Use of coliform count and plankton species in Lawaye River, San Juan, Batangas as Indicators of pollution

Abstract

The Lawaye River in San Juan Batangas is an important source of water for local residents. However, there have been insufficient researches regarding the water quality of the river. This study was conducted to determine the water quality of the Lawaye River using coliform count and plankton species composition. Four sampling sites were setup along the river; boundary, upstream, midstream and downstream. Fecal coliform count in the river was quantified using the multiple tube fermentation method while detection of the coliform Escherichia coli involved the Presumptive, Confirmatory and Completed tests along with the IMViC profiles. Plankton analysis involved the identification of various plankton genus found in the river. Nygaard's and Palmer's indices were then used to determine the river's trophic state and pollution status. The coliform concentration in all sites was found to be well beyond the normal range. Plankton analysis showed that sampling areas in the Lawaye River were found to have different level of organic pollution. The Palmer's and Nygaard7s Indices demonstrated that the downstream and the midstream sites registered the highest probability of having organic pollution while the sites found on the boundary and upsti*eam were comparatively normal and oligotrophic. Factors such as improper waste disposal, effluents from drainage and agricultural runoffs might have contributed to the observed results.