In LA, there hasn’t been a “Day Zero” just yet. They are, however, only 8 places away in global ranking from achieving that. The birthplace of “Waterworld” and home of its cherished stars might well soon host its own real-life version of a dystopian future. Not only is it 9th globally in water-stress levels, but on the national level, it takes the crown.
Los Angeles imports 85% of its water supply from other parts of the state. It feeds on four aqueducts: the two Los Angeles Aqueducts, the Colorado River Aqueduct, and the State Water Project’s California (West Branch) Aqueduct that brings water from the North over the Tehachapi Mountains and into Southern California. LA also depends on local groundwater from the San Fernando Valley aquifer.
Importing so much of its water is a major issue not only for the reasons that it leaves other regions and ecosystems with less water. LA also depends on groundwater, even when often faced with the challenge of this water’s pollution. Groundwater may only represent 11% of usage on average but during dry season, and even more so in long-lasting droughts, groundwater reliance shoots up. This reliance hides a larger problem: land subsidence. Though LA city itself may be safe from sinking or rising sea-levels, the same is far from true for its outskirts and surrounding areas. The over-drafting of aquifers has, despite the presence of recharge pumps, resulted in worrying rates of subsidence due to the collapse and compaction of subsurface structures.
Sinking land is undesirable because the subsidence damages infrastructure such as the California aqueduct. Sinking land has already reduced its carrying capacity by a full 20%. The Los Angeles Aqueducts have also suffered from the combination of subsidence and uplift.
In addition to problems of supply flows, LA’s supplies are also endangered by heavy agricultural water consumption. California’s sunny climate allows a plethora of water- and sun-intensive crops to be grown. The most abundant crop is alfalfa. Why should anyone care for a simple grain, you ask? At 65%, the colourful grass is responsible for a majority of the land use, and water use with it. It is grown as high quality fodder for the state’s dairy industry. In addition to the impact of the agriculture, domestic consumption, though negligible relative to the former, attains levels between 295 and 510 litres per person (ranging from downtown LA to Beverly Hills, respectively) for domestic use daily. These levels are, independent of agriculture, too large when compared to cities such as Amsterdam, a city with, notably, far less water-scarcity.
Los Angeles, with its 4 million water-hungry residents, is over-dependent on imported water, which it is also condemning by encouraging land subsidence under its various aqueducts.
Bottom line: If Los Angeles does not adjust its consumption of water, management of aquifer use and improve resilience of aqueducts, it will be running head first into a irreversible case of water scarcity.
* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂