South Africa: 'High Heat' Blamed for Massive KZN Fish Kill, but Investigations Continue

By Tony Carnie

A combination of high temperature, low oxygen and high levels of ammonia and 'organic pollution' have been implicated in the massive fish kill in a river estuary north of Durban.

No single, conclusive cause has emerged so far to explain the death of several hundred fish at the mouth of the Umhlali River on the KwaZulu-Natal coast on 12 February.

The KwaDukuza municipality said that its preliminary investigations suggest that a variety of factors were to blame, including high water temperatures, high concentrations of ammonia and "organic pollution". Notably, the municipality said laboratory samples showed that E.coli bacterial levels (human sewage) were found to be "within acceptable recreational water quality limits at the time of sampling".

The national Department of Water Affairs (which conducted a separate investigation in conjunction with the KZN provincial department of environmental affairs) said its preliminary examination also pointed to high river water temperatures and resultant oxygen depletion as contributing factors.

However, the national department stressed that it was still waiting for the full analysis of water tests before coming to a conclusion on the cause of the fish kill.

Significantly, the department has confirmed that it also collected treated effluent samples from wastewater treatment works along the Umhlali River and would take enforcement action if any of these samples were found to be non-compliant.

It is understood that Siza Water operates two such facilities on...

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