Application of habitat evaluation procedure for impact assessment studies in Laguna de Bay, Philippines

The assessment of the Laguna de Bay's changing ecological status is imperative in order to address the growing concern of its possible impact on the suitability of the lake to the various user functions and future demands. The innovative use of a water quality evaluation method through the application of the Habitat Evaluation Procedure (HEP) can support ecological impact studies in Laguna de Bay. The scenarios studied included among others: waste load inputs, saltwater intrusion, deepening of the Pasig River, sea level rise and the impact of a special project on the development of large polder islands in the lake. Comparisons of the present condition, with autonomous development and with management intervention were made. The results of the study on the scenarios with autonomous development revealed that the lake, particularly at the western part of the West Bay, will continue to deteriorate if no measures are undertaken to control pollution due to a projected increase in human population and industrial expansion. Assessment results with management intervention indicated that a projected polder island scenario with a sewage plan expanded from two municipalities to four municipalities and with channel deepening seems to be the best management alternative that would significantly improve the suitability of the lake for various user functions.