Lake St Lucia 'seriously ill'

2009-02-26 18:21

Port Elizabeth - World renowned Lake St Lucia, home to hundreds of crocodiles and hippopotami, is seriously ill, according to a leading scientist.

The diagnosis is acute dehydration.

"The patient is in intensive care," Professor Alan Whitfield of the SA Institute for Aquatic Biodiversity told delegates at the Implementing Environmental Water Allocations (IEWA) conference in Port Elizabeth on Thursday.

He said the estuary of which Lake St Lucia is a part, was under threat from "historic and current manipulation" of its freshwater supply.

The solution was to allow the system's main river, the Umfolozi, to once again flow into the lake.

"Lake St Lucia is not only a World Heritage Site; it's also a Ramsar site of international importance. It has been impacted since the 1930s and things are coming to a head in that system now."

These impacts included the removal of wetlands that had once served to filter the water pouring into the estuary down the Umfolozi; and, a decision - reversed in March last year - to divert the river away from the lake.

"A total of 920 million cubic metres [in-flow] has been removed from Lake St Lucia, and in order to fix the situation it needs to be returned."

Soaring salinity levels

Salinity in the lake under "natural flows" was about 60 parts per thousand, but - with the diversion of the fresh water from the Umfolozi - was now well above 100 parts per thousand, almost three times the concentration of sea water.

"The system is going through extremes it's never experienced before," Whitfield warned.

At one time the Umfolozi River had regularly scoured the lake, but a decision had been taken some years ago to divert the river southwards and open a separate mouth.

This had been done to stop the river depositing tons of sediment in the lake. Depriving the system of its single-largest freshwater supply, however, coupled with a decrease in other inflows due to a prolonged drought in the region, caused the lake to shrink and salinity levels to soar.

"This is a World Heritage Site, and South Africa has a responsibility which we're not fulfilling under the current circumstances."

The area was declared a World Heritage Site in 1999.

Whitfield said the situation was "not all doom and gloom", and there was a solution.

"The Umfolozi River is the key to the future of Lake St Lucia, the absolute key, and we've known that for a long time, but we've done absolutely nothing about it," he said.

- SAPA