Millions of acres of farmland in multiple states remain underwater.

At least eight Superfund sites in three states could be affected.

More snow and rain are on the way.

Two weeks after a "bomb cyclone" storm pummeled a large swath of the Midwest with heavy snow, drenching rains and historic flooding, farms remain under water and Superfund waste sites inaccessible.

And more snow and rain are on the way.

Millions of acres of farmland were underwater or threatened by flooding in Nebraska, Missouri, Kansas and Iowa. In South Dakota, a Native American reservation as big as Delaware and Rhode Island combined was battling swamped roads and broken water lines overwhelmed by flooding creeks and rivers.

"Thankful to the SD National Guard, tribal leadership, and volunteers who are working hard to help people in need," Gov. Kristi Noem tweeted after visiting the Pine Ridge Reservation.

Almost 8,000 of the 20,000 people who live on the reservation have had water supplies disrupted, the tribe said. Three people who suffered medical problems died before ambulances slowed by floodwaters could get to them, the tribe said.

“This is going to have a devastating effect on us," reservation President Julian Bear Runner said.

In Missouri, Langston farmer Richard Oswald told the St. Louis Post-Dispatch his 160- acre farm is so besieged by water that he evacuated. He doesn't expect to return for a couple of weeks.

“I’m no youngster,” Oswald says. “I’m 69 years old. I’ve lived here all my life. And I’ve never seen weather like this.”

The Environmental Protection Agency said at least eight contaminated sites in three states affected by the flooding remain inaccessible. Spokesman Ben Washburn said two sites had "real impacts that required action" – the Nebraska Ordnance Plant in Mead, 45 miles west of Omaha, and the Conservation Chemical Corporation in Kansas City, Missouri.

At the Nebraska site, a groundwater treatment system and wells were shut down for two days. Flooding at the Kansas City plant required an increase in the pumping rate of the groundwater treatment system, Washburn said.

Washburn added that no releases of hazardous contaminants have been detected.

A half-dozen other sites are dealing with standing water or are as yet inaccessible, Washburn said. As floodwaters recede and more areas can be reached safely, the EPA will determine whether action is necessary, he said.

Parts of Nebraska, Colorado and South Dakota can expect significantly more precipitation over the next couple of days, in many areas starting as rain before colder air sweeps in and changes it to snow, AccuWeather says.

"Some of this new snow and remaining older snow from the winter eventually will melt and join the high water levels along the Missouri River in the coming days and weeks," Sosnowski said.

Rain and thunderstorms along the southeastern flank of the storm will add to the flooding trouble across the region, meteorologist Renee Duff said.

The news was not all bad. Minnesota Gov. Tim Walz said Tuesday that people should be on guard for localized flooding but that the state is prepared for any catastrophic flooding.

“I don’t want anybody to let their guard down, (but) when it comes to the actual boots on the ground and the organization, very confident,” Walz said.

Contributing: The Associated Press