FORT SMITH, Ark. (AP) — Residents in parts of Arkansas were preparing for what meteorologists on Sunday predicted will be the worst flooding in recorded history along parts of the Arkansas River over the coming week.

The National Weather Service said in the statement that levee “over topping” is likely with “significant impacts to life and property across a very large area.”

The Arkansas River reached 38.2 feet (11.6 meters) on Sunday near Fort Smith, Arkansas, surpassing the historic crest of 38.1 (11.6) feet in April 1945.

Spokeswoman Karen Santos said the city of 80,000 residents that’s on the border with Oklahoma was in “preparedness and warning mode.” She said one home was completely submerged and about 500 homes either have water very close or in them. Authorities predict hundreds more homes and businesses will flood by the time the river crests there Tuesday at 42.5 feet (13 meters).

Across the river from Fort Smith, the tiny town of Moffett, Oklahoma, population about 120, was submerged by Saturday afternoon, Sequoyah County Emergency Management Director Steve Rutherford told the Times Record in Fort Smith.