One afternoon during peak demand, the city – which then relied entirely on groundwater – ran so low on water that the city's water utility could not guarantee domestic service or adequate fire-protection to all customers in higher parts of the city. Climate change is expected to cause snowpack at its headwaters to decline and brings hotter temperatures that further decrease streamflow.Ī dry spell in the summer of 1974 offered Tucson a grim preview of what this water scarcity could be like. In a 2021 study, scientists with the US Geological Survey found that the river may lose nearly a third of its flow in the next 30 years. Last year, for the first time ever, the US government declared a shortage on the river, triggering widespread restrictions across the region.Īnd the situation is expected to get worse. Decades of over pumping and the worst drought in 1,200 years have severely depleted the waterway and the reservoirs it feeds. CAP water is by far the main source, making up 82% of the city's supply.īut the Colorado River, a lifeblood that sustains 40 million people and four million acres of farmland across seven states in the south-western US and two states in northern Mexico, is an increasingly stressed resource. The second is groundwater, pumped from the underlying aquifer. The first is surface water, pumped from the Colorado River through the Central Arizona Project (CAP), a massive, 336-mile (540km) canal and pipeline system that brings water to central and southern Arizona. Similar to many cities in the western United States, Tucson's municipal water supply is drawn from two sources. "Tucson is a really successful example of how rainwater harvesting can be used to bolster existing supplies and ease demand on the system without building new infrastructure," says Paula Randolph, associate director at the Lincoln Institute of Land Policy's Babbitt Center for Land and Water Policy. They joined the city's drive to embrace the practice as part of its suite of water conservation initiatives.Īs a growing number of towns and municipalities in the western United States and around the world are faced with rapidly dwindling freshwater supplies, experts say Tucson's rainwater push may hold valuable lessons about how a city can balance the water budget and increase resilience. Over the past 15 years or so thousands of residents across Tucson, a mostly parched desert city where barely 12 inches (30cm) of rain falls in an average year, have turned to rainwater harvesting to meet some of their household needs. "I've never seen my tanks less than half full," says Little, who sprinkles the harvested rainwater on her vegetable garden and also uses it to cook, drink and irrigate her fruit and shade trees outside the monsoon season. She has two of them, and in late September both were almost full, fed by the abundant summer monsoon rains. The downspout funnels the rainwater that falls on her rooftop into a 1,300-gallon (4,900-litre) plastic cistern in her backyard. "They always clog the little hole where the water goes through," she explains, referring to the opening between the gutters and the downspout. It reads: "This house harvests the rain."Įvery couple of months, 68-year-old Little climbs up a short ladder to clear the leaves from her home's gutters. In front of Val Little's one-story, adobe home near downtown Tucson, in southern Arizona, a small but proud sign stands in the lawn.
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