The Army Corps of Engineers is taking comments this week on plans for a "spring rise" on the Missouri River, with many questions yet to be answered.

"It's a real spider web," said Terry Steinwand, the fisheries chief for the North Dakota Game and Fish Department.

The corps is working to comply with a "biological opinion" issued by the federal Fish and Wildlife Service in 2003. It seeks to release more water from Gavins Point Dam, at Yankton, S.D., on the Missouri during the spring to protect the endangered pallid sturgeon.

The Fish and Wildlife Service gave the corps until 2006 to come up with a plan.

"They think that the rising river levels will cue the fish to start their spawning cycle," said Paul Johnston, a spokesman for the corps in Omaha, Neb. "This is the first time we've deliberately released water to make it happen."

Johnston said hearings scheduled Wednesday and Thursday in Bismarck will discuss the conditions for a spring rise.

"Do you run it all the time? Do you run it just every couple of years?" are among the questions, he said.

"Not only how often, but how big should the rise be? If you're getting a lot of naturally occurring runoff, as we have this year, do you stop running it?" he said.

Johnston said a "spring rise plenary group" will work on the details of the plan. It includes nearly 50 representatives from federal and state agencies, tribes, and other groups.

"It's been a real hot-button issue for bottom-land farmers who are worried about the increased risk of flooding for farm fields," Johnston said. "The other side of that coin is that there has been growing concern from reservoir interests that during a time when things are so dry, additional water would be released in the springtime."

This week's meeting is the second in a series. Johnston said another meeting likely will be held in Omaha in August. The idea is to balance a number of interests, something that historically has not been easy for the corps.

CDR Associates, known as a conflict-management firm, will help conduct the hearings.