More lawsuits have already been sparked this year over management of the Missouri River, as environmentalists say it should be allowed to flow higher in spring and lower in late summer. While they fight for a “natural” cycle that would help endangered wildlife, upriver boating and fishing interests battle downstream barge shippers and cities that want water for drinking and power plants. Paul Johnston at the U.S. Army Corps of Engineers says the agency’s caught in the middle.A year ago in May he says suits were filed against the Corps by the states of Montana, North and South Dakota, and an Indian tribe to prevent water from being released, and a suit filed by Nebraska to ensure water was released downstream and he says they all won. The Corp’s mandate is to manage the river for the benefit of all interests, and it has no instructions on how to do that when the interests conflict with each other. Iowa grain shippers who get fertilizer on the return barges are among those who want operators of the big dams upriver to keep water levels high around here.