The river here is just a kilometre from its source, but the water is already muddy and the natural banks eroded.
This artificial channel may be neat, but it deprives the stream of its natural filteing function. It speeds up the flow of water, causing rapid erosion of the banks.
Once it leaves the park, flowing through Taman Tun, it has been deepened, widened and turned into a concrete channel.
It is linked with the residential drainage network and fed with domestic waste water and leaking sewage.
Near the Damansara Sewage Treatment plant, the river is further contaminanted with animal waste and human sewage.
The river then enters Petaling Jaya at Section 17 (Damansara Intan) and flows through many residential and industrial areas, Piles of garbage are common along the banks. The worst eyesore is in Section 19, where about 800 squater houses are located.
More pollution is pumped into the river at the industrial areas of Sections 13 and 14, before it eventually winds up in Sungai Klang near Kampung Penaga.
But all is not lost, Dr K.Kalithasan of the Global Environment Centre (GEC), the co-ordinator of the River Care Programme, said that at its upper catchment area, the river is clean and bubling as it flows through the secondary jungle.
And, surprisingly, Sungai Pencala supports a limited number of fish such as snakeheads (Ikan Haruan), and eels (Ikan belut) in some stretches, as well as birds like herons and kingfishers.
Kalithasan believes the best way to tackle the pollution of Sungai Penchala is to involve residents and community associations.
The GEC, the Drainage and Irrigation Departments of Selangor and the Federal Territory work with Universiti Teknologi Mara (UiTM), residents associations, river rangers and Friends of Bukit Kiara and Friends of Bukit Gasing, to monitor the river.
Thirteen schools along the river have been roped in as river ranger schools, where the students are taught how to conduct river sampling and bio-monitoring.
This is just one of 146 rivers monitored by the Department of Environment.
Today, water from 10 percent of our rivers cannot be used or is used only for irrigation, based on the Water Quality Index (2005).
Only half of them are clean – safe for drinking or just needing basic treatment. The rest need more intensive treatment.
There are 16 rivers categorised by the DOE as critically polluted. Most of them are in Penang, Selangor and Johor. The government has set a target of rehabilitating them by 2020.
Many species of local fish are no longer found and those that survive are mostly foreign, link the hardly tilapia.
DID director-general Datuk Keizrul Abdullah had said that a study carried out two years ago identified poorly treated or raw sewage as the main river pollutatant.
The flow of sewage into rivers is mainly due to the unwillingness of many owners of homes and business premises to get treatment services for their septictanks.