If it is that easy, yeah it direly needs help. Unfortunately, Ilog Pasig is already a dead river and can't be revived with just mangroves. What it needs to be brought back to life is extensive research, projects and discipline. First, all solid waste and garbage must be taken out from the river. Then, heavy metals must be washed away. Biological substances must be added to make the waters again hospitable for animal life. People mustn't throw their waste into the rivers directly or the streams and canals connecting them.