Survey of Physical, Chemical and Microbial Water Quality of Irrigation Sources in Tarlac, Philippines

Themain sources of irrigation water for irrigating crops comes from major rivers. Usually these water sources which can be used for irrigating various crops could be very vulnerable to contamination. The aim of the study was to determine the physical, chemical and microbial water quality of the different irrigation sources in Tarlac and to compare it with the existing water quality guidelines stipulated in the DENR AO 08 Series of 2016. The water samples collected from the surface water of different rivers were subjected to laboratory analysis. Higher TSS was found to be during wet season as compared during the dry season. Higher COD was found both in dry and wet seasons in Benig river. All of the major rivers have a less than 0.05 mg/l lead and 0.0002 mg/l mercury based from the result of the laboratory analysis. The highest dissolved oxygen was found to be within the Tarlac River both during the dry and wet season. Comparing with the National standards from the DENR the major rivers of Tarlac surpasses the minimum standards of classification of water bodies with dissolved oxygen ranging from 2 to 6 mg/l. The lowest dissolved oxygen was found in Concepcion River during the dry season (5.0 mg/l) and in Rio Chico River (4.8 mg/l) during the wet season. Higher total dissolved solids were observed in the different rivers during the dry season which ranges from 300 to 560 mg/l as compared during the wet season which ranges from 169 to 540 mg/l respectively. The nitrate concentrations of the different rivers in Tarlac shows to be within the range of the National Standards of the DENR. Higher concentrations of E. coli and fecal coliform count were also noted within the different rivers of Tarlac.