Pierre, S.D. ? As a younger man, Jean Ries used to fish the shoreline of the Missouri River near Pierre, trying for walleye and the other fish that make the area a favorite with anglers. The river back then was far more sedate than the sight the 93-year-old this week traveled for three hours to see: a raging, thundering torrent pouring through the Oahe Dam at a rate that rivals Niagara Falls.

“This is unbelievable,” Ries said as he marveled at the water gushing from the rarely used emergency outlet tubes. Ries said the close-up view of the racing, foaming, spraying water was worth the ride from his home in Sioux Falls and his slow walk from a nearby parking lot aided by a wheeled walker.

“I’m really impressed,” Ries said. “I can’t imagine how much water is coming out of this.”

The display at Oahe, and at other dams along the swollen Missouri, is drawing hundreds of sightseers keen to see and photograph the unprecedented spectacle.

The fast water is a result of heavy rains last month in Wyoming, eastern Montana and western North Dakota and South Dakota. The rain, plus heavy snowpack beginning to melt in the Rocky Mountains, has the Army Corps of Engineers increasing water releases through the six Missouri River dams to get rid of water as quickly as possible. Temporary levees have been built to protect Pierre, the capital city, and Fort Pierre.

At Oahe Dam, 5 miles upstream from Pierre, water is flowing through the power plant and the emergency outlet tubes at a record 150,000 cubic feet a second, or slightly more than 1.1 million gallons every second. That’s about 1½ times the average daytime flow rate over Niagara Falls in the summer tourism season.

In normal times, the power plant can handle all the water that needs to be moved through Oahe Dam. But now, about two-thirds of the release at Oahe is flowing at 42 mph through the mile-long, 19.5-foot diameter emergency outlet tubes that run under the giant earthen dam and bypass the power generators, said Eric Stasch, operations manager at the dam. This year is only the third since the dam was completed nearly five decades ago that the outlet tubes have been used, and the first time all six have been opened, he said.

The result is a spectacular show. The water gushing from the tubes pushes plumes of water 20 feet or more into the air. The river foams white the length of a football field downstream, and a fine mist drifting over the area can be seen from several miles away.

The increased flow from the emergency tunnels and nearby power plant has covered roads that normally are used by anglers and sightseers.

“It’s just crazy,” said Kegan Stager, 12, of Fort Pierre.

Scott Gordon, 50, lived most of his life in Pierre and drove up from his home in Yankton, four hours away, to see the roiling water.

“Wow! There’s really nothing else to say,” Gordon said. “I’ve never ever seen water coming out of these tunnels before. Now to see this.”

Stasch closed the viewing area at the outlet tunnels for a week for safety considerations and to cut traffic on a highway used by dump trucks hauling sand to build the levees and fill sandbags. But people clogged the highway as they stopped to take pictures from an overlook, and Stasch eventually re-opened the viewing area. Barriers prevent onlookers from standing at dangerous points where they could be swept away.

Upstream at Garrison Dam in North Dakota, up to 300 people a day are showing up to see water coursing over the spillway and shooting out of regulating tunnels, said Linda Phelps, natural resources manager at the dam. An estimated 2,000 to 3,000 people visited last weekend, she said.

Phelps said officials have worried about people crossing into restricted areas to get a closer look, and rangers are on the scene to control traffic.

“We’d really hate to have to shut it down where they’re not allowed to see it at all,” Phelps said. “It’s a spectacular thing to see.”

At Gavins Point, the last dam on the river and just above Yankton, spectators also are flocking to see water running over the emergency spillway, said David Becker, operations manager at the southeastern South Dakota dam. The parking lot at the spillway is designed to hold about 20 cars, but up to 40 have been parked there in recent days, he said.

“It’s a historic year,” Becker said.

Becker said he has a chart showing annual flows through the Missouri River since 1898, and 2011 is on track to set a record for total water flowing through the river in that time.

At the viewing area below Oahe Dam, up to two dozen cars fill a makeshift parking lot at any given time, even in the middle of a work day.

Derek Moore, 25, an officer at the state women’s prison in Pierre, was fascinated by the gushing water. But he couldn’t forget that the same water is threatening to flood homes and businesses just a few miles downstream.

“I never imagined seeing anything like this around here,” Moore said. “It’s hard to believe, that’s for sure.”