‘Extremely rare event:’ Miles-long microalgae bloom knocks out most of Israel’s desalination plants

A microalgae bloom has spread along Israel's Mediterranean coast. Israel Oceanographic and Limnological Research institute

by  By Laura Paddison

 

A miles-long microalgae bloom in the Mediterranean Sea has been blamed for temporarily knocking offline many of Israel’s major desalination plants this week, threatening its main source of drinking water.

Five of the country’s six coastal desalination plants — which convert seawater into drinkable water — shut down on Sunday, according to Mekorot, Israel’s national water company. Since then, some of these facilities, which are privately owned and operated, have partially resumed operations, but only one was operating at full capacity on Thursday.

“An event of this kind has never occurred before in Israel … it was an extremely rare event,” said Lior Gutman, a spokesperson for Mekorot, although he stressed in roughly 99% of cases, there has been no drinking water shortage. 

 

Still, it’s an alarming situation given the country’s heavy dependence on desalination for drinking water. Israel is arid and has neither big rivers nor abundant rainfall, but its mastery of this technology has made it a water superpower. Desalination now provides at least 65% of its drinking water, with most plants located on the Mediterranean coast.

The problems started at the weekend, as a “sporadic, vast event of contaminates occurred across the Israeli coastline,” said Edo Bar-Zeev, an associate professor in water research at Ben-Gurion University, in Israel. When he and other scientists looked closer, they discovered it was microalgae, tiny organisms that feed on sunlight, carbon dioxide and nutrients in the water — and which can grow rapidly. 

Microscope images of microalgae from the bloom that formed along the Israeli coast. Tali Covas

 

The microalgae bloom — stretching more than a dozen miles at least, according to Bar-Zeev — is believed to have originated in the Nile Delta and traveled northward with the sea’s currents up Israel’s coast. This is “the first time I saw something in this extent,” said Bar-Zeev, who has been testing the coastal water for 20 years.

The country’s desalination facilities mostly use a technology called “reverse osmosis,” where water is pre-treated to remove larger contaminants, before it’s pushed through membranes which filter out salt, bacteria and other molecules to leave clean drinking water. 

 Algae, and the substances they produce, can foul and damage the membranes, said Michael Christopher Low, director of the Middle East Center at the University of Utah. If there’s too much suspended material in the water, the treatment processes cannot keep up. 

 

It’s happened before. A severe “red tide” — a harmful algae bloom — in the Gulf of Oman in 2008 and 2009 affected many desalination plants in that region.

In Israel, the government water system has “stepped in to close the gap” caused by the plant closures, Mekorot’s Gutman said. This has included pumping water from the Sea of Galilee, activating groundwater wells and using national water reserves.

Some cities have faced short-term local restrictions, including on garden irrigation and filling swimming pools, but the the main limitations affected farmers who use drinking water-quality water for irrigation, as opposed to those who use recycled water, Gutman said.

The timing compounded the problem. It happened in summer “when water demand in Israel is at its highest,” he said, adding “the situation has been challenging.” 

Israel's Water Authority places drinking water storage tanks near Damascus Gate in Jerusalem, Israel, on August 31, 2026, as part of emergency preparations after five of Israel's six seawater desalination plants were temporarily shut down. Mostafa Alkharouf/Anadolu/Getty Images

 

A bloom occurs when the right combination of environmental factors in the water come together that allow the algae to grow rapidly, said Tamar Guy-Haim, a marine ecologist at the Israel Oceanographic and Limnological Research Institute. These include nutrients, temperature, light, currents and mixing.

Mekorot said this recent bloom was part of “very unusual combination of factors,” including a sea storm that increased turbidity — the amount of suspended matter in the water — and raised sea temperatures to 86 Fahrenheit (30 degrees Celsius) and above. 

 

The extent of the disruption is striking. Desalination facilities have been forced to close before due to algae or jellyfish, “but multiple facilities over the large portion of our coast is something that is definitely abnormal,” Ben-Zeev said.

It’s something the country needs to figure out how to deal with — and will, he added. “It’s a fair estimation that this will not be a once-in-a-lifetime kind of event … you can assume that this will occur more and more through climate change.”

As the planet heats up, driven by humans burning fossil fuels, the oceans are changing. Temperatures are at record highs, currents are shifting and stronger storms wash more pollutants into the water, including sewage and fertilizers, which can trigger huge algae blooms. 

The Sorek desalination plant near the Israeli city of Rishon LeZion on November 22, 2021. This plant was one of the five temporarily knocked offline. Gil Cohen Magen/Xinhua/Getty Images

 

This temporary crisis also exposes a broader concern, experts say.

Desalination is becoming increasingly popular, especially as the climate crisis drives more severe heat and drought, undermining water security. But this growing dependence on a centralized, technical solution carries risks. “This event is causing considerable alarm and even some criticism that the system is too vulnerable to a dramatic disruption,” Low said. 

 

This could be natural or climate change-driven events, but there’s also the possibility of military and cyber threats. Desalination plants in the Gulf have been targeted and damaged during the US-Iran war, raising significant alarm in a region that depends overwhelmingly on this technology. Hackers have also targeted water facilities, including in the US.

Oil spills are another big concern. “It’s not if, it’s just when an oil spill in the vicinity of desalination facilities will occur,” Ben-Zeev said. A lot of plants are in water-scarce countries that are also big oil producers, such as the Gulf states.

A spill could potentially take plants offline for a much longer time than this microalgae bloom, he added. “That to me is way more worrying.”

Australian ski resorts to close up to a month early due to global heating and El Niño

Snow at Mount Buffalo, Victoria in July. Photograph: Marni Cordell/The Guardian

by  Graham Readfearn Environment and climate correspondent

‘Challenging’ weather conditions and lack of snowfall are being blamed after a winter that broke multiple heat records

Major Australian alpine resorts are closing their ski operations up to a month early after a winter that broke multiple records for heat with limited snow falls being washed away by rain.

Predictions in June that a building El Niño could combine with global heating for a challenging ski season came to pass, with seven resorts either already closed or announcing ski lifts will stop operating this weekend.

This week the Victorian resorts of Mount Buller, Mount Hotham and Falls Creek, together with Charlotte Pass in New South Wales, all announced ski operations would end this weekend.

The Victorian resort of Mount Baw Baw, the NSW resort at Selwyn and Tasmania’s Ben Lomond have already closed. Resorts typically aim to stay open until the first weekend of October.

Video - Footage shows first snow of the year falling at Perisher ski resort in New South Wales

 

Data from the Bureau of Meteorology show Falls Creek and Mount Hotham had their wettest winters in more than 30 years but, together with Mount Buller, they also had their warmest winters on record for average maximum and minimum temperatures.

Watkins said data from weather observations at Cabramurra in Kosciuszko national park suggested alpine winters had warmed by about 2C since the 1960s.

He said that temperature rise would have been the difference between precipitation falling as rain instead of snow. “It would have been a bumper season if it had been 50 years ago,” he said.

The El Niño currently in place in the Pacific Ocean can promote hotter and drier temperatures in Australia’s south-east in winter and spring.

This week the bureau forecast the current El Niño would be the strongest on record and Australian scientists said climate change had made the strength of the event six times more likely.

 

A bureau spokesperson said this winter’s heat was consistent “with a developing strong El Niño” and the season had seen long periods of high pressure in the Tasman Sea that directed warmer air from the north over alpine regions.

“But winter 2026 also experienced relatively warm nights, with cloud cover and moist soils resulting in less overnight cooling,” the spokesperson said.

“This is in contrast with historical El Niño events. This is all occurring against the background of a globally warmer climate, with daily global surface air temperatures since June close to or above the record levels in 2024.”

New South Wales, Tasmania and Victoria all recorded their hottest winters on record this year.

In July, many ski resorts broke all-time heat records for the month with temperatures during one hot spell up to 12C above average.

Climate scientists have been warning for decades that global heating will create a challenging future for Australia’s ski resorts and alpine habitats.

Josh Elliott, chief executive at the representative body Snow Resorts Australia, said there was “no question it has been a challenging season for natural snowfall”.

“This winter was shaped by a combination of abnormally warm weather and climatic variability, but it’s important to remember that in any outdoor environment, that variability can result in some seasons being better than others.

“This is an abnormal season and shouldn’t be considered in isolation as a reflection of what future seasons will look like.”

He said skiing, snowboarding and snow play had still been available in NSW, Victoria and the ACT “since the June long weekend, with all resorts across Australia operating through the July school holidays and beyond”.

“What this season has shown is the importance and value of the investment resorts have made in snow making, with underlying demand for snow holidays remaining strong through July and August.”