Cast and crew are working feverishly between rehearsals this week to remove a thick scum of flood mud coating the stage of the popular Wilder Pageant in Walnut Grove, Minn., ahead of Thursday’s opening performance.

The outdoor drama based on the life of Laura Ingalls Wilder was to have opened last Friday, but the normally tame Plum Creek swelled way beyond its banks, swamping the grounds a mile west of town and putting center stage under water.

Waters receded about as quickly as they came but left the grounds a total mess, said pageant president Errol Steffen.

Shows have been added on Thursdays this week and next week to the schedule of “Fragments of A Dream,” which until last weekend had been called off due to inclement weather only a handful of times in its 40-year history.

But early July rains — as much as 9 inches in the area — led to unprecedented flooding of the grounds a mile west of the southwestern Minnesota town, where the annual production has been staged since 1978.

“The creek has never been this high,” Steffen said, noting the water usually is more than 300 feet from the set and hillside amphitheater.

Jeff Farber caught the flood at its peak on July 4 and posted a video on Facebook. The water has receded, and now crews are trying to replace electrical equipment that was damaged, restore a washed-out seating area and give the set a fresh paint job.

“We will be ready,” Steffens said.

“On the Banks of Plum Creek,” written by Laura Ingalls Wilder and published in 1937, was the fourth of nine novels in her “Little House” series featuring recollections of life in Walnut Grove and elsewhere when she was a child in the 1870s.

The pageant is offering $5 tickets to residents of the flood-ravaged communities of Tracy, Balaton, Walnut Grove, Wabasso, Slayton, Westbrook, Windom, Lamberton, Storden and Jeffers.