Gamtoos Irrigation Board (GIB) chief executive Pierre Joubert said samples would be taken, starting on Sunday. The level of the Kouga Dam had fallen to 7.1%, but was boosted slightly by rain on Monday. The dam used to extend 42km up the Kouga River west of Patensie, but is now just 10km long.
The low water level and high, steep sides of the dam do not make access to the surface easy but GIB's staff would let themselves down by ropes and use a boat to get to a suitable sampling spot, Joubert said.
"Fish haven't started dying yet, but I'm afraid they could if the water keeps on dropping and that could result in a serious health threat.
"We will be doing the sampling approximately twice a week, so this initial step is to get us in the mode and establish a baseline reading."
When the dam was filled in 1970, the trees were not removed and many are still slowly rotting in the water and consuming oxygen. As the water drops, the oxygen available to the fish will be reduced still further and if the process continues, the indigenous kurper and eels and alien bass, carp and barbel could die.
Joubert said if fish did start dying, it would not be easy to drag the carcasses out with a net because of the submerged trees. "I do not know what the answer will be. The dam has never been this low before so we're in new territory."
The dam channels water to Nelson Mandela Bay via a canal and the small Loerie balancing dam near Thornhill. Joubert said even if the Kouga ran dry, his team would ensure that the Loerie was left full, which would allow for supply to continue to Nelson Mandela Bay for some months after that. Besides water from this source, the Bay is also supplied by the Churchill, Mpofu and Groendal dams.
Using the same approach, the Patensie balancing dam would also be left full and this should last the town at least six months if water was used sparingly, he said.
The Klein River at Hankey only runs about half of the time, but fills up rapidly after even slight rains. Joubert said if the Kouga ran dry, the hope would be that this supply would sustain the town until the floods needed arrived. The situation seems to be even more critical for the Gamtoos farmers, with no alternative to the Kouga water available.
Gamtoos Farmers' Association chairman Petrus du Preez said the next months would be critical for citrus orchards in the valley. "The fruit is there but it's small and we need more rain before picking begins in June to ensure it does not drop and increases in size."
There are about 220 Gamtoos farming families as well as 15000 workers in peak harvest season and a range of businesses in the valley. The farmers have already jettisoned their interim cabbage, maize and potato crops to save the whole irrigation quota for their flagship citrus orchards and there is nothing else they can do to save water.
Du Preez said that while a few farmers had sunk boreholes as an option if the Kouga dried up, this was not a solution because of the small volumes produced and the high salt content of the water. "So we are living in prayer and hope the rains will come," he said.
Source: Herald
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