From February to December 2002, two major river systems within the watershed were studied, namely: Talomo River and Lipadas River. A third river, the Bago Aplaya River was included on August of the same year. Its inclusion in the study was based on its critical location between the two other rivers and because of the reported episodes of fish kills in this river.  

The Lipadas River and several segments of Talomo River were already classified by DENR in 1998 and 1995 respectively. However, initial classification was only based on certain physicochemical attributes, namely: pH, DO, BOD and Total Suspended Solids (TSS). In this study other parameters were measured in order to provide additional data relevant to the rivers’ future classification or review of classification. The general objective of this study is to assess the health status of the three rivers. Specifically, this study intended to determine the present health/quality of the Talomo, Lipadas and Bago Aplaya Rivers in relation to the standards of the DENR. The following parameters were used in the analyses: temperature, pH, dissolved oxygen (DO), biological oxygen demand (BOD), total suspended solids (TSS), total coliform (TC) and fecal coliform (FC), nitrate-nitrogen, phosphate-phosphorus and metal residues (Iron, Manganese, Zinc and Lead). It is also the objective of this study to identify the critical parameters that should be closely watched in the future monitoring of the said rivers.

All data were analyzed and compared against the standards provided by DENR Administrative Order 34 for surface waters visa vis the river classification. Based on the analyses and comparisons done, it was noted that certain parameters measured exceeded the set limits on several occasions indicating deterioration in the quality of the rivers from the time they were classified in 1998 and 1995 to the time this study was done. Generally, TC and FC counts as well as lead concentrations were seen to be critically elevated in Lipadas and Talomo Rivers. In Bago Aplaya River, TC and FC as well as DO and BOD were noted to be unfavorable. Relatively, stations nearer the mouth manifest more critical values.