The dam in Singburi burst as waters continued to rise in several provinces, the Thai news agency MCOT reported.
In Angthong, the Chao Phraya River overflowed its banks, deluging numerous villages in the Bang Pa-in district, submerging main roads leading to the provincial seat and flooding portions of Highway 309, partly closing the thoroughfare to traffic.
A sluice failed in Bangchomsri, flooding the Ban Mi and Tha Wung districts in the province of Lopburi.
MCOT said crops were hard hit as the water levels continued to rise.
The Bangkok Metropolitan Administration was closely monitoring the flooding in 27 riverside communities outside a dyke-protected zone and in the low-lying areas in eastern and western Bangkok, the news agency said.
At the Million Years Stone Park & Pattaya Crocodile Farm at Chonburi beach resort, dozens of crocodiles escaped Monday after flood waters caused a rupture in an enclosure holding about 200 of them.
Suthawut Temthub, a spokesman for the crocodile farm, said 29 of the crocodiles have been captured, including one measuring nearly 10 feet long that was found in a pond and captured by staff members who returned it to the farm.
Temthub said residents should notify the farm if they see stray crocodiles and not attempt to capture them because of the danger.