Mary Elmer Dam overflowed, sending water rushing into Sunset Lake near West park drive.
The road became impassable, and after assessing the damage across the city, officials made the decision to start ordering evacuations.
"We've found it necessary to evacuate our immediate downtown area, especially along the rivers, so that any senior citizens who are in the complex along the river can get out safely." said Mayor Albert Kelly.
The area received 6 to 8 inches of rain, and more is expected overnight and into Monday.