When lakes decline, can they recover?

When lakes decline, can they recover? August 27, 2026Some of the world's largest lakes could shrink substantially within this century, with far-reaching consequences for ecosystems and roughly a quarter of the global population living in affected regions. Although restoration efforts have proved successful in some cases, many inland bodies of water face extreme challenges. Caspian Sea: A shrinking giant Despite its name, the Caspian Sea is actually a lake. Bordered by Iran, Russia, Azerbaijan, Turkmenistan and Kazakhstan, it is the largest inland water body on Earth. But its surface area has been rapidly receding since the 1990s. This shift is partly due to the use of dams and water-management practices in the Volga River basin. But hotter conditions driven by burning fossil fuels to power societies is also a contributing factor. Rising temperatues increase evaporation rates. Scientific models project that water levels could fall up to 21 metres (68 feet) by 2100. Even a decline of ten metres could leave large parts of the shallow northern basin dry, eliminating nearly one-third of the lake's current surface area. The consequences are already becoming apparent. Ports require increasingly extensive dredging, fish stocks and wetlands are coming under growing pressure, and habitats used by the endangered Caspian seal are drying out. Scientists also warn that exposed lakebeds could release dust and pollutants. Joint conservation efforts among the five coastal states remain politically challenging. Lake Constance: A pollution turnaround Like much of Europe, lake Constance has been impacted by high temperatures this summer. Bordered by Germany, Austria and Switzerland, the 63km-long lake has experienced high evaporation rates that have caused water levels to fall significantly in some places. In the late 1970s, however, low water levels were not the main concern. At the time, the lake was suffering from severe nutrient pollution and was at risk of ecological collapse. Massive algal blooms and oxygen depletion in deeper waters threatened fish populations and led to swimming bans. The expansion of wastewater treatment facilities and removal of phosphorus from sewage significantly reduced nutrient concentrations, led to the stabilization of lake trout, which had been at risk of disappearing. Local communities also benefited. Around four million people in the southern German state of Baden-Württemberg rely on Lake Constance for their drinking water. Yet the ecosystem is far from fully restored. Shoreline development, invasive species and climate change continue to pose major challenges. Restoring more of the lake's natural shoreline could help strengthen its resilience. Aral Sea: A disaster with glimmers of hope The Aral Sea in Central Asia has become one of the defining examples of how water extraction can devastate even the world's largest lakes. Only a few decades ago, it was the fourth-largest lake on Earth. During the Soviet era, vast amounts of water were diverted to irrigate cotton and rice fields, creating an environmental catastrophe whose effects continue today. By 2010, the surface area had shrunk by more than 50,000 square kilometers. Thirty fish species that once supported commercial operations have disappeared, and entire communities along the former shoreline have vanished with them. The Aralkum Desert has emerged where the water once shimmered, covering roughly 62,000 square kilometres. Today, dust and sandstorms carry salt and toxic residues from the former lakebed across surrounding regions, posing serious risks to human health. But the North Aral Sea has benefited from the Kok-Aral Dam, which raised water levels. Where a return of the lake is considered unrealistic, saxaul shrubs are being planted to stabilise the sand and contaminated dust. According to the Kazakh government, more than 1.8 million hectares have been planted since 2018. Muskegon Lake: The big clean up For decades, Muskegon Lake in the US state of Michigan was polluted by industrial waste and contaminated sediments. Extensive clean-up efforts by local environmental authorities removed contaminated soil and more than 110,000 tons of historic sawmill waste. As a result, 54 hectares of habitat along the shoreline and in surrounding areas were restored. In 2025, authorities finally removed Muskegon from the list of severely degraded lakes. According to the US National Oceanic and Atmospheric Administration (NOAA), the restoration efforts now generate an estimated $28 million (€23 million) in additional recreational value annually and attract roughly 500,000 extra visitors each year. However, the lake is not entirely free of pollution. Authorities continue to warn against eating certain fish species because contaminant levels remain too high. Lake Chad: A region fighting for survival The vast Sahel forms the transition zone between the Sahara Desert to the north and the African savannas to the south. Stretching across the continent from the Atlantic Ocean to the Red Sea, it is home to one of Africa's most distinctive ecosystems: Lake Chad. Shaped by sand, wind and harsh environmental conditions, the wetland ecosystem is a critical source of water for people and wildlife and supports livelihoods across the region. In the 1960s, during periods of high water, Lake Chad covered up to around 25,000 square kilometres, slightly more than the area of New Jersey. During severe droughts in the 1970s and 1980s, it temporarily lost more than 90% of that area. Since then, the lake has partially recovered. Its size now fluctuates considerably depending on rainfall and the season — ranging from roughly 12,000 to 20,000 square kilometres. Climate change, irrigation and deforestation continue to put pressure on the lake. According to aid organisations, its decline has contributed to a wider ecological crisis across the region and threatens the food security of millions of people. Some 30 million people depend on the resources of the Lake Chad basin. Hundreds of bird species migrate from Europe and Asia to Africa each winter, and many use Lake Chad as an important stopover site. Some waterways previously blocked by dams have been reopened. In May, the African Development Bank, the Lake Chad Basin Commission and five neighbouring countries launched investment projects worth $10 million. The funding is intended to help preserve the lake both as a habitat and an economic lifeline for the region. This article was originally published in German.