Integrated management of lakes, reservoirs, and their basins is critical for a climate-resilient planet: an urgent wake-up call from collective amnesia

Natural lakes and engineered reservoirs, accounting for 88% of the Earth's accessible surface freshwater, are essential for addressing the triple – water, environment, and climate – crisis. From here on referred to as lakes and reservoirs, these significant standing (or lentic) bodies are critical in managing the world's water supply and enhancing climate resilience. They provide vital resources such as water, food, and energy while serving as barriers against floods and droughts. Furthermore, they support diverse ecosystems and biodiversity, contributing significantly to communities' well-being, livelihoods, and economies.

As the world's population grows and urbanization expands, the demand for goods and services increases, driving economic development. Total global withdrawals of surface and groundwater have doubled from 2,000 km³ in 1970 to 4,000 km³ in 2022 (Ritchie & Roser 2024), with surface water accounting for two-thirds of this total. The surge in water, food, and energy demand is outpacing supply, leading many regions to experience severe water scarcity. Experts predict that 2030 water demand will exceed supply by 40% (WEF 2023).

Our lakes and reservoirs are rapidly declining and degrading due to human activities, global warming, and aging infrastructure. They are under significant stress, leading to a loss of essential socioeconomic and ecosystem benefits for urban and rural communities. In 2023, the international community – including organizations such as UN-Water, World Meteorological Organization (WMO), United Nations Environment Programme (UNEP), The World Bank, and other agencies – recognized the profound impact of the interconnected global water, environmental, and climate crises on rivers, lakes, reservoirs, and aquifers. These organizations have been some of the major funders and supporters of lake and reservoir management projects worldwide.

Collaboration and partnership are essential to address this crisis and its interconnected challenges, which affect billions facing water, food, and energy insecurity. According to the 2024 World Economic Forum (WEF 2024), the 10 most significant global risks include extreme weather events, the impact of climate change on Earth's systems, biodiversity loss, ecosystem collapse, natural resource shortages, and pollution. These risks underscore the urgency for action and the necessity for integrated solutions.

Lakes hold approximately 87% of the world's accessible fresh surface water. They supply essential water for villages, towns, cities, industries, farms, mines, and livestock and generate electricity. In addition, lakes play a vital role in controlling floods, mitigating droughts, replenishing aquifers, sustaining diverse ecosystems and biodiversity, and supporting fishing, navigation, and recreational activities. Some lakes also receive and assimilate domestic and industrial wastewater.

Lakes and reservoirs share many physical, chemical, and biological processes but differ in many ways. Geological processes have influenced the formation of natural lakes. Approximately 304 million lakes, old and young, large and small, are scattered worldwide (Downing et al. 2006). Around 20 ancient lakes, including Lakes Tanganyika, Baikal, and Zaysan, are about three to over 65 million years old. However, most lakes are relatively young, formed after the last ice age. For instance, Lake Superior is only 10,000 years old.

Lakes, wetlands, and rivers store 104,590 km³ of freshwater globally, with the world's lakes holding about 91,000 km³ (Shiklomanov 1993). The collective storage capacity of reservoirs behind the world's 61,988 large dams is about 8,767 km³ (ICOLD 2023), less than 10% of the total storage capacity of natural lakes. This comparison highlights natural lakes' significant storage capacity and emphasizes their abundance.

Reservoirs created by dam construction have existed for approximately 5,000 years. When a reservoir is formed, it transforms a river – typically a moving or lotic system – into a lentic system, which is characterized by standing water. The oldest operational dam is the Lake Homs Dam, built around 1300 AD across the Orontes River in Syria. It continues to supply water to the people of Homs (Tata & Howard 2024).

According to Downing et al. (2006), over half a million reservoirs cover an area of one hectare or more, including 24 reservoirs larger than 1,000 km² and three that exceed 10,000 km². The development of large dams peaked in the 1970s, with about 1,500 new dams constructed each year. While the growth slowed in the 1990s, dam construction continued in Sub-Saharan Africa, Asia, and Latin America (Perera et al. 2021). By 2020, the number of new large dams decreased to approximately 50 per year (United Nations University 2021).

Some large transboundary lakes are important hubs contributing to regional trade and integration. The North American Great Lakes basin houses over 34 million people, sustains a $6 trillion economy, stores over 90% of North America's surface freshwater supply for millions of people, and critical American and Canadian industries, including steel production, agriculture, automotive, manufacturing, recreation and tourism, maritime transportation, and much more (Great Lakes Commission 2022). The Lake Victoria basin, a global biodiversity hotspot and the second most productive inland fishery globally, supports 40 million people relying on water, livelihood, trade, tourism, and navigation (Lake Victoria Basin Commission 2020).

Building thousands of reservoirs by constructing dams has dramatically increased water storage capacity and improved water, food, and energy security, promoting development worldwide. According to the 2023 register of the International Commission on Large Dams (ICOLD), there is an impressive total of 61,988 large dams and reservoirs, including 31,167 single-purpose dams and 11,002 multipurpose dams registered. They play a vital role in storing water for various uses, such as irrigation, power generation, domestic and industrial needs, flood control, and more (ICOLD 2023). However, despite these advancements, millions still face food, energy, and water insecurity. It is essential to address these imbalances to ensure that everyone in need can benefit from these valuable resources.

In 2020, West Asia, the Caribbean, and Africa experienced heightened food insecurity, with over 700 million people chronically hungry (FAO, IFAD, UNICEF, WFP & WHO 2023). To feed a projected population of 10 billion by 2050, global food production must increase by over 50% (Searchinger 2018). Irrigation, responsible for 72% of global water withdrawal, produces 40% of crops on just 18% of arable land (European Commission 2019). However, inefficient irrigation leads to lake and reservoir depletion, while poor land use and agricultural chemicals contribute to lake and reservoir water pollution.

Thousands of reservoirs and some lakes play an important role in generating hydropower, which accounts for approximately 60% of global renewable energy and 15% of the world's electricity (IHA 2023). Hydropower reservoirs can vary significantly in size; some have substantial storage capacity, while others are smaller, such as those used in run-of-the-river plants or off-stream pumped storage facilities. In addition, hydropower can also be generated from water stored in natural lakes.

Investment in hydropower decreased from $26 billion in 2017 to $8 billion in 2022 (IRENA & CPI 2023). However, investment appears to be rebounding as hydropower remains a vital renewable energy source (IHA 2023). According to the International Energy Agency, hydropower capacity must double to achieve net-zero emissions by 2050 (IEA 2021). Most future electricity demand is expected to come from emerging economies, making hydropower crucial for energy security.

Household and industrial water use accounts for about 12 and 16% of total water withdrawals, respectively (UN-Water 2023). Reservoirs store a large portion of the surface supply for these uses. With approximately two billion people still needing consistent access to safe water, the demand for new supply sources will likely increase. Water supplies also face many challenges – inefficiencies, losses, leakages, theft, and water pollution. Inadequate effluent treatment and effluent disposal present challenges for municipalities and industries worldwide. These issues are likely to worsen as the population grows.

Some reservoirs also play a crucial role in mitigating floods and droughts, which are becoming more frequent and severe. From 1990 to 2022, floods affected over 3.2 billion people, resulting in 218,353 deaths and over $1.3 trillion in damages, with China, India, Bangladesh, the United States, and Venezuela being the most impacted (Liu et al. 2024). In addition, around 1.43 billion people faced drought effects over the last two decades (Browder et al. 2021). Extreme droughts have risen by 233% in the past 50 years, predominantly impacting low- to middle-income nations. Without intervention, including better management of existing water storages and the development of additional reservoirs, vulnerable communities could increase from 3% (1976–2005) to 8% by the late 21st century (Zaveri et al. 2023).

While often beneficial, dams can also impose high costs on local and global communities. If improperly planned and operated, dams can block rivers, displace people, and disrupt livelihoods. Dams have also often damaged downstream wetlands and biodiversity, affecting river-dependent communities. For example, dams significantly contributed to the 85% decline of freshwater species populations since 1970 (WWF 2024).

Dams also create significant inequities as local communities, often left out of planning, face severe social and environmental impacts. In contrast, distant cities and farms benefit from water, power, and flood control. This results in disrupted river ecosystems and reduced livelihoods for those dependent on rivers, further worsening inequalities.

Lakes and reservoirs serve as significant sources of greenhouse gases, specifically carbon dioxide (CO₂) and methane (CH₄), reflecting the repercussions of human activities. Research indicates that lakes contribute approximately 10% of total CH₄ emissions (Bastviken et al. 2004). In 2020, emissions from reservoirs accounted for 5.2% of anthropogenic CH₄ emissions (IHA 2024) — inundation of land and vegetation during the construction of reservoirs results in considerable emissions during the initial years. Furthermore, warmer climates are associated with increased CH₄ emissions, while nutrient runoff from agricultural and industrial activities fosters algal blooms, adversely affecting water quality and further contributing to methane emissions (Waldo et al. 2021). Notably, tropical hydropower reservoirs exhibit substantial greenhouse gas emissions, with higher emission levels observed in shallow reservoirs (Fearnside 2016).

The growing concern about climate change has sparked increased interest in developing dams for water storage and renewable energy generation. For dams to effectively help address the challenges posed by climate change, it is essential to comprehensively assess and mitigate their social and environmental impacts wherever possible. As dam construction and reservoirs increasingly shift to humid tropical regions – where emissions are higher than in other climatic zones – it is crucial to properly consider these emissions in energy policy decisions (Fearnside 2016).

The global water sector faces governance challenges in dam construction including inefficiencies and corruption, which often involve significant graft. Improvements are needed in planning, construction, and resource management. Learning from experiences is essential to avoid mistakes (WCD 2000). Storage development should benefit local communities, not just a few powerful interests. Dam planners must consider long-term environmental and social impacts, ensuring sustainability, equity, and economic viability in decision-making. Both international and national agencies should adopt best practices for addressing dam impacts, including fair resettlement and compensation for displaced communities, and integrating environmental flows into planning (Hirji & Davis 2009a, 2009b; World Bank 2018). Current practices often bias toward confirming pre-made decisions, hindering improved equity and sustainability.

Dam development agencies, including multilateral development banks, bilateral funding organizations, professional associations, the ICOLD, the International Hydropower Association, national governments, and river basin organizations, must enhance their efforts significantly. The existing practices are inadequate and inequitable, resulting in adverse effects on ecosystems, biodiversity, and local communities. These agencies are urged to operate with heightened awareness, responsibility, and transparency in fulfilling their obligations, and they must be prepared to face the consequences of their actions.

Lakes and reservoirs are rapidly depleting and degrading, threatening the benefits that they provide to humanity. Although accurate, uniform, and long-term data for monitoring the physical, chemical, and biological conditions and health of lakes and reservoirs are unavailable, numerous sources have provided the following evidence. These include global reports and analysis, published global studies, innumerable databases, lake and reservoir sedimentation, national assessments, water quality analysis, etc. These studies cover various geographical areas and timescales; lakes and reservoirs have shown extensive degradation for many decades, and there is growing evidence of alarming conditions.

The significant challenges include (a) insufficient sampling, (b) mixed data quality and coverage gaps, (c) changing assessment metrics, (d) focus on water quality over ecosystem parameters, (e) limited funding, (f) sectoral pressures, and (g) inadequate reporting. Current efforts have also used diverse approaches. A coherent framework is essential for sustainable lake basin management, especially amid climate change.

Various factors affect the storage quality, and ecosystem services of lakes and reservoirs, including excessive water withdrawal, wastewater, fertilizers, eutrophication, invasive species, and rising temperatures. Poor land use reduces vegetative cover, leading to increased runoff, erosion, and sediment transport, which harms water quality and reduces reservoir storage.

Notable examples include the International Lake Environment Committee (ILEC) World Lake Database (2024),World Wildlife Fund Global Lakes and Wetlands Database (2024) LakeATLAS (Lehner et al. 2022), and a global lakes water quality database (Naderian et al. 2024). The United States Department of Agriculture's (USDA) G-REALM system enables near real-time tracking of lake and reservoir levels (USDA 2024). A database by Filazzola et al. (2020) offers crucial insights into the impact of global environmental change on chlorophyll levels, compiling data from 11,959 freshwater lakes across 72 countries, including chlorophyll values, water chemistry, and morphometric characteristics.

Pi et al. (2022) mapped 3.4 million lakes, including reservoirs, from 1984–1999 to 2010–2019 and underscored the importance of small lakes, which account for 15% of the total area and contribute significantly to global CO₂ and CH₄ emissions (25 and 37%, respectively). Weyhenmeyer et al. (2024) highlight several human-induced stressors impacting lake health, including temperature, circulation, and nutritional challenges, along with infections. Their study reveals that 115,000 lakes are drying rapidly, potentially affecting over 153 million people.

The World Meteorological Organization's State of the Global Water Resources Study of 2023 indicates significant disruptions in the hydrological cycle. From 1991 to 2020, over 50% of catchments faced reduced river discharge, and more than 60% of reservoirs received below-normal inflow in 2022. This poses serious challenges for water supply management (WMO 2023).

Declining lake and reservoir levels, as highlighted by Yao et al. (2023) and Cooley (2023), are driven by climate change, overabstraction for irrigation, and land degradation. Yao et al. (2023) studied 1,972 large lakes and reservoirs from 1992 to 2020, finding significant declines in 53% of them, with 36% attributed to warming and 20% to consumptive use. Two-thirds of reservoir declines were linked to sedimentation from soil erosion, offsetting much of the storage gains from new dams. Cooley (2023) emphasized the complexities in linking these changes to climate change due to various human factors.

A study by Wang et al. (2018) found that land-locked basins experience significant global water losses. Notable examples include the Aral Sea, Lake Sistan, and Tarim Basin in Asia, as well as Lakes Chad, Turkana, Natron in Africa, and the Great Salt Lake in North America.

Reservoir sedimentation is a significant issue, with Perera et al. (2023) reporting that over 40,000 large reservoirs in 150 countries have experienced storage losses of 13–19%. They project that this could reach 26% by 2050, creating challenges for water supply, irrigation, power generation, and flood control. This will hinder water managers' ability to adapt to a changing climate and meet the needs of a growing population.

A study by Baud et al. (2021) analyzed sediment core samples from 500 lake sites over 150 years to understand sedimentation rates in relation to watershed characteristics. They found that sedimentation rates have nearly tripled since the 1950s due to human population growth and land-use changes from agricultural expansion and urbanization.

Recently, the World Water Quality Alliance, aided by the Global Environment Facility's (GEF) International Waters focal area, has highlighted the severe ecosystem degradation of lakes, threatened their economic and societal value, and resulted in significant losses (WWQA Ecosystems 2023). Failing to act with lakes valued at around US$ 3 trillion could lead to an additional US$ 500 billion loss in benefits over the next three decades (WWQA Ecosystems 2023). Urgent action is needed to restore and protect vital ecosystems.

The United States has conducted national lake assessments using various methodologies. The US Environmental Protection Agency (EPA) is required to submit a report to Congress every two years under Section 305(b) of the US Clean Water Act (CWA) (US Environmental Protection Agency 1972). Over the years, this series of reports has consistently indicated increased lake degradation. In 1971, the EPA surveyed all 50 states, finding 425 ‘problem’ lakes in 40 states (Kettele & Uttormark 1971). A 1983 survey by the North American Lake Management Society (NALMS) identified 4,200 lakes with impaired uses due to pollution (Duda & Johnson 1984). The most recent ‘305(b) Report to Congress,’ available on the EPA website, is from 2017. This report reveals that 45% of the assessed lakes and reservoirs were in ‘least disturbed’ condition, while 55% were’ moderately’ or ‘most disturbed’ (USEPA 2017). Although the assessment methodologies may have changed somewhat, there is evidence that the degradation of lakes has not improved over the decades. In addition, the report does not update the status of more recent assessments, if any exist.

A 2018 environmental assessment in the European Union revealed that approximately half of the evaluated lakes had a moderate, poor, or bad ecological status, which mirrors similar findings in the United States (European Environment Agency 2018). These results underscore the importance of ongoing monitoring and management of lake water quality in both North America and Europe.

In the 1990s, information on African, Asian, and South American lakes and reservoirs was scarce. The GEF has since supported developing countries to address vital water-related issues, especially on transboundary lakes and groundwater basins. Since the mid-1990s, these nations have sought GEF's help to tackle challenges affecting these water bodies, gaining valuable insights into their status through various projects.

Over 20 years ago, the World Bank and the ILEC collaborated on a multiagency initiative for global lake management, funded by the Global Environment Facility (GEF). Section 3 provides more detail on this initiative.

In 2005, ILEC released a report that identified 19 issues affecting 28 national and transboundary lakes, reservoirs, and their basins around the world. It summarizes these problems, which originate from the lake itself, the littoral zone, the basin, with some being regional or global in nature. These are elaborated in Section 3. While a few lakes had seen limited improvements in water quality and other areas, the overall degradation of lake and reservoir basins continued to rise globally.

Recent dam failures have destroyed reservoir storage capacities and associated benefits. They underscore the risks of climate change, including loss of life and infrastructure damage. On September 11, 2023, Storm Daniel caused the failure of the Derna and Mansour dams and their reservoirs in Libya, leading to over 5,000 deaths and 10,000 people missing (Oduoye et al. 2024). On October 4, 2023, the 1,200 MW Teesta III hydropower Dam in Sikkim, India, collapsed after a flash flood from the South Lhonak glacial lake burst. In addition, on April 6, 2024, the Orsk Dam near the Russia-Kazakhstan border collapsed due to heavy rains. Aging infrastructure, inadequate maintenance, and poor governance increase these risks.

Aging dams pose an increasing challenge globally, leading to reservoir storage loss, threats to life and livelihoods, and infrastructure and property damage. According to the American Society of Civil Engineers' 2021 report, by 2030, over 70% of dams and reservoirs in the United States will be over 50 years old, receiving a ‘D’ grade for safety and preparedness (ASCE 2021). Furthermore, 2,300 high-hazard dams lack emergency action plans (ASCE 2021). A report from the United Nations University highlighted that of 58,700 large dams, thousands are over 50 years old and are facing increasing maintenance costs while providing diminishing benefits (United Nations University 2021).

Both developed and developing countries face the risk of dam failures and reservoir storage loss. Farooq (2024) identified 15 significant dam failures occurring between 1802 and 2023, highlighting notable incidents in countries such as Bulgaria, China, France, India, and the United States. One of the most catastrophic events was the failure of the Banqiao Earthen Dam in China in August 1975, which resulted in the deaths of 25,000 people and left nearly 11 million others homeless due to flooding and famine following Typhoon Nina (Nielsen 2024).

Dam and reservoir failures can occur due to various factors, including old structures, weak designs, poor siting, negligence, and insufficient maintenance. Rapidly melting snow, glacier lake outburst floods, and heavy rainfall can also contribute to failures. Regular safety inspections and maintenance are crucial to identifying risks and preventing failures.

The rapid decline and degradation of lakes and reservoirs, along with associated environmental and social challenges, highlight the urgent necessity to restore and safeguard our vital lentic waters. This imperative should be regarded as one of the foremost priorities for adaptation strategies.

Shifting focus from narrow in-lake science research and management (and limnology) to effective management of lakes and their surrounding basins has enhanced both local and regional benefits. Transitioning from single-purpose to multipurpose dams achieves various objectives: supplying water for people and agriculture, generating power, and managing floods and droughts.

Moving to basin-wide management also entails collaborating with the various institutions beyond those that manage just lakes and reservoirs. These include environmental agencies that oversee water quality and pollution regulation and resource management institutions that ensure sustainable water, energy, and fish use. They also include municipal utilities that provide safe drinking water and manage and treat wastewater, land agencies that manage land use, and dam development agencies, including private companies, public utilities, irrigation departments, flood control agencies, and coordinating organizations, which are vital for cooperation in managing transboundary lake basins.

Early efforts in the United States, supported by organizations such as the NALMS and the CWA, were crucial in controlling pollution from point sources. The EPA has published numerous technical reports on managing lakes and reservoirs. The American Water Works Association also released a report titled ‘Reservoir Management for Water Quality and THM Precursor Control’ in 1989.

As nonpoint-source pollution from agriculture and urban runoff became more significant, a broader, basin-wide water quality management approach emerged in both the United States and Europe. The CWA mandates that state governments develop programs to address nonpoint-source pollution, leading to initiatives such as the Lake Champlain Basin Program. Management of the Great Lakes involves collaboration between two federal governments, eight US states, two Canadian provinces, and various Indigenous communities.

Many nations have established water quality standards and pollution control laws, primarily targeting point sources like municipal and industrial effluents. Nonpoint pollution, a rising global concern, remains under addressed except in high-income countries.

The World Bank adopted a Water Resources Management Policy in 1993, promoting Integrated Water Resources Management (IWRM), focusing on basin management and pollution issues (World Bank 1993). In 1995, it analyzed 10 lake basins (Dinar et al. 1995), and, in 1996, it recommended a global Lake Management Initiative (Ayres et al. 1997), publishing a technical note on Lake Management in 2005 (Mee 2003).

Between 1988 and 1999, the UNEP and the International Lake Environment Committee (2024) produced a nine-volume series titled ‘Guidelines for Lake Management.’ The volumes include:

• 1. Volume 1: Principles of Lake Management (edited by Jorgensen & Vollenweider 1988).

• 2. Volume 2: Socio-Economic Aspects of Lake Management (edited by Hashimoto 1991).

• 3. Volume 3: Lake Shore Management (edited by Jorgensen 1990).

• 4. Volume 4: Toxic Substances (edited by Matsui 1992).

• 5. Volume 5: Acidification (edited by Jorgensen 1993).

• 6. Volume 6: Management of Inland Saline Waters (edited by Williams 1998).

• 7. Volume 7: Biomanipulation (edited by De Bernardi & Giussani 1995).

• 8. Volume 8: The World's Lakes in Crisis (edited by Jorgensen & Matsui 1997).

• 9. Volume 9: Reservoir Water Quality Management (edited by Straskraba & Tundisi 1999).

In addition, there was another report titled ‘Lakes/Rivers in Environmental Education’ (Jorgensen et al. 1998).

Both the World Bank and UNEP support GEF-funded lake management programs globally. These three international organizations – the GEF, the World Bank, and UNEP – have led funding lake and lake basin management projects and programs.

During the Second World Water Forum in 2000, the World Water Council introduced the World Water Vision, emphasizing river basin management but overlooking lakes and reservoirs. In response, experts created ‘Lakes and Reservoirs as International Water Systems: Towards World Lake Vision’ in 2002, marking a significant step toward the conservation of natural resources (Jansky et al. 2002).

The Lake Basin Management Initiative (LBMI) was a GEF-funded cooperative program for sustainable lake and basin management, implemented from 2002 to 2005 under the leadership of the World Bank and ILEC. It followed recommendations from Ayres et al. (1997), the 1993 Water Resources Management Policy Paper, and the 2002 World Lakes Vision (Jansky et al. 2002). The collaborative initiative was supported by and involved a multiagency partnership with the GEF, ILEC, LakeNet, the Ramsar Convention Secretariat, Shiga Prefecture, United Nations Development Programme (UNDP), UNEP, United States Agency for International Development (USAID), and the World Bank.

The LBMI produced 28 case studies on managing lakes, reservoirs, and basins worldwide and 17 thematic papers. It also drew input from regional forums held in Burlington, Manila, and Nairobi, with support from 288 experts across 41 nations. An international steering committee of nine partner agencies' representatives guided the initiative. The final report, titled ‘Managing Lakes and Their Basins for Sustainable Use’ (ILEC 2005), was endorsed by all partner agencies. It outlined the future direction for lake basin managers and stakeholders for sustainably managing lakes and their basins.

The LBMI made four significant contributions. First, it highlighted practical lessons learned from its work. Second, it generated new knowledge about 28 lakes and reservoirs. Third, it tackled critical knowledge gaps concerning various lakes. Finally, it extracted valuable lake basin management lessons from projects funded internationally.

The World Bank conducted an analysis of governance in lake basins. This analysis, focusing on monitoring and evaluating LBG, culminated in a final report titled ‘Lessons for Managing Lake Basins for Sustainable Use’ (World Bank 2005). The report incorporated findings from the LBMI and aimed to guide operations related to International Waters for both the World Bank and the Global Environment Facility (GEF).

The World Bank analysis compared the water resource challenges faced in river (lotic) and lake (lentic) basins, evaluated policy and institutional responses for river basin management and lake basin management, and expanded the monitoring and evaluation (M&E) indicators for GEF's International Waters program. It concentrated on fostering an environment conducive to effective LBG. The findings are applicable to the management of national or transboundary rivers, lakes, and reservoirs.

The final report by LBMI (ILEC 2005) and the World Bank (2005) are definitive references for the governance of lake and reservoir basins, especially at a time when we need to enhance them. Their role in enhancing climate resilience to climate change is vital.

Following these 2005 reports, international attention to lake and reservoir management lulled. Two decades later, the global water community is starting to recognize (again) the urgent need for integrated solutions to manage water resources, including lakes and reservoirs. In his opening address at the 10th World Water Forum in Bali on 20 May 2024, Indonesian President Joko Widodo urged collective action to tackle water challenges through knowledge-sharing, innovation, and IWRM implementation.

In March 2022, the United Nations Environment Assembly adopted a Sustainable Lake Management (SLM) resolution, urging member states to address poor land use, pollution, overabstraction, and rising temperatures affecting lakes. This resolution was formally sponsored by the Government of Indonesia. It promotes protection, conservation, and better management of lakes through international cooperation, stakeholder involvement, and enhanced research (UNEP 2022).

The WMO's 2023 Global Water Resources Report highlights drying catchments, reduced river discharges, leading to reduced reservoir inflows, urging better monitoring, data sharing, and cross-border collaboration. It calls for a policy shift to manage increasing water extremes of excess and scarcity effectively (WMO 2023).

In February 2023, the World Bank released a report titled ‘What the Future Has in Store: A New Paradigm for Water Storage’ focusing on integrated management of natural and artificial water storage to tackle water-related challenges, including climate change and hydropower potential (Burke et al. 2023).

The UN-Water World Water Development Report (WWDR) (United Nations 2023) highlights the importance of partnerships in addressing water, food, and energy security. Implicitly focusing on managing rivers, lakes, and aquifers, it calls for integrated solutions for water supply, sanitation, health, and ecosystem sustainability, urging collaboration across sectors like agriculture, industry, and climate change to achieve Sustainable Development Goal (SDG) 6. The report encourages policymakers to enhance change through capacity building, data, innovation, financing, and governance.

Recent developments highlight the importance of comprehensive governance for sustainable management of lakes, reservoirs, and dams. The UN Resolution on SLM is referenced in June 2024 United Nations System-wide Strategy for Water and Sanitation. This strategy addresses the challenges of slow progress on SDGs, rising water insecurity, inadequate funding and lack of integrated approaches. The UN aims to enhance access to sustainable water and sanitation for all. Key focus areas are as follows: (1) prioritizing water and sanitation within organizations and improving advocacy, (2) mobilizing UN system support and partnerships, especially in developing countries, (3) integrating water and sanitation across sectors, (4) accelerating progress through unified support and resource mobilization, and (5) enhancing accountability and transparency through joint reviews (UN-Water 2024).

However, the long hiatus in attention to lakes and reservoirs means that some of the important lessons from the analysis of 20 years ago are not being incorporated into recent documents. The 2022 UN Resolution on SLM emphasizes in-lake issues and limnology but neglects critical areas like policy and basin-wide management. This restricted focus is a setback for effective lake management. In addition, the 2023 World Bank report overlooks the 1993 Water Resources Management Policy and the LBMI from 2005, both vital for the integrated management of freshwater storage. These omissions highlight the need for a more comprehensive approach to global lake basin management.

The LBMI was a collaborative program with nine partners, including three UN-Water agencies and the World Bank, focusing on the sustainable management of lakes and basins. It highlighted the effectiveness of partnership and collaboration. However, both the WWDR 2023 and the 2024 UN-Water Strategy overlook the LBMI, missing an opportunity to emphasize its impact on sustainable management solutions despite the UN Environmental Assembly Resolution on Lakes.

ILBM has been implemented in a few places around the world. It has influenced national water management strategies in Malaysia and Kenya, as well as regional forums and World Lake Conferences, positively impacting projects in East Africa, Europe, East Asia, and South Asia. It has shown promising progress, particularly through ILEC's training programs and workshops.

However, overall progress in the uptake and application of ILBM has been too slow. Complacency within the global water and environmental communities has contributed to outright neglect in using and mainstreaming best practices or hindered resource mobilization for ILBM initiatives. As demonstrated by ongoing initiatives, it is essential to intensify efforts and promote reforms to realize ILBM's full potential.

The Laguna Lake Development Authority and the Asian Development Bank are collaborating to prepare a Comprehensive Master Plan for Laguna de Bay. This plan will be based on ILBM principles to address environmental challenges, wastewater pollution, and urbanization, and to promote climate resilience, which is essential for sustainable regional development (ADB 2024).

The LVBC was established in 2004 to coordinate the management of Lake Victoria and its surrounding basin, promoting economic growth and sustainable development among the East African Community (EAC) member nations. Initially, the commission included the riparian countries of Kenya, Uganda, and Tanzania. In 2007, it expanded to incorporate Burundi and Rwanda, which, although non-riparian, play significant roles in the basin's ecosystem. This expansion illustrates a crucial lesson in ILBM: including all basin countries is essential for effective governance.

The LVBC can now monitor and address critical issues such as the proliferation of water hyacinth and sediment loads entering Lake Victoria from the two non-riparian nations, Rwanda and Burundi. Ultimately, the LVBC enhances the management of Lake Victoria and its surrounding areas, fostering economic growth and sustainable development among its member nations.

The LVBC has made initial progress in areas such as fisheries management, controlling water hyacinth, managing water quality, and implementing poverty reduction programs. However, it still faces significant challenges, including pollution from both point and nonpoint sources, poor land use, unregulated and overextraction of water for hydropower generation (Bosuben et al. 2022), and flooding. The World Bank, in partnership with the Global Environment Facility, supported the Lake Victoria Environmental Management Project Phases 1 and 2.

The North American Great Lakes-Saint Lawrence River Basin system provides an excellent example of national, state/provincial, and local communities working at different scales consistent with the principles of ILBM. Canada and the United States have worked cooperatively under their 1909 Boundary Waters Treaty, with Amendments to the Treaty in 1972 and 1978 and a 1987 Protocol to progressively implement ILBM through the International Joint Commission (Canada and the United States). As described by Duda & La Roche (1997), the states, provinces, and local governments manage the lake basins to correct impaired uses of the waterbodies under integrated approaches for top–down plus bottom–up implementation mandated by the Treaty, Amendments, and Protocol.

In addition, a coordinating binational commission (Great Lakes Commission (GLC)) has assisted the states in this endeavor by helping them develop harmonized approaches across borders that embody ILBM.

In 2022, the GLC adopted an action plan to address the impact of climate change and increased lake level variability to enhance climate resilience. The plan focuses on mitigating risks to water resources, agriculture, navigation, infrastructure, biological organisms, shorelines, coastal zones, and restoration efforts through sharing best practices and coordinating policies. It has helped create a resilient Great Lakes basin that can withstand, adapt to, and recover from climate-related stressors, ensuring equitable well-being across the different lakes and countries (GLC 2022).

We explore two recent dam and reservoir management cases that significantly impact international and interstate basins. The first case involves a US $292 million rehabilitation of the 65-year-old Kariba Dam on the Zambezi River in Southern Africa. This dam, shared by Zambia and Zimbabwe, holds back the largest reservoir in the world.

The second case concerns a US $500 million project focused on the decommissioning and removal of four century-old hydropower dams and their associated reservoirs on the Klamath River, which Oregon and California share. This initiative represents one of the most ambitious efforts in the United States to remove and decommission dams.

The Kariba Hydroelectric Dam and Lake rehabilitation project, approved in December 2014, is currently in progress and is vital for the region's future. With a target completion date of June 2026, this initiative is addressing crucial structural weaknesses and erosion in the dam's foundation to avoid a catastrophic failure that could lead to devastating losses – in both human lives and essential livelihoods, as well as massive power disruptions in the area (ZRA 2024).

According to the Institute of Risk Management South Africa (2015), the failure of this crucial transboundary dam and reservoir could have devastating and wide-ranging consequences for power generation within the Southern African Development Community. Such failure would primarily affect the Kariba and Cabora Bassa dams, impacting millions across the basin and jeopardizing communities and wildlife in the Zambezi Valley. In addition, it would significantly disrupt commerce and livelihoods across Zambia, Zimbabwe, Malawi, Mozambique, South Africa, Botswana, Namibia, Lesotho, and Eswatini (formerly Swaziland) (Institute of Risk Management South Africa 2015). While Zambia and Zimbabwe would directly benefit from the enhanced security and efficiency of the dam and power generation facilities, stable Kariba Reservoir operations would also benefit downstream nations, particularly Mozambique and Malawi, promoting regional stability and growth (ZRA 2024).

However, the El Niño drought continues to pose a challenge, dramatically reducing water flow in the Zambezi River. Coupled with declining water levels in Kariba Lake, this situation underscores an urgent need to address water and energy security for millions relying on these vital resources. Rehabilitation of this critical infrastructure is essential to secure a sustainable future for the entire region.

The United States and Europe are increasingly removing dams due to concerns about aging infrastructure, high maintenance costs, and environmental impacts. Between 1912 and 2023, the United States removed 2,119 dams (American Rivers 2024a), while Europe eliminated nearly 500 dams in 2023 alone (Niranjan 2024).

On 2 October 2024, California's Governor Gavin Newsom announced the successful completion of the Klamath River Restoration Project, approved in 2022, according to the press release ‘Klamath River dams fully removed ahead of schedule’ (Governor of California 2024). This initiative involved the removal of four outdated dams and their reservoirs that had obstructed and stored the river water and altered its natural flow for over a century. As a result of the restoration, nearly 400 miles of the Klamath River are free-flowing. In the process, essential habitats for salmon and other species crucial to the river's ecosystem and the communities that depend on them are being restored and revitalized (American Rivers 2024b).

The project will improve water quality, enhance habitats and salmon fisheries, and support threatened fish species, as well as other wildlife across the basin. In addition, it will return the land to the Shasta Indian Nation, which has historically relied on the river's health. This basin-wide river restoration represents a significant collaborative achievement, involving the Klamath Basin tribes, the states of California and Oregon, and various environmental and fishing organizations (American Rivers 2024b).

Many factors lead to successful dam removal, such as changing societal values, aging structure, increasing climate concerns, rising maintenance costs, strong advocacy efforts, and complex regulatory requirements.

The rehabilitation of the Kariba Dam and Lake and the decommissioning and removal of the four Klamath River dams and reservoir highlight the complexity and significance of a basin-based approach for effective water resource management.

To successfully implement integrated lake and reservoir basin management, it is important to implement both top–down and bottom–up reforms simultaneously through a strategic phased approach, particularly for high-priority basins that have lakes or reservoirs.

This approach may require the following actions:

• 1. Revising national water policies and legislation.

• 2. Enhancing institutional capacity.

• 3. Conducting rapid water resource assessments.

• 4. Involving civil society in the process.

• 5. Establishing and funding an interministerial committee to prepare and implement an Integrated Lake Basin Development and Management Plan.

It may also be necessary to create subbasin interministerial committees to oversee local-level actions.

In addition, developing monitoring and evaluation indicators, along with creating a ‘State of the Lakes and Reservoirs Report,’ is essential for tracking progress. This comprehensive approach is vital to sustain the future benefits of lakes and reservoirs.

Section 4 emphasizes the urgent need for action due to the shortcomings of international environmental and water agencies. These institutions have overlooked past successes and are reinventing the wheel repeatedly. Moreover, they also need to focus more effort and attention on coordination, institutional memory, collaboration, and adherence to best practices – all elements essential for achieving effective, impactful, and climate-resilient development on a large scale.

Global water and environmental policymakers and institutions must wake up from their collective amnesia if progress in lake and reservoir management is to occur.

The global water and environmental community faces a significant policy disparity and misalignment. Despite lakes, reservoirs, and basins holding nearly 90% of the world's fresh surface water, the focus remains on river and dam development. We must prioritize sustainable management of existing freshwater storage to enhance climate resilience and safeguard our planet's future.

The UN Environment Assembly resolution on SLM highlights the urgent need to combat lake ecosystem degradation, aging dams, and climate change. Implementing ILBM is crucial. The global decline in lakes and reservoirs underscores the importance of demand management, improved water and land use, and proactive climate measures. Addressing complex issues like dam repairs and decommissioning requires an integrated basin-wide approach.

Addressing the shortcomings in international water and environmental practices is essential for creating a resilient and livable planet. The environmental community must adopt an ecosystem approach to water management at the basin-wide level, in line with the principles of IWRM and ILBM. The water community also needs to recognize and address the historical inequities associated with dam and reservoir development, prioritizing the needs of local and marginalized communities, as well as ecosystem health.

Practical examples of necessary policy shift to harmonize water, and environmental management practices can be found in the 14 technical notes of the World Bank's water resources and environment series. These notes, prepared to support the implementation of IWRM, cover the following five broad themes, with each note prepared by authors cited below listed individually in the references.

Environmental flow assessment series:

• Environmental flows: concepts and methods (Brown & King 2003).

• Environmental flows: case studies (King & Brown 2003).

• Environmental flows: flood flows (Acreman 2003).

Water quality management series:

• Water quality: assessment and protection (Radstake & Tuinhof 2003).

• Water quality: WWT (Wolff 2003a).

• Water quality: nonpoint-source pollution (Wolff 2003b).

Irrigation and drainage series:

• Irrigation and drainage development (Ochs & Plusquellec 2003a).

• Irrigation and drainage: rehabilitation (Wolff 2003c).

Water conservation and demand management series:

• Water conservation: urban utilities (Versteeg & Tolboom 2003).

• Water conservation: irrigation (Ochs & Plusquellec 2003b).

• Water conservation: wastewater reuse (Van Gool 2003).

Waterbody management series:

• Lake management (Mee 2003).

• Wetlands management (De Shutter 2003).

• Management of aquatic plants (Vermaat 2003).

Many of these themes also address the essential policy shifts required for implementing ILBM.

For instance, the authors of the technical notes, including Versteeg & Tolboom (2003), Van Gool (2003), Radstake & Tuinhof (2003), and Wolff (2003a), discuss essential policy shifts needed for urban water conservation, the reuse of treated wastewater, water quality assessment and protection, and municipal WWT, respectively. In addition, Ochs & Plusquellec (2003b) and Wolff (2003b) highlight the policy shifts necessary to conserve and improve irrigation use and to manage and control nonpoint sources of pollution, respectively.

The recent report to the World Bank Governors, titled ‘Ending Poverty on a Livable Planet’ (World Bank 2023), emphasizes the need to address climate change and water resource management as part of the new mission to end poverty. This report and the recent findings on integrated storage present an opportunity for internal reforms within the World Bank that align with ILBM. These reforms aim to prioritize the sustainable management of lakes and reservoirs and enhance climate resilience.

In addition, the World Bank's reports, including ‘Environmental Flows in Water Resources Policies, Plans, and Projects’ (Hirji & Davis 2009a, 2009b), the ‘Good Practice Handbook on Environmental Flows for Hydropower Projects’ (World Bank 2018), and ‘Integrating Environmental Flows into Hydropower Planning, Design, and Operations’ (Krchnak et al. 2009), provide invaluable lessons and best practices for the planning, design, and operation of both hydropower and nonhydropower dams, all aimed at promoting a livable planet.

UN-Water should use the multiagency LBMI to highlight best practices for cooperation in future WWDR reports. In addition, LBMI can serve as a model for promoting integration in its new System-Wide strategy for water and sanitation. Finally, the UN-Water should seriously consider ‘Integrated Lake and Reservoir Basin Management’ as a theme for a future WWDR.

Other multilateral development banks and agencies should expedite the adoption of integrated management policies following the UN's (2024) reforms, further discussed in our companion paper (Duda & Hirji in press).

The global water and environmental community must unite, collaborate, and implement best practices to sustainably protect and manage critical water storage facilities and their basins before it is too late.

Six recommendations for accelerating global ILBM implementation emphasize the urgent need to protect lakes and reservoirs for water security and climate resilience. They underscore essential international, national, basin, and subbasin-level reforms.

• 1. Mainstream ILBM. Mainstreaming requires collaboration among international and national water, environment, and land communities for effective ILBM. Their collective effort supports the UN Resolution on SLM and enhances the resilience of lakes and reservoirs. ILEC (2005) and the World Bank (2005) are vital resources.

• 2. The international community must take urgent action by (a) utilizing best practices and knowledge for sustainable management of lake and reservoir basins and (b) acknowledging that dam-created reservoirs are lakes needing integrated basin-level solutions, upstream, and downstream.

• 3. Encourage collaboration among water, environment, and land management agencies. UN-Water, regional banks, and the World Bank should prioritize cooperation across these sectors at all levels of governance. The Global Water Partnership should also focus on developing and promoting ILBM training to support global water and environmental policy reforms.

• 4. Promote collaborative reforms at the national level. Environmental ministries should work with water and land ministries through interministerial forums to improve the sustainable management of lakes and reservoir basins. The international community should also support partnerships that promote top–down policy reforms and bottom–up capacity building in local governance.

• 5. Support the implementation of ILBM at both policy and operational levels. Water and environmental communities should utilize accessible ILBM knowledge on key IWRM topics.

• 6. Advance climate resilience at the basin level. Utilize structured climate adaptation frameworks from best practices in international, regional, and national water resource planning and management. Examples include the studies conducted by Hirji et al. (2017) in South Asia and Davis & Hirji (2014) in Zimbabwe, along with numerous other widely available good practices.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.