A source stationed at the facility, speaking on condition of anonymity, said the dam reached 106-per-cent capacity at 6am on Monday, representing 2.58 billion cubic metres of water.
Heavy rains have added 70.9 million cubic metres daily on average and 46.18 million cubic metres have been released each day.
That amount would be increased to 50 million cubic metres later on Monday, the source said.
With the dam reservoir filled to the brim, several sections of adjoining roads are flooded.
But the high water has been good news for operators of raft restaurants on the reservoir.
Diners no longer have to walk far to reach the floating eateries known as Pattaya 2 in Ubolrat district and Bang Saen 2 in Phu Wiang district, said restaurateur Thongsri Srichompoo.
And there are more weekend diners too, since the dam becomes more picturesque at high water levels, he said.