Colombia's capital Bogotá relies on a unique ecosystem called páramos for its water. The tropical plants and moss in the páramo act like a sponge, trapping moisture from the foggy air, storing it in the soil during the dry season, and releasing it gradually.
One páramo, in Chingaza National Park east of Bogotá, provides the city with 70 percent of its water. The remaining amount is from the páramos named Sumapaz, to the south of the city, and Guerrero, to the north.
Chingaza's water is naturally filtered by the páramo, meaning that it needs minimal filtering for human consumption. It is stored in the Chuza Dam; from there, it flows through an underground aqueduct to the San Rafael Reservoir, located in the municipality of La Calera. In case of drought or other incidents, the reservoir holds enough water to supply the capital city for three months.
Although the ecosystem, which is only found in Central and South America, has quenched the thirst of the people of Bogotá for decades, it is now under threat due to farming, coal mining, and climate change. And according to environmental advocates, there's no back-up plan.
"An increase in temperature will generate changes in the structure and composition of the fauna and flora in the páramos," said Patricia Bejarano, the land-use planning manager at Conservation International Colombia. "When this happens, it will put the availability of water at risk. To date, there are no other options to provide Bogotá with water."
Colombia is one of the most water-rich countries in the world, with nearly 50,000 cubic meters (or 1.8 million cubic feet) of water available per person, per year. But according to the Organization for Economic Co-operation and Development, because of a mismatch between where the population is concentrated and available water, more than one-third of the urban population already lives under water stress.
"It's worrying how highly vulnerable the páramos are," Bejarano said. "If action isn't taken now, the consequences will be incredibly difficult. And it's not something the citizens of Bogotá are even aware of." Bogotá has eight million residents and 11 million people live in the urban area.
But Empresa de Acueducto y Alcantarillado de Bogotá, the public authority in charge of Bogotá's water supply, said there is no cause for alarm. When asked what the future of Bogotá's water looked like, spokesperson Maria Fernanda García replied: "It looks fine."
"We have various systems of reservoirs that are used to regulate the sources," she told CityLab. "These are used to supply water for the city, so in terms of quantity, we are not worried."
In answer to whether the levels of water in the páramo had decreased in recent years, García said "no," and added: "We cannot extract a bigger volume of water from the reservoir than what the water basin produces."
Since 2009, Conservation International has been working with local communities and government officials on implementing a strategy to preserve the páramos. Another project, the Nature Conservancy's Bogotá Water Fund, seeks contributions to conserve the tropical forests that line the watershed and filter the water.
"Over the long term, if we don't try to stop the threats the páramo is facing, the land will be destroyed for agriculture and not preserved for providing water," said Alejandro Calvache, the water strategy coordinator for the Nature Conservancy in Colombia.
Cultivation of potatoes and cattle ranching are two culprits in páramo loss. Conservation International estimates that 50 percent of land has been lost in Guerrero, and says potato farming is encroaching on Sumapaz. Guerrero has also been affected by coal mining. Bejarano said the quality of its water is declining: "The treatment the water from Guerrero needs in order to be drinkable is now 15 times more expensive than what we spend on treating Chingaza water."
Although Chingaza is officially a protected area, in reality, resources to enforce that are scarce, and little is done to punish offending farmers.
"If nothing is done, the city's water quality and quantity will be increasingly threatened, and if we lose the páramos completely, in the next 30 years we will run out of water, and we will have to import it from somewhere else," Calvache said.
García, the EAAB spokesperson, said the only concerns the authority has with the water supply are regarding quality, because sources "are being contaminated with domestic and industrial wastewater." She said the agency's Plan B, if the water from the páramos were to run out, would be to use water from the Bogotá River. "Besides the water coming from the páramo system, we produce water from the Bogotá River, which is also regulated by a system of reservoirs," she said.
The Bogotá River is considered one of the most polluted waterways in the world. The average dry-season flow in the river before entering the city is 12 cubic meters per second, and Bogotá discharges an additional 22 cubic meters per second of wastewater, with only a fraction of that undergoing primary sewage treatment.
Calvache highlighted the lack of scientific data available on the city's water quality, and said Bogotá's local government has not been consistent in providing support for the páramos. "We need a renewed commitment from the mayor ... and we cannot be successful without their support."
If climate change affects the páramo's almost year-round rainy season, the consequences could be devastating. Less rain would mean less moisture in the air to be absorbed by the flora, so the water levels in the reservoir would eventually decline, and the páramos would not produce as much water.
"Despite what the EAAB says, there is no Plan B," Calvache said. "It is our water factory, and if we don't protect it, we will have no water to drink."