Flooding slowly subsided Wednesday in several northeastern Oklahoma communities, but meteorologists warned about more problems because lakes and reservoirs were already full.
Water also was ebbing in southeastern Kansas, but more rain fell Wednesday on hard-hit Texas.
More than two weeks of soaking weather has caused widespread flooding in the three states. The weather has been blamed for 11 deaths in Texas in the past two weeks, and two people are missing.
While the wet weather had moved out of Oklahoma, heavy rain spread across wide areas of Texas on Wednesday, causing minor street flooding.
At least 20 Texas counties were under flash flood warnings, and the Trinity River in the Dallas-Fort Worth area was expected to crest at 37 feet (11.3 meters) during the night, about 7 feet (2.1 meters) above flood stage.
About 50 Oklahoma Army National Guard troops worked 12-hour shifts providing security in flooded neighborhoods. And at least 1,000 people were out of their homes throughout southeast Kansas, said Sharon Watson, spokeswoman for the Kansas adjutant general.
The 42,000 gallons (158,982 liters) of crude oil that spilled into the Verdigris River when flash flooding hit a refinery in Kansas had mostly dissipated, and there was no indication any of the oil reached Oklahoma's Lake Oologah, a source of municipal water for several communities, officials said.
Experts believe the thick, sticky oil had been captured by trees and other vegetation upstream from the lake, said Skylar McElhaney, a spokeswoman for the Department of Environmental Quality.