The Army Corps of Engineers is also sending out a warning, alerting users of the Columbia River of low water levels downstream from Bonneville Dam. This coming Saturday, the Corps plans to shut off flows that provide for spill over Bonneville and other Columbia River projects. Those spills are intended to help flush juvenile salmon downstream to the ocean. That extra flow is no longer needed, though water will still be flowing through dam powerhouses. At the same time, they’re going to start storing water behind Grand Coulee Dam for a variety of projects. By Labor Day, water levels on the Columbia from Bonneville to Longview could be as much as four feet lower than they would have been on Friday, the 30th. Boaters are advised to use extreme caution, particularly when anchoring in shallow areas. Water levels could drop considerably in just few hours, due to the multiple effects of low seasonal flow, the flow reductions from the dams and the cycles of the tides. Other low-water hazards will also become more prominent.