Cookies help us run our site more efficiently.

By clicking “Accept”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. View our Privacy Policy for more information or to customize your cookie preferences.

‘We need more shade’: how US’s hottest city is cooling its least protected community

News Feed
Wednesday, April 17, 2024

It was a relatively cool spring day in Phoenix, Arizona, as a tree planting crew dug large holes in one of the desert city’s hottest and least shaded neighborhoods.Still, it was sweaty backbreaking work as they carefully positioned, watered and staked a 10-ft tall Blue palo verde and Chilean mesquite in opposite corners of resident Ana Cordoba’s dusty unshaded backyard.“If I ever retire, I’d like to be able to spend more time outside. The weather is changing, so I am really happy to get these trees. We need more shade,” said Cordoba, 75, a legal secretary, whose family has lived in Grant Park for more than a century.Over the course of three days in early April, arborists planted 40 or so desert adapted trees in Grant Park, as part of the city’s equity-driven heat mitigation plan to create a shadier, more livable environment amid rising temperatures and hundreds of heat related deaths.Phoenix is America’s fifth largest and hottest city, a sprawling urban heat island which has expanded without adequate consideration to climate and environmental factors like water scarcity and extreme heat. ​Multiple heat records were broken last year including 133 days over 100F (37.7C), and 55 days topping 110F (43C).Ana Cordoba, 75, in her backyard with two new trees, dreams of sitting under their shade one day. Photograph: Tamuna Chkareuli/The GuardianOnly around 9% of Phoenix is protected by tree canopies, yet this citywide figure masks vast inequities between wealthy, majority white neighborhoods like Willo (13% coverage) just two miles north of Grant Park (4%). One census tract in the north-west of the city, Camelback East, has 23% tree cover.“This is one of the city’s oldest neighborhoods – and one the most neglected,” said Silverio Ontiveros, a retired police chief turned community organizer who drummed up interest for the tree planting by knocking on doors and putting fliers through every neighbor’s letterbox.“Our goal is to change the inequity and create enough shade to provide residents and passersby reprieve from the heat. For that we need many more trees, but we also need to take care of them,” added Ontiveros, as he walked through the neighborhood making sure the right families got the right trees.The city contractors plant the trees for the residents who applied for the program. Photograph: Tamuna Chkareuli/The GuardianGrant Park is a majority Latino community in south Phoenix situated next to a sprawling electrical substation – a hot and dusty neighborhood with ​​200 or so homes, but no stores and plenty of empty lots and boarded-up houses. It was once a thriving neighborhood – one of the few places where people of color could live due to discriminatory housing policies that lasted most of the 20th century.Redlined neighborhoods like Grant Park still have higher pollution levels, less vegetation, more noise pollution and higher temperatures. In recent years, the local outdoor pool was shuttered and scores of trees cut down by a previous administration to prevent homeless people from gathering in the shade.“This is one of the hottest parts of the city because the people here don’t have political power,” said Leo Hernandez, 78, the master gardener at the thriving community garden where he created a butterfly sanctuary for migrating monarchs. “We need shade, but trees also suck up carbon dioxide, create places to socialize and healthier, happier neighborhoods.”Susan and Silverio Ontiveros. Photograph: Tamuna Chkareuli/The GuardianSilverio Ontiveros. Photograph: Tamuna Chkareuli/The GuardianTrees have multiple benefits in urban areas which include cleaner air, improved physical and mental health, water conservation, increasing wildlife habitat, CO2 storage and sequestration and lower temperatures through shade.The city is mostly concerned with reducing the urban heat island effect and improving public health, and its 2010 shade masterplan set out a goal of achieving 25% citywide canopy cover by 2030. Amid little progress and rising heat mortality and morbidity, in 2021 Phoenix established the country’s first office of heat response and mitigation. Its community tree planting program is now being rolled out to public schools, churches and homes in qualifying census tracts – low-income neighborhoods with little shade.Residents can choose from a list of 19 native and desert adapted trees including the Texas olive, Chinese red pistache and Chilean mesquites. The trees, which are a couple of years old and pretty heavy, are planted by contracted arborists. For insurance reasons, they must be within the property – not the sidewalk – and not too close to walls or power lines. Each household also gets a tree kit – a 100-ft hose, irrigation timer and instrument to measure the soil pH and moisture, as well as written care instructions.Grant Park community is one of the most neglected parts of the city – there is barely any shade in the area. Photograph: Tamuna Chkareuli/The GuardianThis is the fourth tree planting initiative in Grant Park, but the other schemes involved donations of smaller, younger trees which residents themselves had to plant in the dry, rocky earth. Several didn’t survive last summer’s heatwave when temperatures hit 100F (37.7C) on 31 consecutive days, while others died from overwatering or a lack of attention.Tree planting has become increasingly popular among corporations, governments and environmental groups alike in recent years, with mixed results. In Turkey, 90% of the government’s 11m new trees died within months, while polluting industries including mining and fossil fuel companies have been accused of trying to greenwash environmental and climate harms.“It is very hard to grow trees here, our environment is very extreme, so we’re doing everything we can to help them survive, which includes giving people the choice so they have species they love and feel excited about,” said Kayla Killoren, the heat office tree equity project coordinator. “There’s been a lot of greenwashing, and some people are weary and think it’s a scam at first, until they see their neighbors get trees planted.”The city distributes the tree care kits for the community. Photograph: Tamuna Chkareuli/The GuardianIn Phoenix, a 75 to 80% survival rate would be considered a success, according to Killoren.So far, 700 trees have been planted with scores more events planned throughout April and May, and will resume again in the fall after the summer heat. The project is mostly funded through non-profits, local and federal government grants including millions of dollars from the Covid stimulus package – the 2021 American Rescue Plan – and the Inflation Reduction Act.There’s a long way to go and limited funds. According to American Forests, more than 800,000 more trees are needed to achieve 15% canopy cover for every residential block in the city.The slow progress in improving tree coverage has frustrated many Phoenix residents, and in May, the heat team will present a new master shade plan to the city council, setting out more nuanced data-driven goals for homes, sidewalks and parks to replace the 25% citywide one. At the heart of the plan will be tackling shade inequalities that make rising temperatures increasingly deadly for the city’s most vulnerable communities, according to David Hondula, who leads the office of heat response and mitigation.Evangeline ‘Vengie’ Muller, 75, on her front porch. Photograph: Tamuna Chkareuli/The Guardian“The core concepts driving the masterplan are improving public health and livability by creating more shade in the places people spend most time,” said Hondula.In Grant Park, the community celebrates every single tree but it will likely take years to create adequate shade to provide residents – including unsheltered neighbors and passersby – adequate protection from the worsening heat.“We’ve always had to fight for everything here, we’re neglected but I love my neighborhood,” said Evangeline Muller, 75, who loads up her golf buggy with buckets to water the trees when it gets really hot. “Trees mean health, they give life, and I’m not going to stop fighting for my community.”

Phoenix broke several heat records last year. Now Grant Park, which has inequitable tree cover, is seeing a tree planting drive that promises some respite from 100F temperaturesIt was a relatively cool spring day in Phoenix, Arizona, as a tree planting crew dug large holes in one of the desert city’s hottest and least shaded neighborhoods.Still, it was sweaty backbreaking work as they carefully positioned, watered and staked a 10-ft tall Blue palo verde and Chilean mesquite in opposite corners of resident Ana Cordoba’s dusty unshaded backyard. Continue reading...

It was a relatively cool spring day in Phoenix, Arizona, as a tree planting crew dug large holes in one of the desert city’s hottest and least shaded neighborhoods.

Still, it was sweaty backbreaking work as they carefully positioned, watered and staked a 10-ft tall Blue palo verde and Chilean mesquite in opposite corners of resident Ana Cordoba’s dusty unshaded backyard.

“If I ever retire, I’d like to be able to spend more time outside. The weather is changing, so I am really happy to get these trees. We need more shade,” said Cordoba, 75, a legal secretary, whose family has lived in Grant Park for more than a century.

Over the course of three days in early April, arborists planted 40 or so desert adapted trees in Grant Park, as part of the city’s equity-driven heat mitigation plan to create a shadier, more livable environment amid rising temperatures and hundreds of heat related deaths.

Phoenix is America’s fifth largest and hottest city, a sprawling urban heat island which has expanded without adequate consideration to climate and environmental factors like water scarcity and extreme heat. ​Multiple heat records were broken last year including 133 days over 100F (37.7C), and 55 days topping 110F (43C).

Ana Cordoba, 75, in her backyard with two new trees, dreams of sitting under their shade one day. Photograph: Tamuna Chkareuli/The Guardian

Only around 9% of Phoenix is protected by tree canopies, yet this citywide figure masks vast inequities between wealthy, majority white neighborhoods like Willo (13% coverage) just two miles north of Grant Park (4%). One census tract in the north-west of the city, Camelback East, has 23% tree cover.

“This is one of the city’s oldest neighborhoods – and one the most neglected,” said Silverio Ontiveros, a retired police chief turned community organizer who drummed up interest for the tree planting by knocking on doors and putting fliers through every neighbor’s letterbox.

“Our goal is to change the inequity and create enough shade to provide residents and passersby reprieve from the heat. For that we need many more trees, but we also need to take care of them,” added Ontiveros, as he walked through the neighborhood making sure the right families got the right trees.

The city contractors plant the trees for the residents who applied for the program. Photograph: Tamuna Chkareuli/The Guardian

Grant Park is a majority Latino community in south Phoenix situated next to a sprawling electrical substation – a hot and dusty neighborhood with ​​200 or so homes, but no stores and plenty of empty lots and boarded-up houses. It was once a thriving neighborhood – one of the few places where people of color could live due to discriminatory housing policies that lasted most of the 20th century.

Redlined neighborhoods like Grant Park still have higher pollution levels, less vegetation, more noise pollution and higher temperatures. In recent years, the local outdoor pool was shuttered and scores of trees cut down by a previous administration to prevent homeless people from gathering in the shade.

“This is one of the hottest parts of the city because the people here don’t have political power,” said Leo Hernandez, 78, the master gardener at the thriving community garden where he created a butterfly sanctuary for migrating monarchs. “We need shade, but trees also suck up carbon dioxide, create places to socialize and healthier, happier neighborhoods.”

Susan and Silverio Ontiveros. Photograph: Tamuna Chkareuli/The Guardian
Silverio Ontiveros. Photograph: Tamuna Chkareuli/The Guardian

Trees have multiple benefits in urban areas which include cleaner air, improved physical and mental health, water conservation, increasing wildlife habitat, CO2 storage and sequestration and lower temperatures through shade.

The city is mostly concerned with reducing the urban heat island effect and improving public health, and its 2010 shade masterplan set out a goal of achieving 25% citywide canopy cover by 2030. Amid little progress and rising heat mortality and morbidity, in 2021 Phoenix established the country’s first office of heat response and mitigation. Its community tree planting program is now being rolled out to public schools, churches and homes in qualifying census tracts – low-income neighborhoods with little shade.

Residents can choose from a list of 19 native and desert adapted trees including the Texas olive, Chinese red pistache and Chilean mesquites. The trees, which are a couple of years old and pretty heavy, are planted by contracted arborists. For insurance reasons, they must be within the property – not the sidewalk – and not too close to walls or power lines. Each household also gets a tree kit – a 100-ft hose, irrigation timer and instrument to measure the soil pH and moisture, as well as written care instructions.

Grant Park community is one of the most neglected parts of the city – there is barely any shade in the area. Photograph: Tamuna Chkareuli/The Guardian

This is the fourth tree planting initiative in Grant Park, but the other schemes involved donations of smaller, younger trees which residents themselves had to plant in the dry, rocky earth. Several didn’t survive last summer’s heatwave when temperatures hit 100F (37.7C) on 31 consecutive days, while others died from overwatering or a lack of attention.

Tree planting has become increasingly popular among corporations, governments and environmental groups alike in recent years, with mixed results. In Turkey, 90% of the government’s 11m new trees died within months, while polluting industries including mining and fossil fuel companies have been accused of trying to greenwash environmental and climate harms.

“It is very hard to grow trees here, our environment is very extreme, so we’re doing everything we can to help them survive, which includes giving people the choice so they have species they love and feel excited about,” said Kayla Killoren, the heat office tree equity project coordinator. “There’s been a lot of greenwashing, and some people are weary and think it’s a scam at first, until they see their neighbors get trees planted.”

The city distributes the tree care kits for the community. Photograph: Tamuna Chkareuli/The Guardian

In Phoenix, a 75 to 80% survival rate would be considered a success, according to Killoren.

So far, 700 trees have been planted with scores more events planned throughout April and May, and will resume again in the fall after the summer heat. The project is mostly funded through non-profits, local and federal government grants including millions of dollars from the Covid stimulus package – the 2021 American Rescue Plan – and the Inflation Reduction Act.

There’s a long way to go and limited funds. According to American Forests, more than 800,000 more trees are needed to achieve 15% canopy cover for every residential block in the city.

The slow progress in improving tree coverage has frustrated many Phoenix residents, and in May, the heat team will present a new master shade plan to the city council, setting out more nuanced data-driven goals for homes, sidewalks and parks to replace the 25% citywide one. At the heart of the plan will be tackling shade inequalities that make rising temperatures increasingly deadly for the city’s most vulnerable communities, according to David Hondula, who leads the office of heat response and mitigation.

Evangeline ‘Vengie’ Muller, 75, on her front porch. Photograph: Tamuna Chkareuli/The Guardian

“The core concepts driving the masterplan are improving public health and livability by creating more shade in the places people spend most time,” said Hondula.

In Grant Park, the community celebrates every single tree but it will likely take years to create adequate shade to provide residents – including unsheltered neighbors and passersby – adequate protection from the worsening heat.

“We’ve always had to fight for everything here, we’re neglected but I love my neighborhood,” said Evangeline Muller, 75, who loads up her golf buggy with buckets to water the trees when it gets really hot. “Trees mean health, they give life, and I’m not going to stop fighting for my community.”

Read the full story here.
Photos courtesy of

Thirsty work: how the rise of massive datacentres strains Australia’s drinking water supply

The demand for use in cooling in Sydney alone is expected to exceed the volume of Canberra’s total drinking water within the next decadeSign up for climate and environment editor Adam Morton’s free Clear Air newsletter hereAs Australia rides the AI boom with dozens of new investments in datacentres in Sydney and Melbourne, experts are warning about the impact these massive projects will have on already strained water resources.Water demand to service datacentres in Sydney alone is forecast to be larger than the volume of Canberra’s total drinking water within the next decade. Continue reading...

As Australia rides the AI boom with dozens of new investments in datacentres in Sydney and Melbourne, experts are warning about the impact these massive projects will have on already strained water resources.Water demand to service datacentres in Sydney alone is forecast to be larger than the volume of Canberra’s total drinking water within the next decade.In Melbourne the Victorian government has announced a “$5.5m investment to become Australia’s datacentre capital”, but the hyperscale datacentre applications on hand already exceed the water demands of nearly all of the state’s top 30 business customers combined.Technology companies, including Open AI and Atlassian, are pushing for Australia to become a hub for data processing and storage. But with 260 datacentres operating and dozens more in the offing, experts are flagging concerns about the impact on the supply of drinking water.Sydney Water has estimated up to 250 megalitres a day would be needed to service the industry by 2035 (a larger volume than Canberra’s total drinking water).Cooling requires ‘huge amount of water’Prof Priya Rajagopalan, director of the Post Carbon Research Centre at RMIT, says water and electricity demands of datacentres depend on the cooling technology used.“If you’re just using evaporative cooling, there is a lot of water loss from the evaporation, but if you are using sealers, there is no water loss but it requires a huge amount of water to cool,” she says.While older datacentres tend to rely on air cooling, demand for more computing power means higher server rack density so the output is warmer, meaning centres have turned to water for cooling .The amount of water used in a datacentre can vary greatly. Some centres, such as NextDC, are moving towards liquid-to-chip cooling, which cools the processor or GPU directly instead of using air or water to cool the whole room.NextDC says it has completed an initial smaller deployment of the cooling technology but it has the capacity to scale up for ultra-high-density environments to allow for greater processing power without an associated rise in power consumption because liquid cooling is more efficient. The company says its modelling suggests power usage effectiveness (PUE, a measure of energy efficiency) could go as low as 1.15. Sign up to get climate and environment editor Adam Morton’s Clear Air column as a free newsletterThe datacentre industry accounts for its sustainability with two metrics: water usage effectiveness (WUE) and power usage effectiveness (PUE). These measure the amount of water or power used relative to computing work.WUE is measured by annual water use divided by annual IT energy use (kWh). For example, a 100MW datacentre using 3ML a day would have a WUE of 1.25. The closer the number is to 1, the more efficient it is. Several countries mandate minimum standards. Malaysia has recommended a WUE of 1.8, for example.But even efficient facilities can still use large quantities of water and energy, at scale.NextDC’s PUE in the last financial year was 1.44, up from 1.42 the previous year, which the company says “reflects the dynamic nature of customer activity across our fleet and the scaling up of new facilities”.Calls for ban on use of drinking waterSydney Water says its estimates of datacentre water use are being reviewed regularly. The utility is exploring climate-resilient and alternative water sources such as recycled water and stormwater harvesting to prepare for future demand.“All proposed datacentre connections are individually assessed to confirm there is sufficient local network capacity and operators may be required to fund upgrades if additional servicing is needed,” a Sydney Water spokesperson says.In its submission to the Victorian pricing review for 2026 to 2031, Melbourne Water noted that hyperscale datacentre operators that have put in applications for connections have “projected instantaneous or annual demands exceeding nearly all top 30 non-residential customers in Melbourne”.“We have not accounted for this in our demand forecasts or expenditure planning,” Melbourne Water said.It has sought upfront capital contributions from the companies so the financial burden of works required “does not fall on the broader customer base”.Greater Western Water in Victoria had 19 datacentre applications on hand, according to documents obtained by the ABC, and provided to the Guardian.skip past newsletter promotionSign up to Clear Air AustraliaAdam Morton brings you incisive analysis about the politics and impact of the climate crisisPrivacy Notice: Newsletters may contain information about charities, online ads, and content funded by outside parties. If you do not have an account, we will create a guest account for you on theguardian.com to send you this newsletter. You can complete full registration at any time. For more information about how we use your data see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotionThe Concerned Waterways Alliance, a network of Victorian community and environment groups, has flagged its concerns about the diversion of large volumes of drinking water to cool servers, when many of the state’s water resources are already stretched.Cameron Steele, a spokesperson for the alliance, says datacentre growth could increase Melbourne’s reliance on desalinated water and reduce water available for environmental flows, with the associated costs borne by the community. The groups have called for a ban on the use of drinking water for cooling, and mandatory public reporting of water use for all centres.“We would strongly advocate for the use of recycled water for datacentres rather than potable drinking water.”Closed-loop coolingIn hotter climates, such as large parts of Australia during the summer months, centres require more energy or water to keep cool.Danielle Francis, manager of customer and policy at the Water Services Association of Australia, says there isn’t a one-size-fits-all approach for how much energy and water datacentres use because it will depend on the local constraints such as land, noise restrictions and availability of water.“We’re always balancing all the different customers, and that’s the need for residential areas and also non-residential customers, as well as of course environmental needs,” Francis says.“It is true that there are quite a lot of datacentre applications. And the cumulative impact is what we have to plan for … We have to obviously look at what the community impact of that is going to be.“And sometimes they do like to cluster near each other and be in a similar location.”One centre under construction in Sydney’s Marsden Park is a 504MW datacentre spanning 20 hectares, with six four-storey buildings. The CDC centre will become the largest data campus in the southern hemisphere, the company has boasted.In the last financial year, CDC used 95.8% renewable electricity in its operational datacentres, and the company boasts a PUE of 1.38 and a WUE of 0.01. A spokesperson for the company says it has been able to achieve this through a closed-loop cooling system that eliminates ongoing water draw, rather than relying on the traditional evaporative cooling systems.“The closed-loop systems at CDC are filled once at the beginning of their life and operate without ongoing water draw, evaporation or waste, ensuring we are preserving water while still maintaining thermal performance,” a spokesperson says.“It’s a model designed for Australia, a country shaped by drought and water stress, and built for long-term sustainability and sets an industry standard.”Planning documents for the centre reveal that, despite CDC’s efforts, there remains some community concern over the project.In a June letter, the acting chief executive of the western health district of New South Wales, Peter Rophail, said the development was too close to vulnerable communities, and the unprecedented scale of the development was untested and represented an unsuitable risk to western Sydney communities.“The proposal does not provide any assurance that the operation can sufficiently adjust or mitigate environmental exposures during extreme heat weather events so as not to pose an unreasonable risk to human health,” Rophail said.

Costa Rica’s La Fortuna Waterfall Ranks in Top 1% Globally on TripAdvisor

La Fortuna Waterfall in Costa Rica received TripAdvisor’s “Best of the Best” award for the second straight year in the Travellers’ Choice 2025 rankings. This honor places the site among the top 1% of attractions globally, based on millions of traveler reviews and ratings. The waterfall, a key draw in the Arenal Volcano National Park […] The post Costa Rica’s La Fortuna Waterfall Ranks in Top 1% Globally on TripAdvisor appeared first on The Tico Times | Costa Rica News | Travel | Real Estate.

La Fortuna Waterfall in Costa Rica received TripAdvisor’s “Best of the Best” award for the second straight year in the Travellers’ Choice 2025 rankings. This honor places the site among the top 1% of attractions globally, based on millions of traveler reviews and ratings. The waterfall, a key draw in the Arenal Volcano National Park area, attracted roughly 1,000 visitors daily in 2024. The waterfall is about 4 kilometers from the center of La Fortuna in San Carlos, the 70-meter cascade requires a descent of about 530 steps to reach its base. The path includes safety rails, rest spots, and water stations amid native forest trees. At the site, travelers find a restaurant, gift shops, restrooms, and other services. Admission costs $10 for Costa Rican nationals and $20 for international visitors, with reduced rates for those with disabilities. A non-profit group, the Integral Development Association of La Fortuna (ADIFORT), oversees the site. Founded in 1969, ADIFORT directs revenue toward road improvements, environmental care, education, sports, cultural programs, town upkeep, and safety measures. This model ties tourism directly to local progress. The area forms part of a 210-acre biological reserve in premontane tropical wet forest, at 520 meters above sea level. It marks the headwaters of the La Fortuna River. Along the trail, visitors pass an orchid path, butterfly garden, frog habitat, and bee hotel, adding to the natural appeal. Travelers like to visit the waterfall for its clear waters and the chance to swim at the base, though heavy rains can limit access during the rainy season. Reviews highlight the well-maintained facilities and the rewarding hike, despite the steep return climb. The award reflects consistent high marks for the experience, solidifying our country’s reputation in ecotourism. Officials note that sustainable management keeps the site pristine while benefiting residents. As visitor numbers grow, the focus remains on balancing tourism with conservation. This latest win shows the waterfall’s role in showcasing not only Costa Rica’s biodiversity but also our community-driven initiatives. The post Costa Rica’s La Fortuna Waterfall Ranks in Top 1% Globally on TripAdvisor appeared first on The Tico Times | Costa Rica News | Travel | Real Estate.

People living along polluted Thames file legal complaint to force water firm to act

Residents claim raw sewage and poorly treated effluent as result of Thames Water’s failings are threat to healthCommunities across south-east England are filing the first coordinated legal complaints that sewage pollution by Thames Water negatively affects their lives.Thames Water failed to complete upgrades to 98 treatment plants and pumping stations which have the worst records for sewage pollution into the environment, despite a promise to invest in them over the last five years. Continue reading...

Communities across south-east England are filing the first coordinated legal complaints that sewage pollution by Thames Water negatively affects their lives.Thames Water failed to complete upgrades to 98 treatment plants and pumping stations which have the worst records for sewage pollution into the environment, despite a promise to invest in them over the last five years.People in 13 areas including Hackney, Oxford, Richmond upon Thames and Wokingham are sending statutory nuisance complaints to their local authorities demanding accountability from Thames Water and urgent action.At several sites it is not just raw sewage from storm overflows that causes pollution but also the quality of treated effluent coming from Thames Water facilities, which presents a direct threat to public health, the campaigners say.At Thames’s Newbury sewage treatment plant, raw effluent discharges into the River Kennet, a protected chalk stream. Data shows raw sewage discharges from the plant increased by 240% between 2019 and 2024 from 482 hours to 1,630 hours. Thames says the plant is among its 26 most polluting sites.Thames wants the water regulator, Ofwat, to allow it to charge customers £1.18bn over the next five years for the upgrades it has failed to carry out. But the regulator has refused to let it pass the full cost on to customers, allowing only £793m, as it deems bill payers have already funded the upgrades. It says any escalation of costs should be borne by Thames Water.With the company failing to act, people living in the catchment are turning to statutory nuisance complaints under section 79 of the Environmental Protection Act 1990. In letters to their local authorities, they are asking for decisive action by Thames to stop its sewage pollution that is causing harm along the river.A statutory nuisance is an activity that unreasonably interferes with the use or enjoyment of land and is likely to cause prejudice or injury to health.Those living in the area say sewage pollution from Thames’s failing sites and infrastructure has made rivers unsafe and disrupted recreation, sport, local businesses and everyday enjoyment.They cite a 16-year-old rower from Henley rowing club who became unwell after training on the river; tests confirmed he had contracted E coli. His illness coincided with his GCSE exams, preventing him from revising and sitting some papers.In West Berkshire, people are highlighting the case of a kayaker who capsized and became unwell over the following days. And at Tagg’s Island in Hampton, south-west London, five children became ill after playing in the River Thames near Hurst Park.Laura Reineke, who lives in Henley-on-Thames and founded the campaign group Friends of the Thames, said: “People here are fed up with living beside a river that’s being treated like an open sewer. We’ve submitted a nuisance complaint to our local authority because what Thames Water is doing is unacceptable.”Citizen testing of the river has found treated effluent leaving the Henley plant has contained E coli at levels 30 times higher than bathing water safe levels, calculated using Thames Water’s data released under an environmental information request.“Local residents are angry and determined to hold this company accountable for the damage it’s causing to our river and our community,” Reineke said.Thames has already received a record £104m fine by Ofwat over environmental breaches involving sewage spills across its network, after failing to operate and manage its treatment works and wastewater networks effectively.Amy Fairman, the head of campaigns at River Action, which is supporting the coordinated complaints, said: “This action is about fixing sewage pollution in the Thames for good, not compensating people for past failings.“Each local authority must investigate these complaints and, where statutory nuisance is found to exist, issue an abatement notice and take enforcement action. Councils now have a legal duty to act.”She said there was extensive evidence of performance failures at Thames Water, which was on the brink of insolvency. Despite this ministers had not put the company into special administration, a process that would allow for urgent infrastructure upgrades, put public interest ownership and governance first, and protect communities and the environment.Thames Water was approached for comment.

Gold clam invasion in NZ threatens drinking water for millions of people

The invasion threatens more than water. Clams could foul dam intakes and reduce hydroelectric efficiency in a river that generates 13% of New Zealand’s power.

Michele Melchior, CC BY-NDAs a geochemist studying New Zealand’s freshwater systems, I’ve spent years tracking the subtle chemical shifts in our rivers and lakes. But nothing prepared me for the rapid transformation unfolding in the Waikato River since the invasion of the Asian clam (Corbicula fluminea, also known as the freshwater gold clam). First detected in May 2023 in Lake Karāpiro, a reservoir lake on the Waikato, this bivalve is now altering the river’s chemistry in ways that could jeopardise drinking water for up to two million people, disrupt hydroelectric power and undermine decades of ecosystem restoration efforts. Our team’s work reveals how these clams are depleting essential minerals like calcium from the water, impairing arsenic removal during treatment and signalling a rapid escalation with broader impacts ahead. Gold clams now dominate the river bed in many areas, with densities exceeding 1,000 individuals per square metre. Michele Melchior, CC BY-ND Native to eastern Asia, the gold clam can self-fertilise and spreads via contaminated gear, birds or floods. Climate change will likely accelerate its invasion. The problem is already spreading quickly beyond the Waikato River. A recent detection in a Taranaki lake has led to waterway closures. And warnings for the Whanganui River underscore the urgent need for national vigilance. A silent invasion with big consequences The Waikato River stretches 425 km from Lake Taupō to the Tasman Sea, powering nine hydroelectric dams and supplying drinking water to Auckland, Hamilton and beyond. It’s a taonga (cultural treasure) central to Māori identity and the subject of a landmark restoration strategy, Te Ture Whaimana o Te Awa o Waikato, that aims to revive the river’s mauri (life force). In late 2024, arsenic levels in treated Waikato water briefly exceeded safe limits of 0.01 milligrams per litre (mg/L), triggering alarms at treatment plants. Investigations ruled out typical culprits such as geothermal spikes. Instead, our analysis points to the clams. By filtering water and building calcium carbonate shells, the clams are drawing down dissolved calcium by 25% below historical norms. But calcium is crucial for water treatment processes because it helps bind and remove contaminants such as arsenic. Our modelling estimates the clams are forming up to 30 tonnes of calcium carbonate daily in Lake Karāpiro alone. This suggests lake-wide densities averaging around 300 individuals per square metre. 2025 surveys show hotspots with up to 1,134 clams per square metre. The result? Impaired arsenic removal. Without stable calcium, flocs (clumps of particles) don’t form properly, letting arsenic slip through. While the exceedances were short-lived and contained through quick adjustments, they exposed vulnerabilities in a system optimised for historically consistent river chemistry. Field teams survey the rapidly expanding population of freshwater gold clams in the Waikato River. Michele Melchior, CC BY-ND How the clams are changing the river The gold clam isn’t just a filter-feeder; it’s an ecosystem engineer. Each clam can process up to a litre of water per hour, sequestering calcium for shells while releasing ammonia and bicarbonate. Our data from 2024-2025, collected at multiple sites, show these shifts are most pronounced in deeper waters. Statistical tests confirm patterns absent in pre-invasion records. Longer residence times in the reservoir lake (up to seven days) exacerbate the issue. Faster flushing correlates with higher growth rates, as clams ramp up activity. But prolonged retention in warmer months can lead to hypoxia (low oxygen), with the potential to trigger mass die-offs that release toxins or mobilise sediment-bound arsenic. Lake Karāpiro water column temperature and dissolved oxygen levels (from November 2024 to October 2025) show oxygen depletion in deep water during warmer summer conditions, likely exacerbated by the gold clam. Author provided, CC BY-NC-ND These changes threaten more than water treatment. Clams could biofoul dam intakes and reduce hydroelectric efficiency in a river that generates 13% of New Zealand’s power (25% at peak). Native species like kākahi (freshwater mussels) face competition and shifts in nutrient cycling could fuel algal blooms, clashing with restoration goals. Climate risks and stressors in a warming world Amid these ongoing changes, climate projections indicate that hot, dry events – such as prolonged heatwaves or droughts – are likely to become more frequent. Such conditions could reduce river flows and elevate water temperatures, lowering dissolved oxygen levels and creating low-oxygen zones. If clam densities continue to rise exponentially, a mass die-off might occur. This would release pulses of ammonia and organic matter that further deplete dissolved oxygen. This, in turn, could promote arsenic mobilisation from sediments and harmful algal blooms in nutrient-enriched, stagnant waters. This could necessitate supply restrictions for affected communities. Ecologically, it might kill fish and disrupt native biodiversity. Economically, it could interrupt industries reliant on the river. From the Waikato to a nationwide threat The invasion isn’t contained. The clam, which can produce up to 70,000 juveniles annually, thrives in warm, nutrient-rich waters. It is notoriously hard to eradicate once established. In mid-November, the Taranaki Regional Council confirmed the gold clam in Lake Rotomanu. Just days later, warnings were issued to boaties on the Whanganui River, urging rigorous “check, clean, dry” protocols. Without intervention, the clams could reach other systems, including the Clutha or Waitaki, and compound pressures on New Zealand’s already stressed freshwaters. Our research highlights the need for integrated action. Monitoring should expand, incorporating environmental DNA for early detection and calcium isotope tracing to pinpoint clam impacts. Water providers could trial calcium dosing during peak growth periods. But solutions must honour Te Tiriti o Waitangi principles. Collaboration with iwi and blending mātauranga Māori (indigenous knowledge) with science, such as using tikanga indicators for water health, is essential. Biosecurity measures including gear decontamination campaigns are critical to slow spread. Field teams are counting invasive gold clams on the banks of the Waikato River. Michele Melchior, CC BY-ND This invasion intersects with New Zealand’s evolving water policy framework, particularly the Local Water Done Well regime which replaced the repealed Three Waters reforms in late 2023. Councils are now implementing delivery plans and focusing on financial sustainability and infrastructure upgrades. The Water Services Authority Taumata Arawai continues as the national regulator, enforcing standards amid an estimated NZ$185-260 billion infrastructure deficit. Recent government announcements propose further streamlining, including replacing regional councils with panels of mayors or territories boards, while encouraging amalgamations to simplify planning and infrastructure delivery. These changes aim to make local government more cost-effective and responsive to issues such as housing growth and infrastructure funding. But a hot or dry event could test the effectiveness of water policy, potentially straining inter-council coordination for shared resources such as the Waikato River and highlighting gaps in emergency response. Globally, the gold clam has cost billions in damages. New Zealand can’t afford to wait. By acting now, we can protect Te Awa o Waikato and safeguard water security for generations. Adam Hartland receives funding from the Ministry of Business, Innovation and Employment via grant LVLX2302.

Suggested Viewing

Join us to forge
a sustainable future

Our team is always growing.
Become a partner, volunteer, sponsor, or intern today.
Let us know how you would like to get involved!

CONTACT US

sign up for our mailing list to stay informed on the latest films and environmental headlines.

Subscribers receive a free day pass for streaming Cinema Verde.
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.