Keep Water of Banica River Clean
Banica River is one of the major sources of domestic water in Dumaguete City. However, with the advent of modern technology and the rapid increase in population, coupled with increasing demands for space, the river has been transformed into a filthy drainage canal.
This was the assessment of biologist Dr. Esther Carumbana, a professor at Negros Oriental State University (NORSU), Dumaguete City. She said, “Knowledge on water quality and biodiversity will enable us to understand the future impacts of climate change on the river system and on the people who are directly or indirectly dependent on the river and its resources.”
There is a need to prevent the deterioration of the river system, she stressed in the 2014 concluded multi-disciplinary study on “Water Quality and Aquatic Biodiversity Relative to the Socio-Economic Conditions in the Banica River, Negros Oriental,” funded by the office of Research Extension and International Linkages (REXIL)-NORSU. Negros Oriental is endowed with a number of river systems extending from the north up to the southern end of the province. One of these rivers is Banica River which carved and molded the hydrologic landscape of Dumaguete City as well as the towns of Valencia and Bacong where it passes through.
The economic potentials of the river require that its biological and physico-chemical properties be assessed, Carumbana said. Part of the study was conducted to gather data on the physical and hydrological characteristics of the river, as well as the species composition, abundance and distribution of fish and macro invertebrates during the dry and wet seasons in three segments of the river.
There were three sampling sites. These were Sampling Site 1 (upstream) in Barangay Apolong, Valencia, Negros Oriental; Sampling Site 2 (midstream) in Barangay Candau-ay, Dumaguete City; and Sampling Site 3 (downstream) in Barangay Tinago, Dumaguete City.
For their source of water for drinking, the residents living along the riverbanks generally have faucets supplied by the water districts in Valencia and Dumaguete City. The residents, who served as respondents in the study, also use water from the faucet to flush their toilets, although in the midstream section, there are some who indiscriminately throw their wastes directly into the river.
In the Banica River, the physico-chemical characteristics of water are favorable for growth and survival of fish and crustaceans. However, Carumbana noted that the small sizes of the fish, shrimps, crabs and mollusks that were collected would indicate that the resources are overexploited. The study was conducted for six months: three months during the wet season (September-November 2011) and three months during the dry season (March-May 2012).
During every sampling, atmospheric and water temperatures as well as salinity of the water were measured with the use of an ordinary field thermometer and an Atago portable refractometer, respectively. Three trials were made for each parameter and the averages were then computed.
Carumbana explained that using plastic gallons, water was collected from the three sampling sites for determination of the levels of nitrate, phosphate, total suspended solid (TSS) and total dissolved solids (TDS). The water samples were placed in an ice chest and transported to the Analytical Services Laboratory of the Chemistry Laboratory in Silliman University for chemical analysis.
Concerning biological parameters, the study cited four samplings. These were sampling for fish, benthos, crustaceans, and coliform bacteria analysis.
Sampling of water for coliform counts was first done during the rainy month of November 2010 and continued during the dry months of April, March and June 2011. Water samples in three replicates per site were analyzed for the presence of coliform bacteria using membrane filtration method in EMB agar. The standard used for safe water was based on World Health Organization standard.
The density of the coliform bacteria was highest in November, especially upstream and downstream. It is also seen that in March and June, the coliform bacteria were more abundant downstream than upstream and midstream but in April, the bacteria were more abundant upstream and midstream than downstream. Total coliform count (using the formula MPN/100 ml) showed that in November it got .0006; June and March got almost the same counts, .0003; and in April, .0001.
“Banica water is not potable,” stressed Dr. Carumbana in a recent interview. In her report, she said, some of the respondents disposed of their animal/agricultural wastes directly into the river while others just left them unattended and allowed them to decompose and mixed with the soil.
Carumbana said, this is alarming because when it rains, the polluted soil will become eroded and eventually enter the river, thus enhancing contamination and hastening deterioration of the river water quality. Moreover, due to the unavailability of proper drainage systems throughout, sewage water coming from various households is directly drained into the river.
In view of the ideal topographic location, availability of space, abundant water, favorable climate and low maintenance cost, a considerably large proportion of the population along the Banica River also engage in livestock-raising for supplementary income as well as source of animal protein, consisting primarily of poultry and cow or carabao upstream, poultry and pigs in the midstream section, and poultry and pigs downstream.
In general, the cause of the deterioration of the water quality and biodiversity of the Banica River is “anthropogenic” or mainly human activities, the study cited. Thus, to improve and prevent further worsening of its present ecological status, the study recommended that the residents in cooperation with the local government unit should exert effort and exercise political will to implement proper method of deposition and collection of solid wastes.
Some student organizations, university outreach programs, city and barangay councils took part in cleaning the river, but mostly it is for voluntary undertakings, not really sustainable, Carumbana said.—Joy G. Perez, SU Research & Environmental News Service