Updated

The controlled water release of two major reservoirs has reportedly started Monday and flooding could be worse in some surrounding areas.

The process will likely add more water to already-flooded roads, but is intended to prevent flooding into residential neighborhoods, Fox 26 Houston reported.

Residents living near the Addicks and Barker reservoirs designed to help prevent flooding in downtown Houston, were warned Sunday that a controlled release from both reservoirs would cause additional street flooding and could spill into homes. Rising water levels and continuing rain was putting pressure on the dams that could cause a failure without the release.

The Army Corps of Engineers early Monday started the water releases at the reservoirs ahead of schedule after water levels increased dramatically in a few hours' time, a Corps spokesman said. The timetable was moved up to prevent more homes from being affected by flooding from the reservoirs, Corps spokesman Jay Townsend said. He added that water levels were rising at a rate of more than six inches per hour in both reservoirs.

Meanwhile, officials in Fort Bend County, Houston's southwestern suburbs, late Sunday issued widespread mandatory evacuation orders along the Brazos River levee districts. County officials were preparing for the river to reach major flood stages late Sunday. County Judge Robert Herbert said at a news conference that National Weather Service officials were predicting that the water could rise to 59 feet, three feet above 2016 records and what Herbert called an "800-year flood level." Herbert said that amount of water would top the levees and carries a threat of levee failure.

The Associated Press contributed to this report