A rare sewage leak into a stream near Ashdod this weekend caused an ecological disaster, killing thousands of fish and tens of thousands of other organisms.
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The sewage was diverted into the Lachish stream, south of Ashdod port, because the pumping station near Ashdod’s main sewerage line was shut down on Saturday to enable a hole in the pipeline to be repaired. The sewage flow lasted for about 10 hours, during which thousands of cubic meters of sewage were dumped into the stream.
The resulting shortage of oxygen in the stream killed thousands of flathead grey mullet fish. Tens of thousands of other organisms that live on the streambed or drink its waters were also killed.
Both the Ashdod municipality and environmental organizations have been working to rehabilitate the Lachish stream for many years, but the sewage dump isn’t expected to be a major setback to that effort. The stream should naturally regain its normal oxygen levels within weeks; the exact timetable will depend on rains expected to begin soon, and on the progress of planned rehabilitation work at the site.
In contrast, returning the number of fish and other organisms to their former levels is expected to take several months.
“The stream has recovered very nicely in the past, and it will recover again,” the environmental organization Zalul said in a statement. “The rains will come, wash everything away and the contamination will subside. The amount of water in the stream will rise, and then it will all be diluted with fresh, new water. This incident isn’t permanent, but it shouldn’t have happened and it’s too bad that it did happen.”
Ashdod’s main sewerage line is about six kilometers long, and maintenance periodically requires it to be taken out of operation and emptied. In this case, because of the decision to shut down the nearest pumping station as well, the sewage was diverted to an emergency outlet that opens into the Lachish stream.
Ashdod also has an older, smaller sewerage line that was taken out of operation when the new line was installed. Gad Ofer of Ashdod’s municipal environmental corporation said that in theory, the sewage dump into the Lachish stream could have been prevented by diverting the sewage instead into this older line, which runs parallel to the new one. But bureaucratic obstacles had made it impossible to reopen the old line, he said.
The Lachish stream, which begins west of Hebron, is about 70 kilometers long. Much of it is dry during the summer, but a 3.5-kilometer section near Ashdod has water year-round.
The flathead grey mullet is a salt-water species, but its eggs do best in less salty water so the fish often spawn in the Lachish delta. Many flathead grey mullets have also moved into the freshwater part of the stream and adapted to life there, but they cannot lay their eggs in fresh water.