Ricardo Sangüesa, a small avocado farmer, is staring out over a dry, cracked landscape. But he’s not in California; he’s in the Ligua Valley, in central Chile. Stray dogs wander through the empty Ligua riverbed, which is littered with trash. The only green he can see are the avocado trees, which grow in green squares that form a peculiar patchwork along the sides of the valley. According to Sangüesa, the river has been drained to feed the trees.

“Because they’re overexploiting the water by throwing it at the hills, the river has dried up,” he explains. “It’s as if someone used a paper towel to suck up the river.”

As summer fades, and, with it, the northern hemisphere’s avocado season, Chilean avocados are starting to appear on supermarket shelves across the United States. Chile is second only to Mexico in avocado production, in avocado exports to the U.S., and in per capita avocado consumption. In fact, about 10 percent of all the avocados consumed in the U.S. come from Chile—and they fetch so much that Chileans call them “green gold.”

But generating that income comes at a price: In Chile’s semiarid central valley, an acre of avocado trees requires about one million gallons of water every year—about the same amount of water that an acre of lemon or orange trees would require. Since the early 1990s, the number of acres planted with avocados has grown more than seven-fold in Chile, from around 9,000 acres in 1993 to 71,000 today. Ninety percent of that acreage belongs to large-scale Hass avocado producers. To irrigate their farms, these producers have drilled deep wells and used so much of the region’s waters that small farmers with shallow wells–and some nearby towns–are left with no water.

“La Ligua is one of the leading examples in the country of groundwater overuse,” says Carl Bauer, an expert in Chilean water rights at the University of Arizona in Tucson. “There’s been a huge increase in groundwater pumping in the last ten years. This is true throughout the central and northern part of the country.”

Avocado trees use a lot of water everywhere, of course. A group of Mexican scientists is trying to figure out how to genetically modify the tree so it uses less water. And, in Perú, which has increased its avocado exports to the U.S. in recent years, water conflicts between large and small producers are also unfolding. But, in central Chile, unregulated land use, water privatization, and drought have created a perfect storm of overuse.

There’s no law in Chile that prevents producers from planting on hillsides, Professor Bauer explains, even though “it’s pretty obvious that it’s an unsustainable use of groundwater.” Chile’s semi-arid central valleys traditionally had vegetation only on the valley floor: The hillsides were barren.

There are currently no laws regulating water use in Chile. In 1981, under Augusto Pinochet’s dictatorship, water rights were privatized and then promptly over-allocated. In recent years, powerful landowners and politicians have been fined (link en Español) for stealing groundwater to which they don’t own the rights. As a result, a bill that would increase the fines for those who steal water has been slowly making its way (link en Español) through the Chilean Senate since January 2012 .

Climate change and drought have compounded Chile’s water problems in recent years. As the planet warms, more of Chile’s winter precipitation falls as rain and goes directly to the Pacific Ocean instead of getting stored in the country’s glaciers. As a result, glacial melt—which provides 20 to 25 percent of the summer flow in Chile’s rivers—has lessened. Several years of drought have added insult to injury.

Everyone proposes a different solution to this problem. Adolfo Ochagavía, a member of Palta Hass Chile—the largest avocado growers’ association in the country—argues the only problem is water capture and believes the solution lies in building more infrastructure, such as large reservoirs, for retaining water.

Felipe Martín, former president of the Chilean government’s National Irrigation Commission, says the solution lies in improving water users’ organizations in the Ligua Valley. These organizations, under Chilean law, should monitor water flow, determine how much water can and should be allocated, and ensure that no one takes more water than they are due. Carl Bauer, of the University of Arizona, says strengthening users’ organizations would be a good first step, but ultimately the government will need to institute some water regulation. And Rodrigo Mundaca, a water activist in the region, takes the most extreme stance: He calls for the nationalization of all of Chile’s water resources.

Ideally, both U.S. and Chilean consumers would also be able to help by trying to buy avocados grown by small farmers.

But that’s harder than it sounds. Juan Enrique Lazo, the president of Palta Hass Chile, estimates that 90 or 95 percent of the Chilean avocados sold in the U.S. come from large producers. Furthermore, most grocery stores won’t release information about the source of their avocados. That said, many of the avocados sold by U.S. supermarkets in the fall and winter come from Chile—and, of the many grocery stores we contacted for this report, only Trader Joe’s told us that they try to source avocados from smaller farms.

“When you eat an avocado that comes from [a large producer in] Chile, think about the fact that the water used to produce it is water that homes in the country’s most humble communities now lack,” says water activist Rodrigo Mundaca. “It’s water that the country’s men and women now don’t have for their basic needs.”