ST. PAUL, Minn. — Minnesota officials toured waterlogged areas of the state Friday, saying the severity and breadth of flooding make a federal disaster request a near certainty and a special legislative session a possibility.

After heavy rains over several days, farm fields are under water, roads have been washed out, dams have failed and water has infiltrated homes from the far north to the far south of Minnesota. Four state parks have been fully or partially closed because of high water.

"The damage is really unprecedented and very widespread," Gov. Mark Dayton said before boarding a plane to southern Minnesota along with U.S. Sens. Al Franken and Amy Klobuchar. Dayton has already declared a state of emergency in nearly half of Minnesota's counties.

Minnesota is on the cusp of breaking records for its wettest June, with more rain on the way this weekend.

Damage assessments already total in the millions even before surveying can start in many places soaked by downpours over the past week. Some lakes and rivers swelled to record levels, with others not expected to crest for days, if not weeks.

Another 20 Minnesota National Guard soldiers were mobilized to help shore up levees and lift stations around Henderson. That's on top of the 100 sent to Koochiching County along the Minnesota-Canadian border the day before. A temporary floodwall was being erected around the downtown airport in St. Paul in case a rising Mississippi River overflows its banks.

In Minneapolis, a large section of mud gave way on a cliff near the Mississippi River. The slide occurred not far from a hospital near the University of Minnesota's campus. Minneapolis Assistant Fire Chief Charles Brynteson said the hospital building is sound.

"The building itself is set on bedrock," Brynteson said.

Two motorists accelerated to safety as the mud and debris were falling.

"They very easily could have been trapped. It was close. Had they been in it, that would have pushed them right into the river," he said.

Once the waters subside, officials say they'll move quickly to tally damage estimates to get a presidential disaster declaration application moving. If federal money is made available, the state must match 25 percent of the covered costs. Last session, lawmakers established a $3 million contingency fund to get money out faster and reduce the need for legislative approval.

But Dayton said the extent of the flooding means "there's a very good chance that we'll exhaust that fund." He wouldn't rule out summoning legislators back to St. Paul for a summer special session to approve more money.

The federal help would cover only public assets, such as repairs to roads, water treatment plants and government buildings. Some emergency response costs could also be included.

Submerged fields could wipe out the corn and soybean crops on affected farms. But Agriculture Commissioner David Frederickson said most farmers have crop insurance to mitigate some of their losses.

"They might be able to replant soybeans but that window is closing really fast," Frederickson said.

People with damage to their homes or businesses may be eligible for grants and low-interest loans.