Several bulk water supply projects on the upper portion of the Kaliwa River Watershed have been proposed by the Philippine Government since the 1970s, with the intent of relieving Metro Manila of its overdependence on the water supplied by Angat Dam. Most of these have focused on a particular site in Barangay Laiban in Tanay, Rizal, on the upper portion of the Kaliwa River Watershed to which the Laiban Dam belongs, and the projects have thus often been referred to as Laiban dam or Kaliwa dam, although multiple projects have been referred to using either name.
Due to controversies regarding the project's environmental impact and its potential effect on local communities, notably including a community of Remontado Dumagat people who consider the area part of their ancestral lands, these projects have been controversial and have thus been alternatingly approved, deferred, cancelled, and reapproved by the Philippine Government at different times since the late 1970s.
Proposed dam sites
Dams have been proposed on two separate locations within the Kaliwa River watershed: one upstream in Tanay, Rizal, which is sometimes called the "Laiban Dam", and another Downstream, in Quezon Province. Both have been referred to as the Kaliwa Dam, but since 2012, the Quezon site is the one disitinguished as "Kaliwa Dam" when the two sites are both being discussed.
The Kaliwa Watershed
The Kaliwa Watershed forms part of the Sierra Madre Biodiversity Corridor (SMBC), and has been identified by the Southern Sierra Madre Wildlife Center of the Environmental Studies Institute of Miriam College as one of the SMBC's 14 priority biodiversity conservation sites. It is described as "an important wildlife habitat that contains dipterocarp trees, a wide array of birds, mammals, amphibians and reptiles, some of which are threatened and endemic species."
In 1999 the Kaliwa Watershed, evaluated at the time as "degraded due to anthropogenic pressures", was classified as a protected area under the National Integrated Protected Areas System.
The terrain is generally mountainous, surrounded by slopes > 50%, consisting partly of forested hills and partly of cultivated land, with some slash and burn cultivation (kaingin) areas present. Its elevation is from 220 masl (meters above sea level) to 1,530 masl. A number of small creeks run through the lower slopes, all eventually connecting to the main river.
The Laiban sub-watershed site in Tanay, Rizal
The Laiban site where the project is supposed to be built is a Barangay of municipality of Tanay in the province of Rizal, east of Metro Manila. It contains he 180 ha Laiban sub-watershed, a microbasin of the bigger Kaliwa Watershed, nestled in the southeastern portion of the Sierra Madre Mountain Range.
Barangays on the site also serve as home to the indigenous Remontado Dumagats.
Downstream site in Quezon Province
The other proposed site for the dam and reservoir is further east and downstream on the east-flowing Kaliwa river, located in the Barangays of Pagsanjan in the town of General Nakar and Magsaysay in the town of Infanta. Proposals for the construction of this downstream dam still involves the placement of conveyance tunnels and reservoir areas in the upstream Tanay, Rizal site.
Previously discontinued proposals
Manila Water Supply III project during the Marcos administration
The history of projects on the Kaliwa River watershed began with the conception of the Manila Water Supply III project in November 1979 during the administration of President Ferdinand Marcos. However, instructed the MWSS to look for alternative sites. The MWSS identified the Kaliwa River basin to be the most viable alternative, and began the first World Bank feasibility study on the damming of the Kaliwa river in 1979.
During that time, however, the Philippine economy had gone into rapid decline because Marcos' debt driven deficit spending made the Philippines vulnerable when the United States increased its interest rates in the third quarter of 1981. The ensuing collapse of the Philippine economy, worsened by the political pressure after the assassination of Benigno Aquino, led to slow development of the Laiban dam project until Marcos was forced out of office and into exile by the 1986 People Power Revolution.
By 1989, the succeeding administration of Corazon Aquino reviewed the project and determined that costs had ballooned so high that the project had to be shelved.