Toxic Waters

Toxic Waters

8 August, 2014
Red Tide Alert
"Good enough" is not good enough

If you happened to be on the South Side of Hong Kong Island in the past two weeks, particularly near Deep Water Bay, you may have noticed a thick layer of sludge floating on the waters surrounding Ocean Park and Middle Island.  These bays on the South Side are home to some of the most expensive real estate in the world, yet our ocean at their doorstep continues to be a recipient of our sewage and other wastes.
Why are our waters still so polluted? Last year the Hong Kong government made one of the biggest environmental moves in decades, by banning trawling in all of Hong Kong waters.  This is an amazing opportunity to help the ocean to heal itself, but unfortunately the government has not followed up with complementary actions, which could really boost the chances of success by improving water quality along the way.
Recently the Hong Kong Government has suggested that the water quality in the harbour is “good enough”.  It is “good enough”, so they say, to postpone the next stage of the HATS sewage treatment project (Harbour Area Treatment Scheme stage 2B).  This is government “speak” for “let’s take this off the list of things we are going to think about because it costs money and we think we can get away with not doing it right now”.  To deliver this “justification of postponement” they have used the threat of high infrastructure costs to put a question of affordability into the minds of legislators, the public, and the press.   Their likely over-estimated budget of now HK$30bn, is almost triple the $11bn predicted in 2004.  
How did they get the price so wrong?  Technology improves with time and generally decreases in price. Yes, construction costs can rise, but rarely does this mean a tripling of costs in such a short time period. To draw an analogy, money spent now on climate change mitigation will save us from spending far more in the future, and it is the same with sewage abatement. Cleaning our degraded waters later will end up  up costing us much more. Based on some of the other infrastructure costs in the city, this project, with or without revised expense estimates, will deliver wide ranging, long term impacts for the health and benefit of our community, where are waters areour biggest natural asset.
This situation is a perfect example of “shifting baselines”. We have forgotten what things used to be like (which included the ability to see the bottom of the sea at the Star Ferry in the 1960’s), and now simply compare to what we know from the past 10-15 years. When we compare from a short time frame, we are not using the proper baseline of what it naturally used to be like. We are simply saying to ourselves “it is less bad,” but is that really enough?
In a contradiction of its own making, the Government states on the home page of the HATS website that “With Stage 1 fully commissioned in late 2001, the overall harbour water quality has substantially improved, which means that you can enjoy a cleaner harbour.”
However, raw data also posted on their website shows no improvement in key indicators of water health within a period from 1986 to 2012 for the harbour area.
Key indicators such as dissolved oxygen (DO) show absolutely no improvement over this entire time period.  DO is fundamental to the health of a marine system, and at levels below 5 mg/l (milligrams per litre) many fish species are stressed, while with levels  below 3 mg/l, many cannot survie.. There have also been no significant changes the number of E Coli present in the waters of the western harbour area (a measure of contamination from sewage and risk to public health through infections) even though a large investment has been made to divert sewage to the Stonecutter Island Sewage Treatment Plant and have it disinfected before being dumped.
Another key water quality indicator that has not changed over this period is called BOD (or Biological Oxygen Demand). Think of the Harbour as your pet dog and think of BOD as the number of calories in your dog food. If you feed your dog too much she will end up fat, sick and generally unhappy. Your dog is not smart enough to say no to food, and neither is the harbour. The marine organisms in the harbour will eat anything that gets pumped into the harbor, and when they do, they burn oxygen in the process, reducing the oxygen levels in the water which can stress other organisms dependent on oxygen. 
When too much of the right “food” appears, these nutrients cause Red Tide (or Harmful Algal Blooms – HAB), and these instances are becoming increasingly common in Hong Kong. Key work done in Tolo Harbour and around the world has shown a significant link between reductions in BOD (ie, making your dog eat less), and reductions in Red Tides. Eutrophication, or increased human nutrient load, delivers increased levels of Nitrogen and Phosphorus in the water which contribute the most to HAB, yet the government has done nothing to combat this except set up a warning system for red tides.
Hong Kong’s population of over 7 million people generates around 2.8 million M3 of sewage per day.  93% of that is treated in some way, but the vast majority is only through primary treatment (screening and degritting), and this does nothing to reduce the BOD of chemical pollution or E Coli levels of the emitted water. 
If we want clean, healthy, clear and enjoyable waters for both marine life and ourselves we need make sure that the government continues with previously scheduled plans for sewage treatment upgrades.  Great work has been done so far, and the HATS project has made some good steps, but with Red Tides increasing, now is not the time for the Government to relax and say that the Harbour water quality is “good enough”.  It isn’t, and we should all let the Government know that “good enough” is NOT good enough.

By: Doug Woodring & Darren Catterall of Ocean Recovery Alliance


Be the first to comment on this Article

Popular content