SARMIENTO SAYS that red tide still occurs in some places, and his agency issues a bulletin every month to announce where the problem areas are located to warn both the consumers and the fisherfolk about the dangers of harvesting and eating shellfish from these sources. BFAR’s records show that red tide usually occurs after a long dry spell or during the summer months of March and April.

	[photo by Jaileen Jimeno]

Sarmiento and other experts say there is no one big hot spot in the country for harmful algal bloom. Our water systems are interconnected and as past red tide occurrences have told us, the bloom can spread rapidly from one area to another. Algae move around, and actively swim toward the light. Water currents also transport algae from one body of water to the next.

Adriano, meanwhile, isn’t optimistic that red tide will cease to appear anytime soon, given the deteriorating or already bad water quality of many of our lakes, rivers, and coastal waters. Aside from untreated domestic waste and mariculture activities, bodies of water across the country have been polluted by farms that raise hogs, chicken, and cattle and generate high organic wastewater (but with no appropriate wastewater treatment facilities). Industries also get away with discharging heavy metals and hazardous wastes into the waterways.

Adriano mentions surface runoffs as well as among the water pollutants. He says these happen when “you deforest a mountain or engage in mining, disturbing the topsoil.” Or, he continues, “you convert agricultural land into a (residential) subdivision — that’s bound to have surface runoff. It rains, the topsoil goes with the surface water flow, and ends up in (a water body). The topsoil has nutrients that help propagate organisms, which in turn lead to (red tide) that kills the fish.”

Red tide or no red tide, though, it may be wise to find out first where that fish you’re about to buy came from. In its five-year study of the country’s 196 inland surface waters (192 rivers and four lakes), the EMB found 13 percent as having poor quality, based on the amount of dissolved oxygen (DO). Fish and other aquatic organisms need at least five milligrams per liter (mg/L) of oxygen to live. DO that is below this level cannot sustain aquatic life. Although the surface waters deemed to have poor quality still have some life, whatever are able to survive there are bound to be loaded with toxins and bacteria.

During the EMB study, these registered poor water quality owing to their low DO levels: San Juan River, Parañaque River, Navotas-Malabon-Tullahan-Tinejeros River, and Pasig River in Metro Manila; Guadalupe River in Cebu; Meycauayan and Bocaue Rivers in Bulacan, and Calapan River in Oriental Mindoro.

Recently, Marilao River in Bulacan landed in the news for having water quality that is so bad it actually ranks among the world’s worst. In the EMB study, the river was found to have a high annual total dissolved solids (TDS) levels that ranged from 1,785 to 3,265 mg/L. TDS is an indicator of the presence of a broad array of chemical contaminants; experts say that the level should not be more than 500 mg/L for good quality water. The primary sources of TDS in receiving waters are agricultural runoff, leaching of soil contamination, and industrial or domestic sewage.

The EMB also singled out Pampanga River in Region 3 for having high levels of Total Suspended Solids (TSS), which measures the amount of undissolved solid particles in water such as silt, decaying plant and animal matter, and domestic and industrial wastes. Ideally, the TSS level should not be above 25 mg/L; the EMB, however, did not specify what the Pampanga River’s TSS levels were.

BUT DON’T swear off seafood just yet. The inland surface waters that EMB considers to have good water quality (47 percent) still outnumber those with poor quality, based on DO levels. And of the 26 coastal and marine water bodies the EMB surveyed, about 54 percent had managed to maintain good water quality during the time of the study. So long as the fish and other marine products that you are serving come from these (and there was no recent environmental disaster there), then any trip to the hospital afterward may be more likely to be caused by gluttony or the cook’s severe lack of culinary skills.

The EMB actually classifies water bodies into three groups. Aside from inland surface waters and coastal and marine waters, there is also groundwater, which the Bureau evaluates according to how safe it is for drinking.

	FISHERMEN going out to sea. [photo by Jaileen Jimeno]

As for being habitats for creatures that end up on the dinner table, the EMB determines that an inland surface water body has good water quality when it has low amounts of TDS and TSS, as well as low levels of biochemical oxygen demand or BOD. The latter determines the amount of oxygen required for the decomposition of organic matter from a pollution source. Higher BOD levels means more pollution. If the BOD is less than 30 mg/L, then that may be good quality water.

Both inland surface waters and coastal and marine waters must also have zero or very low heavy metal content to be described by the EMB as having good water quality. The Bureau failed to mention a benchmark level for this for inland surface waters, but for coastal areas, it says that as far as mercury content is concerned, it should not be more than .002 mg/L. The EMB also monitors water bodies for lead, copper, and cadmium content.

The EMB singled out these rivers for having particularly low TSS levels and good water quality: Nagan (upstream and downstream), Akutan, and Tanudan Rivers in the Cordillera Autonomous Region; Laoag River in Region 1; Mabayuan River in Region 3; Saaz and Patalon Rivers in Region 9; Sibulan and Manurigao Rivers in Region 11; and Cabadbaran River in Caraga. The lowest BOD levels in the study were recorded at four rivers in Caraga — Taganito, Magallanes, Taguibo, and Bislig Rivers — which all registered figures that were below one mg/L, implying low organic pollution sources from surrounding areas.

For coastal waters, the EMB considered Sarangani Bay —- an important fishing ground for tuna — in Region 12 as having good water quality.