acquired June 2, 2022
acquired June 13, 2023

Reservoirs Run Dry in Montevideo



The water supply for millions of people in and around Uruguay’s capital city of Montevideo reached critically low levels in the Southern Hemisphere fall and winter of 2023. The shortage occurred as two main freshwater reservoirs serving the region—Canelón Grande and Paso Severino—have nearly run dry.

Paso Severino reservoir, the larger of the two reservoirs, was estimated to hold just 2.4 percent of its 67-million-cubic-meter capacity on June 28. Increasingly salty water poured from household taps, and the government implemented emergency actions to provide citizens with drinking water.

The image on the right, acquired by the Operational Land Imager-2 (OLI) on Landsat 9, shows the reservoir on June 13, 2023, approximately one week before the Uruguayan government declared a water crisis. The image on the left shows the reservoir about one year earlier, on June 2, 2022. This image was acquired by the OLI on Landsat 8.

The images are false color to make it easier to distinguish the water, which in 2023 saw the largest decrease in volume in its history. With this band combination (6-5-3), water appears dark blue and vegetation appears light green. Indeed, ground-level observations align with some of the stark differences between the two scenes, finding grass growing where there used to be water.

The region is in the throes of a multi-year drought, the consequences of which have come into sharp focus in the past few months. In late April, anticipating near term water shortages, the water utility began stretching the supply by mixing in brackish water from the Río de la Plata estuary.

Soon after, in early May, the country increased the limit of allowable sodium levels in the water system to 440 milligrams per liter (mg/L). As points of comparison, many U.S. state and federal agencies advise a maximum concentration of 20 mg/L for very low sodium diets and 270 mg/L for moderately restricted sodium diets. While the Uruguayan government stated that the utility’s water is potable, it advised people who are pregnant, have high blood pressure, or suffer from kidney disease to limit or avoid drinking tap water.

A state of emergency took effect in the Montevideo metropolitan area on June 19. With the measure, the government guaranteed a drinking water supply to hospitals and other critical institutions, and it removed taxes on bottled water. In addition, it will provide funds to hundreds of thousands of Montevideo residents to buy bottled water, according to news reports.

The country has recently invested in water infrastructure projects, including the development of a new potable water source. In the meantime, however, relief will have to come in the form of rain.

NASA Earth Observatory images by Wanmei Liang, using Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.