When I was a child, my father used to tell me stories about how they would take a dip in the Pasig River and they could see plenty of fish as well as the stones and the sand on the river bed and bank. I myself don't remember that clean a Pasig River anymore. They say people started to notice the pollution in the 1930's, a few years after manufacturing facilities and factories were built along the river. The river started to accumulate a layer of pulp and sediment. It began having a bad odor. Dead fish started floating on the river.

Herrera, H. F. (2013, March 12). Pining for a clean Pasig River. The Manila Times, pp. A4, A5.