IRRIGATION PROJECTS THREATENED BY SAND AND GRAVEL QUARRY SITES

August 19, 2021, 10:34 AM

NIA Central Office – The National Irrigation Administration (NIA) infrastructure projects are being threatened by sand and gravel quarry sites. These operate too close to irrigation facilities and structures leading to the adverse effects of excessive quarrying activities such as exposed foundation of said structures, scoured riverbanks, and degraded river beds.

In Region XI, the Padada River Irrigation System located in Hagonoy, Davao Del Sur is experiencing the effect of quarrying activities adjacent to it. Diversion dam of Padada RIS suffers severe damages and exposed sheet piles threatening the foundation of the dam due to severe erosion apparently caused by the quarrying operations downstream. Also, the relocated diversion dam of Sta. Cruz River Irrigation System situated in Liliw, Laguna under NIA Region IV-A is being threatened again by severe erosion due to quarrying operations downstream. This after the original dam about 800 meters downstream was totally damaged in 2006. These are not isolated cases but rather are a nationwide occurrence. Based on the initial inventory by NIA, there are 116 irrigation systems/projects affected by quarrying activities nationwide.

Quarry operators excavating more than the prescribed 1-meter extraction-depth limit, excessive quarrying, including those of river boulders which limit speed of river flow, leading to the diversion of the river course and a steeper river slope resulting in rapid erosion of riverbanks, and the coverage of the quarrying area not effectively marked and delineated using high and conspicuous markers all poses negative effects in irrigation projects nationwide.

With Sibalom River Irrigation System in Iloilo, Regional Project Monitoring Committee (Region 6) chaired by the National Economic and Development Authority reported on July 09, 2021 that “the diversion dam is in danger of being severely damage which may be attributed to intensive and improper quarrying within 1 kilometer downstream, since its end seal and concrete blocks are getting eroded due to continued lowering of the riverbed by around 1 meter with spillway already hanging which may soon crack and disintegrate.” NIA technical survey recommended that the quarry area should be 2.8-kilometer away downstream of the diversion dam to allow for the river basin to return to its original elevation and protect the existing irrigation structures.

NIA is calling for the support of the Department of Interior and Local Government (DILG) and the Department of Environment and Natural Resources (DENR) in the strict enforcement and support of the Regional Project Monitoring and Evaluation System (RPMES) for the safeguard and protection of public infrastructure, as well as the preservation of the integrity of the river system supporting irrigation projects, and the review of Section 79. (a) of DAO No. 2010-21 (Implementing Rules and Regulations of Republic Act No. 7942 “Philippine Mining Act of 1995” for further studies for the appropriate delineation of the radius of prohibited quarry areas adjacent to public infrastructure as set forth in Section 79. (a) of DAO No. 2010-21.

This continuous collection of boulders and aggregates in the downstream portion of NIA’s structures are causing the rapid erosion of the riverbed which results in the weakening of protecting walls and similar structures. Damage of this kind will eventually lead to the collapse of the entire structure.

NIA Top Management Officials, headed by Administrator Ricardo R. Visaya, assures that the Agency is doing its best to reduce every risk of losing irrigation water supply to our farmer stakeholders and the damage to public property that will entail immense costs for repair and rehabilitation.