Are the phosphate wheels turning?

15 June 2011

We are a few days short of a year since the previous Minister of Water Affairs got all warm and fuzzy about taking the phosphate out of detergents.  She said it should be done as soon as is feasible – well South Africa reached that situation before she made her statement!  Note how the article kicks off “the government is poised to demand…” , they must be pretty cramped up by now having been poised for so long. Certainly no crouching tiger, hidden dragon stuff here! Read more »

Bruma Lake: When will they ever learn?

15 June 2011

Although I have not seen the 50/50 documentary on the “progress” with rehabilitating Bruma Lake, I understand that the project is still mired in the search for a silver bullet remedy.  If I had R10 for every time snake oil remedies get touted I could have retired to the Karoo long ago – although with this fracking nonsense I would now perhaps have to move.

The floating wetland technology is both proven and bullet proof and if applied correctly could sort out Bruma Lake pretty quickly – and a whole slew of other dodgy waterbodies that are a health risk and an eyesore.  The technology has an indefinite lifespan and once installed is maintenance-free.  Yes, its expensive but its a “once-off cost, problem solved, get on with the next thing” option.  There is no point in cheap and nasty solutions that have to be repeated, time and again. Read more »

Just how toxic are they?

15 June 2011

Blue-green algal scum in a farm dam.

I have had some queries regarding the toxicity of the compounds produced by cyanobacteria and to answer this I am posting the following table that provides relative comparison to other biological toxins (various blue-green algae are highlighted in green). I have also included cyanide for purposes of comparison).  The numbers in the table are based on intraperitoneal injection (into the abdomen basically) and express the amount of toxin per kg body weight that will be fatal to 50% of a test population.  I will update this table to include the lethal does via oral ingestion.




15 June 2011

Ohio has made some changes to its algal warning levels in an attempt to keep lakes open for recreation as much as possible.  The changes include:

  • Posting warning signs only at public beaches, and not at other locations at contaminated lakes or ponds;
  • Warning people to avoid all contact with water only if high concentrations of toxins are found and at least one person is sick or a pet dies.

These approaches are fine for protection against acute toxicity – and one can see the logic behind what they are trying to achieve.  However, the threat of chronic and/or low-level exposure still remains. Read more »


12 June 2011

Pygmy chaemeleon, 21 mm long (Photo: Bill Harding)

Recreational guidelines for liver and neuro-cyanotoxins, locally and overseas, dictate a cutoff threshold at 1 microgramme per liter.  Where this is applied, recreation is prohibited under the levels fall into the safe zone again.  Andersen Lake (Washington State, USA) has such a restriction in place due to an anatoxin (neurotoxin) concentration of 2.7 microgrammes per liter.  South Africa has, currently, no facilities for the routine assay of algal neurotoxins.

Not-so-Grand Lake is in the news again as a debate ensues over whether to build a multi-million dollar marina, or fix the lake.  Answer seems obvious – why would you want a marina on an algal-polluted lake? – but then that hasn’t stopped people from flocking to Hartbeespoort Dam and building all manner of fancy developments, despite the water quality and risk to human health.

A useful little article on respecting transboundary water issues in the Sudan here.


10 June 2011

Dragonfly in the rainforest (Photo: Bill Harding)

A quiet day for algal issues.

Update for Buckeye Lake, with toxin levels at the main beaches, available here.  Multiple measures to reduce nutrient loading to Lake Champlain are being introduced, including residential rain gardens.  Eutrophication management often relies on the sum of many small measures to achieve large successes!  See also here.

A new method for detecting cyanotoxins is being developed and that could eventually support a rapid (field?) test.  Of course the dipstick “pregnancy-type” test kits have been around for a while, producing an “at the shoreline” result within minutes.

Berries, Bats and Blue-green algae in False Bay

9 June 2011

Sheila Jeftha (FBWPG) thanks Bill Harding for his talk

Is there an environmental component to the etiology of neurodegenerative diseases such as Motor Neuron Disease, Parkinsons, Alzheimers or even Progressive Supranuclear Palsy?  Today I presented the evidence, which suggests that this hypothesis may well be true, to the members of the False Bay Women’s Probus Group. Read more »


9 June 2011

Pembroke Pond remains closed after reports of two girls who became sick after coming into contact with the water.  Plans are afoot to oxygenate Osoyoos Lake (Canada) – but its hard to tell what the cause and effect pathways are that are leading to problems in this lake.  Very few oxygenation projects have been successful – the hydrodynamic structure and layering in a lake are there for a reason – so disruption of this needs to be based on rigorous evaluation or swapping one problem for another may be the outcome.  Upside is that it can be put back as it was by simply switching off the aerator.

Nitrogen and phosphorus concentrations decreased in streams of the Santa Ana Basin during 1975–2004, as improved wastewater treatment was implemented basinwide. Nutrient concentrations in the San Joaquin Basin during the same period increased in association with increased land application of nutrients. In the Sacramento Basin nutrient trends were mostly downward.  Read more here. Read more »


8 June 2011

Climate change will have a profound and negative impact on our water resources – with less water and poorer quality being pretty much certain.  Some scary new information out today (see here) echoes this blogger’s warnings about ignoring proper management of dams in South Africa-

  • Climate scientists predict truly alarming changes to various African waterways. UK government researcher Sir Nicholas Stern recently predicts that a 3-6 degree Celsius increase in temperature in the next few years will result in a 30 per cent to 50 per cent reduction in water availability in Southern Africa.
  • A 2006 study by climate experts at the University of Cape Town revealed that even a small decrease in Africa’s rainfall could drastically reduce river flows, affecting a quarter of the continent.
  • For example, a 10 per cent reduction in rain over the Johannesburg area could lead to a 70 per cent drop in the Orange River’s levels.
  • By trapping river-borne nutrients, dams can lead to the growth of toxic algaes. Massive algal blooms in reservoirs in the ex-USSR, South Africa, and California have rendered reservoirs unfit to drink. Four hydro dams in California have nearly killed off the fisheries of the Klamath River, and made the river unsafe for drinking or swimming.
  • Water stored for months or even years behind a major dam may become lethal to most life in the reservoir and in the river for many kilometres below the dam. Reservoirs that also receive treated effluents from upstream towns and cities are more apt to have this problem“. Read more »


7 June 2011

Blooms of blue green algae (BGA) have returned to Strathclyde Loch in Motherwell and have disrupted water sports. BGA can produce toxins harmful to humans and animals.  Read more »