SIOUX FALLS, S.D. (KELO) — The water in the Yellowstone River that charged through the Yellowstone National Park should end up in the Missouri River and eventually, South Dakota.

The national park was closed as of June 14 because of mudslides and damage caused by the flooded Yellow Stone River. The river joins the Missouri River at Williston, North Dakota.

The river gauges at Williston are the ones to watch to learn what the Yellowstone River’s impact could be in South Dakota, said Eileen Williamson, of the U.S. Army Corps of Engineers Missouri River Basin public affairs office in Omaha, Nebraska.

The forecast is for flood stage at Williston, “but there is a levy there. No flooding is expected at Williston because the levy should keep the river (in),” Williamson said.

The water will move south from Williston and reach Lake Sakakawea and the Garrison Dam. “At Garrison, the reservoir should be able to capture runoff,” Williamson said.

If it’s enough water, “we may increase the release…at Oahe. It depends on what the conditions continue to look like,” she said.

“There may be a slight rise (in water levels) at Sakakawea and a slight rise at Oahe,” Williamson said.

The long-term impact of the flooding on the Yellowstone River depends on the water is all rain or if it includes rain and snowmelt, Williamson said.

“The storm may have exhausted the (snow) runoff,” Williamson said.

The Missouri River typically gets snowmelt in June, July and August, even into September. The storm may have melted snow and carried it away in the river with rainwater.

“We may see that the rest of the snowmelt has been taken care of for the rest of the season,” Williamson said.

Before the storm in Yellowstone, the Army Corp had forecast snowmelt run off for the coming months, she said.

The Army Corps will be examining the storm’s impact on snowmelt tomorrow, Jun 15, Williamson said.

“We will know more in the coming days,” Williamson said.

Water levels at three of the four reservoirs in the state are below the annual flood control zone. Fort Peck is 12.1 feet below, Oahe is 10.4 feet and Garrison is 7.2 feet. Those levels are still above historic minimums of 2011, the Army Corps said on June 9. The Fort Randall reservoir is 5.3 feet above the annual flood control zone.

Missouri River water levels can affect recreation but also the energy produced.

The six mainstem power plants generated 558 million kWh of electricity in May, the Army Corps said. “Typical energy generation for May is 797 million kWh. The power plants are expected to generate 7.1 billion kWh this year, compared to the long-term average of 9.4 billion kWh,” the Army Corps said on June 9.