Marikina River

Also known as: Ilog Marikina · Marikina Valley river system

Definition

The Marikina River is the largest tributary of the Pasig River, draining a roughly 680-square-kilometer basin that rises in the Sierra Madre mountains of Rodriguez, Rizal — where the early-twentieth-century Wawa Dam once supplied Manila’s water — and flows south through San Mateo and the Marikina Valley before joining the Pasig River in Pasig City. Its channel runs roughly 27 kilometers through the urban valley, with the full river system measured at about 78 kilometers. Because most of Metro Manila’s eastern rain funnels into this single waterway, the river doubles as the metropolis’s most watched flood gauge, its water level broadcast like a vital sign during every typhoon. (Wikipedia — Marikina River)

At Pasig, the Manggahan Floodway diverts the bulk of the Marikina’s peak flow into Laguna de Bay, protecting the Pasig River corridor from Manila flooding; the confluence with the Pasig sits 6.75 kilometers downstream of the floodway gates. Repeated record floods — led by Tropical Storm Ondoy (Ketsana) in 2009 and Typhoon Ulysses (Vamco) in 2020 — have made the river both a symbol of urban flood risk and the focus of long-running channel-improvement and riverfront-rehabilitation programs, including the Marikina River Park and the Riverbanks Center development. (Wikipedia — Marikina River, Wikipedia — Manggahan Floodway)

Identities

Source Type	Identity
Wikipedia	Marikina River
Wikidata	Marikina River (Q3551251)
DBpedia	Marikina_River
ProductOntology	N/A
Wiktionary	N/A
Library of Congress Subject Headings (LCSH)	N/A
MeSH	N/A
NCBI Taxonomy	N/A
AGROVOC	N/A
Google Scholar	Marikina River basin flooding Ondoy flood control Metro Manila
ConceptNet	N/A
OpenCyc	N/A

Also Known As

Ilog Marikina
Marikina Valley river system

Examples and Analogies

Metro Manila’s flood barometer: During storms, news anchors read the Marikina River’s gauge the way doctors read a fever chart — above roughly 16 meters the river spills its banks, and by 20 meters whole barangays are under water.
Pressure-relief valve: The Manggahan Floodway works like a radiator overflow pipe: when the Marikina River surges, the gated channel bleeds most of the peak flow into Laguna de Bay instead of letting it pile up in the narrow Pasig River.
Retail riverbank: The Riverbanks Center treats the river as a shop window — a 23-hectare riverfront of outlet malls and museums built deliberately beside a flood-prone channel, an alignment of commerce and hazard that Ondoy would test in 2009.

Usage Scenarios

1. Flood Control and Warning for Metro Manila

The river’s level is monitored continuously, with alarm levels triggering citywide evacuation in Marikina; in the July 2024 Habagat enhanced by Typhoon Carina (Gaemi), the river hit its third and highest alarm, rising past 20.6 meters and prompting declarations of a state of calamity. The Manggahan Floodway, completed in 1986, meanwhile diverts up to roughly 2,400 cubic meters per second of peak flow to Laguna de Bay. (Wikipedia — Marikina River, Wikipedia — Manggahan Floodway)

2. Recreation and Riverfront Development

Marikina City has developed the riverbanks into the Marikina River Park, and the 23-hectare Riverbanks Center — opened April 1999 on the site of a former textile mill — anchors riverfront recreation with an outlet mall, a 20,000-capacity outdoor amphitheater, the Philippine Science Centrum, and the giant Marikina shoes that once contended for a world record. (Wikipedia — Riverbanks Center)

3. Channel Improvement and Dredging

The national government’s Pasig–Marikina River Channel Improvement Project, financed with Japanese official development assistance, has been building dikes, river walls, and dredged channels along the Pasig and Marikina rivers since the Ondoy disaster, with the fourth and final phase now under construction. (DPWH, JICA)

4. Habitat and Urban Fisheries

The river historically supported native fish such as martiniko, ayungin, and biya, and hosts small-scale fishing and boating — although invasive janitor fish now dominate much of the channel. (Wikipedia — Marikina River)

Strategies

Keep the floodplain clear: enforce river easements and relocate structures inside the channel’s natural overflow zone before, not after, the next record flood.
Complete the phased Pasig–Marikina channel improvement works — dredging, dikes, and river walls — and maintain them as a single system with the Manggahan Floodway gates.
Reforest and protect the Upper Marikina River Basin Protected Landscape in Rodriguez and San Mateo, where deforestation drives siltation that raises the riverbed.
Use the river’s gauge-driven alarm protocol as the city’s primary early-warning instrument, pairing it with pre-positioned evacuation centers.
Convert the riverbanks into public parkland and esplanades that double as floodable open space during storms.

Security and Safety Measures

Residents should treat the river’s alarm levels as evacuation orders, not advisories: during Ondoy in 2009 a month’s rain fell in less than 24 hours, catching thousands on the riverbanks, and during Ulysses in 2020 the river reached about 22 meters — surpassing Ondoy — and submerged most of Marikina. (Wikipedia — Marikina River)
Never shelter in basement or ground-level spaces near the channel during rainfall alerts; even riverside malls have been inundated, as SM City Marikina’s basement was in 2011. (Wikipedia — Marikina River)
Avoid contact with floodwater, which mixes sewage and river water and raises leptospirosis risk after every inundation.
Report illegal dumping and structure-building inside the easement, which choke the channel and accelerate flood rise.
Fisherfolk and boaters should avoid the channel during dam and floodway gate operations, when currents change abruptly.

Historical Context

The Marikina River supplied Manila’s first upland water through Wawa Dam, built in the early 1900s inside what is now the Pamitinan Protected Landscape. During the American period an engineered levee at Tumana cut off a meander, leaving the “Patay na Ilog” (Dead River) as a ghost channel, and the valley industrialized around the waterway — the Universal Textile Mills that once stood on the Riverbanks site was described as Asia’s largest textile mill at the time. (Wikipedia — Marikina River, Wikipedia — Riverbanks Center)

The river’s modern history is written in flood marks. Ondoy (Ketsana) on September 26, 2009 dropped one month of rain in under 24 hours, flooding around 80 percent of Metro Manila and 25 provinces, killing at least 246 people, and submerging the entire Riverbanks complex; Pedring (Nesat) in 2011 and the Habagat of 2012 followed, and Ulysses (Vamco) in November 2020 pushed the river past its Ondoy benchmark to about 22 meters, submerging most of Marikina City. After each disaster, dredging, dike-raising, and the Japan-backed channel improvement program expanded, while Marikina City rebuilt its river parks and cleared its easements. (Wikipedia — Marikina River)

Challenges and Controversies

Record Flooding and Slow Flood Control

Despite a channel-improvement program begun after Ondoy in 2009, the river has set successive record levels — Ulysses in 2020 and the July 2024 Carina-enhanced Habagat both forced mass evacuations and states of calamity — feeding a running public debate over why multibillion-peso flood-control works, including the still-unfinished final phase of the channel improvement project, have not stopped the inundation of Marikina’s riverside barangays. (Wikipedia — Marikina River, DPWH)

Upstream Deforestation and Siltation

Deforestation in the Upper Marikina River Basin Protected Landscape has contributed to heavy siltation of the channel, reducing its carrying capacity; environmental groups and local officials continue to clash with quarrying and land-conversion interests in the Sierra Madre headwaters. (Wikipedia — Marikina River)

Invasive Janitor Fish

Janitor fish (armored catfish), present since the late 1990s, have displaced native species and burrow into riverbanks; Marikina City passed Ordinance 004 (2007) funding an eradication drive with cash incentives, but the population remains entrenched. (Wikipedia — Marikina River)