Scientists have declared November's experimental man-made flood of the Grand Canyon a success—at least for now. The endeavor, which saw researchers pump up the flow of water through the Glen Canyon Dam from its usual 8,000 cubic feet per second to 42,300 for 24 hours, appears to have done what it was supposed to do: create new sandbars, campsites, and fish habitats, the Arizona Republic reports. More than half the beaches and sandbars the team was monitoring grew substantially, with some nearly doubling in size.
But the looming question is how long the effects will last. "Every time we do a flood, it builds sandbars," says one research hydrologist. "And they tend to erode in the six months to a year following the floods." Overall sandbar buildup has been on a downward trend for years, in part because the dam blocks the Colorado River's sediment flow. Some believe frequent flooding is required, while others call for even more drastic measures, like transporting sand around the dam—or breaching it altogether.