Sanitation work crews of the summer capital have been busy scrubbing down its only sewage treatment plant (STP) after failing its recent performance evaluations.
Baguio was slapped with a notice of violation after its outdated and overworked treatment facility failed tests conducted by the Environmental Management Bureau (EMB) of the Department of Environment and Natural Resources in December, due to high biochemical oxygen demand (BOD), lawyer Rhenan Diwas, city environment and parks management officer, informed the Baguio City Council on June 1.
BOD measures the abundance of organic matter in waterways that consumes all the oxygen required by native marine life.
In February, the Baguio STP failed again because of a buildup of phosphate and oil attributed to kitchen cooking oil in the Balili River, where treated domestic water is discharged in this part of the city.
I have reminded restaurants and eateries not to dump cooking oil in our sewers,’ Diwas said.
Work crews have literally been wiping down STP turbines and other equipment to remove the oil, and will purchase submersible tanks as an extra measure to contain pollutants in a bid to pass the next round of tests this month, he said.
‘Moral imperative’
Mayor Benjamin Magalong and the local government’s city managers have long intended to modernize and improve Baguio’s STP and its entire septic network, some of which date back to the 1930s, decades after the mountain resort city was designed, built, and opened in 1909 by the American colonial government.
Back in 2019, the local government expected to focus most of its resources on repairing and expanding sewer coverage as its ‘moral imperative’ to ensure that four rivers emanating from their Baguio headwaters are reasonably clean.
These are the 24-kilometer Balili, which exits at the farmlands of Benguet neighbor La Trinidad; 33-km Bued that traverses Kennon Road; 6-km Asin-Galliano that discharges into Tuba, Benguet; and 88-km Ambalanga that flows to the mines of Itogon, Benguet.
In 2020, water quality samples taken from Balili River confirmed that it contained 160 quadrillions of fecal coliform bacterial count. The La Trinidad government has been dealing with households along the Balili riverbanks suspected of draining their septic tanks into the waterway.
Since 2011, a consortium of Baguio and Benguet universities has been developing action plans to regulate riverside settlements in order to rehabilitate the river.
A cluster of La Trinidad houses that was turned into a colorful mural and has been a major tourist attraction towers over the portion of Balili that leads out of Baguio.
Patchwork repair
But the polluted water could also be traced back to the increased volume of septage that has overwhelmed the 35-year-old Baguio STP. Built in 1986 by Japan’s Tobishima Corp., the facility can process only 8,600 cubic meters of wastewater per day, which is equivalent to 57,334 people in a city populated by 368,426, per the 2024 census.
Overpopulation and overdevelopment has increased the STP wastewater volume to 12,000 cu.m. and is suspected to include sewage transported surreptitiously by poso negro (septic desludging) trucks from some Benguet towns, Diwas said.
An urban carrying capacity report in 2019 concludes that Baguio resources to address liquid waste were breached in 2007.
Lowell Barton Jr., the EMB point man overseeing the Baguio case, said his agency has stopped short of elevating Baguio’s violations to the Pollution Adjudication Board (PAB), which could impose a P25,000 daily fine until the rivers are cleaned. The PAB could even order the STP to shut down, which could trigger ‘a domino effect no one wants,’ Barton told the council.
Diwas said the city government has resorted to patchwork repair jobs to keep the STP running smoothly while it negotiates for grants or loans to begin a massive overhaul of the facility which would require P1.2 billion, or to replace it with a modern system that costs P2.9 billion, he told the council.
The STP in its current condition only serves 4,000 commercial and residential connections in roughly 65 barangays out of the total 128 heavily populated villages.
A $63-million loan from the Asian Development Bank (ADB), negotiated in 2020 and reduced in 2025 to $45 million, was removed as a national government priority last year over delays in securing final council endorsement.
Mark Lapid, chief operating officer of the Tourism Infrastructure and Enterprise Zone Authority, offered to provide P500 million when he attended this year’s Baguio Flower Festival.
Magalong had also applied for a second P500-million grant at the Department of Public Works and Highways.
Gradual upgrade
Diwas said Baguio has drawn up a gradual upgrade and expansion of its sewage networks until 2035, intending to increase sewer connections by 19,000 households.
Magalong and his predecessor, now Baguio Rep. Mauricio Domogan, also addressed pollution issues by regulating and then finally banning all piggeries from operating inside the city.
Baguio’s sewerage program is tied to the city’s overall campaign to ease the impact of climate change on a mountain city, which the ADB described in a 2023 study as the recipient of the highest precipitation (rainfall) in the country.
‘As per the hydraulic and hydrodynamic analysis, the rapidly changing climate will result in a noticeable rainfall increase in Baguio over the intermediate future period of 2031-2060,’ projected at about 20 percent, the study said. This affects how groundwater aquifers are recharged and how flooding impacts the rivers leaving the city.