"The peak flood may be around 13.5 lakh cusec against peak flood level of 15.82 lakh cusec recorded in 2008. This situation is likely to continue for the next two days which will be crucial," special relief Commissioner P K Mohapatra said.
"The situation is critical as excess water from Mahanadi river will not be released into the sea easily due to the full moon on Monday. We are ready to face the eventuality," he told reporters here.
A total 10.8 lakh people of 2550 villages in 19 districts had already been affected due to floods. While eight people had died, three were missing.
Two deaths each were reported from Jajpur and Mayurbhanj districts, while one death each took place in Bhadrak, Dhenkanal, Kendrapara and Sambalpur districts. Three persons were swept away by flood waters in Nayagarh district and are missing.
With flood waters entering low laying areas, 60,723 people in 11 districts were evacuated and provided shelter in safe places, he said.
The state government said there was no major breach anywhere though there were reports of inundation of the road to Konark Sun Temple due to a breach in river Bhargavi in Puri district.
Official sources said 10,560 houses have so far been damaged.
Mohapatra said at least 152 relief camps with free kitchens were opened in Angul, Balasore, Bargarh, Boudh, Cuttack, Jagatsinghpur, Jharsuguda, Mayurbhanj, Puri, Sambalpur and Subarnapur districts.
A naval ship carrying a Chetak helicopter, relief materials and defence crew had already left Vishakhapatanam for Paradip.
"We have also decided to engage the MI-17 helicopter stationed here ... Though MI-17 is meant for anti-Maoist operations, we have sought permission from MHA for its use in relief and rescue activities," he said.
The state government has also requested the defence ministry to come to its rescue if the situation worsens, Mohapatra said adding 1,400 boats including 200 mechanised vessels were kept ready.
Orissa government has also issued directions to the district collectors to close schools in their respective areas in view of the situation.
Meanwhile, the entire coastal region in Mahanadi delta is set to encounter severe flood as the water level at Hirakud dam rose to 629.25 feet against its capacity of 630 feet.
In order to discharge excess water from the reservoir, 59 gates - 55 sluice and four crest gates were kept open since yesterday, official sources said.
"About 500 weak points have been identified on river banks and embankments, of which 28 may breach. Engineers and experts have been sent there to keep vigil," he said.
There was slight respite due to reduced rainfall in upper catchment of river Mahanadi in Chhattisgarh and less downpour in downstream areas, he added.