The National Weather Service is warning that flooding in parts of South Dakota and northern Iowa could soon reach historic levels. Weather Service hydrologist Kevin Low said during a telephone briefing Wednesday that “major and perhaps historic” flooding is possible later this month at some spots on the Big Sioux and James rivers.

The service is projecting that the James River near Scotland, South Dakota, a town of about 800 residents, will reach a record 21.1 feet on Monday, shattering the old record of 20.5 feet set in 1984. The Big Sioux River in South Dakota and Iowa is expected to reach near-record levels in some places.

The worst of the flooding so far has been in Nebraska, southwestern Iowa and northwestern Missouri. Hundreds of residents have been displaced and well over 100 miles of levees in the three states have been breached or overtopped.