North Carolina is one of the biggest hog-farming states in the US, with about 9 million pigs being raised on some 2,300 farms. That equals a lot of manure—about 10 billion pounds of wet animal waste are produced in the state a year, according to the Waterkeeper Alliance. Farms store the pigs’ feces in uncovered, earthen lagoons, some the size of football fields. And now they’re at risk of becoming a public health hazard when Hurricane Florence touches down.

The storm is set to sweep through North Carolina on Thursday or Friday, and the manure lagoons are squarely in its path. A farming journal urged hog farmers to prepare for the storm.

We’ve seen this before: 2016’s Hurricane Matthew inundated 14 hog manure lagoons. In the days leading up to the hurricane’s landfall, some farmers pumped waste out of their lagoons and hauled it away in an effort to limit the damage.