Is Gaza sewage behind shutdown of Israel’s desalination plants?

Israel’s water supply has taken a massive hit after algae forces days-long shutdowns of desalination plants, with Gaza sewage suspected as a possible cause of the sudden algae proliferation.

By World Israel News Staff

Untreated sewage flowing from the Gaza Strip may have helped fuel an extraordinary bloom of microscopic organisms that temporarily crippled most of Israel’s Mediterranean desalination network, Israeli scientists say, raising new concerns over the environmental consequences of Gaza’s wastewater infrastructure.

Five of Israel’s six major Mediterranean desalination facilities were forced offline at the height of the crisis after unusually turbid seawater overwhelmed their filtration systems.

The disruption affected plants stretching from Ashkelon northward, forcing authorities to reduce water supplied for agriculture and public landscaping while drawing more heavily on wells, reservoirs and the Sea of Galilee.

Researchers have since identified the organism responsible as a cyanobacterium belonging to the genus Synechococcus, a tiny photosynthetic bacterium commonly grouped with microalgae. Scientists are still working to identify the precise species and determine why it suddenly multiplied to such extraordinary concentrations.

One of the explanations under examination is that unusually warm Mediterranean waters combined with nutrient-rich sewage entering the sea from Gaza to create favorable conditions for the bloom.

Dr. Avner Gross, head of the Climate Change Laboratory at Ben-Gurion University of the Negev, said Synechococcus requires several conditions to proliferate rapidly: warm water, strong sunlight and nutrients including phosphorus and nitrogen.

Satellite imagery regularly shows algae-rich waters near Egypt’s Nile Delta, where agricultural fertilizer runoff enters the Mediterranean. But Gross said the pattern observed farther north led him to suspect an additional source.

“In our case, I currently have no other explanation except a pollution source in the southern Gaza Strip,” Gross said.

He separately described the increasingly warm Mediterranean as “a bathtub in August,” arguing that gentle, steady winds could have helped spread nutrient-rich water northward along Israel’s coastline.

The hypothesis has been echoed by Israeli environmental organizations.

Noga Armi, CEO of the marine conservation group Zalul, said sewage entering the Mediterranean provides precisely the nutrients capable of accelerating blooms of microscopic photosynthetic organisms.

“The scientific link is well established,” Armi said, arguing that untreated wastewater from Gaza was likely one of the factors contributing to the episode.

Gaza’s sewage infrastructure is currently operating at a fraction of its previous capacity. According to figures cited by UNICEF, all six major wastewater treatment plants in the Strip are out of operation and roughly 70% of sewage pumping stations are not functioning.

The Palestinian Water Authority has estimated that tens of thousands of cubic meters of untreated wastewater are entering the Mediterranean each day, with additional sewage leaking into the ground.

Years before the current war, failures in Gaza’s wastewater system periodically sent untreated sewage northward with Mediterranean currents. In 2017, sewage pollution contributed to the temporary closure of the Ashkelon desalination facility, demonstrating how environmental conditions in Gaza can directly affect Israel’s drinking-water infrastructure.

Gidon Bromberg, Israel director of EcoPeace Middle East, said Gaza’s sewage crisis presents a serious challenge for Israel.

“No one can ignore the science and the fact that we all share the same environment,” Bromberg said.

However, some scientists downplayed the role Gazan sewage played in the recent algae bloom.

Prof. Tamar Guy-Haim, a marine ecologist at Israel’s National Institute of Oceanography, has said the likelihood that sewage from Gaza was the primary cause is relatively low.

One major complication is the appearance of similar seawater turbidity considerably farther south.

A desalination facility near El-Arish in northern Sinai began experiencing problems on August 30 and was forced to operate at reduced capacity. Because El-Arish lies south of Gaza relative to the coastal currents implicated in the Israeli bloom, problems there suggest the phenomenon may have originated closer to Egypt and moved north.

Researchers have already pointed to the Nile Delta as a likely source of the Synechococcus population itself.

Nutrient runoff from the Nile, abnormally high sea temperatures and favorable currents may therefore have produced the bloom independently, with Gaza sewage potentially acting as an additional source of fertilizer as the organisms moved north.

Researchers from Israel Oceanographic and Limnological Research, Ben-Gurion University and the Technion have been working with desalination operators to identify the organism genetically and determine what combination of temperature, nutrients and ocean conditions produced the event.