The National Irrigation Administration (NIA) is now trying to reach out to the Department of Environment and Natural Resources (DENR) and the Department of Interior and Local Government (DILG) as certain sand and gravel quarry sites start to threaten several irrigation projects in the country.
In a statement, NIA asked for the support of the DENR and DILG in the strict enforcement 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.
NIA argued that some sand and gravel quarry sites in the country “operate too close to irrigation facilities and structures leading to the adverse effects of excessive quarrying activities, such as the exposed foundation of said structures, scoured riverbanks, and degraded river beds”.
Based on the initial inventory by NIA, there are 116 irrigation systems and projects in the country that are affected by quarrying activities.
In Region 11, for instance, the Padada River Irrigation System located in Hagonoy, Davao Del Sur is now experiencing the effect of quarrying activities adjacent to it, NIA said.
The diversion dam of Padada RIS particularly suffers severe damages and exposed sheet piles, threatening the foundation of the dam. This is due to severe erosion caused by the quarrying operations downstream.
At the same time, NIA said the relocated diversion dam of Sta. Cruz River Irrigation System situated in Liliw, Laguna under NIA Region IV-A is also 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,” NIA said. "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".
Meanwhile, referring to the Sibalom River Irrigation System in Iloilo, Regional Project Monitoring Committee in Region 6, chaired by the National Economic and Development Authority (NEDA), also reported recently 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.”
Thus, 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.
“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 said.
For his part, NIA Administrator Ricardo R. Visaya assured 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.