Assessing water quality and classifying river ecosystem via landscape approach

The continuous growth in human population increases pressure on the natural resources, which result in environmental degradation. Such effects created growing concerns on freshwater ecosystem not only due to its water supply function but also because of its importance on the life support system, in general. The Lian-Palico River in Nasugbu, Batangas and Tanay River in Tanay, Rizal [Philippines] are examples of freshwater ecosystem. Both classified as Class C, these are considered safe for recreational use, propagation of aquatic life, and industrial use. But as this classification does not really reflect the true state of the rivers, Dano and Villamor (ERDB) evaluated water quality and classified the river ecosystem of the two river systems using the landscape approach. The project also determined the range of consumptive and non-consumptive uses and identified critical parameters as inputs for the ecosystem health risk assessment and classification of the river systems. Findings of the study revealed the following: Using the water quality index, aquatic macro-invertebrates, and current uses in assessing the rivers, the two river systems were found to have a very high level of coliform and organic pollutants way above the limit for Class C waters. The low level of dissolved oxygen in the lower reach of Lian-Palico River may trigger fish kill anytime. Sensitive families of insects in the river can serve as useful indicators on the health condition of the river particularly in far areas where chemical analysis is a problem. The project recommended that the current system of river classification should be modified to reflect their present condition. Specifically, the present classification (Class A,B,C and D) should be refined by incorporating the water quality index system. The two classification systems that can be considered are as follows: a) incorporate the health of the river and the limitations or problems in the rivers; and b) revise the current system and use the health status of the river system. This meant using the classification from very bad to excellent condition plus the subscript indicating the major problem of the river.