Abra River Laden with Toxic Nitrate, Heavy Metals, Cyanide – SLU Study

The mighty Abra River, one of five largest rivers in the country straddling the Mountain Province and Benguet as headwaters downstream to Ilocos Sur, is plagued by pollution.

Northern Dispatch
Posted by Bulatlat

BANGUED, Abra (410 kms. North of Manila) – The mighty Abra River, one of five largest rivers in the country straddling the Mountain Province and Benguet as headwaters downstream to Ilocos Sur, is plagued by pollution.

A probe by the Saint Louis University (SLU) College of Engineering’s Applied Research and Development Studies found that the river, the home of the famous Abra river eel and very dear heritage resource of the Abreños, is no longer fit for domestic use.

The scientific study “The Abra river system water quality monitoring”, written by Josephine Aries Dulay, coordinator of SLU’s Environmental Research Laboratory that came out in the Northern Luzon Research Journal ( 2007), concluded that “except for temperature, all parameter readings exceeded allowable limits or did not meet minimum required concentrations set forth in Department of Environment and Natural Resources Administrative Order (DAO) 34 for the rivers to be classified Class AA (public water supply class I), Class A (public water supply class II), or Class B (recreational water class I).”

The findings indicate that the river is polluted.

Data sampling for the research was started in October 2004. The sampling was performed on a quarterly basis.

Water samples were taken from different sites along the length of the Abra River system and were analyzed in terms of physic-chemical characteristics which include temperature, pH, dissolved oxygen, total suspended solids, total dissolved solids, biochemical oxygen demand, nitrates, lead, mercury, chromium, and cyanide concentrations.

The samples were taken from the headwaters in Guinaoang in Mankayan town in Benguet as control sample, the Lepanto Consolidated Mining Company’s mill outlet, tailings dam spillways, Lepanto Bridge, Kayan, Gitlangan, Bulaga, Patungkalew, Banoen, Manabo, Bucay, Bangued, Banaoang, Caoayan, and Santa.

“During samplings at the mill outlets and tailings dam spillway, no life forms in these parts of the river were observed,” Dulay said.

Dulay also noted an alarming presence of toxic substances. There are high nitrate concentrations, heavy metals, and cyanides, she found out. She attributed the nitrates to fertilizers, domestic and industrial effluents, and animal manure.

Heavy metals present are lead, mercury, and chromium in concentrations much higher than acceptable limits. Although these metals are naturally present in the environment, “if found in excessive amounts, they are most likely due to industrial discharges,” Dulay explained.

Cyanide has also been found to be in concentrations above the acceptable limits, “especially at the mill outlet and the mine tailings spillway,” the study reads.

“Cyanide is the most common chemical used to extract gold from ore despite the fact that leaks or spills of this chemical is extremely toxic to fish, plant life, and human beings,” the study noted.

Cyanide can break down with sunlight and oxygen, but the low amount of dissolved oxygen (DO) in the water hinders it from breaking down. The low DO also means the water cannot support aquatic life.

No longer fit for humans

“Due to the pollution, the river may no longer be able to fulfil its productive and life-sustaining functions, as the river’s assimilation and self-purifying capacity is greatly impaired,” Dulay said.

Abra River stretches from Mountain Province passing through Ilocos Sur and Abra. It used to be rich in aquatic resources supporting the needs of the communities it traverses.

Growth in population, urbanization, technological advancement as well as mining, Dulay said, have contributed to the river’s pollution.

Aside from mining, deforestation and slash and burn activities in the upland area, illegal logging and tunnel shoring in mining areas causing soil erosion and river siltation, and use of chemical pesticides, herbicides, and fertilizers by the farmers nearby also cause pollution.

Dulay insisted that while the research may hurt, she studied the Abra River to assess its capacity to receive waste discharge and later recover from the disturbance, to classify the river according to guidelines set by Department Administrative Order No. 34 of the Department of Environment and Natural Resources (DENR).


The SLU professor added, “Abra River still has the capacity to regenerate if proper management of waste disposal is met, sounding that she wanted people to open their eyes to the reality.”

She suggested dredging, like what Marcopper did in Marinduque, which can be done to be able to bring back the ecological system of the riverbed. She likewise suggests oxidation to destroy cyanide molecules.

Mining operations and environmental protection can go together, Dulay said, but “radical changes in mining practices and stricter government implementation of environmental laws” must be done.
She further suggested that mining companies utilize available technologies for the treatment of contaminated fresh surface water, efficient on-site reduction of metal and the control, storage, and beneficial utilization of mine tailings. Northern Dispatch / Posted by Bulatlat.com

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