MWSS: LGUs given prior notice on dam spilling operations during Typhoon Ulysses

The Metropolitan Waterworks and Sewerage System (MWSS) on Wednesday reiterated that prior notice was given to the concerned local government units (LGUS) on the spilling operations of Angat and Ipo Dams during the intense rainfall brought about by Typhoon Ulysses.

In a statement, the MWSS said the elevation of the dams a month before Ulysses was low enough to absorb the expected 112 to 200 millimeters of rainfall, with inflow and outflow of excess water being balanced to ease pressure on cities and flood plains reached.

"MWSS adhered to the protocol in the management of both Angat and Ipo dams prior to spilling. Prior notice was given to concerned LGUs and other agencies involved on the spilling operations to ensure not only the safety of the dam but also residents that may be affected by the spill," the statement read.

A series of typhoons hit the Philippines earlier this month, the latest of which was Typhoon Ulysses (international name: Vamco), which claimed at least 67 lives and leaving billions in damage.

The release of water from the Angat Dam contributed to floods in nearby areas such as Calumpit in Bulacan, where water levels rose to as high as seven feet.

Most of the excess water during the Angat Dam spilling operations goes to Ipo Dam, which is managed by the MWSS. To prevent overtopping, the MWSS said it opens radial gates to release water slowly.

The water then goes to the La Mesa Reservoir as the final diversion point, which does not have gates when its elevation reaches the spilling level.

"To prevent excessive flood water to Metro Manila, MWSS promptly acted by initiating the closure of the Umiray tunnel to decrease the inflows to Angat Dam. Ipo Dam radial gate openings, including the aqueduct gates were adjusted to decrease inflows to La Mesa Dam," the MWSS said.

The MWSS said it has also been undertaking medium and long-term solutions to address flooding, from the perspective of an integrated watershed management approach.

"The MWSS's annual program, which started in 2017, is the planting of one million trees to reforest Umiray, Angat, Ipo, and La Mesa watershed. Through partnerships with like-minded organizations, the one million target has been exceeded annually, with other watershed areas expanded to include Upper Marikina, Laguna de Bay, Kaliwa, and Manila Bay," it said. — RSJ, GMA News