World Lake Day 2026; August 27th.

FORUM: "Strengthening Global Cooperation for Sustainable Lake Management." World Lake Day 2026. Lakes and reservoirs contain more than 90% of the world's liquid surface freshwater. They are the lifeblood of ecosystems, driving local economies, securing food and drinking water for billions , and regulating local climates. Despite their critical importance, lakes globally face unprecedented threats from pollution, agricultural runoff, climate-induced evaporation, and rapid biodiversity loss. The observance of the World Lake Day serves as an opportunity to reaffirm the importance of lakes, while also providing an international platform for countries and diverse stakeholders to collaborate in advancing their conservation and sustainable use. Recognizing the critical importance and compounding crises faced by lakes, a special event to commemorate World Lake Day is being organized to elevate the global political and technical profile of sustainable lakemanagement. Specifically, the event aims to: • Showcase good practices and lessons learned. • Mobilize support: Highlight Global Wetland Watch as one of the global Earth observation initiatives that provides standardized information on inland water and wetland ecosystems, supporting improved lake monitoring, policy development, and international reporting. • Catalyse Science-to-Policy Action: Convene a multi-stakeholder panel of experts , policymakers , and UN representatives to propose actionable pathways for integratinglake protection into national strategies, including on climate and biodivers ity. • Bridge to the upcoming World Lake Conference: Build momentum toward the WorldLake Conference (WLC21) schedule to take place in June 2027 in Dares Salaam, Tanzania. Follow the conversations with the hashtags: #worldlakeday, #lakemanagement, #naturallakes, #artificiallakes, #27August, #GenerationRestoration.

EVENTS: On August 27th 2026 from 10:00 to 11:30 am (TBC) at United Nations Headquarters Conference Room 11 will be held an in-person event to mark the World Lake Day 2026. Read the concept note, the agenda programme and Register to participate!

- Preliminary Programme -

 This programme assumes a 90-minute event. 

10’ Opening session: - Opening remarks -Tentative speakers  Rafael Peralta (Director of NY Office)  Japan - Indonesia.

10’ Technical Showcase: Earth Observation for Lake Monitoring - Demonstration of Global Wetland Watch and how satellite-bas ed monitoring supports lake extent, wetland monitoring, national reporting, and evidence-based management. Tentative speakers - UNEP – GWW (Stuart Crane, remotely) 

30’ MultiStakeholder Panel Discussion: From Science to Policy.

Suggested guiding questions : • How can lake conservation be better integrated into national climate and biodiversity strategies? • What lessons can countries s hare through South-South and triangular cooperation? • What technical and financial support is needed to accelerate action? • How can momentum be sustained toward the 21st World Lake Conference? 

30’ Interactive Discussion / Q&A -Tentative speakers: Audience.

5’ Closing Remarks - Key takeaways - Invitation to the 21st World Lake Conference (WLC21) - Clos ing -Tentative speakers: Tanzania.

LIVESTREAM: Watch Commemorating World Lake Day: Strengthening Global Cooperation for Sustainable Lake Management!

Recognizing the critical importance and compounding crises faced by lakes, a special event to commemorate World Lake Day is being organized to elevate the global political and technical profile of sustainable lake management. Lakes and reservoirs contain more than 90% of the world's liquid surface freshwater. They are the lifeblood of ecosystems, driving local economies, securing food and drinking water for billions, and regulating local climates. Despite their critical importance, lakes globally face unprecedented threats from pollution, agricultural runoff, climate-induced evaporation, and rapid biodiversity loss.

Related Sites and Documents: Draft Concept Note & Website.

UPCOMING EVENTS: The 21st World Lake Conference (WLC21) will be hosted in Tanzania in July/August 2027 by the Water Institute in collaboration with the International Lake Environment Committee (ILEC).

PUBLICATION:  America’s Cleanest and Dirtiest Lakes: 2026 Report on Lake Pollution and Water Quality. Lake has released our 2026 report ranking the cleanest and dirtiest lakes in the United States. Discover why Lake Chelan ranks #1 on the cleanest lakes list, and get acquainted with the factors that influence a lake’s position on the cleanest list and the dirtiest list. Download the Report as PDF

• Lake Chelan is the cleanest lake in America, due to its low mineral levels and low turbidity.
• The Great Salt Lake is the dirtiest lake in the US right now, with by far the heaviest mineral load of any ranked lake (134,500 mg/L Total Dissolved Solids), as well as the lowest dissolved oxygen levels (3.65 mg/L) and the highest ammonia levels of any lake in the top ten dirtiest (0.92 mg/L).
• Over 60 major lakes in America were assessed across eight different categories.
• The Cleanest and Dirtiest Lakes at a Glance

A new report has revealed the cleanest and dirtiest lakes in America, with Lake Chelan ranking as the cleanest, while the Great Salt Lake in Utah ranks as the dirtiest due to its saline levels. The study, conducted by vacation rental platform Lake.com, analyzed all the available chemical data from the National Water Quality Monitoring Council (NWQMC) for 100 of America’s largest lakes, sampled from January 1st, 2021, until July 30th, 2026. The study evaluated eight of the most commonly measured characteristics that can indicate a lake’s cleanliness level:

• Dissolved oxygen
• Ammonia
• Lead
• Phosphorus
• Sulfate
• Total dissolved solids
• Turbidity
• pH levels

A total of 67 lakes reported at least three of these pollution factors and therefore qualified for the study. The findings were put into an index to produce a pollution score out of 10 to determine the safest and most dangerous lakes based on hygiene, pollution and more.

At the other end of the scale, Lake Chelan in Washington state is the cleanest lake in America. Lake Chelan has turbidity of just 2.00 NTU, meaning it’s extremely clear, and one of the lowest TDS levels at 30.25 mg/L. Lake Chelan also experiences low sulfate levels of 3.65 mg/L.

However, Lake Superior, which was the cleanest lake in last year’s report, ranks a close second with the lowest turbidity of any lake (0.54 NTU), low TDS levels (74 mg/L), and high oxygen levels (10.58 mg/L).

The Great Salt Lake in Utah is America’s dirtiest lake. Its water carries an extremely high mineral load, with total dissolved solids (TDS) of 134,500 mg/L, which is much more than any other lake in the study. TDS refers to the total minerals within water, including sulfates, chlorides, calcium, magnesium, potassium, bicarbonates and sodium, and indicates the general quality of water. While not necessarily a direct indicator of pollution itself, the levels highlight how dangerous it could be to ingest any water from the Great Salt Lake due to its extreme chemistry.

The Great Salt Lake is also the most poorly oxygenated lake in the ranking, with dissolved oxygen of just 3.65 mg/L. If this level were to drop below 2, the lake would become hypoxic, meaning fish would suffocate. It also reports the highest ammonia of any lake in the top ten dirtiest ranking at 0.92 mg/L, along with elevated lead at 2.09 µg/L. The Great Salt Lake is not a freshwater lake and is a terminal lake; therefore, there is no outlet for any mineral or chemical buildup.

Lake McConaughy in Nebraska and Lake Winnebago in Wisconsin rank second and third dirtiest, respectively. Lake McConaughy has turbidity levels of 5.50 NTU, while Lake Winnebago, Wisconsin’s largest inland lake, is ranked so low due to its high levels of phosphorus, which are 0.09 mg/L, along with a pH deviation of 1.58.

The fourth dirtiest lake in America is Lake Vermilion in Minnesota. Lake Vermilion is the second least oxygenated lake, behind the Great Salt Lake, with dissolved oxygen of just 3.90 mg/L.

Devils Lake in North Dakota is the fifth dirtiest lake in the country and is likely to be the smelliest of all, as it has the highest levels of sulfate (639 mg/L) due to no natural outlet to dilute sulfates over time. The smell of sulfate is often described as similar to ‘rotten egg’.

Despite ranking as the eighteenth dirtiest lake overall, Lake Moultrie in South Carolina is the most lead-contaminated lake included in the study, with samples detecting lead at 17.2 µg/L. There is no safe level of lead.

Lake Mattamuskeet in North Carolina shows the highest ammonia of any freshwater lake in the top ten, estimated at 0.67 mg/L. Ammonia should not be present at all in clean water, and when levels reach 0.53 mg/L, the water begins to become harmful to fish.

“America’s largest lakes remain, on the whole, clean and pleasant to swim in. Even the lakes at the top of our dirtiest table sit within the range you would expect for large natural bodies of water, which shows that there is good maintenance and care for them.

“However, with that in mind, some monitoring of lakes throughout the country is uneven from one lake to the next, so anyone looking to visit a lake, particularly swimmers, needs to check any signage near their local swimming spot and follow the advice given to them. No lake in the ranking is inherently dangerous, but you could be at risk of a stomach bug.” David Ciccarelli, CEO of Lake.com

Other publications: Research papers of the International Lake Environment committee Foundation (ILEC)

World Lake Day 2025; August 27th.

FORUM: “Lakes: the lifeblood of our planet.” World Lake Day 2025. Lakes serve as a crucial source of fresh water, supporting drinking water supplies, agriculture, and industry. Lakes also play a key role in maintaining biodiversity, offering a habitat for countless species of fish, plants, and wildlife. Beyond their ecological significance, lakes contribute to climate regulation by keeping the planet cool, absorbing the floodwater and storing carbon. Additionally, they provide recreational and economic opportunities, attracting tourism, fishing, and other activities that support local communities. Lakes are affected by a combination of overuse, pollution and climate change. Lake pollution is frequently caused by inflows from fertilizers, contaminants and solid waste being dumped directly, or flushed into lakes via rivers, and this is worsened by global warming – leading, for instance, to more frequent and intense floods. The water levels of lakes are also changing dramatically. Rising temperatures and changes to cloud cover, which are leading to decreasing ice cover, are increasing the rate of water evaporation. Which action can be taken to safeguard these vital freshwater. Follow the conversations with the hashtags: #worldlakeday, #lakemanagement, #naturallakes, #artificiallakes, #27August, #GenerationRestoration.

EVENTS: We need to act now. This World Lake Day 2025, let's be aware of the problem lakes are facing and protect them today for a sustaining life tomorrow. The United Nations General Assembly Invites all States Members of the United Nations, members of the specialized agencies and observers of the General Assembly, as well as the organizations of the United Nations system, other international, regional and subregional organizations and other relevant stakeholders, including civil society, the private sector and academia, to observe World Lake Day in an appropriate manner through activities aimed at education and awareness-raising of the importance of lakes and preserving, conserving, restoring and sustainably managing lake and related ecosystems. Join UNEP and partners in the mission to conserve, protect, and restore them to their former glory! Register to participate!

Statement of Inger Andersen; Under-Secretary-General of the United Nations and Executive Director of the United Nations Environment Programme (UNEP) on World Lake Day 2025; August 27th.


When you think of water, you might picture rivers rushing to the sea or waves crashing on a tropical shore. But the quiet giants of our freshwater systems – lakes – hold 90 per cent of the planet’s surface fresh water. They are life-support systems for millions, providing drinking water, irrigation, food and recreation. They shelter biodiversity, regulate climate and buffer communities against floods and droughts. Yet, like many freshwater ecosystems, lakes are often overlooked in global discussions on water solutions.

From the Great Lakes of Africa to the mountain reservoirs of Asia, lakes sustain billions of lives. They store water, moderate temperature, support fisheries and underpin agriculture. They are also biodiversity havens for countless species.

But lake ecosystems are fragile. Today, they are being put under increasing pressure from climate change, pollution and unsustainable land use. Evaporation rates are rising as global temperatures climb. Nutrient runoff from agriculture fuels algae blooms, turning once-clear waters into oxygen-starved dead zones. Water abstraction for farms and cities shrinks lakes, while invasive species disrupt ecological balance.

A recent analysis by the United Nations Environment Programme (UNEP) revealed a stark figure. Surface water bodies, such as lakes, are shrinking or being lost entirely in 364 basins worldwide. The degradation of lakes is not just an environmental threat; it also affects communities that rely on them for survival.

Indonesia is leading the fight to protect lakes. Since championing the first-ever United Nations Environment Assembly resolution on Sustainable Lake Management in 2022, the country has helped place lakes at the centre of global water discussions, including during the United Nations 2023 Water Conference and the tenth World Water Forum, in which lakes featured prominently in the Ministerial Declaration.

With the recent adoption of the United Nations System-wide Strategy on Water and Sanitation, the stage is set for even greater cooperative action. But why this urgency? Because lakes are under siege.

To understand the fate of lakes, we need to zoom out to the global hydrological cycle – the invisible thread linking glaciers, rivers, wetlands, aquifers and seas. Glaciers, often called “water towers of the world”, feed many of the planet’s lakes and rivers. Nearly 1.9 billion people depend on these frozen reserves for drinking water, irrigation and hydropower.

But climate change is melting glaciers at unprecedented rates. Recognizing this, 2025 marks the United Nations International Year of Glaciers’ Preservation. The year 2024 was the warmest year on record, and in 2023 alone, glaciers lost more than 600 gigatons of ice – the greatest loss in five decades. As they retreat, a new phenomenon is reshaping mountain landscapes: the explosive growth of glacial lakes. These lakes can be both lifelines and risks. They store meltwater, acting as buffers during drought. But they also pose catastrophic risks through glacial lake outburst floods, which can devastate entire valleys.

Despite their importance, lakes remain among the least monitored water bodies on Earth. Unlike rivers, which often have established gauging stations, lakes are poorly studied, particularly in low- and middle-income countries.

UNEP is working to change this. Through tools and initiatives such as the Freshwater Ecosystems Explorer, the UNEP lakes portal, the United Nations Decade on Ecosystem Restoration and integrated water resources management frameworks, efforts are underway to close data gaps and improve policies, plans and approaches. But we need to scale up, and scale up fast.

UNEP launched a landmark, transboundary initiative in the Lake Tanganyika Basin that works across Burundi, Democratic Republic of Congo, Tanzania and Zambia to protect biodiversity, restore critical wetlands and degraded landscapes, support sustainable fisheries management and enhance water security. It will rehabilitate 1,700 hectares of ecosystems and foster catchment-wide governance through community engagement and basin-level monitoring, all underpinned by the commitment of UNEP to integrated water resource management.

Lakes may seem remote, but their health determines our own. They are essential parts of the global hydrological cycle – a topic that is on the table for discussion at the seventh session of the United Nations Environment Assembly, to be held in December 2025. Like other freshwater ecosystems, lakes are important buffers against drought, engines of local economies and cradles of biodiversity. They are also sentinels, warning us of the accelerating impacts of the climate crisis.

Protecting freshwater ecosystems like lakes is not optional. It is central to biodiversity, water, energy and food security, and offers climate resilience.

Member States, guided by the leadership of Indonesia, must adopt an integrated water resources management approach to enhance lake protection and restoration. Greater investments in infrastructure, data and innovative solutions are crucial to meet the targets of Sustainable Development Goal 6 – clean water and sanitation for all – and ensure long-term sustainability for both human and ecosystem needs.

Now, the challenge is global: to safeguard these blue jewels. Not just for their beauty, but for the billions who depend on them. Because when lakes thrive, life flows everywhere.

Inger Andersen; Under-Secretary-General of the United Nations and Executive Director of the United Nations Environment Programme (UNEP).

PUBLICATION: Dive into the Healthy and Productive Lakes Portal. Learn about the diversity of lake ecosystems, explore their vital role in human development and planetary health, uncover the threats they face, and access tools and resources.