Water exploitation in the USA, from the drying of Owens Lake to the risks for the Great Salt Lake

The United States is famous for the immense natural parks, deserts and large lakesapparently unaffected by the presence of man. The vast spaces of North America have in fact often allowed important urban centers to develop at considerable distances between them, with thousands of km² of an almost uninterrupted nature to separate them. Unfortunately, the resource hunger of cities with millions of inhabitants pushes to exploit the territory heavilyeven 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 a enormous impact on the surrounding lakesto the point of leading them to dry up, as already happened in the 1920s at Owens Lake in California.

However, a dried-up lake is not just a depleted “resource”, but can turn into one source of pollution dangerous for human health. Lake sediments, especially if free of effluents, are rich in alkali metals and toxic elements, like thearsenicwhich can be scattered by the wind for hundreds of km, once exposed to the elements: a phenomenon that is difficult to counteract, with enormous economic and social costs.

The drying up of Owens Lake

The Los Angeles (LA) area grew enormously in the early 1900s: from 319,000 to 576,000 inhabitants in the municipality of LA alonefrom 420 thousand to 786 thousand inhabitants considering the entire county. Providing drinking water for a constantly growing population led local authorities to search for increasingly distant resources, and among these the Owens Lake, 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 dried up, despite the protests of the inhabitants of the Owens valley still remembered today as “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 todrying up of the valley: evaporation and sedimentation lead in fact toaccumulation of alkaline substances in lake bedswhich once left “discovered” from lack of water they can be eroded and moved by the wind for hundreds of km.

Owen Lake thus became the major source of airborne dust and PM10 of the USA, with potentially carcinogenic effects for the inhabitants of the surrounding areas. Decades of legal battles and the interest ofEPA (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.

Cost to date more than 2.5 billion dollars, the project is a system of irrigated areas, planted vegetationgravel covered areas and puddles of “salty brine”solutions with extreme concentrations of salts where evaporation is controlled. The annual water consumptionestimated for these works, is equal to that of 240 thousand American families.

The project 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 they also damage infrastructure and modify the distribution of vegetation, leaving the lake “uncovered” in subsequent dry periods.

The Lake Owen project shows, in short, how a severely disturbed ecosystem can become so fragile 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 largest prehistoric lake Bonnevilletoday a flat salt desert: the area is famous for the annual “Bonneville Speedway“, land speed record competition, mentioned in the film with Anthony Hopkins, “Indian – The Great Challenge”.

The lake is evaporativea basin that receives water from tributary rivers or from atmospheric precipitation but it does not “discharge” its waters into other rivers. This type of lakes therefore only loses water evaporationincreasing over time the concentrations of salts in its waters and progressively depositing other elements, too 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 water consumption of the surrounding urban areas, in particular Salt Lake Citysite 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 additional 71% of water for crops such as those of alfalfa (also called alfalfa) used as forage for farms. There presence of mining industrieswhich 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 in 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 the corrective actions have already cost more than a billion dollars and the Trump administration has frozen others 50 million in fundsaimed at a water replenishment program.

Local programs for the exploitation of groundwater provide subsidies to farmers, who however risk… having to abandon the alfalfa crop 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 theexpansion of lithium extractiona metal currently highly sought after for the production of batteries and increasingly seen as a strategic asset at an international level: le industry pressures tend to complicate further 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 affecting not only agriculture itself, but also others industries such as ski tourism. Other studies have demonstrated the fatal impacts the spread of fine particles such as PM10 or PM2.5 and of heavy and toxic metals such asarsenicwhich could affect the health of the inhabitants of the surrounding areas or even of entire US states: one environmental catastrophe of enormous dimensions compared to the example, sadly known to Californians, of Owens Lake.