The United States is famous for its immense natural parks, deserts and large lakes, apparently unaffected by the presence of man. The endless spaces of North America have in fact allowed important urban centers to develop, often at considerable distances from each other, with thousands of km2 of an almost uninterrupted nature to separate them. Unfortunately, the hunger for resources in cities with millions of inhabitants pushes them to heavily exploit the territory, even modifying it hundreds of kilometers away. The water consumption of metropolises such as Los Angeles, or urban agglomerations such as Salt Lake City, can have an enormous impact on the surrounding lakes, to the point of leading them to dry up, as already happened in the 1920s at Lake Owens in California.
However, a dried-up lake is not just an exhausted “resource”, but can become a source of pollution dangerous for human health. Lake sediments, especially if free of effluents, are rich in alkaline metals and toxic elements, such as arsenic, which can be spread by the wind for hundreds of km, once exposed to the elements: a phenomenon that is difficult to combat, with enormous economic and social costs.
The drying up of Owens Lake
The area of Los Angeles (LA) grew enormously in the first decades of 1900: from 319,000 to 576,000 inhabitants in the municipality of LA alone, from 420 thousand to 786 thousand inhabitants considering the entire county. Providing drinking water for a steadily growing population led local authorities to search for increasingly distant resources, and among these was identified Lake Owens, about 350 km from the city (220 miles).
With an estimated historical extension of approximately 290 km2 (110 square miles), this lake had a size comparable to that of the largest Italian lakes such as Garda or Maggiore: in less than 20 years, however, it was completely drained, despite the protests of the inhabitants of the Owens valley still remembered today as the “Water Wars” and also told in a 1974 film, “Chinatown”, with Jack Nicholson among the protagonists.
The drying up of the lake did not simply lead to the drying up of the valley: evaporation and sedimentation lead in fact to the accumulation of alkaline substances in the lakebeds, which once left “uncovered” by the lack of water can be eroded and moved by the wind for hundreds of km.
Lake Owen thus became the largest source of airborne dust and PM10 in the USA, with potentially carcinogenic effects for the inhabitants of the surrounding areas. Decades of legal battles and EPA interest (Environmental Protection Agencythe American Environmental Protection Agency) finally led to the approval of a gigantic project, born in 1998 and supported by the Los Angeles Department of Water and Power, to mitigate sediment erosion.
Costing more than $2.5 billion to date, the project is a system of irrigated areas, planted vegetation, areas covered with gravel and “salty brine” pools, solutions with extreme concentrations of salts where evaporation is controlled. The annual water consumption, estimated for these works, is equal to that of 240 thousand American families.
The project has led to the formation of a new ecosystem in the area, with the return of plants and fauna that have disappeared for decades, but the work is still very fragile and subject to the “attacks” of extreme climatic events: hot and dry years alternate with periods of exceptional rainfall, which help to cover larger surfaces, but also damage infrastructures and modify the distribution of vegetation, leaving the lake “uncovered” in subsequent dry periods.
In short, the Lake Owen project shows how a seriously disturbed ecosystem can become so fragile as to require enormous capital to safeguard it, with results that can be called into question by just one “wrong” year.
The alarm for the Great Salt Lake due to water exploitation
Knowing the history of Owens Lake, the USA cannot help but look with extreme concern at the fate of a much larger lake, the Great Salt Lake in the state of Utah. Its average extension, recorded in the period 1847-1986, is 4400 km2(more than 10 times the area of Owens Lake) with abundant fluctuations, due to the shallow depth and the flat, desert area that surrounds it. The lake is in fact what remains of the larger prehistoric lake of Bonneville, today a flat salt desert: the area is famous for the annual “Bonneville Speedway” races, a competition for land speed records, mentioned in the film starring Anthony Hopkins, “Indian – The Great Challenge”.
The lake is of the evaporative type, a basin that receives water from tributary rivers or from atmospheric precipitation but does not “discharge” its waters into other rivers. This type of lake therefore loses water only through evaporation, increasing the concentrations of salts in its waters over time and progressively depositing other elements, including heavy metals in its sediments: a situation shared with other basins such as the famous Aral Sea between Kazakhstan and Uzbekistan.
The periodic fluctuations in themselves already exposed large areas of sediment to the wind during the dry seasons, but for decades the situation of the lake has been worsened by the consumption of water from the surrounding urban areas, in particular Salt Lake City, home of the 2002 Winter Olympics and in the future the 2034 ones.
The city consumes 17% of the water removed from the tributary rivers, but the real problem is due to the strong agricultural vocation of the County, which consumes a further 71% of the water for crops such as alfalfa (also called alfalfa) used as fodder for livestock. The presence of mining industries, which exploit the sediments accumulated over millennia, further aggravates the situation.
The Great Salt Lake between industrial pressures and recovery programs
As indicated in 2022 by Joel Ferry, a legislator of the Utah House of Representatives, Salt Lake is today “an environmental atomic bomb”: years of heavy rainfall like 2023 manage to contain the damage, but corrective actions have already cost more than a billion dollars and the Trump administration has frozen another 50 million in funds, aimed at a water supply program.
Local programs for the exploitation of groundwater provide subsidies to farmers, who however risk having to abandon alfalfa cultivation with a huge impact on the related economy, from livestock farming to mechanical support for working the fields.
Limitations in the use of water prevent the expansion of the extraction of lithium, a metal currently highly sought after for the production of batteries and increasingly seen as a strategic asset internationally: pressure from the industry tends to further complicate the administration’s efforts to stop the “bleeding” of the Great Salt Lake.
As also highlighted by a study by Brigham Young University, however, inactivity could lead to the disappearance of the lake in 5 years and affect, in addition to agriculture itself, other industries such as ski tourism. Other studies have demonstrated the deadly impacts of the spread of fine particles such as PM10 or PM2.5 and heavy and toxic metals such as arsenic, which could affect the health of the inhabitants of the surrounding areas or even of entire US states: an environmental catastrophe of enormous dimensions compared to the example, sadly known to Californians, of Owens Lake.
