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Manila hopes greening its shorelines will yield cleaner water and less flooding

Source(s):  Citiscope

By Keith Schneider, Citiscope

MANILA, The Philippines — After dawn on a hot morning, Filipino fishermen fling fishing nets in the dark, waist-deep polluted waters of Laguna de Bay, the big freshwater lake that forms the eastern border of Metro Manila. Not far away, farmers cultivate rice in small paddies along the lake’s southern shore in Calamba, a lakeside city of 450,000 residents.

As one of the three largest freshwater lakes in southeast Asia, Laguna de Bay is counted on to serve these and other life-sustaining purposes — waterborne transportation, a source of drinking water, recreation, flood control. But like every other major surface-water resource in this bursting metro region of nearly 13 million people, Laguna de Bay’s deteriorated condition has turned the shallow 90,000-hectare (350 square-mile) lake into an environmental and economic menace.

The lake is the centerpiece of a flood and sewage crisis in Metro Manila that is amplified by the region’s location in a warm-water Pacific Ocean corridor that is generating storms with greater intensity and unloading more rain than the landscape can manage. With each storm, flooding gets worse. More people die. And more people are sickened by the tide of raw sewage that flushes out of septic tanks and overflows the banks of contaminated black rivers.

Designed and built by Spain, Manila has become a quintessentially Asian metropolitan area of the 21st century — animated with new business and real estate ventures, and teeming with people and traffic. Yet pollution and flooding represent dangerous consequences of Metro Manila’s runaway growth, and major risks to its rising economic strength.

For decades, the Philippine government and municipal public works departments have spent billions of pesos on drainage canals, pumping stations, treatment plants, and other hard fixes made of concrete and steel. Now authorities are adding soft-path solutions principally aimed at better managing stormwater and cleaning up the capital region’s filthy waterways.

Bamboo boost

Laguna de Bay’s ecological health and its capacity to store more water are central to the campaign. Regional officers of the Philippine Department of Environment and Natural Resources (DENR) recently held a public meeting in a big lakeside community centre in Calamba. The event lured so many attendees that the hall, easily capable of seating 400, filled quickly. Latecomers listened through open windows while sitting in the shade of citrus trees.

What attracted the overflow crowd wasn’t an issue of conflict, like proposing to tear down a neighbourhood for a new power station. Rather, it was to promote one of those soft-path solutions to Laguna de Bay’s pollution and flooding problems. A few blocks away, along a fertile stretch of lakeshore, the environment department had planted a small grove of bamboo trees to demonstrate how natural remedies could be easier, cheaper, and more effective in taming erosion, soaking up nutrients, and curbing siltation and plant growth that has been polluting Laguna de Bay and making it shallower.

“These bamboo plants are a start of a much larger planting program for the lake and for the country,” says Eusebio Jacinto, a DENR staff officer in Calamba. “Our plan is to plant 1.6 million hectares of bamboo, and 600,000 hectares of mangrove. We’ve got to find better ways to keep pollution and sediments from getting into the lake and rivers.”

Jacinto explains that bamboo and mangroves are native to the Philippines and well regarded as soil stabilizers and nutrient sponges. The Philippine government, in partnership with cities in Metro Manila and the Laguna de Bay watershed, is prepared to spend 8 billion pesos (USD 161 million) to replant much of the mangrove and bamboo shoreline lost over the past several decades to development. By slowing erosion and absorbing nutrient pollution, Jacinto says, siltation should diminish, Laguna de Bay’s water will get cleaner, and its capacity to store floodwater should improve.

The DENR is participating in several other cost-effective cleansing and flood-control measures that impact the lakeside cities of Metro Manila. Much of Laguna de Bay is covered in floating fish pens that release nutrient-rich wastes that aquatic plants love. Philippine law limits fish-pen management to 9,000 hectares (35 square miles), but the DENR found that fish pens occupy 12,315 hectares (48 square miles). Many of them are managed by fish-producing companies with close ties to members of the Philippine Congress. The environmental agency, defying Congressional opposition, has begun to remove fish pens, especially those operating without licenses.

City and district authorities also are clearing garbage and plants from the Pasig River and its tributaries that drain Laguna de Bay. A smaller project has started to clear garbage from sewage transport infrastructure — pipes and culverts — that block wastewater from arriving and leaving treatment plants. The idea is to provide more drainage capacity.

In a third demonstration project, the ABS-CBN Foundation, a unit of the country’s biggest media company, led the restoration of the La Mesa Watershed near Quezon City to slow erosion and prevent informal settlements from ruining a drinking-water reservoir. The project principally involved resettling families outside the watershed, planting trees in a forest area, and establishing La Mesa Ecopark, a popular recreational hiking, garden, picnic and swim center. Thousands of Filipinos use the park on weekends.

“We did not need a lot of big machines and heavy equipment to restore the forest,” says Sarah Charisma Alcayde-Agcaoili, who worked on both projects over the last decade and is the Ecopark director. “We did it with a lot of volunteers who worked with their hands and their feet.”

New approach

What is so striking about the current low-tech, relatively low-cost approach to pollution prevention and flood reduction is how much it differs from previous measures. In the late 20th century, authorities embraced a decidedly brute-force approach that cost billions of pesos and has not worked effectively.

In 1983, authorities completed the Napindan Hydraulic Control System, essentially a two-way dam, to manage salt water from Manila Bay flowing into Laguna de Bay during high tides and storms, and to control floodwaters draining from Laguna de Bay. It was constructed where the region’s two major rivers, the Marikina and the Pasig, meet close to the lake.

Three years later, public works authorities completed the Manggahan Floodway, a 10 km (6 mile) canal that diverts floodwaters from the Marikina River to Laguna de Bay and is meant to keep stormwater out of the Pasig River. The idea was, first, to reduce flooding in Manila and neighbouring cities by diverting water to Laguna de Bay; and second, to temporarily store flood waters in the lake by closing the Napindan gates.

The two structures, say residents, not only are failing to produce the desired fix, but also appear to be making flood and health consequences worse. A stampede of new business starts and population growth in Metro Manila — 200,000 more residents annually since 1990 — is filling the shallow lake with sediment and making it less capable as a stormwater storage reservoir. Significantly, a third of Metro Manila’s built environment sits in designated floodplain areas.

Rapid growth also has outraced treatment of sewage and industrial waste. Less than 20 percent of the region’s wastewater is treated, according to the Metropolitan Waterworks and Sewerage System, the major treatment utility. Millions of homes collect wastewater in septic tanks. Every year, billions of litres of raw human waste pour from informal settlements into the lake, and thence into the rivers to create the filthy Manila Bay on Manila’s west side.

“We’ve had floodwaters in the last couple of years that didn’t drain away for months in some of the communities around the lake,” says Jacinto of the DENR.

Frequent flooding

Not terribly long ago, residents say, severe flooding accompanied only the biggest storms. In 2009, and again in 2012, for example, heavy monsoon rains caused over half of the metropolitan region to flood. The 2012 storm drowned more than 20 residents.

Today, flooding occurs after virtually every storm, even the mild ones. “It doesn’t take much now to put a lot of water in people’s homes,” says Herminio Buerano Jr., one of the region’s prominent environmental leaders, and the president of the Coalition of Clear Air Advocates of the Philippines. “It’s going to affect growth. At some point people will start moving away.”

Last year the Laguna Lake Development Authority, a regional enforcement and planning unit of the DENR, completed its latest lake management master plan. The chapter on flood control is rich in detail about reforesting watersheds around the big lake and Metro Manila, controlling sedimentation with new coastal bamboo and mangrove plantations, more strictly regulating land uses, and even compensating homeowners and businesses to move out of floodplains.

But hard fixes continue to attract the government’s attention. The master plan’s authors note a need to build the Parañaque Spillway, a 40 km (25 mile) underground drain to transport Laguna de Bay floodwaters directly to Manila Bay. The current estimated cost is at least USD 2 billion. Contemporary planners note that with additional investment the spillway could have a dual purpose — during the dry season it would serve as a vehicular tunnel to ease Manila’s ferocious traffic congestion.

The spillway idea was initially proposed by planners in the regime of Ferdinand Marcos in the 1970s. It periodically surfaces following intense flooding, and then vanishes for a while. In 2009, for instance, President Gloria Macapagal-Arroyo briefly became a spillway supporter.

At the time, Felino Palafox Jr., one of the country’s most prominent urban planners, appeared at a public meeting on the spillway and succinctly summed up what happens when 20 rivers and so much untreated waste drain into Laguna de Bay without an outlet. “It’s like having a toilet,” he said, “without a flush.”

Citiscope is a nonprofit news outlet that covers innovations in cities around the world. More at

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  • Publication date 22 Jun 2017

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