Friday, March 30, 2012

Request for additional information about Punggol and Serangoon Reservoirs

* Parts of the email have been removed for conciseness*

I read with interest about the blog posts which you have made about the newly opened Punggol Reservoir as well as the overall knowledge that you have about water quality monitoring. Given your enthusiasm and expertise in this field, we hope that you will be able to furnish us with some of the details that we require, such as:

- An overall idea of the environmental monitoring process

- The critical parameters which are monitored and their baselines [understand from Greenspan that, for water, this includes: Dissolved Oxygen (DO), Temperature, Turbidity, pH, Conductivity, Chlorophyll-a and Nitrate (NO3)]

- How often/when are samples collected for testing?

- Are there any typical steps taken if the baseline conditions are exceeded?

It would be beneficial if some of the information are specific to the Punggol/Serangoon Reservoirs.


Like all other reservoirs on mainland Singapore, Punggol and Serangoon Reservoirs (PSR) are under the purview of PUB. The water quality in these reservoirs is definitely monitored though little detail has been publicised - type of water quality parameters monitored, frequency of monitoring, results and implications of the water quality data.

You may want to try the following reference books to find out more about water quality monitoring
  1. Water quality monitoring : a practical guide to the design and implementation of freshwater quality studies and monitoring programmes, edited by Jamie Bartram and Richard Ballance
    I find it useful as it covers the topic comprehensively though it may be slow reading at times. Published on behalf of United Nations Environment Programme, World Health Organization
  2. Water quality assessments : a guide to the use of biota, sediments, and water in environmental monitoring (2nd ed), edited by Deborah Chapman
    This is a follow-up to the above title. Again, useful and comprehensive. Published on behalf of UNESCO, United Nations Educational, Scientific, and Cultural Organization, WHO, World Health Organization, UNEP, United Nations Environment Programme

You are indeed right. Dissolved oxygen (DO), temperature, turbidity etc. are relatively easy to measure and hence routinely monitored, probably around once a week (my estimate, feel free to dispute).

I am sure many other parameters are also measured. (Just look at the WHO drinking water guidelines - they have about 200 parameters.) For example, heavy metals, pesticides, oil, volatile organic compounds (VOCs) are good bets. Even the fancy ones like dioxins and radioactivity are possible candidates. Of course, the frequency of monitoring of these chemicals (and radioactivity) depends on the cost and effort of analysis (e.g. expensive lab instruments or tedious lab preparation steps are needed), the likelihood of these chemicals existing in our reservoirs and their impact on health and environment. I won't be surprised if some of the fancy parameters are measured only once a year.

The parameters monitored in our reservoirs probably exceed those given in WHO drinking water guidelines. And PUB is probably going into biological monitoring using macroinvertebrates (bugs). Check out my previous post, Water trends in the next decade, for more information on this topic.

Figure: Serangoon Reservoir with a dam in the distance. The dam serves to separate fresh water in the reservoir from salt water in the sea.

Figure: Punggol Reservoir with Sengkang Floating Wetland in the foreground

For water quality monitoring  (WQM) in our reservoirs, setting up limits for the water quality parameters can be a bit tricky. Do we apply drinking water guidelines to reservoir water? Probably not.

Or do we apply guidelines for aquatic life? Countries such as USA, Canada etc. already have such guidelines. Do we use their guidelines? Again, probably not as the environmental conditions are quite different between Singapore and say, USA. Even if we develop our own guidelines, I am certain every reservoir will be different from one another e.g. geology. How do we factor these differences into our guidelines? Hence, I always believe that baselines for each reservoir will have to be established based on long term WQM. Any deviation from those baselines may then be further investigated. As far as I know, PUB's guidelines (if any) for reservoir water quality have never been publicised.