The Muntinlupa City government explained that the occurrence of algae bloom or “liya” in Laguna Lake that is emitting a foul smell is a periodic occurrence and steps to mitigate this are already being undertaken
“Algae bloom, also known as Liya is a periodic occurrence in Laguna de Bay, particularly in the Central Bay and West Bay wherein Muntinlupa City is located. Those commonly found in Laguna Lake are blue-green algae, green algae and diatom. They are natural food for the fishes, and combined with environmental conditions such as sufficient sunlight, high water temperature, and calm water, the algae can grow at a very fast rate,” Muntinlupa Lake Management Office head Herminio dela Cruz told Mayor Jaime Fresnedi in a letter.
In an advisory last June, the Laguna Lake Development Authority (LLDA) said the algae bloom “could have been triggered by the combination of various factors such as the prolonged hot weather and calm lake condition this summer followed by the heavy influx of nutrients into the lake particularly nitrate and phosphate from the tributaries after the rainy season started this June.”
Dela Cruz said that algae bloom “becomes harmful when it decomposes in the process due to direct exposure to sunlight that lessens the dissolved oxygen in the water and causes stress to the fish and can cause fish kill.”
He said Muntinlupa residents, especially those who live along the lake's shore, experience foul odor being emitted by algae bloom due to decomposition.
Extreme sunlight during summer causes the algae bloom to decompose and emit foul odor while during “amihan” or northeast monsoon, the direction of the wind plays a major role in building up algae bloom and water lilies along the shoreline of Laguna Lake, Dela Cruz added. Climate change is also a factor in algae bloom, he said.
The LMO has implemented programs and activities to lessen the problem of algae bloom in Laguna Lake.
Its Sagip-Ilog program is regularly conducted in coordination with barangays covered by the Laguna Lake. The hauling of garbage and water hyacinth from waterways lessens the problem, he said.
Four solar paddle wheels were installed in four areas to help increase oxygen supply to the lake to protect fish hatchery and fish cages.
Dela Cruz added that high powered submersible water pumps were also placed in strategic locations to serve as oxygen support in places where the paddle wheels cannot reach. Motorized boats are also used to create water activity in the lake to minimize the decay of algae bloom.
“Rest assured that the Lake Management Office does not rest in looking for ways to prevent/minimize and mitigate the present situation. The Strong Southwest Monsoon (Habagat) and strong rainfall can be a factor to help minimize and/or eliminate the decaying algae bloom along the territorial jurisdiction of Muntinlupa in Laguna de Bay,” according to Dela Cruz.