La Mesa Dam still overflowing, five other dams spilling; retaining dams eyed for Marikina

By MARK D. MERUEÑAS, GMA News

Published August 7, 2012 9:48pm

The La Mesa Dam is still filled to overflowing early Wednesday morning after several days of moderate to intense rainfall while five other dams have spillgates open, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said. At 0.37 meters above its normal high water level, the La Mesa Dam is at overflow as of 2:00 a.m. The Ambuklao Dam has five spillgates open and Binga Dam has seven gates raised. Two spillgates of the San Roque Dam are up while the Ipo Dam has four gates open. Only one spillgate is raised at the Magat Dam. Long term solutions in Marikina

Meanwhile, Marikina City Vice Mayor Jose Fabian Cadis on Tuesday said the government is planning to construct "retaining dams" on the upper portion of the Marikina River to help control water rushing from the mountains of Rizal during a heavy downpour.

Cadiz, who is currently sitting as acting mayor, revealed the plan in light of the torrential rains over Luzon in the last two days brought by the southwest monsoon.

The monsoon has already dumped - among other places - rainwater into the mountains of Rizal that rushed down the Marikina River, a main water channel that leads all the way to the Laguna Lake.

Throughout the day, water coming from several mountainous parts of Rizal has already caused the Marikina River to swell past the 20 meter mark - at exactly 20. 6 meters - just three meters below the water level of the Marikina at the height of the deadly Typhoon Ondoy in September 2009.

"Ang Marikina ay naghahanap ng permanent solution at may plano ang national government na mag-construct ng retaining dams sa upper Marikina River kung saan pipigilin ang ragasa ng tubig," Cadiz said in a television interview Tuesday night.

Retaining dams are reservoirs built to accumulate large amount of water for various purposes including land irrigation, power generation, water supply, and - in the Marikina River's case - flood control.

Cadiz admitted that the plan is still at the "drawing stage" but he is hopeful the project pushes through within the next few years.

"Nasa drawing stage pero kami ay nakasisigurong hindi ito drawing (This project is already in the drawing board and I assure the public we are not making this up)," Cadiz said.

According to Cadiz, the bulk of the water causing the Marikina River to swell during a heavy downpour comes from the rainwater originating from the mountain of Rizal, particularly from Antipolo City and the municipalities of Rodriguez and San Mateo.

"Kami ay nagiging biktima ng tubig na hindi naman galing sa Marikina," Cadiz said.

For now, the local government will have to make do with efficient pre-emptive measures like the current imposition the five-level alarm system.

Through the system, residents are advised to prepare (at 16 meters), made to voluntarily evacuate (at 17 meters), or forced to evacuate their abodes (at 18 meters) depending on the rising water levels.

A standing city ordinance also prevents residents at least 96 meters away from the center of the Marikina River.

"Nasusunod po iyang ordinansang iyan... kaya lang ngayon ay tumaas talaga ng sobra ang tubig," Cadiz explained. — ELR, GMA News

Tags: dams, waterlevel, spilling, spillgates