The heavy rain expected from Hurricane Florence could flood hog manure pits, coal ash dumps and other industrial sites in North Carolina, creating a noxious witches' brew of waste that might wash into homes and threaten drinking water supplies.

Computer models predict more than 3 feet of rain in the eastern part of the state, a fertile low-lying plain veined by brackish rivers with a propensity for escaping their banks. Longtime locals don't have to strain their imaginations to foresee what rain like that can do. It's happened before.

In September 1999, Hurricane Floyd came ashore near Cape Fe...