Senate Minority Leader Aquilino Pimentel Jr. is eyeing a class-action lawsuit against those responsible for the reported simultaneous release of excess waters from three dams that resulted in the flooding of Metro Manila and nearby Rizal towns last week.

As this developed, Rep. Jonathan dela Cruz of party-list Abakada Guro revealed that the House of Representatives is set to conduct an investigation on what really caused the massive flooding that left thousands of families homeless and hundreds dead.

Pimentel, whose house in Fairlane Subdivision in Marikina City had been submerged in the flood, said he is now in the process of gathering information and trying to identify the ones who “recklessly and negligently” ordered the opening of the dams without warning and without thinking of the consequences.

“After things shall have settled down a bit, I will initiate the filing of a civil complaint against these irresponsible people for the unwarranted and negligent opening of the dams that contributed to the flooding in Metro Manila,” Pimentel said at the weekly “Kapihan sa Sulo” forum in Quezon City.

The veteran lawmaker said he received information that the Angat and Ipo dams in Bulacan and La Mesa dam in Quezon City simultaneously released huge quantities of water at the height of Tropical Storm “Ondoy.”

Pimentel said this information gives him reason not to believe initial reports that flood waters were caused just by heavy rains brought by the recent typhoon.

He said the three dams, with the help of Ondoy’s rain, probably caused the rapid rise of floodwaters in the Marikina River system.

“There’s something wrong with the way the waters from the dams had been released. If I’m not mistaken, there are lines in the dam that indicate how much should be released and that could have not been followed by the administrators of the dams,” Pimentel said.

Pimentel said that once he has gathered sufficient evidence to file the civil case, he would welcome other flood victims to join him.