TULSA COUNTY, Oklahoma - Tulsa-Area Emergency Management says residents living in the 100-year flood plan need to prepare for evacuations. 

Officials say as of noon Thursday, The Corps of Engineers began releasing 250,000 CFS from the Keystone Dam, and this will cause flooding in Tulsa County. 

Residents near the Arkansas River should be aware of the water release and flooding - and be prepared to evacuate.

The Corps said they will release 250,000 cubic feet of water per second until Sunday then gradually decrease that number as water levels recede. They didn't anticipate the number to get higher; however, it was at 253,000 at 2:27 p.m. Thursday.

Parts of Sand Springs and western Parts of Tulsa County are expected to see the first impacts in a couple of hours - central Tulsa in about 4 to 6 hours and south Tulsa County along the river in 8 to 10 hours.

Tulsa Police and the Tulsa County Sheriffs office have already been going to areas anticipated to be impacted and encouraged those people to leave.  The Red Cross has set up three different shelters as well to help people being evacuated.

I spoke one-on-one with David Williams from the Army Corps of Engineers.  He says so far the dam and levee system is performing like it was designed to.

"Understand that a dam like Keystone is designed to mitigate downstream flood risk, but it doesn't eliminate downstream flood risk. At this point we are trying to minimize the releases," he said.

Mayor G..T Bynum says they want to be very transparent throughout this process. That's why they posted detailed information on the city website. There you can see new maps showing the areas engineers think could be flooded at the 250,000 cfs water release.

"Folks can go to that and see all of the mapping that we're utilizing to manage this response and also be able to utilize that mapping to make their own decisions about what types of steps they need to take to protect themselves," Bynum said.

Officials began sounding the flood sirens along the Arkansas River every 30 minutes for 6 hours starting at 3 p.m. Thursday. 

People who live near Candle Stick Beach, areas south of Wekiwa Road, Town and Country neighborhood, houses around the Boy's Home, Meadow Valley, Garden City, Cherry Hill, Wind River, and any housing divisions south of 121st from the river to Sheridan, says officials.  Creeks and streams could see back-flow. 

People should expect multiple street closures along the Arkansas River area. 

To see the City of Tulsa's flood map, click here. 

If you're concerned, you can also all 211 - 24 hours a day.

See the video below to watch the whole news conference.