Des Moines County sheriff's officials shot the pigs Tuesday, not long after they completed their journey to the levee near Kingston, as much as 9 miles from a farm near Oakville.
Officials said they killed the pigs over worries that they would weaken the levee. Onlookers said the animals were having a difficult time trying to maneuver their way off of the sandbags, and that they scurried back into the water as people approached.
"Basically you cannot have something with a hoof walk on plastic and not poke a hole in the plastic and let water into it," said LeRoy Lippert, chairman of the emergency management commission. "Hogs, they have a tendency to root and that would not have been good either."
He said the state veterinarian and other agencies were consulted, and the 10 to 16 animals euthanized was minimal.
"It happens every day. My gosh, that's what slaughterhouses do - that's how we get bacon and pork chops," Lippert said. "It's just one of the casualties of the flooding situation."
The carcasses were left at the site and treated essentially as road kill, he said.
"You don't get them out of the mud and over the dike when you're worried about people and peoples' property," Lippert said.
He noted that out of about 36,000 pigs in the Oakville area, officials estimated that only a thousand or so were left behind when the floodwaters came through.
"We trucked them as far as 200 miles away to other hog farms so that they would be taken care of," he said.
Louisa County Sheriff Curt Braby said he had heard about the incident, and understood why the pigs needed to be killed.
"They did not want to take a chance on losing a city due to a few hogs," he said.
Jeff Campbell, a farmer carrying sandbags on his four-wheeler, said on Tuesday that he spotted pigs swimming away from the flooded hog farm near Oakville. They were climbing the levee, poking holes in the plastic that covered it, he said.
One tired pig was lying at the bottom of the levee "like a pink sandbag," Campbell said.