Flooding of the kind seen across the northern U.S. this spring and summer is unprecedented in modern times. Changes that will occur as a result will range from landscape -- human developments and wildlife habitats will be lost, and some new ones (of the latter) made -- to political, as Congress doubtless will begin hearings later this year to try to pin blame on someone for the disastrous flooding now occurring particularly on the Missouri River, from Montana to Missouri.

It's a disaster that is far from over. Some of the largest dams in the world are built on the Missouri, some constructed more than a half- century ago, and water is rushing through them at levels that are testing the nerves of many observers, if not the Army Corps of Engineers itself.

A significant letup of pressure on the dams isn't expected until August.

A prime walleye fishing destination for many Minnesotans, the Missouri and its entire watershed are also visited each fall by tens of thousands of Minnesota hunters. Some seek ducks, others pheasants, deer, grouse or other wildlife.

For these sportsmen, the notion that state boundaries any longer restrict their consideration of what's important environmentally or recreationally is anachronistic. They might live in the Twin Cities or Winona or Ely, but the Missouri is where they fish.

Similarly, the Souris River, which is now flooding Minot, N.D., might be the placid stream they cross while goose hunting in October.

For these Minnesotans in particular, some considerations:

• Incessant rains that have inundated prairie Canada, Montana and the Dakotas this spring and early summer virtually ensure that duck production this summer will be high, according to Delta Waterfowl and Ducks Unlimited, both of which have offices in Bismarck. Breeding duck numbers were down 9 percent in North Dakota this spring, but with so much water on the landscape, surveyors might have missed some birds, or ducks that were in North Dakota last year might be in South Dakota, Montana or Canada this year, also enjoying excellent habitat. So the fractional decline is inconsequential.

"It will be a banner duck production year," said Rick Warhurst of Ducks Unlimited in Bismarck. "I've never seen anything like the water we've got in the state."

John Devney of Delta Waterfowl agreed: "Brood survival is always high in these conditions," he said.

• Duck hunting success in North Dakota and prairie Canada could vary widely this fall, however -- regardless of the number of ducks produced. So much water exists across the region that ducks likely will be widely scattered, making them difficult to find. Additionally, some back roads might remain underwater or otherwise impassable.

• Fish native to the Missouri, such as the endangered pallid sturgeon, likely will benefit from the massive amounts of water moving through the system, and from the river shoreline expanding beyond its traditional high-water marks. "For the river ecosystem as a whole, the flooding might in fact be beneficial," Mike Olson of the U.S. Fish and Wildlife Service in Bismarck said Thursday.

• Wetland drainage has contributed to the region's flooding. Pattern tiling is occurring at a rapid rate in portions of the Dakotas, and wetland drainage continues also in Saskatchewan, where the Souris River originates before flowing south to Minot, then back north, to Manitoba.

• That said, primary causes of the spring and summer flooding include heavy soil saturation across the region last fall; heavy snowfall last winter; extraordinary rainfall this spring and summer; and the continuation of what is now a years-long wet period. Additionally, snowpack in the Rockies is at or near record levels for so late in the year, contributing to woes on the Missouri, which flows north from Three Forks, Mont., before turning east and eventually meeting up with the Yellowstone River.

"There's a real lack of understanding by the public about how the Missouri River system is managed," retired U.S. Fish and Wildlife Service field supervisor Al Sapa said Thursday from his home in Bismarck. "People are looking for someone to blame, including the Corps of Engineers, but they manage the system according to a law."

The Missouri moved through Bismarck during a 1970s flood at 68,000 cubic feet per second (cfs), Sapa said.

"We're now looking at 150,000 cfs releasing from the dam here. It will continue that way until August. We've never seen anything like this."

Dennis Anderson • danderson@startribune.com