CITY OF SAN FERNANDO— Rain, floodwater and sewage draining into the Pampanga River caused oxygen in water to drop to extremely low levels, killing thousands of fish downstream in Candaba, Masantol and Macabebe towns last week, according to a report of the Bureau of Fisheries and Aquatic Resources (BFAR).
A water quality assessment conducted by BFAR revealed that dissolved oxygen (DO) in portions of the river fell between 1.28 milligram per liter and 1.41 mg/l, said Gonzalo Coloma Jr., the bureau’s fish health officer in Central Luzon.
The ideal level so fish can process oxygen and breathe is 5 mg/l.
High nutrient content
“The extremely low DO level obtained from Pampanga River may be due to the high nutrient content of water coming from the Upper Pampanga River, which originates from Nueva Ecija, Tarlac and Bulacan,” Coloma said in the report.
“This was evident by the presence of gray to brownish color of the water during the time of the sampling,” he added.
“This, together with the decaying organic materials like garbage and dead plants (particularly water lilies) at the bottom of the river, aggravated the condition of the water.”
Other possible contributors to the low dissolved oxygen level were sewage discharges from houses, commercial establishments, and poultry and swine farms along the tributaries of the Pampanga River, the report said.
Dead fish floating
Former Masantol Vice Mayor Marcelo Lacap Jr., who alerted the BFAR on the incident, said fishermen reported seeing dead fish floating as early as 5 a.m. on Thursday.
This was the first massive fishkill incident here since the 1990s when thousands of fish went belly-up due to wastes discharged into the river.