The costs of eutrophication – can we afford them?

5 February 2012

Come on in. The water's lovely! (Photo: Bill Harding)

Eutrophication is a process, accelerated by man, whereby streams, rivers and particularly lakes and dams, become enriched with nutrients (nitrogen and phosphorus).  These nutrients originate from various combinations of wastewater (sewage effluent) disposal, runoff from farms and storm water runoff from built-up areas. If not heeded, the outcome over time is that the dam or lake becomes dominated by algal blooms, the ecology of the lake declines and there is a threat of toxins produced by some forms of algae.

Not to be ignored is the fact that it is not just the nutrients.  If the primary source is wastewater, then this implies that all sorts of pollutants, in addition to the nutrients, are also going to be there (see Are you drinking someone else’s drugs?).  

In South Africa (Droplets primary country of interest), some 45% of our water resources are impaired by eutrophication, with the primary source of the problem being sewage effluents.

Eutrophication has a cost, in fact a whole lot of them.  These include (in no particular order – but maybe you would like to try and rank them in order of importance):

  • Reduced recreational and sporting opportunities
  • Tourism losses
  • Increased costs of drinking water treatment
  • Increased costs of industrial water treatment (pharmaceuticals, food and beverage, electronics)
  • Problems for crop irrigation and export issues
  • Risks to livestock and aquaculture
  • Reduced property values
  • Ecological degradation of water resources
  • Health risks (human and animal), especially chronic impacts to human capital

During the past 10 years, various countries have made provisional assessments of the costs associated with eutrophication.  These evaluations are mostly incomplete as they do not include all the indirect costs that “knock on” from eutrophication.  They also do not include the long-term costs of incurring health problems from long-term, chronic exposure to polluted water- by whichever means an individual may come into contact with it.  In some instances the build-up of pollutants in fish has resulted in a complete revision of the “safe” fish consumption limits published in some parts of the world.

Here are some examples of costings, rounded off into US dollar values for ease of comparison:

  • Australia: $165 million per annum.
  • England and Wales: $182- $247 million per annum.
  • United States: $2.2 billion per annum.

These are substantial sums of money – on a recurring annual basis and which, in  all probability, only represent a fraction of the total cost – as noted in all of the studies.

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