River system assessment of the Mount Makiling subwatershed in the municipalities of Los Baños and Bay, Laguna, Philippines
2014
Cando, E.N.T. III
The hydrology and chemistry, fish assemblages and socioeconomic profiles of the six Mt. Makiling subwatershed: Dampalit, Anos, Callos, Molawin, Maitim and Cambantoc-Calo in Los Baños and Bay, Laguna were assessed from November 2012 to May 2013. Fourteen sampling stations comprised of the pollution point sources, upstream and midstream areas of the creeks were established. All stations excluding the upstream areas of Dampalit and Molawin were hypereutrophic and exceeded the DENR [Department of Environment and Natural Resources] standards for surface water in terms of fecal coliform concentration. The low water quality was attributed to the untreated effluents from the domestic, industrial-commercial, and research and academic institutions. Concentrations of heavy metals such as Crsup 6+, Pbsup 2+, and Cdsup 2+ in all stations were below the detectable limits set by the DOST [Department of Science and Technology]: the occurrence of 'Habagat' precipitated 1424.2 mm of rainwater which dispersed it to Laguna de Bay. Ten species of ichthyofaunal assemblages were identified with Giuris margaritacea (33.73%) and Channa striata (5.41%) as dominant and present in all stations. Comparing all subwatersheds, Molawin and the highest index values for diversity (H'=1.93), richness (S'=2.30) and evenness (E'=0.927) and low in terms of dominance (D'=0.342): except in CEAT outfall where the condition was hypoxic. Household income and level of environmental awareness contributed to the contamination and pollution of the subwatersheds. Extreme poverty and low educational attainment increased the exposure and vulnerability of the households towards skin disease, gastrointestinal complications and other illness.
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