As of 9am Thursday, the dam was discharging water at 550.69 cubic metres per second, or 47.58 million cubic metres per day, according to a report on the website. The inflow was at 652.68 cubic metres per second, or 56.39 million million cubic metres per day.
Pasak Jolasid dam has a maximum capacity of 960 million cubic metres and the water level was 930.25 million cubic metres as of 9am Thursday. However, the dam normally stores 785 million cubic metres, so the current level is 118.5% of its normal level.
As of Wednesday, the dam was draining about 466 cubic metres per second but needed to increase the volume of outgoing water to make way for incoming water, said Phanukij Disphueng, director of the 10th Royal Irrigation Office.
This would cause water levels to rise by about 30cm in Saraburi and between 30cm and 50cm in Tha Rua, Nakhon Luang, and Phra Nakhon Si districts of Ayutthaya, he said.
A warning about expected higher water levels was issued to alert local leaders of communities along the rivers, especially those near the Pa Sak River.
The water discharged from the Pasak Jolasid dam would reach the Rama VI dam in Ayutthaya's Tha Rua district, that is currently draining about 513 cubic metres of excess water per second, he said.
The dam would have to increase the drainage volume to 600 cubic metres per second to cope with the incoming water, he said.
Tha Rua district chief Withit Pinnikorn said communities in low-lying areas and near rivers would inevitably face the worst flooding.
Arun Ruangnetr, the owner of a crocodile farm in the district, said his 140-rai farm where 70,000 crocodiles were kept was not affected by floods there.
Even during 2011's big flood, his farm was spared because it was surrounded by a 2-metre concrete wall, Mr Arun said.
Meanwhile, more than 100,000 people in eight districts of Ayutthaya have been hit by floods, Ayutthaya's Disaster Prevention and Mitigation Office said.
The water levels continue to rise between 5cm and 10cm every day, despite the Royal Irrigation Department's assurance the volume of water currently being released from the Chao Phraya dam has been steadily maintained at 2,195 cubic metres per second.
This has raised doubts over the accuracy of the department's information about water drainage.
Sam Khok district in neighbouring Pathum Thani province, also affected by water overflowing the banks of Chao Phraya River, appears to be facing worse flooding as water levels continue to rise.
In Sukhothai, more than 300 rice farmers blocked the entrance to the provincial airport in Sawankhalok district with e-taen (makeshift farm trucks).
The protesters demanded the airport authorities drill hole through the earthen dyke built around the airport so that flood water can drain out through the airport.
They said about 6,000 rai of paddy fields were being flooded and the rice was dying.
The protesters said they have just discovered that the real cause behind serious flooding in four tambons every year over the past 10 years was the airport's blocking of the floodway.