A microalgae bloom some 100 kilometers long clogged intake pipes at Israeli seawater desalination plants in late August, forcing facilities serving Ashkelon, Ashdod, Palmachim and both Sorek plants offline or sharply curtailed while Hadera remained at full capacity, according to a Jewish Journal commentary published on 29 October 2026 Jewish Journal. The incident highlights the exposure of coastal water infrastructure to cross-border sewage and biological risks.
Key takeaways
- A microalgae bloom about 100 kilometers long clogged seawater desalination plant intakes in late August, and the affected plants went offline or were sharply curtailed Jewish Journal.
- All six Israeli desalination plants were running again by late October, although several remained only partially operational Jewish Journal.
- At the end of August, researchers found algae concentrations off Gaza were the highest in 14 years of measurement, twice the prior year’s peak and three to four times earlier levels Jewish Journal.
- No toxin had been confirmed, but the Synechococcus strain involved had not yet been identified or cleared Jewish Journal.
- All six wastewater treatment plants in Gaza were destroyed or out of service, while an estimated more than 150,000 cubic meters of raw sewage flowed into the sea each day Jewish Journal.
Algae bloom forces desalination curtailment
The eastern Mediterranean sent a bloom toward Israeli intake pipes after late-August winds pushed surface water north and then toward the shore, according to the commentary Jewish Journal. Ashkelon, Ashdod, Palmachim and both Sorek plants went offline or were sharply curtailed, leaving Hadera at full capacity; three weeks later, output was only about half Jewish Journal.
Six weeks after the acute disruption, all six plants were operating again, although several were only partially restored Jewish Journal. In mid-September, the Water Authority told the Knesset State Control Committee that national desalination output stood at about 60% of normal and was expected to remain there through the end of the year Jewish Journal. Mekorot National Water Company drew heavily on the Sea of Galilee and reduced water to farmers while the shortfall continued Jewish Journal.
The commentary said a change in weather, rather than improved preparedness, ended the acute phase, and it noted that the associated El Niño was forecast to strengthen through winter, with specialists expecting blooms to return Jewish Journal.
Untreated sewage and an unidentified algal strain
Researchers at Ben-Gurion University’s National Institute for Climate and Environmental Policy, including Avner Gross and Anton Lokshin, found end-of-August algae concentrations off Gaza were the highest in 14 years of measurement Jewish Journal. The commentary said the readings were twice the previous year’s peak and three to four times earlier levels, while the Israel Meteorological Service linked the unusual wind systems to an El Niño at its strongest summer intensity since 1950 Jewish Journal.
“No toxin has been confirmed, but the strain involved, a Synechococcus, has not yet been identified or cleared,” the commentary reported Jewish Journal. It also identified a documented pesticide application near a public beach as the more concrete exposure recorded at that point Jewish Journal.
All six wastewater treatment plants in Gaza were destroyed or out of service, and the commentary cited estimates of more than 150,000 cubic meters of raw sewage entering the sea each day Jewish Journal. It noted that Gaza’s sewage was significant not only because of volume, but because of its location and the northward direction of coastal currents Jewish Journal.
State Comptroller Joseph Shapira described cross-border water pollution as “Israel’s most serious cross-border environmental hazard” in a 2017 audit that found no responsible government policy or agency and a dormant Joint Water Committee Jewish Journal. A 2024 audit found that algal toxins and other biological threats to desalination plants had never been surveyed Jewish Journal.
Specification read
The reported sewage flow was more than 150,000 cubic meters per day, equivalent to more than 150 MLD, but the source did not report a design flow, population equivalent, BOD, COD or treatment-class capacity for a replacement plant Jewish Journal. The project scale therefore cannot be converted into a plant size or equipment duty from the available evidence; a buyer would need the design horizon, flow series, influent characterization and receiving-water limits before selecting equipment.
The event bears directly on the biological and tertiary-treatment barrier. A conventional train for a wastewater plant of this type would normally progress from screening and primary treatment through biological treatment—such as A2/O, MBR, MBBR, SBR or UASB—to tertiary treatment and disinfection, with DAF or zero-liquid-discharge configurations where the reuse, discharge and residual requirements justify them municipal wastewater treatment. The reported failure involved sewage reaching coastal waters, while the desalination response faced an unidentified biological strain, making verified biological removal, filtration and disinfection important to the operating case integrated sewage treatment.
If your plant looks like a coastal or cross-border discharge system with flow in m³/day, BOD/COD in mg/L, industrial or municipal service, and tightening reuse or effluent-compliance pressure, this is what it means for you: the inlet water must be treated to a demonstrable effluent standard, monitored for the actual biological risk, and specified so that downstream intake protection is part of the design basis rather than an emergency assumption water purification. No project price was reported for this event, so the $15 million figure in the supplied extract cannot be attributed to the described incident or used in a cost comparison Jewish Journal.
FAQ
What wastewater flow rate was reported for the sewage entering the sea?
The commentary cited estimates of more than 150,000 cubic meters of raw sewage flowing into the sea each day from Gaza, where all six wastewater treatment plants were destroyed or out of service Jewish Journal. This is an environmental discharge estimate, not a reported design flow for a replacement treatment plant, and no plant capacity or population equivalent was supplied.
What treatment stages would a plant of this scale need for coastal discharge?
A plant at the reported discharge scale would require screening, primary treatment, biological treatment and tertiary treatment or disinfection, with the exact train selected against influent characteristics, effluent limits and reuse requirements municipal wastewater treatment. The source did not report BOD, COD, nitrogen, phosphorus or pathogen limits, so it does not support specifying an MBR, MBBR, SBR, A2/O, UASB, DAF or zero-liquid-discharge configuration.
How much would the treatment plant cost?
No treatment-plant construction or procurement cost was reported for this event Jewish Journal. A reliable cost comparison would require at least the design flow, treatment objectives, site constraints, reuse destination, effluent standard and delivery schedule, none of which were supplied in the source.
How should a buyer select monitoring and biological treatment equipment?
The source reports that the Synechococcus strain involved had not been identified or cleared, while a 2024 audit found no survey of algal toxins or other biological threats to desalination plants Jewish Journal. For scoping, the supplier should therefore define monitoring parameters, sampling points, alarm thresholds, verified treatment performance and response actions rather than relying only on routine effluent BOD or COD compliance integrated sewage treatment.
