slowing down as sediment builds up. This is true in the U.S., too.”