SMC’s previous work (e.g. Tullahan, Pasig, San Juan, etc.) has shown measurable increases in depth and capacity, according to the Department of Environment and Natural Resources.
By removing silt and debris, the flow improves, which helps rainfall runoff exit faster rather than backing up. This is especially useful in low-lying areas where backflow or overflow accumulates.
No immediate cost to taxpayers/government:
The agreement includes annual river maintenance, which is critical — many past river cleaning/dredging efforts fail because once the initial work is done, upkeep isn’t sustained.
Scope vs scale: Laguna is large, with many rivers, tributaries, drainage systems. Widening all narrow rivers by 30% is significant, but floods are caused by multiple tributaries, topography, rainfall intensity, upstream land use, drainage systems, and backflow from Laguna de Bay etc. If upstream drainage, soil erosion, or improper development aren’t addressed, flooding can still happen.
Without controlling sources of siltation (erosion upstream, construction, dumpings, river walls putting soil back), rivers will gradually resilt again. Maintenance helps, but if upstream practices remain uncontrolled, the problem recurs.
Policy, permits, coordination
River widening/dredging often involves land rights, environmental permits, house/building encroachments, flood control infrastructure, coordination between multiple LGUs, and sometimes national agencies. These can slow things down or complicate implementation.
Extreme weather / climate change
With heavier rains, more frequent typhoons, sea level rise, and extreme events, even expanded river capacity might not be enough. Flooding might still happen (though perhaps attenuated).
Laguna Lake & downstream constraints
Laguna’s rivers drain into Laguna de Bay. If the lake is already high (e.g. due to heavy rain, high watershed runoff), or if there’s backflow, or if outlets are blocked, widening/rivers alone may not suffice. Also, the lake itself may need management (lake dredging, water level regulation, upstream inflows).
Not a silver bullet
SMC’s solution with Laguna is a large-scale and well-funded initiative that addresses one of the major contributing causes of flooding: silted, narrowed river channels.
If implemented well and sustained, it will significantly help reduce flooding in many parts of Laguna, especially in areas where overflowing rivers are the primary cause.
However, it is not a silver bullet.
To truly solve flooding, this project must be part of a broader integrated flood management strategy: controlling upstream erosion, ensuring good land use practices, maintaining drainage infrastructure, dealing with lake/laguna-lake water level, handling climate change impacts, enforcing regulations, and ensuring coordination among multiple jurisdictions.
