More than 1,100 farmers in Nebraska have been ordered by the state’s Department of Natural Resources to halt irrigation of their crops because the rivers from which they draw water have dropped due to a worsening drought.

The orders come as the central United States bakes under the worst drought in a quarter century which has parched corn and soybean crops and sent prices of both commodities to near-record highs.

As of Friday, orders have been sent to a total of 1,106 farmers in the country’s No. 3 corn producing state and fourth-largest soybean state, the department confirmed on Monday.

The orders affected only irrigation systems that draw from surface water, mostly rivers and creeks, and not systems that draw from wells, a department spokesman said.

Nearly the entire state is under some level of drought, more than half of it classified as severe drought or worse, according to the weekly U.S. Drought Monitor.