“Mural” is the largest artwork that Jackson Pollock ever produced: a colossus, 8 feet high and 19 feet across (2.4 metres by 5.8 metres). It was commissioned in 1943 by the collector Peggy Guggenheim for the entrance hall of her New York apartment. “Mural” is an abstract work, but if you stare at it for long enough, figures seem to emerge within the mêlée of yellow, pink and deep, angry black. Bodies, both human and animal, rush from one end of the canvas to the other, and burst out, as if hurtling towards the viewer. Pollock described the work to a friend as a “stampede”. 

There was a brief thought that Pollock should paint “Mural” directly onto the wall, but Guggenheim’s friend, the artist Marcel Duchamp, suggested it would be better on canvas; that way it would be movable. For historians, it marks a crucial turning point in Pollock’s career, when he began experimenting with the style he’s known for, splashing the canvas with paint and allowing streams of colour to flow.

In 1948 Guggenheim decided to donate “Mural” to the art department of the University of Iowa in Iowa City. It is the jewel in a large and eclectic collection that includes works by Henri Matisse, Pablo Picasso, Robert Motherwell and Philip Guston. Following the construction of the university’s own museum, then known as the University of Iowa Museum of Art, in 1969, the art was displayed in a low, square building just metres from the Iowa river. 

The campus’s proximity to the water makes for a picturesque setting—but a precarious one, as Rodney Lehnertz, the university’s director of planning, design and construction at the time, told me. Flash floods, which the university is less at risk of, arrive suddenly: a crash of liquid and no time to prepare. Other kinds of flood events are more complex. There are hints, certain preceding conditions—regular rainfall, frozen land—that evolve over months or years; undeniable after the fact, even if in the immediate aftermath of disaster it is soothing to say that nothing could have been done.